Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE: Method of selecting a classification track based on pull
time of a first train block
FIELD OF THE INVENTION
The invention relates to a process for managing
operations in a railroad switchyard. The invention also
encompasses a technological platform and individual
components thereof to implement the process.
BACKGROUND OF THE INVENTION
A railroad network normally contains one or more
switchyards in which cars are routed from tracks leading
from a departure point to tracks going to a destination
point. A
typical switchyard has four main components,
namely receiving tracks, a car switching mechanism, a set
of classification tracks and a set of departure tracks.
Incoming trains deliver cars in the receiving tracks. The
cars are processed by the switching mechanism that routes
individual cars to respective classification tracks.
Two types of switching mechanisms are in use today.
The first one is a hump switch. Switch yards that use a
hump switch are referred to as hump yards. A hump switch
yard uses a hump over which a car is pushed by a
locomotive. At the top of the hump the car is allowed to
roll on the other side of the hump under the effect of
gravity.
Retarders keep the car from reaching excessive
speeds. The hump tracks on which the car rolls down the
hump connect with the classification tracks. A
track
switch establishes a temporary connection between the hump
tracks and a selected one of the classification tracks
such that the car can roll in the classification tracks.
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A departure train is constituted when the requisite number
of cars has been placed in a set of classification tracks.
When the departure train leaves the switchyard, the set of
classification tracks become available for building a new
departure train.
The second type of switch mechanism is a flat switch.
The principle is generally the same as a hump yard except
that instead of using gravity to direct cars to selected
classification tracks, a locomotive is used to push the
car from the receiving tracks to the selected set of
classification tracks.
In order to increase the efficiency of switching
operations railway companies have developed the concept of
car blocking. Under this concept, a block of cars, hence
the name "blocking", may be logically switched as a unit
in a switch yard. A block is established on a basis of
certain properties shared by the cars belonging to the
block. For instance cars that have a common destination
point on their route can be blocked together. A "block"
is therefore a logical entity that helps making switching
decisions. For reference it should be noted that
generally, two types of blocks exist. There
is the so
called "yard block" and a "train block". For clarity, the
term "block" alone in the present specification
encompasses either a yard block or a train block.
The principle of blocking, either yard blocking or
train blocking increases the efficiency with which cars
are processed at switch yards.
However, it also brings
constraints. Very often a train block must be assembled
from cars that arrive on different incoming trains. The
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train block will be complete and available for departure
only when all the cars that make up the train block have
arrived at the switch yard. If one or more of the cars
are delayed the train block cannot be completed and the
entire departing train that pulls this train block may
leave without the train block. Such occurrence may create
a cascading effect throughout entire segments of the
railroad network and have significant financial
repercussions for the railroad operator. Specifically, it
is not uncommon for an operator to guarantee car arrival
times to customers and delays incur financial penalties
that may be significant.
Against this background, it can be seen that a need
exists in the industry to develop more refined processes
to manage operations in a switch yard such as to increase
the efficiency with which cars are switched.
SUMMARY OF THE INVENTION
As embodied and broadly described herein the
invention provides system for computing car switching
solutions in a railway switch yard, the system
comprising:
a) an input for receiving:
i) first data
conveying information about one or
more arrival trains arriving at the switch yard,
an arrival train including a plurality of cars;
ii) second data conveying information about
departure trains to depart the switch yard;
b) a processing entity for processing the first and
second data and compute car switching solutions for
the cars;
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c) an output for releasing third data conveying the car
switching solutions.
As embodied and broadly described herein, the
invention provides a method for computing car switching
solutions in a railway switch yard, the method
comprising:
a) receiving at an input of a computing apparatus:
i) first data conveying information about one or
more arrival trains arriving at the switch yard,
an arrival train including a plurality of cars;
ii) second data conveying information about
departure trains to depart the switch yard;
b)processing with the computing apparatus the first
and second data and computing car switching
solutions for the cars;
c) releasing third data conveying the car switching
solutions.
As embodied and broadly described herein, the
invention also provides computing car switching solutions
in a railway switch yard containing a plurality of cars,
the system Comprising;
a) a processing entity for:
i) computing an expected switch time for each car;
ii) utilizing the computed expected switch time to
compute a car switching solutions for each car;
b) an output for releasing data conveying the car
switching solutions.
As embodied and broadly described herein the
invention also provides method for computing car
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switching solutions in a railway switch yard containing a
plurality of cars, the method including;
a) computing an expected switch time for each car;
b) utilizing the computed expected switch time to
compute a car switching solutions for each car;
c) releasing at an output data conveying the car
switching solutions.
As embodied and broadly described herein, the
invention also provides system for computing car
switching solutions in a railway switch yard containing a
plurality of cars in a switching queue to be sequentially
switched to respective classification tracks, the system
comprising;
a) a processing entity for iteratively computing
switching solutions for each car as the car
progresses through the switching queue;
b) an output for releasing data conveying at least one
of the car switching solutions computed by the
processing entity.
As embodied and broadly described herein the
invention also provides a method for computing car
switching solutions in a railway switch yard containing a
plurality of cars in a switching queue to be sequentially
switched to respective classification tracks, the method
comprising;
c) iteratively computing switching solutions for each
car as the car progresses through the switching
queue;
d) releasing data at an output for conveying at least
one of the car switching solutions.
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As embodied and broadly described herein the
invention also provides a system for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks, comprising:
a) an input for receiving first data conveying
information about an ETA of a car at the switch
yard;
b) a processing entity for processing the first data
and compute a car switching solution by using as a
factor the ETA of the car.
As embodied and broadly described herein the
invention also includes a method for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks, comprising:
a) receiving at an input first data conveying
information about an ETA of a car at the switch
yard;
b)processing the first data and computing a car
switching solution by using as a factor the ETA of
the car.
As embodied and broadly described herein the
invention also includes a system for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks, comprising:
a) an input for receiving:
i) first data conveying information about one or
more arrival trains arriving at the switch yard,
an arrival train including a plurality of cars;
ii) second data conveying information about two or
more departure trains to depart the switch yard;
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b) a processing entity for processing the first data
and the second data to compute car switching
solutions concurrently locating a first set of cars
and a second set of cars in a common classification
track, wherein the first and second sets of cars
belong to train blocks of different departure
trains.
As embodied and broadly described herein the
invention also provides a system for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks, comprising:
a) an input for receiving:
i) first data conveying information about one or
more arrival trains arriving at the switch yard,
an arrival train including a plurality of cars;
ii) second data conveying information about two or
more departure trains to depart the switch yard;
b) a processing entity for processing the first data
and the second data to compute car switching
solutions concurrently locating a first set of cars
and a second set of cars in a common classification
track, wherein the first and second sets of cars
belong to train blocks of different departure trains
As embodied and broadly described herein the
invention also provides a system for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks wherein a first
classification track holds a first train block, the
system comprising:
a) an input for receiving data conveying information
related to a pull time of the first train block;
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b) a processing entity for determining if space exists
in the first classification track to receive cars
that belong to a second train block, by using as a
factor the information related to the pull time of
the first train block.
As embodied and broadly described herein the
invention also provides a method for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks wherein a first
classification track holds a first train block, the
method comprising:
a) receiving at an input data conveying information
related to a pull time of the first train block;
b) determining with a computing apparatus if space
exists in the first classification track to receive
cars that belong to a second train block, by using
as a factor the information related to the pull time
of the first train block.
As embodied and broadly described herein the
invention also provides a system for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks wherein a first
classification track holds a first train block, the
system comprising:
a) an input for receiving data conveying information
related to an arrival profile of a second train
block;
b) a processing entity for determining if space exists
in the first classification track to receive cars
that belong to the second train block, by using as a
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factor the information related to the arrival
profile of the second train block.
As embodied and broadly described herein the
invention also includes method
for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks wherein a first
classification track holds a first train block, the
method comprising:
a) receiving at an input data conveying information
related to an arrival profile of the first train
block;
b) determining with a computing apparatus if space
exists in the first classification track to receive
cars that belong to a second train block, by using
as a factor the information related to the arrival
profile of the first train block.
As embodied and broadly described herein, the
invention also provides a system for computing car
switching solutions in a railway switch yard containing a
switch, a plurality of classification tracks and a
reswitching track, the system comprising:
a) an input for receiving first data conveying
information about a rate of arrival of cars at the
switch, wherein the cars belong to a given train
block;
b) a processing entity for computing a car switching
solution for one or more cars of the given train
block, wherein a computation of a car switching
solution includes a selection of at least one car
switching option among a set of car switching
options, one car switching option of the set
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including switching the car of the given train block
to a classification track and another car switching
option of the set including switching the car of the
given train block to the reswitching track, wherein
the processing entity uses as a factor the
information about the rate of arrival of cars at the
switch in selecting between a car switching option
to switch the car to a classification track and a
car switching option to switch the car to the
reswitching track;
c) an output for releasing second data conveying the
car switching option selected by said processing
entity.
As embodied and broadly described herein the
invention also provides a system for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks wherein a first
classification track holds a first train block and a
second classification track holds a second train block,
the system comprising:
a) a processing entity for:
i) computing available space in the first
classification track for receiving cars from a
third train block that is different from the
first and second train blocks;
ii) computing available space in the second
classification track for receiving cars from the
third train block;
iii) selecting among the first and
second
classification tracks at least in part on the
basis of the computing of available space;
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iv) computing switching solutions for cars of the
third block on the basis of the selecting;
b) an output for releasing data conveying one or more
of the car switching solutions.
As embodied and broadly described herein the
invention also provides a method for computing car
switching solutions in a railway switch yard containing a
switch, a plurality of classification tracks and a
W reswitching track, said method comprising:
a)receiving at an input first data conveying
information about a rate of arrival of cars at
the switch, wherein the cars belong to a given
train block;
b)computing with a computing entity a car
switching solution for one or more cars of the
given train block, wherein a computation of a
car switching solution includes a selection of
at least one car switching option among a set
of car switching options, one car switching
option of the set including switching the car
of the given train block to a classification
track and another car switching option of the
set including switching the car of the given
train block to the reswitching track, wherein
said computing uses as a factor the information
about the rate of arrival of cars at the switch
in selecting between a car switching option to
switch the car to a classification track and a
car switching option to switch the car to the
reswitching track;
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c)releasing at an output second data conveying
the car switching option selected on a basis of
said computing.
