Note: Descriptions are shown in the official language in which they were submitted.
CA 02406361 2002-10-15
STEEL CABLE SUSPENDED ENERGY ABSORBING AND IMPACT
ATTENUATING BARRIER SYSTEM
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to a displaceable and compressible crash
barrier and
associated cable barrier and suspending system used to absorb the energy and
attenuate
the impact of an incident colliding vehicle or racecar without permanent
deformation,
frequent repair or replacement, or causing a 'pocketing' response to the
incident vehicle
or racecar.
More specifically, this invention relates to an improved energy absorbing and
impact
attenuating burner system for use as a motorsports or traffic safety barrier
comprising a
plurality of overlapping, impenetrable barrier sections forming a continuous
barrier at the
periphery of or at a distance from the roadway or racing surface suspended in
a generally
vertical configuration with respect to the race track or roadway by a
plurality of steel
cables positioned at different heights above and parallel to the roadway or
racing surface
and displaced from the existing concrete barrier so as to allow for an energy
absorbing
medium or media to be placed between the existing concrete burner and the
suspended,
overlapping impenetrable barrier sections.
DESCRIPTION OF PRIOR ART
Automobile racing tracks require a burner that defines the outer limits of the
race track to
prevent racecars from leaving the racing surface, and to contain any debris
from the
normal course of the racing event or racing collisions which occur during the
racing event
within the confines of the race track. Roadways also require verge and median
barriers to
prevent vehicles from leaving the roadway. Automobile racing tracks also
require a
barrier that defines a spectator area physically separate and remote from the
racetrack to
provide a safe environment for spectators. A necessary and increasingly
important
characteristic of this type of burner that has emerged as vehicle and racecar
speeds have
CA 02406361 2002-10-15
increased is that it must have some degree of energy absorbing and impact
attenuating
properties to minimize physical damage to vehicles and racecars and injury to
drivers and
occupants upon collision with the barrier.
Historically, a number of devices have been utilized primarily for the purpose
of defining
the outer limits of the racing surface or track and defining a remote
spectator area -
devices such as hay bales, dirt beans, wooden and metal railings, concrete
abutments,
wire fencing or combinations of the above. In particular, steel fencing, such
as Armco,
and concrete abutments, such as concrete barners with a rectangular surface
parallel to
and in a vertical orientation to the racetrack and with associated wire
containment
fencing, serve as barriers commonly utilized in European, Asian and North
American
automobile racing events respectively. Concrete barrier systems have become
commonplace in North American racing because they are modular, not dislodged
or
damaged after an impact with an incident racecar, do not require repair within
or between
racing events, and have no associated parts that may be dislodged during the
collision
that cause a danger to other racing vehicles, drivers or spectators.
However, while the latter barner systems serve well to define the outer limits
of the
racetrack and contain ordinary or extraordinary racing debris, they do so by
providing a
fixed, hard surface ('hard wall') that does not have any significant energy
absorbing and
impact attenuating properties to reduce peak impact forces and assist in
preventing
serious injury to a racing driver or significant damage to the racecar. The
impact
absorbing responsibility of such a collision lies almost solely with the
racecar.
A commonplace and economical solution used in road racing applications is to
supplement the existing racetrack barrier system, e.g., concrete barners,
metal barners
and terms, with tire barners consisting of used automobile tires lying
horizontally and
bundled several tires high in adjoining vertical columns, sometimes with a
rigid tube
placed in the tire opening of the vertical column, to provide energy-absorbing
characteristics (refer to Federation Internationale de L'Automobile Standard
8861-2000,
FIA Energy Absorbing Inserts for Formula One, Tire Barriers Standard). These
tire
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barners are typically used in applications where the racetrack barrier system
is at a
distance from the racing surface itself such as may be the case in road racing
circuits; that
is, where a section of pavement, gravel trap or grass field intercedes between
the racing
surface and racetrack barrier system. However, tire barners are not useful in
applications
where the racing surface and barrier system are immediately adjacent to one
another, e.g.
oval racetracks, because significant impacts with an incident racecar during
the event can
dislodge the tire barner module itself or break the tire bundles causing the
dislodged tires
or associated hardware from the barner to be a safety hazard to the racing
event.
Additionally, the speeds associated with racecars in oval race tracks would
cause a
snagging hazard.