As embodied and broadly described herein the
invention also includes a method for computing car
switching solutions in a railway switch yard containing a
plurality of classification tracks wherein a first
classification track holds a first train block and a
second classification track holds a second train block,
the method comprising:
a) computing with a computing entity an available space
in the first classification track for receiving cars
from a third train block that is different from the
first and second train blocks;
i) computing with the computing entity available
space in the second classification track for
receiving cars from the third train block;
ii) selecting among the first and second
classification tracks at least in part on the
basis of the computing of available space;
iii) computing switching solutions for cars of the
third block on the basis of the selecting;
b) an output for releasing data conveying one or more
of the car switching solutions.
As embodied and broadly described herein the
invention provides a system for computing car switching
solutions in a railway switch yard containing a switch, a
plurality of classification tracks and a reswitching
track, the system comprising:
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a) an input for receiving first data conveying
information about a size a given train block to be
assembled at the switch yard;
b) a processing entity for computing a switching
solution for one or more cars of the given train
block, wherein a computation of a switching solution
includes a selection of at least one switching
option among a set of switching options, one
switching option of the set including switching the
car of the given train block to a classification
track and another switching option of the set
including switching the car of the given train block
to the reswitching track, wherein the processing
entity uses as a factor the information about the
size of the given train block in selecting between a
switching option to switch the car to a
classification track and a switching option to
switch the car to the reswitching track;
c) an output for releasing second data conveying the
switching option selected by said processing entity.
As embodied and broadly described herein the
invention also provides a method for computing car
switching solutions in a railway switch yard containing a
switch, a plurality of classification tracks and a
reswitching track, the method comprising:
a)receiving at an input first data conveying
information about a size of the given train
block to be assembled by the switch yard;
b)computing with a computing entity a car
switching solution for one or more cars of the
given train block, wherein a computation of a
car switching solution includes a selection of
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at least one car switching option among a set
of car switching options, one car switching
option of the set including switching the car
of the given train block to a classification
track and another car switching option of the
set including switching the car of the given
train block to the reswitching track, wherein
said computing uses as a factor the information
about the size of the given train block in
selecting between a car switching option to
switch the car to a classification track and a
car switching option to switch the car to the
reswitching track;
c)releasing at an output second data conveying
the car switching option selected on a basis of
said computing.
As embodied and broadly described herein the
invention provides a system for computing car switching
solutions in a railway switch yard containing a switch, a
plurality of classification tracks and a reswitching
track, the system comprising:
a) an input for receiving first data conveying
information about a pull time of a given train block
to be assembled at the switch yard;
b) a processing entity for computing a switching
solution for one or more cars of the given train
block, wherein a computation of a switching solution
includes a selection of at least one switching
option among a set of switching options, one
switching option of the set including switching the
car of the given train block to a classification
track and another switching option of the set
including switching the car of the given train block
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to the reswitching track, wherein the processing
entity uses as a factor the information about the
pull time of the given train block in selecting
between a switching option to switch the car to a
classification track and a switching option to
switch the car to the reswitching track;
c) an output for releasing second data conveying the
switching option selected by said processing entity.
As embodied and broadly described herein the
invention also provides a method for computing car
switching solutions in a railway switch yard containing a
switch, a plurality of classification tracks and a
reswitching track, the method comprising:
a) receiving at an input first data conveying
information about a pull time of a given train block
to be assembled at the switch yard;
b) computing with a computing entity a car switching
solution for one or more cars of the given train
block, wherein a computation of a car switching
solution includes a selection of at least one car
switching option among a set of car switching
options, one car switching option of the set
including switching the car of the given train block
to a classification track and another car switching
option of the set including switching the car of the
given train block to the reswitching track, wherein
said computing uses as a factor the information
about the pull time of the given train block in
selecting between a car switching option to switch
the car to a classification track and a car
switching option to switch the car to the
reswitching track;
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c) releasing at an output second data conveying the car
switching option selected on a basis of said
computing.
As embodied and broadly described herein the
invention provides a system for computing car switching
solutions in a railway switch yard containing a set of
classification tracks, the set of classification tracks
including a first classification track that is empty and
a second classification track containing cars that belong
to a first train block, the system comprising:
a) a processing entity for computing car switching
solutions for cars associated with a second train
block different from the first train block, said
processing entity assigning different orders of
preference in searching for available space for cars
that belong to the second train block, to the first
and second classification tracks;
b) an output for releasing data conveying car switching
solutions computed by said processing entity.
As embodied and broadly described herein the
invention also provides a method for computing car
switching solutions in a railway switch yard containing a
set of classification tracks, the set of classification
tracks including a first classification track that is
empty and a second classification track containing cars
that belong to a first train block, the method
comprising:
a) computing with a computing entity car switching
solutions for cars associated with a second train
block different from the first train block, said
computing assigning different orders of preference
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in searching for available space for cars that
belong to the second train block, to the first and
second classification tracks;
b) releasing at an output data conveying car switching
solutions computed by said computing entity.
As embodied and broadly described herein the
invention also provides a system for computing car
switching solutions in a railway switch yard that has a
switching queue, a switch and a plurality of
classification tracks, said switching queue holding a
plurality of empty cars, the system comprising:
a) an input for receiving:
i) first data conveying information about one or
more arrival trains arriving at the switch yard,
an arrival train including a plurality of cars;
ii) second data conveying information about
departure trains to depart the switch yard, one
of the departure trains including a particular
empty car;
b) a processing entity for computing car switching
solutions to assemble the departure trains, the car
switching solutions being such as to substitute an
empty car from the plurality of empty cars to the
particular empty car;
c) an output for releasing data conveying the car
switching solutions.
As embodied and broadly described herein the
invention also provides a method for computing car
switching solutions in a railway switch yard that has a
switching queue, a switch and a plurality of
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classification tracks, the switching queue holding a
plurality of empty cars, said method comprising:
a) Receiving and an input:
i) first data conveying information about one or
more arrival trains arriving at the switch yard,
an arrival train including a plurality of cars;
ii) second data conveying information about
departure trains to depart the switch yard, one
of the departure trains including a particular
empty car;
b) computing car switching solutions to assemble the
departure trains, the car switching solutions being
such as to substitute an empty car from the
plurality of empty cars to the particular empty car;
c) releasing at an output data conveying the car
switching solutions.
As embodied and broadly described herein the
invention also provides A method for computing car
switching solutions in a railway switch yard containing a
plurality of cars, said method including:
a)computing with a computer arrangement an expected
switch time for one or more of the plurality of
cars;
b)utilizing the computed expected switch time to
compute a car switching solution for the one or more
cars;
c)releasing at an output of the computer arrangement
data conveying the car switching solutions, wherein
the railway switch yard has a plurality of
classification tracks, wherein a first
classification track of the
plurality of
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classification tracks is capable of receiving a
first train block, wherein said method includes
determining with the computer arrangement if space
exists in the first classification track to receive
cars that belong to a second train block, by using
as a factor information related to a pull time of
the first train block.
BRIEF DESCRIPTION OF THE DRAWINGS
A detailed description of examples of implementation
of the present invention is provided hereinbelow with
reference to the following drawings, in which:
Figure 1 is a schematical illustration of a hump
switch yard;
Figure 2 is a high level block diagram of a prior
art computer based switch yard management system;
Figure 3 is a high level block diagram of a computer
based switch yard management system according to a non-
limiting example of implementation of the invention;
Figure 4 is a more detailed block diagram of the
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system shown in Figure 3;
Figure 5 is a graph illustrating the process of
allocating two separate train blocks of cars to a single
classification track;
Figure 6 is a flowchart illustrating an iterative
process for computing car switching solutions according
to a non-limiting example of implementation of the
invention;
Figures 7 and 8 are more detailed flow charts of the
general process illustrated in Figure 6;
Figure 9 is a flowchart illustrating a logical
process for selecting an occupied a classification track
in which to switch a car;
Figure 10 is a flowchart illustrating a logical
process for determining if a car should be rehumped based
on small train block size;
Figure 11 is a flowchart illustrating a logical
process for determining if a car should be rehumped based
on arrival rate;
Figure 12 is a flowchart illustrating a logical
process for selecting a classification track to receive
only a portion of a train block;
Figures 13 and 14 illustrate logical processes for
performing empty car substitution.
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In the drawings, embodiments of the invention are
illustrated by way of example. It is
to be expressly
understood that the description and drawings are only for
purposes of illustration and as an aid to understanding,
and are not intended to be a definition of the limits of
the invention.
DETAILED DESCRIPTION
Figure 1 is an illustration of a hump switching yard
in which the management process of the invention can be
implemented. The hump switching yard 10 has four main
components namely receiving tracks 12, a hump 14,
classification tracks 16 and departure tracks 17. The
receiving tracks 12 include railway sections in which an
incoming train delivers cars to be switched.
The receiving tracks 12 lead to the hump 14. The
hump 14 includes a set of tracks 20 that lead to the hump
crest 18 that is the highest elevation of the hump 14.
Cars are pushed by a locomotive on the tracks 20 up to
the hump crest 18 at which point the car rolls down the
hump 14 by gravity toward the set of classification
tracks 16. The car passes through retarders 22 that will
reduce its speed allowing it to gently coast in anyone of
the selected classification tracks 16. A
track switch
24, located downstream the retarders 22 temporarily
connects the hump track 12 to a selected one of the
classification tracks 16 such as to direct the car to the
desired classification track 16.
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The receiving tracks 12, therefore, form a switching
queue in which cars that are delivered to the switching
yard 10, await to be switched.
The classification tracks 16 lead to the departure
tracks 17.
Specifically, the classification tracks are
arranged into groups, where each group leads to a
departure track 17. The hump switch yard 10 shown in the
drawings includes 10 classification tracks organized into
two groups of five tracks. Each
group of five tracks
connects to the departure track 17.
Generally, the classification tracks 16 are used to
assemble train blocks. Train
blocks are pulled out of
the classification tracks into the departure tracks 17
where the actual departure train is built. The departure
tracks 17 allow assembling trains having more cars than a
single classification track can hold. When a complete
train (short train) is assembled into a single
classification track 16, the departure train leaves that
track directly by passing through the departure track 17.
It should be appreciated that Figure 1 is a very
simplified illustration of a hump switch yard in that the
number of tracks shown has been significantly reduced for
clarity purposes. An
average size hump yard typically
contains many more classification tracks than what is
shown in Figure 1. For example it would not be uncommon
for a switchyard to have 80 or more classification tracks
organized into physical groups of tracks, where each
group connects to a departure track. In addition, there
will normally be a larger number of departure tracks 17
than what appears on the drawing.
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The hump switch yard 10 also includes a reswitching
track that allows to "recirculate" cars from a position
downstream the switch 24 to a position upstream the
switch 24. In a
typical hump switch yard, such as the
yard 10 the reswitching track is called "rehump track".
The rehump track is shown at 26 in Figure 1. The rehump
track 26 originates downstream the track switch 24 and
lead to the hump tracks 20 at the base of the hump 20.
The purpose of the rehump tracks 26 is to provide a
buffering mechanism where one or more cars can be
temporarily put in storage without blocking the flow of
other cars through the hump switch yard 10. For
instance, situations may arise where one or more cars in
the receiving tracks 12 cannot be switched in any one of
the classification tracks 16. This
may be due, for
example to the lack of space availability in the
classification tracks 16. It is
common practice for a
hump switch yard 10 to periodically hump the cars in the
rehump tracks 26. Such
rehumping involves pushing the
cars over the hump 20 such that they can be switched to a
selected classification track 16. If a
car cannot be
routed to any one of the classification tracks 16 it is
put back in the rehump tracks 26 for a new humping cycle.
The following description of a non-limiting example
of implementation of a switch yard management process
will be done in connection with a hump switch yard 10 of
the type described earlier.
However, it should be
expressly noted that the principles of the invention
apply equally well to a flat switch yard. Accordingly,
the invention should not be limited to a hump switch yard
but encompasses a flat switch yard as well. A flat switch
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yard operates generally in the same way as described
earlier in that incoming trains deliver cars at the input
side of the flat switch yard, a switching device routes
the individual cars to classification tracks to assemble
departure trains in departure tracks.
Figure 2 illustrates a block diagram of a prior art
control system 28 for use in managing the operations of a
hump switch yard 10. Specifically, the control system 28
includes two main components, namely the Service
Reliability System (SRS) component 30 and the Hump
Process Control System (HPCS) 32. The SRS component 30
is in essence a railway traffic management system that
keeps track of the rolling stock inventory throughout the
network. It is used to manage the flow of railway traffic
over a complete railway network or a portion thereof.
The SRS component 30 is a computer based system that
reflects the railway operations by showing information on
trains, schedules, waybills, trip plans and train delays.
The SRS component 30 has a number of sub-systems that are
integrated to one another. Some
of the sub-components
are briefly described below:
= Waybill - a computer file that provides details and
instructions on the movement of cars. Cars and
units cannot move without a waybill;
= Service Scheduling - the service scheduling sub-
component is based on a trip plan that specifies the
events a shipment must follow from origin to
destination. A
trip plan identifies the train
connections for each car and provides a destination
Estimated Time of Arrival (ETA). The
service
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scheduling sub-component continuously monitors the
movement of each shipment and compares its progress
to the trip plan. If
the service scheduling
determines that a shipment will not meet the
established requirements, it triggers alarms;
= Yard Operating Plan/Daily Operating Plan (YOP/DOP) -
the YOP sub-component defines how assets (crews,
cars, locomotives and tracks) are allocated to
support yard related activities. The DOP is derived
from the YOP and contains instructions for
industrial assignments;
= Yard, Industry and Train (YIT) - the YIT sub-
component allows users to report train and car
movements such as train arrivals and departures,
yard switches, exchange of cars with other
railroads, and the placing and pulling of cars at a
customer sidings.
= Intermodal - this sub-component includes functions
for gating-in, gating-out, assigning, ramping, de-
ramping as well as maintaining inventories of
Intermodal equipment.
The SRS component 30 includes a processing function
that is illustrated as a single block, but it can be
implemented also in a distributed fashion.
It should be expressly noted that the SRS component
30 is merely an example of a railway traffic management
system and other railway traffic management systems can
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be used without departing from the spirit of the
invention.
The HPCS component 32 operates the track switch in
the hump switch yard 10. Essentially, the HPCS component
32 is a car switch control system that determines on the
basis of inputs the position of the track switch 24 such
that a car or a series of cars over the hump, will be
directed to the desired classification track 16. Broadly
stated, the HPCS component 32 has two main goals, namely:
= Deliver the cars to the correct classification track
16;
= Insure that the cars will arrive in the
classification track 16 fast enough to reach the
cars already in the track but slow enough for a safe
coupling (or reach the far end of the track if it is
empty);
As in the case with the SRS component 30, the HPCS
component 32 is illustrated as a single block but it can
be implemented in a distributed fashion.
It should be expressly noted that the HPCS component
32 is merely an example of a car switch control system
and other car switch control systems can be used without
departing from the spirit of the invention.
As shown by Figure 2 a human intervention 34 is
required to interface the SRS component 30 and the HPCS
component 32. Specifically, the SRS component identifies
the trains that are scheduled to arrive at the hump
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switch yard 10 and the trains that are scheduled to
depart the hump switch yard 10. On
the basis of this
information a hump list is manually produced. The hump
list determines in which classification track the various
cars will go. The hump list is then loaded into the HPCS
component 32. The HPCS component 32 performs the
switching as the cars are humped, according to the
specific switching instructions in the hump list.
In order to simplify the car switching logic, it is
customary to assign classification tracks 16 to
destinations. For
instance there is the "Edmonton"
classification track, the "Montreal" classification
track, etc. Cars that go to Edmonton are switched to the
Edmonton classification track, cars that go to Montreal
are switched to the Montreal track, etc.
Note the communication link 35 between the HPCS
component 32 and the SRS component 30. This
link 35
illustrates the exchange of data between the two
components, for instance the HPCS component 32 notifying
the SRS component 30 of events or conditions occurring in
the hump switch yard 10.
Figure 3 is a block diagram of control system 44 for
use in managing the operations of the hump switch yard
10, according to a non-limiting example of implementation
of the invention. The control system 44 includes three
main components two of which are shared with the prior
art control system 28 described earlier.
Specifically,
the control system 44 includes the SRS component 30, the
HPCS component 32 and a Dynamic Track Allocation (DTA)
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controller 46. The DTA controller 46 is responsible for
allocation of cars to the classification tracks 16.
Figure 4 is a block diagram of the DTA controller
46, showing the relationships with the SRS component 30
and the HPCS component 32. The DTA controller 46 has a
computing platform including a processor 47 that
communicates with a machine readable storage unit 49,
commonly referred to as "memory" over a data bus. Inputs
and outputs (I/O interface) 51 allow the DTA controller
46 to receive and send data to the SRS component 30 and
the HPCS controller 32, via the SRS component 30. In
addition, the I/O 51 communicates with a user interface
53 that allows the DTA controller 46 to communicate
information to the yard master and receive commands or
other inputs from the yard master. In essence, the user
interface 53 shows the yard master the switching
solutions that the DTA controller 46 is developing.
Those switching solutions can be implemented either
automatically, i.e. pending an input from the yard master
that stops the process, the proposed switching solutions
are executed, or they may require explicit conformation
from the yard master. For
instance unless the yard
master inputs at the user interface 53 a command to
explicitly implement or authorize the switching solution
presented by the DTA controller 46 on the user interface
53, no action is taken by the system.
Note that while the diagram at Figure 4 depicts the
DTA controller 46 as a single unit, it can also have a
distributed architecture without departing from the
spirit of the invention.
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The functionality of the DTA controller 46 is
software defined. In
other words, the logic that
determines how cars are to be switched is implemented by
executing software by the processor 47. The software in
the form of program code is stored in the memory 49. The
software reads data inputs received from the SRS
component 30, and from the user interface 53. On
the
basis of those inputs, the DTA controller 46 generates
outputs to the user interface 53. The output to the user
interface 53 is intended to display information to inform
the yard master on the switching solutions the DTA
controller 46 has reached. Optionally, an output may also
be directed to the HPCS component 32, which contains
switching commands that determine the positions of the
track switch 24 and effectively implement the switching
solutions developed by the DTA controller 46.
It should be expressly noted that the present
invention does not absolutely require the generation of
control signals to the HPCS controller 32. While
this
option is considered advantageous, variants can be
envisaged where there is in fact, no direct command given
by the DTA controller 46 to the HPCS component 32. For
instance, the DTA controller 46 can compute switching
solutions that are presented to the yard master or
another operator and manually implemented or manually
authorized.
As indicated earlier, the DTA controller 46
determines how the hump switch yard 10 will allocate cars
in the classification tracks 16. This
is done on the
basis of various parameters that will be discussed below.
In addition, the DTA controller 46 is provided with some
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degree of flexibility in determining the make up of train
blocks such as, for example, collapse train blocks when
it is not appropriate to continue assembling them or
splitting big train blocks into smaller ones in order to
make better use of existing space in classification
tracks 16. Another feature of the DTA controller 46
logic is allowing a dynamic car re-distribution. This is
particularly suitable for empty cars that need to be
delivered by the railroad operator to the customer or car
owner.
In the example illustrated in Figure 4, the DTA
controller 46 logically resides between the SRS component
30 and the HPCS component 32. As such the DTA controller
46 receives information from the SRS component 30 about:
= Incoming trains (trains to be received in the hump
switch yard 10), in particular:
o Identification of the train (Train ID)
o The Expected Time of Arrival (ETA);
o Point of origin;
o Destination;
o Identification of the train blocks that make up
the train;
o The number of cars in each train block;
o The identification of each car (car ID);
o The destination of the car;
o The route of the car;
o If the car carries cargo, the type of cargo; and
o If the car is empty the customer that has
requested the car to be moved.
= Departure trains (trains the switch yard 10 is
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expected to assemble);
o Identification of the train (Train ID)
o The Expected Time of Departure (ETD);
o Identification of the train blocks that make up
the train;
o The number of cars in each train block;
o The identification of each car (car ID);
o The destination of the car;
o The route of the car;
o If the car carries cargo, the type of cargo; and
o If the car is empty, the customer that has
requested the car to be moved.
In order to make classification track assignments to
individual cars, the DTA controller 46 creates
representations in the memory 49 of the rolling stock
that transits through the hump switch yard 10 by using
hierarchal objects. Generally, three types of objects
exist:
= A train object. A train object is associated with
each train (arrival train or departure train) and it
has properties such as:
o A train identifier (train ID);
o Expected time of arrival (ETA);
o Origin;
o Destination;
o Route; and
o Identification of train blocks that make up the
train.
= A train block object. A train block object is
associated with a block of cars and has the
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following properties:
o A train block identifier (train block ID);
o Number of cars making up the train block;
o Identity of the cars making up the train block;
o Destination of the train block; and
o Route of the train block from the origin to the
destination.