Those skilled in the art have previously described energy absorbing or
attenuating
elements in a plurality of barner modules manufactured of a variety of
materials such as
wood, metal, polymers, elastomers, or rubber to be utilized for absorbing the
impact of
incident colliding vehicles. Yunick (1997, US Patent 5,645,368) described a
racetrack
consisting of barrier modules including a base mounted on the barrier support
surface
delineating two crash barrier rings circumscribing the racing surface with the
inner ring
in a juxtaposed relationship with the racing surface. Yunick's invention
relates also to
racetracks and their construction, more particularly to new vehicle racetracks
constructed
with novel and improved crash barners. However, the novel barrier method
described by
Yunick cannot be integrated easily, if at all, with existing barrier systems
found at
existing racetracks.
Muller (1998, US Patent 5,851,005) described the use of hexagonal metal
elements to
absorb incident impacts, however, the impact absorbing capabilities of such a
device are
exhausted after a single severe impact and afford no further impact absorbing
properties
for collisions that may occur immediately after this first impact or prior to
repair. Arthur
(1999, US Patent 6,276,667) described the use of cylindrical elements of a
rubber or
polymer material that may retain their impact-absorbing characteristics after
an initial
severe impact. Muller and Arthur have both chosen to align the impact
absorbing
hexagonal or cylindrical elements such that the long axes are parallel and
longitudinal to
CA 02406361 2002-10-15
the vertical surface of the existing barrier rather than orthogonal. Such
alignment
provides for only limited collapse or compression of the elements as defined
by the
material, and width of the hexagonal or cylindrical elements. Moreover,
longitudinal
alignment of similar hexagonal or cylindrical elements does not provide for as
efficient
energy absorbing or impact attenuating characteristics as by placing the
hexagonal or
cylindrical elements in a horizontal alignment, such as is the case when
placing a
honeycomb-type energy absorbing medium with its thickness (T) direction
parallel to the
racing surface and generally perpendicular to the existing concrete barrier.
More recently, those skilled in the art have considered barriers whereby
materials of
relatively low density, for example, low, medium or high density foam, have
been placed
in front of the existing concrete barrier system to provide energy absorbing
and impact
attenuating characteristics generally known as 'soft wall' barriers. Due to
the relatively
low density of these materials, however, a significant depth of material is
required to
attenuate racing vehicles, thus decreasing the overall usable surface of the
racetrack.
Moreover, these materials are generally not resilient and a single impact may
exhaust or
significantly reduce the energy absorbing and impact attenuating
characteristics of such
barriers. In addition, unless a combination of materials of various densities
is utilized in
the 'soft wall' barrier design, the energy absorbing and impact attenuating
properties of
such a system are also of a single phase owing to the single density energy-
absorbing
medium.
Thermoset elastomers (TSE) consisting of cross-linked polymer chains have also
been
considered for 'soft wall' applications. Safari Associates, Inc. utilize a
material called
MolecuthaneTM for soft wall applications in automobile racing. While TSE
barriers may
be designed with suitable energy absorbing and impact attenuating
characteristics in their
thickness direction, and may provide mufti-phase absorption and attenuation
due to layers
of differing densities, they may cause a 'pocketing' response as described
below and are
also generally not recyclable as thermoplastic elastomers (TPE) are.
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CA 02406361 2002-10-15
Other 'soft wall' barrier solutions such as sacrificial inertial barriers that
utilize frangible
burners containing energy absorbing dispersible mass including sand and water
(Fitch,
1999, US Patent 5,957,616) have been described. A single, severe impact with
the
frangible barrier will not only exhaust or significantly reduce its energy
absorbing and
impact attenuating capabilities, but also may contaminate the racing surface
with the
dispersed energy-absorbing material.
However, 'soft wall' barrier solutions may result in a 'snagging' or
'pocketing'
characteristic that snags incident cars upon impact when they penetrate the
relatively soft
materials thereby causing a very fast deceleration of the incident car that in
fact may
cause significant damage to the driver in the collision of the car with the
'soft wall' due to
the pronounced deceleration forces associated with the 'pocketing' response.
A solution in prior art to the problems of 'soft walls' and 'pocketing'
responses is to use
an impenetrable outer surface to the barrier system such as high-density
polyethylene,
guardrails or rectangular metal tubing.