= A yard block object. A yard block object is
associated with a block of cars and has the
following properties:
o A yard block identifier (yard block ID);
o Number of cars making up the yard block;
o Identity of the cars making up the yard block;
o Origin of the yard block;
o Destination of the yard block; and
o Route of the yard block from the origin to the
destination.
= Car objects. A car object is associated with a
single car and has the following properties:
o Car identifier (car ID);
o Car owner;
o If car carries cargo the type of cargo;
o If car is empty the customer identifier that has
requested the car to be moved;
o Origin;
o Destination; and
o Route between origin and destination.
Normally, train objects that represent incoming
trains will cease to exist when the train arrives at the
hump switch yard 10 since the train is dismantled. An
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exception to this is a situation where the incoming train
transits through the hump switch yard 10 in which case it
remains intact.
Departing trains are represented by
train objects that begin their existence at the hump
switch yard 10, having been assembled from cars that
originate from one or more dismantled incoming trains.
Incoming train block objects may cease to exist if the
train block is disassembled and the individual cars are
used to make up other train block objects. For example a
train block arriving at the hump switch yard 10 may
contain cars having different destinations. For the sake
of this example, say that half of the cars need to be
delivered to city A while the other half to city B. In
such case the train block is disassembled and the cars
that go to city A are switched to form alone or in
combination with other cars from a different train a new
train block that will travel to city A. The
cars
directed to city B are switched in a similar manner. In
this situation, two new train blocks are created at the
hump switch yard 10, from one or more incoming train
blocks.
Another possibility is for train blocks to be
modified, instead of ceasing to exist or beginning to
exist. A train block can be modified by augmenting the
train block, such as by adding to it one or more cars or
diminished by removing from it one or more cars.
Finally, a train block may remain unchanged such as when
it simply transits through the hump switch yard 10. In
such case, the train block is physically dismantled into
individual cars but the switching operation is conducted
such as to reassemble the original train block.
Alternatively, the train block can be routed directly to
the departure tracks 17 such as to circumvent the switch
24.
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As far as individual car objects, they remain
unchanged as they transit through the hump switch yard
10.
The DTA controller 46 receives from the SRS
component 30 data that describes the incoming trains so
that the DTA controller 46 can determine the details of
the rolling stock to be processed. The DTA controller 46
also receives information on the departure trains that
the hump switch yard 10 is expected to assemble.
In a specific example of implementation, the DTA
controller 46 receives form the SRS component 30 the
following information:
= The trains scheduled to arrive to the hump switch
yard 10. The SRS component 30 simply provides the
identity of the train (the train ID);
= The trains that the SRS system expects the hump
switch yard to make. The
SRS component simply
provides the identity of the train (train ID).
Once the DTA controller 46 is made aware of incoming
trains and the requirement to build departure trains, the
train ID information allows the DTA controller 46 to
determine all the necessary information down to the
individual car. More particularly, the train ID allows
determining the properties of the train object and the
properties of the train block objects derived via the
train object and the properties of the car objects
derived via the train block objects. This data will then
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allow the DTA controller 46 to compute switching
solutions.
It should be expressly noted that the above
description of the manner in which information is
provided to the DTA controller 46 is strictly an example
and should not be constructed in any limiting manner.
Many different ways to deliver information to the DTA
controller 46 exist that allow characterizing the
incoming trains and the departing trains without
departing from the spirit of the invention.
The various functions and features of the DTA
controller 46 according to a non-limiting example of
implementation will be described below in conjunction
with the process flowchart in Figures 6 and 7. The
flowcharts include a decision tree that allows the DTA
controller 46 to find car switching solutions based on
specific cases. It is to be expressly noted that the
following description is provided only as an example of
the operation of the DTA controller 46 and should not be
used in a manner to limit the scope of the present
invention.
Generally speaking, the DTA controller 46 implements
an iterative process that periodically computes car
switching solutions. Those
solutions are of temporary
nature in the sense that they are re-computed at each
iteration cycle. The
switching solution is frozen in
time when the car is committed for switching. A car that
is being pushed over the hump up to the hump crest 18 is
considered committed for switching. Generally, a car is
"committed for switching" when it is close enough to the
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switch 24 such that the condition of the hump switch yard
10, in other words the parameters that determine or
influence the switching solution computed by they DTA
controller 46 are unlikely to change significantly until
the actual switching event occurs. In
other words, the
latest switching solution in existence when the car has
reached a position in the hump switch yard 10 where it is
"committed for switching" is likely to remain valid until
the car is actually switched since the events and
W conditions in the hump switch yard 10 are unlikely to
change in an appreciable manner during the time frame the
car transits from the position "committed for switching"
to the switch 24.
The flowchart on Figure 6 illustrates generally the
iteration cycle. The process enters the decision block
600 where the DTA controller 46 determines if the car is
committed for switching. In
the affirmative, the
previous solution (the flowchart assumes that a previous
solution has been computed) is maintained. In such case,
this solution can be presented to the yard master of the
hump switch yard 10 as being the final solution.
If the car is not yet committed for switching, the
process continues to step 602 which computes a switching
solution which is either an updated solution or a first
solution for this car. The solution is stored by the DTA
controller 46 and will be used as a final solution if,
during the next iteration cycle, the car is found to be
committed for switching. The process then loops back to
decision step 600 and it is thus continuously repeated.
When the switching solution computation step 602 is
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invoked it will process information to select a
classification track 16 for each car or block of cars to
be humped. Cars
are humped in a given sequence which
typically is the sequence in which they arrive at the
hump switch yard 10. In
general, the track assignment
logic that is implemented by the switching solution
computation step 602 has the following characteristics.
It is to be expressly noted that the characteristics
discussed below are not to be considered limiting as they
W may change without departing from the spirit of the
invention. In
particular, a system that omits a
particular characteristic, uses an altered characteristic
or implements a new characteristic should not be
considered outside the scope of the invention:
1. Expected switch time in computing switching
decisions.
The switching solution computation step 602
uses as a basis for finding a switching
solution for a given car, the expected switch
time for that car. This roughly represents the
time at which the switching solution
computation step 602 expects the car to be
switched. The
switching solution will vary
with the events and conditions of the hump
switch yard 10 at the expected switch time.
For example, if the expected switch time is
prior the time the train is scheduled to depart
then the switching solution will attempt
putting the car in a classification track such
that it can be made part of the train. On the
other hand, if the switch time is after the
departure time of the train then it will be
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plain that different options need to be
considered since that particular train is no
longer available.
The expected switch time is an approximation
that takes into account one or more factors, as
it will be discussed later in connection with a
specific example.
2. Dynamic classification track assignment
Switching solution computation step 602
dynamically assigns classification tracks to
train blocks. By "dynamic" is meant that the
classification tracks are not constrained to
certain destinations or trip plans. In other
words, at some point a classification track may
be assigned to train block that goes to
destination A and sometime after the train
block is completed or pulled, the same
classification track is assigned to a train
block that goes to destination B. A
consequence of the dynamic classification track
assignment is that a classification track may
contain two or more blocks having different
destinations, in other words they are
associated with different departure trains. In
this example, the train blocks are in order of
their time of departure. The
train block
farther from the hump 16 departs before or at
the same time as the train block closer to the
hump 16. Figure 5 shows this characteristic in
greater detail. The
graph shows a single
classification track having a total of 50 cars
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capacity and the number of cars that are
assigned to the classification tracks at
different times.
Initially, only cars that
belong to train block A are being assigned to
the classification tracks. Train block A is
closed at 9:30. The
closure occurs either
because the train block is complete (all the
cars that originally form part of the train
block have arrived on time and are delivered to
the classification track) or closed prematurely
by the DTA controller 46. At about 9:30 cars
from train block B are delivered to the
classification tracks. At 12:30 train block A
is pulled out of the classification tracks and
only cars from train block B remain. This
example illustrates a situation where cars that
belong to different train blocs simultaneously
reside in the same set of classification
tracks. By adequately controlling when the
first train block (the one farthest from the
hump 16) closes and the respective pull times
of the train blocks (the train block farthest
from the hump 16 is pulled at an earlier time
than the train block closest to the hump 16),
the process can be adequately managed without
creating a conflict such that a car or a train
block in the classification tracks is prevented
from being pulled out by a car or a train block
of cars having a latter pull time.
In the above example, train blocks A and B are
part of a different train.
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3. Car arrival time considerations
When determining if available space exists in a
given classification track the DTA controller
46 will take into account the arrival times
(ETA) of the various cars in the hump switch
yard 10.
4. Pull time considerations
When determining if available space exists in a
given classification track the DTA controller
46 will take into account the time at which one
or more of the cars that are presently switched
in the classification track or scheduled to be
switched therein will be pulled to make up
space.
5. Multiple classification track assignment modes.
Optionally, the DTA controller 46 has the
capability to accept static assignments in
connection with one or more of the
classification tracks 16. A static assignment
can be maintained permanently or semi-
permanently and it associates the
classification track 16 with a departure train
having a given destination. Such static
assignments, if used, would normally be
programmed in the DTA controller 46 in a manner
to allow the switching solution computation
step 602 to take this factor into account when
computing switching solutions. The static
assignments can be specified to the DTA
controller 46 via the user interface 53 by the
yard master. For example, the yard master of
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the hump switch yard 10 may decide that one or
more specific classification tracks will be
dedicated for the next 12 hours to cars on the
train going to Toronto. Via suitable inputs on
the user interface 53 the track identifier(s)
is entered and the destination associated with
that track(s) as well or any other suitable
parameter. When
the switching solution
computation step 602 sees a car to be switched
that is directed to a destination other than
Toronto, it automatically discounts the
statically assigned classification track(s).
On the other hand, should a car present itself
that goes on the Toronto train, then the
switching solution computation step 602 will
consider the statically assigned classification
track(s) for that car. The
system can be
designed to handle static assignments in a
rigid manner such as for instance, direct cars
that go to a destination to which one or more
classification tracks 16 are statically
assigned only to those classification tracks.
Another option is to use some degree of
flexibility in that the static classification
tracks are considered first and if no space is
available, then the cars are allowed to use a
classification track having a dynamic
assignment. The
static assignment can be
removed in the same fashion as it was applied,
namely through the user interface 53.
The DTA controller 46 holds in its machine
readable storage media a representation of the
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status of each classification track 16. This
may be in the form of any suitable machine
readable file stored in the memory 49 (shown at
Figure 4). The
file contains the identifiers
of the various classification tracks and a
reference for each classification track as to
whether it is to be used for dynamic assignment
or for a static assignment. When
used for a
static assignment the file may also specify
certain characteristics such as the destination
the classification track is to be assigned to,
and any other parameter that may be useful.
Another such parameter is the time frame during
which the static assignment is maintained. In
such instance, the yard master enters the end
points of the time frame during which the
static assignment is to be maintained along
with any other suitable parameters. The
end
points would normally be the beginning of the
time frame and the end of the time frame. When
the time frame expires the DTA controller 46
may automatically switch the classification
track 16 to the dynamic assignment mode, may
issue an alert to the yard master or do both,
in other words automatically switch the
assignment mode and issue a notification such
that the yard master is made aware of the
event.
When the yard master changes classification
track assignments via the user interface 53,
the changes are reflected in the file such that
during execution of the switching solution
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computation step 602 the logic will be made
aware of the correct assignment of each
classification track 16.
Finally, note that assignments can be specified
via the user interface 53 on the basis of
classification track groups instead of being
done on a single track basis. For
instance,
referring back to Figure 1, the yard master may
W simply specify the assignment of an entire five
classification track group.
6. Classification track grouping. This notion can
be implemented in hump switch yards 10 where
the classification tracks are physically
arranged into groups, as shown for example in
Figure 1. The
logic implemented by the DTA
controller 46 is designed such that a departure
train that is to be assembled will be assigned
a most preferred group of classification tracks
16 and a second most preferred group of
classification tracks 16. In other words, the
cars that go in the train will be preferably
put in the classification tracks of the most
preferred group. If there is no space in the
most preferred group, the second most preferred
group will be considered. Optionally, a third
most preferred group can also be used, such as
to provide classification track space when the
second most preferred group is full.
The notion of a preferred group avoids
scattering the train blocks for a given
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departure train all over the classification
tracks. The logic of establishing a preferred
classification track group is to try placing as
many of the train blocks as possible that
belong to the same train in the fewest possible
classification tracks that are physically close
to one another. This
simplifies the train
block pulling operation by comparison to a
situation where the train blocks are scattered
over many classification tracks that may be
physically remote from one another.
Preferably, the most preferred set of
classification tracks and the second most
preferred set of classification tracks are
physically close to one another such as to
simplify the train block pulling operations.
The hump switch yard 10 shown in Figure 1
illustrates two groups of classification tracks
and one of those could be designated as a most
preferred while the other as the second most
preferred. Thus, the most preferred group and
the second most preferred group are immediately
adjacent to one another. The
same logic can
also be followed in connection with the third
most preferred group, in that it can be
selected such that it is close to the most
preferred and second most preferred group and
preferably immediately adjacent thereto.
It is important to appreciate that the notion
of preferred groups is not restricted to switch
yards, either hump yards or flat yards that
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have physical groups of the type shown in
Figure 1. Even when the classification tracks
16 are not physically grouped, they can still
be logically associated into groups. In
such
case, groups can be defined by assigning two or
more adjacent classification tracks to a group,
either most preferred, second most preferred,
etc.
Generally, groups of classification tracks are
associated with departure trains. Once
a
preferred group has been established, either a
physical group or a logical group, that group
is maintained until all the cars scheduled to
depart have been delivered in the
classification tracks. After
that, the
association between the classification track
groups and the train is dissolved, in other
words groups can be assigned to a new train to
be built.
It should be noted that the classification
track groups do not need to be completely empty
of cars before being assigned to a new train.
The assignment process is essentially a logical
step and a re-assignment can occur as long as
there is space in the group to receive cars for
a new train. The two following situations can
arise:
o The group is closed to cars that belong to
a new train as long as no more cars that
belong to the current train are scheduled
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to arrive in the group. Once
all cars
have arrived, the group of classification
tracks can begin receiving cars associated
with the new train.
o The group is open to cars from a new train
as long as there is space for the cars on
any one of the classification tracks that
make up the group. This implies that cars
for the current train can still be
received in any other classification track
of the group.
Consider for example
classification track group made up of 10
tracks. Track
9 holds a train block of
cars that is complete. The
other tracks
1-8 and 10 hold train blocks that are
still incomplete. The
entire group can
now be assigned to a new train since cars
for the new train can be placed in track
9, while cars for the current train are
still arriving in the other classification
tracks of the group. In this example, the
group is assigned during a certain time
period to two different trains.
The DTA controller 46 holds in its machine
readable storage media a representation of the
different classification track
groups,
specifically, identifying which classification
tracks belong to which group and which
departure train is currently assigned to which
classification track group. In
the case of a
physical grouping of the type shown in Figure
1, the identification of the classification
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tracks with relation to the groups will likely
be the same as the physical layout and unlikely
to change over time.
However, in instances
where no physical groupings exist, the number
and identity of the classification tracks that
make up the groups can dynamically change. The
assignment of a given classification track
group (most preferred, second most preferred,
third most preferred, etc.) can be done
manually by the yard master This operation is
effected via the user interface 53 or can also
be done automatically
7. Non-preferred classification track groups.
In selecting which classification track groups
to assign to a departure train as most
preferred, second most preferred, third most
preferred etc, there is a possibility, as
discussed in the previous example, to co-assign
the same group of classification tracks to
different trains. In such, case consideration
is given to the relationship between the
departure times of the trains. Classification
track groups will not be co-assigned to trains
that depart at times that are close to one
another in order to avoid a potential
congestion on the tracks. Such
congestion is
likely to arise if train blocks for different
trains are pulled at about the same time from
the same group of classification tracks.
8.Rehumping for pull time.
Cars to be switched to classification tracks
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may be sent to the rehump tracks 26 when the
departure time of the train block to which they
belong is far away. This
avoids a situation
where a few cars may train block a
classification track for a long time period
necessary for all the other cars that belong to
the train block to arrive. In
this case the
buffering function of the rehump tracks 26 can
be put to use. The decision to temporarily put
W cars on
the rehump tracks takes into account
the following factors, individually or in
combination with one another:
a. The pull time of the train block. For
example if the train block is to be pulled
many hours away, it is a good candidate
for rehumping;
b. The size of the train block. If the train
block is small, say a few cars, it is
possible to allow all the cars that belong
to the train block to accumulate in the
rehump tracks 26. Then
the cars of the
entire train block are humped and placed
in the appropriate set of classification
tracks;
c. The rate at which the cars of a given
train block arrive. Even
if the train
block is large and may not be contained
entirely in the rehump tracks, at least
some of the cars that arrive first can be
held temporarily in the rehump tracks
until space is available in any set of
classification tracks. At this point, the
cars stored in the rehump tracks can be
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humped in the selected set of
classification tracks and the remaining
cars that make up the train block are
directed to the selected set of
classification tracks.
9.Rehumping for arrival rate.
Cars to be switched to classification tracks
may be sent to the rehump tracks 26 when they
arrive at a very slow rate. This could occur
in connection with a given train block and
where the first few cars of the train block
arrive very slowly. Those
cars can then be
directed to the rehump tracks and held there
until the rate of arrival of the cars for that
train block increases, at which point the cars
are switched into classification tracks.
10.Preemptive closure of a train block.
If a train block is kept open for a long time
period, cars that belong to other train blocks
may have to be sent to the rehump tracks.
Rehumping cars consumes resources which
translates into additional operational costs.
When a large number of cars may need to be
rehumped, it may make more sense to close the
train block and thus open space on the
classification tracks. When
a train block is
prematurely closed, the cars arriving post
closure that were intended for the closed train
block need to handled somehow. For
instance
the late cars can be assembled into a new train
block.
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11.Empty car substitution.
Empty cars, are associated with a trip plan, as
any other railway car. To improve the overall
car switching process at the hump yard 10,
empty car (a car that does not carry cargo and
is directed to a location to pick up a
shipment) substitution can be implemented where
a given empty car that is currently available
for switching can be substituted for another
empty car that may be late or unavailable for
switching. In addition to the physical car
substitution, the records in the SRS component
30 are updated to indicate that the first car
(the car that is available) has now taken the
place of the second car (the unavailable car)
in the trip plan of the second car.
The exemplary characteristics outlined above will be
better understood with relation to the following specific
examples. It
should be expressly noted that
characteristics are provided as examples and should not
be interpreted as being essential to the invention in any
way.
Figure 7 is a high level flowchart of the logic that
is implemented by the DTA controller 46 to switch cars,
in particular the step 602 shown at Figure 6. The
decision tree represented by the flowchart is followed
sequentially. If at
anyone of the steps a switching
solution is found the car is switched and the process
terminates. If no solution is found at a particular step
the process continues to the next step.
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The process starts at 900. At
that decision step
the DTA controller 46 determines if the car is on "pull
back". A car on "pull back" is a car that is currently
in position to be pushed over the hump 20 (or being in
position at the hump 20); therefore it is committed for
switching.
Accordingly, if the decision step 900 is
answered in the affirmative any previous switching
solution computed for this car by the DTA controller 46
is presented as final solution over the user interface 53
(step 901). If
this assessment is answered in the
negative the process continues at step 902 that
determines if the yard block to which the car is assigned
exists. This
is effected by looking at the data made
available to the DTA controller 46 from the SRS
component. This data includes information about the yard
blocks in the hump switch yard 10. If no
yard block
exists for the car, in other words the decisions step 902
is answered in the negative the car is sent to rehump at
step 904. Once in the rehump tracks the car will be
periodically rehumped and the above described processing
done again. If at this time a yard block for the car is
found then the process would branch to decision step 906.
Decision step 906 determines if the yard block to
which the car is assigned is a static train block. A
static train block is a train block that is associated
with a static classification track. As
discussed
earlier, a static classification track is one that may be
assigned to cars or train blocs associated with a
departure train going to a predetermined destination.
Accordingly, if the decision step 906 is answered in the
affirmative, the switching solution is determined by
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consulting the representation of the classification
tracks in the DTA controller 46. As previously indicated,
this representation provides information on the
statically assigned classification tracks and details
about such assignment, in particular the destination of
the blocks put on those classification tracks.
As discussed earlier, a static classification
assignment can be done via the user interface 53.
If no static classification track 16 has been
assigned for the car, the process continues to step 910
that queries if a train block exists for the car. This
determination takes into account the expected switch time
of the car. If an
outbound train cannot be found that
carries the train block, then it is not possible to
perform a dynamic track assignment. The car is therefore
directed to a rehump track 24 (step 912).