The Indy Racing League (IRL) and Indianapolis Motor Speedway (IMS) installed a
barrier system on the inside of Turn 4 in 1998 called the Polyethylene Energy
Dissipating
System (PEDS) utilizing 5-foot long overlapping, high density, polyethylene
impact
plates with two 16-inch diameter polyethylene cylinders bolted behind the
impact plates
acting as the energy absorbing medium. However, the high-density polyethylene
impact
plates are not sufficiently resilient when positioned on the outside of a
curve to avoid
penetration and subsequent 'snagging' or 'pocketing' by an impacting racecar.
Fitch (1999, US Patent 5,921,702) described a displaceable highway safety
barrier system
extending along the side of a roadway that includes a number of skid
assemblies resting
without attachment on a supporting surface adjacent to the roadway. However,
such
displaceable guardrail barriers require many mounting and interface members
and
significant space requirements. Fitch (2000, US Patent 6,010,275) also
described a
compression guardrail including a rail extending longitudinally along a
roadway with a
CA 02406361 2002-10-15
plurality of fixed support posts spaced behind the rail and resilient
compressible energy
absorbing means mounted between the rail and the posts. However, in both
systems
described by Fitch, the barrier itself is a continuous, strong, impenetrable
surface and,
while bendable, as such is not easily displaceable or compressible, therefore
not
providing as efficient an energy absorbing or impact attenuating response as
possible.
The Indy Racing League (IRL) and Indianapolis Motor Speedway (IMS) have
developed
a barrier system in conjunction with the Midwest Roadside Safety Facility at
the
University of Nebraska -Lincoln called the SAFER (Steel and Foam Energy
Reduction)
barner that was installed on the outside of turns at IMS in the spring of
2002. The barner
consists of four rectangular structural steel tubes welded together forming
sections, each
section joined to the next by heavy steel internal splines. Bundles of 2-inch
thick
polystyrene sheets are placed between the structural steel tube barrier and
the existing
concrete barrier. However, once again the barrier itself is a continuous,
strong,
impenetrable surface and as such is not easily bendable, displaceable or
compressible,
therefore not providing as efficient an energy absorbing or impact attenuating
response as
possible. The SAFER barrier has been described by those skilled in the art
(Bill Milliken,
Milliken Research Associates and John Fitch, Race Safety) as an extremely
rigid wall,
one whose section inertia is so high on the structural steel tubes that they
can't possibly
bend or deflect to absorb enough energy, thus not utilizing the energy
absorbing medium
(polystyrene blocks) effectively.
An effective and efficient racing safety barrier should resist damage or
breaking, avoid
snagging of incident vehicles or racecars, bend or displace to absorb a
significant amount
of impact energy, and redirect the incident vehicle or racecar without
bouncing it back
across the traffic stream. Thus, an object of an improved energy absorbing and
impact
attenuating barrier is to utilize the advantages of a 'soft wall' system,
i.e., effective
energy absorption due to the compression of an energy absorbing medium or
media, with
the advantages of a 'hard wall' barrier, i.e., without the inherent
detrimental 'pocketing'
response, yet provide for improved energy absorption by providing a more
bendable,
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CA 02406361 2002-10-15
displaceable and compressible barner system as compared to fixed, continuous,
'hard
wall' systems such the IRL SAFER system.
One such way of accomplishing the aforementioned characteristics of a more
efficient
racing safety barrier is to utilize a multiple cable barrier to 'suspend' an
impenetrable
barrier in overlapping sections such that the impacted section or sections are
capable of
displacing a significant distance against the tension or elastic stretching of
the suspending
cables so as to compress an energy absorbing media or medium, thus effectively
absorbing impact energy and attenuating the impact in a controlled fashion.
Those skilled in the art have described multiple cable barriers as traffic
safety barriers
decades ago; such cable barriers were largely replaced by better-performing
and lower
maintenance concrete and metal beam barriers. However, modern cable barrier
designs
perform significantly better than those used in the 1950s and 1960s and have
advantages
over concrete or metal beam barners such as being inexpensive and quickly
constructed,
and are relatively forgiving barriers that can more gradually attenuate the
impact of an
incident vehicle even in large angle collisions. Multiple cable (for the
purposes of this
description the term cable is synonymous with wire rope) safety barriers have
been
adopted by some U.S. states as guardrails and median barriers where the median
or
shoulder allows for sufficient deflection of the cables (Oregon Department of
Transportation, Weak Post Three-Cable Guardrail and Median Barrier Report;
Oklahoma
Department of Transportation, Brifen Four-cable Safety Fence). Multiple cable
or wire
rope safety barriers are also utilized extensively in other countries around
the world such
as Australia and the United Kingdom.