The computation of the expected switch time for a
given car is an approximation of the time at which the
car is expected to be available for switching. Several
factors can be used in making this determination, for
example:
a. The number of cars that are presently in the
hump switch yard 10 and that are yet to be
switched;
b. The rate or arrival of cars in the switch yard;
c. The rate at which cars are switched;
d. Resources available to prepare the cars for
switching.
Factor (a) and factor (b) allow determining, at any
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given time, how many cars will be in the queue awaiting
switching.
Recall that this information is readily
available to the DTA controller 46 from the SRS component
30.
Factor (c) can be a rate computed on the basis of
the operations in the hump switch yard 10 that occurred
in the past couple of hours. For
example, a car
switching rate can be computed on the basis of the number
of cars switched in a given time frame, say the last two
hours. A car switching rate can also be computed
theoretically by taking into account resources available
(factor d) in the switch yard to perform the operations
necessary to prepare the cars for switching. One
such
operation is the mechanical inspection of the cars. One
such resource is the number of crews that can perform the
preparation for switching, namely the mechanical
inspection. By
considering the average number of cars
that a crew can mechanically inspect it is possible to
compute the rate at which cars can be made available for
switching. Another possibility is to take into account
the rate computed on the basis of switching activities
that have occurred in the past previous hours and adjust
it to take into account variation in the number of crews,
for instance increase the predicted rate if the number of
crews increases or decrease the rate if fewer crews will
be available.
The DTA controller 46 can on the basis of the above
factors determine for a given car, the number of cars
that precede it in the humping queue. Then on the basis
of the switching rate, an expected switching time for the
car can be computed.
Note that the expected switching time for the car
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can remain static or can be periodically updated, such as
at each iteration cycle where a new switching solution is
computed. A
static expected switching time is a time
that once computed is re-used at every iteration cycle.
In contract, the expected switching time can be re-
computed periodically as the car moves up through the
queue of cars that are to be switched. In this fashion,
a more precise approximation can be obtained. The period
at which the expected switching time is re-computed can
vary. One
possibility is to do it at every iteration
cycle at which a switching solution is computed.
At decision block 914 the process determines if
there is an existing classification track for the train
block to which the car belongs. This
query will be
answered in the affirmative if the car is not the first
car of a train block. In other words, a classification
track has already been assigned to the train block. On
the other hand, if the car is the first car of the train
block then the query will be answered in the negative.
If this query is answered in the affirmative, in other
words the car is not the first car in the train block and
a classification track 16 has already been assigned to
this train block, then the process continues to step 916
shown at Figure 8. Step 916 determines if the car will
in fact fit the classification track assigned to the
train block. As it will be described below, in principle
there should be enough space on the classification track
16 assigned to the train block since when the first car
of the train block is switched, the switching solution
that determines which classification track will receive
the car, not only looks for space for that particular
car, but also for space for cars that belong to the train
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block and that will be subsequently switched. This will
be described later. So while in principle space should
be available, the step 916 still tests for available
space to take into account some special factors. For
instance, there may be situations when more than one
classification track may have been assigned to the train
block in which case, the process will determine which
classification track is the best candidate for receiving
the car. In
such case, the DTA controller 46 will
determine the space available in each assigned
classification track 16. For
the sake of this example,
assume that two classification tracks 16 have been
assigned to the train block. if not enough space is
available in one of the classification tracks 16 and
space is available in the other classification track 16,
the DTA controller 46 will compute a switching solution
directing the car to the classification track 16 having
the requisite space. On
the other hand, if space is
available in both classification tracks 16, the DTA
controller 46 will compute the best fit, in other words
it will chose as a solution the classification track 16
that will leave the least amount of free space when the
car is switched to it.
When the step 916 is executed, the classification
track 16 that is tested for available space is retrieved
from the memory of the DTA controller 46. In
other
words, when a classification track is assigned to the
first car of a train block, the relationship between the
train block and the classification track is stored in the
memory of the DTA controller 46. When subsequent cars
for that train block arrive and are to be switched, the
DTA controller consults this information to determine
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which classification track 16 has been assigned to the
train block and will then test for available space there.
If the decision block 916 is answered in the
negative, in other words no space is available for the
car in the classification track(s) assigned to the train
block, then the processing continues with an overflow
logic thread that aims to find a place for the car on
another classification track. The logic overflow process
W is shown by bloc 917. This logic is generally similar to
the process starting at step 922 and ending at step 940.
Those steps will be described in greater detail later.
If decision bloc 916 is answered in the affirmative,
the process continues with decision bloc 919 which
determines which departure train the car will be directed
to. Step
919 is an option that is useful in
circumstances when the car has an expected switching time
close to the pull time of the block. In other words, it
may not be fully known at the time the switching solution
is computed if the car can make the classification track
before the pull time of the block. By default, the logic
of the DTA controller 46 is designed such as to try
fitting the car on the earliest departure train. So, the
logic will compute switching solutions that put the car
in a train block having a departure time close or
slightly before the expected pull time (the extent of
what constitutes "close" or "slightly before" is
programmed in the DTA controller 46 and can be in its
simplest for predetermined time periods). In some cases,
the pull time may be delayed and the car will in fact
make the current train.
Similarly, the actual switch
time of the car can occur slightly before the expected
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switch time in which case the car will also be able to
make the current train.
In short, as long as the expected switching time is
close enough to the pull time of the current block the
DTA controller 46 will compute switching solutions (step
921) that put the car with train block scheduled to
depart shortly. Only
when the spread between the
expected switching time and the pull time exceeds a
threshold or the current block is actually pulled or for
some other reason it becomes obvious that the car cannot
make the train scheduled to depart shortly, then a
different switching solution is computed (step 923) that
puts the car in a train block with a latest train. The
label in Figure 8 "same day train?" assumes that a
departure train leaves every day. Hence, if the car does
not make the current train, it will be put at step 923 at
on the next day train.
Referring back to Figure 7, if decision step 914 is
answered in the negative, in other words no
classification track has been yet assigned to the car
because this is the first car of a train block, than the
processing branches toward a series of steps that will
first determine if it suitable to buffer this car instead
of immediately switching it. The
buffering process,
identified by the reference numeral 927 includes a first
decision step 931. That
decision step assesses the
desirability of temporarily putting the car, and perhaps
the following cars that belong to the same train block,
in the rehump tracks 26. Generally, it is desirable to
limit as much as possible the amount of time cars from a
train block reside on the classification tracks 16 since
the space that is occupied by the cars cannot be used for
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any other purpose. This problem may arise when the cars
that make up a train block progressively arrive at the
hump switch yard 10 over a long time period. For
instance, when a first car is delivered, a switching
decision is made and space is reserved for the entire
train block on the classification tracks 16. That space,
therefore, cannot be used for other purposes until the
last car of the train block arrives, which may be many
hours away. A
possible approach is to use the rehump
M tracks 24 as a temporary buffer and thus free space on
the classification tracks 16. This
option can be
implemented when certain conditions are met. Train block
size is one those conditions. It is desirable to put the
car in the rehump tracks 24 when the overall size of the
train block is small. If the
determination at step 931
indicated that the size of the train block to which the
car belongs is small, among other conditions discussed
below, the DTA controller 46 will compute a switching
solution according to which the car is directed to the
rehump tracks 26. Figure
10 is a flowchart of the
process steps that take place under step 931.
The process starts at step 800. At
step 802 the
Number of Cars Remaining for the Next departing Train
(NCRNT) for a given train block is computed. The NCRNT
is the number of cars for the train block that have an
expected switching time before the scheduled pull time of
the train block. NCRNT takes into account cars that are
presently in the hump switch yard 10 and also cars that
have not yet arrived but have an ETA such that their
expected switching time will still occur before the train
block pull time. The
DTA controller 46 receives
information on the various parameters necessary to
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compute NCRNT from the SRS component 30, such as
information on the identity of the train block and its
characteristics, as well as the ETA of the cars that make
up the train block. The DTA controller 46 can compute
the expected switching time for each car as described
earlier and on the basis of the expected pull time of the
train block that is also available or derived from
information in the SRS component 30, the NCRNT value is
computed.
At decision step 804 the DTA controller 46
determines whether a car will be switched to
classification tracks 16 or to the rehump tracks 26. The
decision is based on the computed value NCRNT and the
pull time of the train block from the classification
track 16. In the specific example of implementation, if
NCRNT is relatively small, less than 5 cars and the pull
time of the train block is more than 7 hours away then a
switching solution is computed to put the car in the
rehump tracks 26 (step 806).
Otherwise, the DTA
controller 46 proceeds to step 933 in Figure 7. The
specific parameters in this example should not be
interpreted in a limiting manner since those parameters
can widely change without departing form the spirit of
the invention.
Specifically, For instance, the NCRNT
parameter can be increased to more than 5 cars when the
rehump tracks 26 have a lot of space and can accommodate
a significant number of cars. The 7
hours period can
also be altered without departing from the spirit of the
invention.
Decision step 933 tests for another condition that
may result in the car being sent to the rehump tracks 26.
This condition is the rate of arrival of cars at the
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switch 24. If the rate is low, i.e., the cars making up
the train block will have respective expected switching
times spread over a long time period, then it is
advantageous to temporarily place the car on the rehump
tracks before switching the car in any one of the sets of
classification tracks 16. The flowchart of Figure 11
illustrates this process.
The process starts at step 1100. At step 1102 the
rate of arrival of cars for the train block is computed.
This rate is established by determining the number of
cars that will be present in the hump switch yard 10 over
a predetermined time period, say the next 5 hours. The
number of cars is the sum of the cars presently in the
hump switch yard 10 and those that are scheduled to
arrive within the predetermined time period. As with the
previous example, this information is made available to
the DTA controller 46 from the SRS component 30.
Decision step 1104 determines if the rate of car arrival
is above or below a threshold. For example the threshold
may be five cars. So if the rate is five cars or more in
the next five hours, step 933 is answered in the
negative. Otherwise, if the rate is less than five cars
in the next five hours, then a switching solution to
rehump the car is issued at (step 1108). It will
be
appreciated that the specific values provided are merely
examples and they can be widely vary without departing
from the spirit of this invention.
Note that the rate of arrival factor may also be
refined by computing the expected switching times of the
cars making up the train block instead of the looking
only at the number of cars of the train block presently
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in the hump switch yard 10 and the ETA of the cars that
have not yet arrived.