Thus, this invention relates to an improved suspended rather than fixed 'hard
wall' barrier
system of overlapping, impenetrable, dependent barrier sections that form a
continuous
crash barrier system capable of significant displacement, tensioning or
elastic stretching
of the steel suspending cables, and compression of an associated energy
absorbing
medium or media said energy absorbing medium or media used in this embodiment
to
enhance the energy absorption characteristics because of the limited distance
for
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CA 02406361 2002-10-15
deflection of the suspending cable and banter sections to absorb the impact
energy of
vehicles or racecars colliding with barner systems used on roadways or race
tracks
including, but not limited to, oval, tri-oval, speedway, super speedway,
temporary street
circuits, road racing courses, drag racing or any combination of the former.
The steel
cable suspended energy absorbing and impact attenuating burner system of this
invention
is installed in a prescribed fashion as described herein independently or with
existing
concrete barrier systems thereby interacting with incident colliding vehicles
or racecars
from a multitude of incident angles and in a multitude of orientations to
displace in a
controlled fashion, due to the tensioning or elastic stretching of the
associated steel
suspending cables and, in the preferred embodiment, compression of an
associated
energy absorbing medium or media, to absorb energy and attenuate the impact of
the
vehicle or racecar thereby decreasing the peak force of impact and
deceleration as
described in multiples of the force of gravity (g-force) and increasing the
time as
measured in milliseconds over which the peak gforce is exerted thereby
reducing injury
to the vehicle or racecar driver and damage to the incident colliding vehicle
or racecar.
Peak g-forces of deceleration resulting from impact and time over which the
impact
energy are absorbed are particularly significant in collisions between a
racecar and an
energy absorbing and impact attenuating burner system. Peak gforces associated
with
the impact must be reduced as much as possible and the length of time that
impact energy
is dissipated as measured in milliseconds must be increased as much as
possible.
The steel cable suspended energy absorbing and impact attenuating burner
system of this
invention may also be used in applications not associated with existing
concrete burners
to replace existing fixed steel or metal guardrail systems such as Armco
fencing on
roadways or in road racing circuits. In this embodiment of the invention, an
energy
absorbing medium or media may not be associated with the application and the
energy
absorbing response of the steel cable suspended energy absorbing and impact
attenuating
barrier system largely is due primarily to the displacement of the barrier
section or
sections against the tension or elastic stretching of the suspending steel
cables.
CA 02406361 2002-10-15
Upon impact by an incident racecar with the improved steel cable suspended
energy
absorbing and impact attenuating barner system of this invention, the racecar
will firstly
impact a suspended impenetrable barrier section or sections without any
harmful
'pocketing' characteristic, causing the suspended impenetrable barner section
or sections
to absorb energy of the collision by displacing in the direction of the impact
against the
tension of the steel suspending cables as the slack is taken up and potential
elastic
stretching of the cables, and compressing the energy absorbing medium or media
placed
in the space between the existing concrete barrier and plurality of
impenetrable apron
sections. The specified overlapping configuration of the plurality of
impenetrable apron
sections described herein will naturally redirect the car back to the racing
surface due to
the decreased compressive strength of the trailing segment of the plurality of
impenetrable barrier sections with respect to the leading segment of the
plurality of
impenetrable apron sections. After impact, the tensioning and potential
elastic stretching
of the steel suspending cables, and compression and elasticity of the energy
absorbing
medium or media will serve to rebound and partially realign the plurality of
impenetrable
barrier sections to their original positions (resting state). The impenetrable
barrier
sections are made of a material that is relatively impenetrable and inflexible
with respect
to the impact energies of the vehicle or racecar. Such materials include but
are not limited
to plate steel, rectangular or round tubing or beams, and sheet metal
guardrails (e.g.
Armco), however it is important that the barrier sections form a smooth
continuous
barrier surface with no significant abutments or openings. Complete
realignment of the
improved energy absorbing and impact attenuating barrier system described
herein is
quickly accomplished by repair crews.