Assuming now that the decision step 933 is answered
in the negative, in other words the conditions that would
trigger a rehumping solution have not been met, the
process continues with decision step 920. In most cases,
when the processing reaches this step the car for which a
switching solution is being computed is the first car for
a train block. Generally, the computations for finding a
solution are more complex than in the case when
subsequent cars are switched since the DTA controller 46
is not only looking for space for the first car but is
also reserving space for the subsequent cars of the train
block.
Step 920 first looks for an empty classification
track in the preferred group. When
several empty
classification tracks are available within the preferred
group, one option is to randomly choose one. This is
suitable when all the empty classification tracks have
the same capacity, in other words each empty
classification track can accommodate the same number of
cars. When
empty classification tracks with different
capacities are available an option is to choose the one
that best fits the train block. In
this context "best
fit" means a classification track that will contain the
least amount of empty space when the entire train block
will be delivered in the classification track. The "best
fit" computation can be done for each empty
classification track by subtracting the train block size
from the track capacity. This computation can be made in
terms of number of cars or in terms of cumulative car
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length to take into account cars having different
lengths. If an
empty classification track is found at
step 920 a switching solution is computed (step 935).
Otherwise the process continues at decision step 922
which is the same as decision step 920 except that the
search for an empty classification track is done in the
second most preferred classification track group. Again,
if no solution is found at step 922, step 924 performs
the same operation, this time looking for an empty
classification track in the third most preferred
classification track group.
If anyone of the decision blocks 920, 922 or 924 is
answered in the affirmative, in other words an empty
track is found for the train block, the DTA controller
will make an entry in the records in its memory 49 such
as to associate the selected classification track with
the particular train block. Such association is made by
marking the selected empty classification track as
"opened" and marking all the other classification tracks
as "closed" as far as that train block is concerned. As
indicated above this is done by writing the appropriate
data in the computer files or records that the DTA
controller 46 processes to perform its management
functions.
Accordingly, when switching solutions are
computed for any subsequent cars of that train block, all
classification tracks that are marked "closed" are
disregarded and the search for switching options is
constrained to the "opened" classification track.
Referring back to step 914, which is looking for an
existing track for a train block, the "closed" or
"opened" status of the classification track allows the
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DTA controller 46 to identify the correct classification
track that is to receive the car.
Once a classification track is marked as "opened" in
connection with a certain train block, that
classification track is also marked as "closed" for any
other train block. This ensures that the classification
track will receive only cars for the relevant train
block.
The "open" status of a classification track is
negated when the switching solution for the last car of
the train block has been computed. In other words, the
train block is now complete.
Similarly, the "closed"
status of the classification track with regard to any
other train block is also negated, thus allowing cars of
another train block to be directed to the classification
track.
If no switching solutions have been found at anyone
of the steps 920, 922 and 924, indicating that no empty
tracks for the train block are available in anyone of the
preferred classification groups, the DTA controller 46
continues with decision step 926 that tries to find space
for the train block in an already occupied track.
The process will try to find space first in the most
preferred group, then the second most preferred group,
then the third most preferred group before considering
other options. The decision step 926 tries to determine
if an occupied classification track 16 exist in the most
preferred group that can accommodate the train block or a
portion thereof. As
discussed previously, the DTA
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controller 46 will consider only those classification
tracks 16 that have train blocks marked "complete", hence
the track is open to receive a new train block. All the
other classification tracks 16 in the most preferred
group that hold cars but where the train blocks are not
yet complete are from a logical process point of view
marked "closed".
Assuming that the process locates a
single occupied track with a closed train block, hence
available to receive a new train block, the process will
then determine if enough space exist for the new train
block on the track.
In a specific and non-limiting example of
implementation, the available space in the classification
track equals not the currently available space on the
classification tracks but the space that is made
available to the new train block considering that train
blocks currently occupying the set of classification
tracks will be pulled at certain times in the future
(train block pull profile vs. car arrival profile).
More specifically, the computation of the available
space takes into account the pull time of the train block
that currently occupies the track and the ETA, or
expected switching time of the cars that make up the
train block for which space is being sought. For
instance, assume a classification track 16 having a 50
car capacity. Train
block A made up of 30 cars that
occupies the classification track 16 is scheduled to be
pulled at noon (current time is 10:00 AM). The DTA
controller 46 needs determining if there is available
space for departure train block B that is made up of 40
in the same classification track 16. The arrival profile
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of the cars making up train block B in the classification
track 16 is such that 19 cars will arrive at 11:00 AN, 5
at 3:00 PM and 16 at 3:30 PM. The
computation of the
available space in the classification track 16 is done at
different points in time that generally coincide with the
arrival of the cars making up train block B. For instance
the available space at the following times will be:
= 11:00 AM - one car;
= 12:00 AM -19 cars considering that train block
A was pulled;
= 3:00 PM - 24 cars;
= 3:30 PM - 10 cars.
By checking if available space exist at the ETA, or
expected switching time of each car in the new train
block, the process can determine if, enough space will
exist for it in the classification track 16. The train
block B is deemed to "fit" in the classification track 16
if for every train block B car that arrives, space exists
to receive it.
In determining the time at which cars arrive in the
classification track 16, one option is to use only the
ETA of the cars available from the SRS component 30. The
ETA provides a rough estimate of the time the cars would
be present in the classification track since it does not
take into account the preparation time for switching such
as the mechanical inspection. Never
the less, in some
applications the ETA can provide a reasonable indication
of the time the cars will arrive in the classification
track 16 and as to make the assessment.
Another more
refined option is to use the expected switching time of
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the cars which is computed as described earlier.
In the case where the process finds a single
classification track 16 that can accommodate the new
train block then the process terminates by issuing the
switching solution.
However, in the instance where
several classification tracks exist in the most preferred
group of classification tracks that can all hold a
complete train block, and that can accommodate the new
train block, hence the new train block "fits" two or more
classification tracks in the most preferred group, then a
number of options arise that are considered by the DTA
controller 46 to find the best solution. This situation
is illustrated in the flowchart at Figure 9. The process
starts at 700. At step 706 the process will compute the
degree of "fit" in each classification track that can
hold the new block. The degree of "fit" is represented
by the Left Over Room (LOR) for each classification track
option. The LOR is the free space in the classification
track that will remain after all the cars of the new
train block cars have arrived. In the above example, the
LOR at 3:30 will be of 10 cars.
In Figure 9 the DTA controller 46 will select at
step 710 the classification track that has the lowest LOR
and thus provides the best "fit". Since
LOR is space
that is difficult to use in practice, selecting the
classification track with the lowest LOR results in most
cases in a better utilization of the available space.
When a classification track has been found to
accommodate the new train block, then the records of the
DTA controller 46 are marked such that:
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= For every car of the new train block all the
classification tracks 16 will be seen as
"closed", hence not available, with the
exception of the selected classification track
16. This ensures that the subsequent cars of
the new train block will be constrained to go
to the selected classification track 16.
= The selected classification track 16 will
appear as "closed" for every car that belongs
to a train block other than the new train
block. Again this ensures that only cars from
the new train block are directed to the
selected classification track 16. The selected
classification track will be released from the
"closed" status only when the new train block
is completed, in other words all the cars from
that train block have been delivered in the
selected classification track 16.
Now assume, for example, that the process under step
926 in Figure 7 fails to identify an occupied track in
the most preferred track group that can hold the entirety
of the new train block. The next step is to terminate
process step 926 and initiate process step 928. Process
step 928 is similar to process step 926 with the
exception that it looks for space for the new train block
in the second preferred group of classification tracks.
Similarly, if no space can be found for the new train
block in the second preferred group of classification
tracks, the process continues to step 930 that will
consider the third preferred group of classification
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tracks.
If no space is available in anyone of the preferred
groups then the process will look for space outside the
preferred groups. The
same pattern described earlier
will be repeated. More specifically, the step 932 will
search for an empty classification track but outside the
preferred groups (most, second and third). If
such an
empty classification track is found then a switching
M solution is issued.
Otherwise, the process continues
with step 934 that will consider all occupied tracks with
closed train blocks outside the preferred groups.
If no space for the train block has been found so
far, the process continues with step 936 which is
described in greater detail with reference to the
flowchart on Figure 12. This
point in the overall
process indicates that no classification track 16 exists
that can accommodate the entire train block. The
DTA
controller 46 will now try identifying a classification
track 16 that can accommodate most of the train block but
not all of it.
The process starts at step 1402. At step 1404 the
DTA controller 46 will compute the available space on
each set of most preferred classification tracks 16 with
closed train blocks (i.e. classification tracks 16 that
can receive cars from another train block).
Classification tracks 16 with train blocks that are still
open are disregarded. The computation of the available
space takes into account the pull profile of the existing
train block(s) and the arrival profile of the cars of the
current train block as described earlier. The result of
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the available space computation essentially determines
how many cars will fit in each classification track with
a closed train block. The DTA controller 46 retains in
memory the classification track 16 that can hold the
largest number of cars.
The same computation is performed in connection with
the classification tracks 16 in the second preferred
group (step 1406), in the third preferred group (step
1407) and then for classification tracks (step 1408)
other than those in the most preferred, the second
preferred group (step 1406) and the third preferred group
(step 1407).
The results of the four computation operations are
compared at decision step 1410. Generally, the selection
logic is designed to favor a classification track
according to the following order of preference:
= the most preferred group of classification tracks;
= the second preferred group of classification tracks;
= the third preferred group of classification tracks;
= Tracks that are outside the most preferred, second
preferred and third preferred groups of
classification tracks.
This order of preference is applied unless a
classification track at a less preferred level can hold
significantly more cars.
One example of decision thresholds is to select a
classification track in the most preferred group unless
the available classification track from the second
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preferred group can hold at least 5 more cars. The same
or different threshold can be applied to other preference
levels as well. For
example the classification track
returned by step 1407 (third preferred classification
track) is selected if it can accommodate 10 cars or more
than the classification track in the second preferred
group.
Once the decision on which classification track 16
W to use is made and the appropriate records in the DTA
controller 46 are marked to open that classification
track only to cars of the new train block and similarly
close the selected classification track 16 to cars from
any other train block, then a processing is initiated to
determine how to handle the overflow. Several
options
exist:
= Direct the excess cars to rehump tracks 26.
This option is suitable if the number of excess
cars is low. So, for instance, a
threshold
could be set such that if the number of excess
cars is at or below the threshold they are
directed to the rehump tracks 26. In a
specific and non-limiting example of
implementation, the threshold could be five
cars. The DTA controller 46 will then mark its
records that the cars which make up the
overflow are to be sent to the rehump tracks
26. For instance, each car object of the train
block can be marked by the DTA controller 46 to
the effect that it has only two switching
options, one being the rehump tracks 26 and the
other the selected classification track 16.