Accordingly, several objects and advantages of the steel cable suspended
energy
absorbing and impact attenuating barrier system of the invention described
herein are:
(a) the energy-absorbing characteristics of the steel cable suspended energy
absorbing
and impact attenuating barrier system are not broken or exhausted after a
single impact
such as is the case in energy absorbing barner systems utilizing a light
density crushable
material such as foam (Nelson, 1999,US Patent 5,860,762) or metal (Muller,
1998, US
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CA 02406361 2002-10-15
Patent 5,851,005) that do not provide energy absorbing or impact attenuating
characteristics for a secondary incident following the primary impact prior to
repair being
effected.
(b) the steel cable suspended energy absorbing and impact attenuating barrier
system is
integrated easily and inexpensively with the existing concrete barrier system
as compared
to other 'soft wall' and 'hard wall' designs so as to be practical and
economical.
(c) the steel cable suspended energy absorbing and impact attenuating barrier
system is
relatively compact yet more efficient as compared to existing 'hard wall' or
'soft wall'
safety barners or other safety barriers because an energy absorbing medium or
media is
used in addition to the tensioning and potential elastic stretching of the
cables to attenuate
the incident vehicle upon displacement of the barrier sections.
(d) the steel cable suspended energy absorbing and impact attenuating barrier
system
elements are fixed with a minimum of hardware to the existing concrete barner
system in
a manner that prevents elements from being dislodged or damaged such that they
or
debris from them may be dangerous to other drivers, vehicles or spectators.
(e) there are no dispersible elements of the steel cable suspended energy
absorbing and
impact attenuating barrier system that will interfere with the racing circuit
or cause
consequence to the race after impact and consequent rupture of the energy
absorbing
barrier such as is the case with frangible barners.
(f) the energy absorbing characteristics of the steel cable suspended energy
absorbing and
impact attenuating barrier system are mufti-phase due to the inherent
compressive
strength of the barner sections due to their mass, cable tension and
elasticity, and energy
absorbing medium or media rather than providing a single phase attenuation due
to the
use of a single energy absorbing medium of consistent density, shape,
configuration or
physical dimension.
CA 02406361 2002-10-15
(g) the steel cable suspended energy absorbing and impact attenuating barner
system is
relatively more efficient in its energy absorbing response than current 'hard
wall' barrier
systems due to the ability of the suspended barrier sections to be
significantly displaced
in the direction of the impacting force of the collision energy and
significantly compress
the associated energy absorbing medium or media.
(h) the energy-absorbing and attenuating characteristics are designed such
that in relative
terms, the steel cable suspended energy absorbing and impact attenuating
barrier system
is:
~ relatively 'hard' for crash energy below approximately 5 to 10 times the
multiple
of the force of gravity (5-lOg). That is, the suspended barrier sections do
not displace
significantly and the racing vehicle primarily absorbs the bulk of the impact,
thus not
sacrificing absorption characteristics of the wall for inconsequential
collisions, nor
having 'soft' portions of the wall that an incident racecar could interact
with (e.g.,
puncture, get impeded by, get caught up with) in highly oblique collisions.
This is
achieved by means of the overlapping, impenetrable barrier sections positioned
in
intimate contact and in a prescribed fashion external to the energy absorbing
medium or
media and facing incident colliding vehicles or racecars.
~ relatively 'firm', yet progressively more energy absorbing and impact
attenuating
as compared to current 'hard wall' barrier systems for crash energy between
approximately 10 to 40 times the multiple of the force of gravity (10-40g).
That is, the
overlapping, impenetrable barrier sections displace on impact causing the
slack of the
suspending steel cables to be taken up, tensioning and potentially elastically
stretching
the steel cables, and partially compressing the associated energy absorbing
medium or
media, and the vehicle or racecar and said steel cable suspended energy
absorbing and
impact attenuating barrier system share the impact energy of the crash. Due to
the
preferred displacement of the trailing segment of the impenetrable barrier
section or
sections, the steel cable suspended energy absorbing and impact attenuating
barrier
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CA 02406361 2002-10-15
system will also assist in redirecting the incident vehicle or racecar back
onto the racing
surface after the collision.
~ relatively 'soft' for crash energy above approximately 40 times the multiple
of the
force of gravity (40g). That is, the overlapping, impenetrable barrier
sections displace
significantly on impact causing the slack of the suspending steel cables to be
taken up,
tensioning and potential elastic stretching of the suspending cables, and
compressing the
associated energy absorbing medium or media whereby the steel cable suspended
energy
absorbing and impact attenuating barrier system absorbs a shared but
increasingly larger
portion of the impact energy of the crash than current 'hard wall' barner
systems. Due to
the preferred displacement of the trailing segment of the impenetrable barrier
section or
sections, and the rebounding of the impenetrable barrier section or sections
against the
tension and elastic stretching of the suspending steel cables and compression
of the
energy absorbing medium or media, the steel cable suspended energy absorbing
and
impact attenuating barrier system will also assist in redirecting the incident
vehicle or
racecar back onto the racing surface after the collision.