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Since the classification track 16 is full when
the car arrives at the hump, the logic will
direct the car to the rehump tracks 26. When
the cars in the rehump tracks are humped, then
the logic is run one more time and if space is
now available in the selected classification
track, then the switching solution to direct
one or more cars in that classification track
16 is issued.
= Place the cars of the train block in two
separate classification tracks. In
other
words, the overflow is sent to a different
classification track 16 instead of waiting for
space to be available in the selected
classification track 16. Under
this option,
the train block as far as its processing by the
DTA controller 46 is concerned is handled as
two separate train blocks, which are to travel
on the same departure train. In other words
the selected classification track 16 that holds
the initial part of the train block is
considered to hold a closed train block, in
other words no further cars are expected in
that classification track 16 for the same train
block. At
the same time, the overflow is
considered from the point of view of the DTA
controller 46 logic to become a train block and
it is treated as such. The logic starting from
step 920 is performed to find a suitable
location for that "new" train block. Since it
will not be desirable to locate the overflow
physically remote from the initial part of the
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train block, the logic may be constrained to
look for space only in the most preferred
classification track.
Finally, the logic also
needs to take into account constraints that
arise at train block pull time due to the train
block splitting. In
particular it would be
highly desirable to synchronize the train block
pulling operation on the two classification
tracks such that the train block parts are
physically joined to one another in the
departure train;
= Pre-empt the selected classification track
(step 938 in Figure 7). This
option is an
extension of the second option above, the
exception being that two train blocks are being
created out a single train block. Recall that
in the previous case, the train block splitting
was only an operation internal to the DTA
controller 46 and the result was still a single
train block, as far as the departure train is
concerned. Here, a single train block creates
"officially" two separate train blocks. The
new train block that is made up of the overflow
has essentially the same properties as the
original train block, such as destination, etc,
with some differences such as the number and
identity of cars that make up the new train
block. Moreover, the original train block also
needs to change in that now it has fewer cars.
Finally, the departing train object also needs
to be updated, since it now contains one more
train block. Those
changes are handled by
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modifying the records in the DTA controller 46.
Since the DTA controller 46 is aware of the
identity of the cars making up the overflow, it
will:
- Create a new train block object to encompass
the overflow by also copying relevant
properties from the prior train block object
(such as destination, etc.);
- Modify the existing train block object by
adjusting for the cars that have been excised
and are now part of the newly created train
block object;
- Update the train object to add to it a new
train block object.
All those changes must also be communicated to the
SRC component 30 such that the railway operations, once
the train has left the hump switch yard 10 can be
conducted by taking into account the existence of a new
train block. The
necessary information can be
communicated to the SRS component 30 manually. This can
be done by an operator that will access the system and
make the necessary changes.
Another possibility is to
allow the DTA controller 46 to communicate directly with
the SRS component 30 such as to change the records of the
SRS component 30.
If the step 938 is answered in the negative, in
other words a switching solution is not possible, the
final option is the step 940 that issues a switching
solution to sends the car to the rehump tracks 24.
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In the above examples, the DTA controller 46 is
designed to compute a switching solution and tell the
yard master or any other operator where the car should
go. In
this embodiment, the DTA controller 46 assists
with the switching process and it is up to the yard
master to validate the choices made by the DTA controller
46 and then authorize their implementation. In a
possible variant, not shown in the drawings, the DTA
controller 46 can be designed such as to communicate
switching commands directly to the HPCS component 32. In
this fashion, the DTA controller 46 will cause the HPCS
component 32 to implement the switching solutions,
bypassing the human operator. This system would require
a communication link between the DTA controller 46 and
the HPCS component 32 over which commands and data can be
exchanged between both entities.
A possible variant to the general process described
earlier in connection with Figures 8 and 9 is to provide
a special treatment of empty cars in order to take
advantage of the inherent flexibility they possess, in
terms of being substitutable for one another. Cars that
carry goods have to be switched in a way to reach the
destination of the goods. In contrast, a given empty car
does not need to comply with the preset trip plan. What
matters from a customer's perspective is to receive an
empty car; it is far less critical which specific car is
being sent since any empty car (that matches the customer
requirements) will do.
In summary, the process described in Figures 8 and 9
treats the empty cars as any other car and they are
switched as per the parameters establishing which train
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block they go to. Figure 13 shows a variant where the
specificity of the empty cars is recognized by the DTA
controller 46 such as to perform substitutions, wherever
possible.
The process starts at 1300. At
step 1302 the DTA
controller will identify all the empty cars in the hump
yard 10. In essence the DTA controller 46 maintains in
the memory 49 a list of all the empty cars that are
currently in the hump switch yard 10 and that have not
yet been switched. This
list is continuously being
updated to take into account cars that are being switched
and cars that are arriving with inbound trains. Every
time an empty car is switched and placed in a
classification track 16 the list is updated to remove
that car from the list.
Similarly, every time a new
train arrives, if that train contains empty cars they are
added to the list.
The DTA controller 46 is capable of distinguishing
between empty cars and cars that are not empty by
inspecting the records associated with the respective car
objects available from the SRS component 30.
The DTA controller 46 computes at step 1304 the
expected switching time of each empty car in the dynamic
list maintained by the DTA controller 46. The expected
switching time is an information that can be added to the
list or it can be cross-referenced on the basis of the
car ID information. In other words, the DTA controller
46 can be designed such that it computes the expected
switching time for all cars in the hump yard 10 yet to be
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switched and the expected switching time for the empty
cars can be extracted on the basis of car ID information.
At step 1306 the DTA controller 46 will identify all
the train blocks that the switch yard 10 is to make
(departing train blocks) that have not yet been pulled
and that contain empty cars. Again this identification
is made based on the records provided by the SRS
component 30. The
inquiry made at step 1306 will
essentially produce a list of train blocks that contain
empty cars. Those departure train blocks are either in
the process of being assembled or will be assembled in
the future. Note
that the train blocks identified at
step 1306 are defined in the DTA controller 46 records in
terms of specific cars making up the train blocks. In
other words, a train block containing one or more empty
cars specifies unique car ID numbers, not just any empty
car.
At step 1308 the DTA controller 46 will determine if
anyone of the specific empty cars required for the train
blocks to be assembled will be available on time.
Available on time means that the particular empty car has
an expected switching time prior to the pull time of the
block. Step 1308 is expected to produce a shorter list
of blocks containing empty cars where at least one empty
car specified for each block will not be available on
time. This
may be caused by the arrival train that
brings the empty car being late. Since
the DTA
controller 46 is made aware of the ETA of each car via
the SRS component 30 it can determine for any given car
if can be switched before the pull time of the departing
train block.
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Decision step 1310 determines if an empty car
substitution is possible. Once
a block has been
identified where an empty car will be late, the DTA
controller 46 looks for other empty cars in the hump
switch yard 10 that can be substituted to the late car.
Since a list of all the empty cars in the hump switch
yard 10 has been compiled at step 1302 and their
respective expected switching times are known, then the
W DTA controller 46 can determine by searching that list if
there is an empty car having an expected switching time
before the pull time of the block, hence available to be
substituted for the missing or late car. If a
substitution is possible then the substitution is
performed. This entails switching the car ID numbers in
the records associated with the two cars. Specifically,
the ID of the car that is currently available in the hump
switch yard 10 replaces the ID of the car that is late in
all the records of the DTA controller 46 and also in the
records of the SRS component 30.
Similarly, the ID of
the car that is presently in the hump switch yard 10 is
replaced by the ID of the car that is late. Hence, when
the car that is late actually arrives it will be directed
to the train block that was to receive the other car.
If no substitution is possible, in other words the
decision step 1310 is answered in the negative, the DTA
controller 46 does nothing and the situation is handled
as per the process described in connection with Figures 8
and 9.
A variant of the process illustrated in Figure 13 is
shown at Figure 14. The process starts at 1400. At
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steps 1402 and 1404 a list is made of the empty cars
available in the hump switch yard 10 and their respective
expected switching times. Those
steps are identical to
steps 1302 and 1304 described earlier. Next, step 1406
identifies the train blocks to be assembled that contain
empty cars, similar to step 1306. At step 1308 the DTA
controller 46 will compute a best fit map, trying to
match the available empty cars to the demand, i.e., the
empty car slots in the departure train blocks. The best
fit algorithm can match an empty car to an empty car slot
in a departure train block when the expected switching
time for the empty car has not exceeded the pull time of
the departure train block. As a match is found, the DTA
controller 46 will write at step 1410 the car ID number
in all the electronic records of the empty car that is
part of the departure train block.
Specifically, the
records of the DTA controller 46 that issue switching
solutions will indicate the particular empty car is to be
directed to the classification track that contains other
cars of the block and also data is communicated to the
SRS component 30 such that the SRS component 30 is made
aware of the association of that specific empty car with
the train block.
The embodiment in Figure 14 is different from the
embodiment in Figure 13 in that at the onset a pool of
empty cars is created and as an empty car is needed for a
departure train block, then an empty car is taken from
the pool, the choice as to which car to take is made on
the basis of the expected switching time of the car and
the pull time of the departure train block.
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A possible refinement of the empty car substitution
process is to perform the substitution as described
earlier but to classify the empty cars according to type,
style or category. In
many cases, not all empty cars
that are placed on the railroad network can be
substituted for one another. For example, an empty box
car to carry dry goods is not likely to be substitutable
to an empty car to carry liquids, for obvious reasons.
Accordingly, the above substitution process is preformed
in the same manner but for specific car categories. This
allows performing substitution only among cars that can
perform similar or identical functions. Specifically, if
a car to carry liquid goods is late or missing only a
similar category car will be allowed to substitute the
missing or late car.
The manner in which this refinement is implemented
is to create car categories in the records of the DTA
controller 46. In a
given category one car can be
substituted in terms of functionality to any other car in
the same category. The number of categories can vary and
will depend on the number of different types of cars in
circulation on the railroad network. For
each car
category the substation logic described earlier is run.
This ensures that in the case of a substitution the
customer will receive a car that will match his/her
requirements.
Although various embodiments have been illustrated,
this was for the purpose of describing, but not limiting,
the invention.
Various modifications will become
apparent to those skilled in the art and are within the
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scope of this invention, which is defined more
particularly by the attached claims.
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