(i) that, where it is understood that the impact absorbing and attenuating
barrier system is
not required to be installed adjacent to the existing concrete burner system
around the
racetrack in its entirety, that contoured or tapered end-piece components be
designed and
manufactured with a similar function to define the beginning and end of the
energy
absorbing and impact attenuating barrier system that do not pose a hazard.
(j) the steel cable suspended energy absorbing and impact attenuating barrier
system
manufacturing and installation process is simple thereby offering both an
economical and
practical advantage.
Further objects and advantages of the steel cable suspended energy absorbing
and impact
attenuating barrier system described herein are to provide an energy absorbing
and
impact attenuating barrier system for roadways and race tracks that are inert
to
environmental forces, require a minimum of maintenance and repair, and
maintain a
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CA 02406361 2002-10-15
surface for other previously defined functions of the concrete barrier system,
e.g.
advertising.
Still further objects and advantages will become apparent from review and
consideration
of the ensuing description and drawings.
SUMMARY OF THE INVENTION
Briefly, in the present invention a steel cable suspended energy absorbing and
impact
attenuating barrier system is described that provides absorption of impact
energy from a
colliding vehicle or racecar. The improved energy absorbing and impact
attenuating
barrier system for use as a motor sports or traffic safety barner described
herein
comprises a plurality of overlapping, impenetrable barner sections forming a
continuous
barrier at the periphery of or at a distance from the roadway or racing
surface suspended
in a generally vertical configuration with respect to the race track or
roadway by a
plurality of steel cables, and displaced from the existing concrete barrier by
an energy
absorbing medium or media. The steel suspending cables are held in place by
cable
support rings in which said suspending steel cables are free to slide back and
forth in said
cable support rings, said suspending steel cables having a designated slack or
tension per
barrier section depending on the desired maximum displacement of the
impenetrable
barrier section and impact energy, said cable support rings being fixed to the
impenetrable barrier sections, said suspending steel cables being fixed at
their terminus to
an immovable structure, said plurality of impenetrable barrier sections of
which are
positioned in a specified overlapping manner with respect to the direction of
traffic. The
plurality of impenetrable barner sections are anchored to existing concrete
barriers or
other structures by means of a plurality of generally horizontal steel cables
which also
attach to the cable support rings perpendicular to the direction of the steel
suspending
cables. An energy absorbing medium or media is positioned in the space between
the
concrete barriers and steel cable suspended impenetrable barner sections.
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Because the steel cable suspended energy absorbing and impact attenuating
barner
system of this invention is displaceable and not fixed, and comprises sections
to form a
continuous barner rather than a continuous inflexible or norrdisplaceable
impenetrable
barner as compared to those of prior art, the present invention offers an
improved energy
absorbing and impact attenuating response. The energy absorbing and impact
attenuating
response is provided by the tension and elastic stretching of the suspended
steel cables
against the displacement of the sections upon impact, and the compression of
the energy
absorbing medium or media by the displaced barrier section or sections. A
further
improvement of the present invention is the ability of the barrier system to
redirect
impacting vehicle or racecars back onto the roadway or racing surface in the
direction of
traffic resulting from the decreased compressive strength of the trailing
segment of the
impenetrable barrier sections relative to the leading segment.
The above discussed and many other features, objects and advantages of the
present
invention will be better understood by reference to the following detailed
description and
accompanying drawings.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to the ensuing diagrams, an exemplary steel cable suspended
energy
absorbing and impact attenuating barrier system 10 is shown generally in FIG.
1 wherein
said barner system is an energy absorbing barner for racecars on oval race
tracks
comprising a plurality of overlapping impenetrable barrier sections 11, 12,
13, 14, 15
forming a continuous barrier with respect to the roadway or racing surface and
direction
of travel of the racecar. In the preferred embodiment, the exemplary steel
cable
suspended energy absorbing and impact attenuating barrier system 10 is shown
integrated
with an existing concrete barner commonly used at oval racetracks. However,
the
exemplary steel cable suspended energy absorbing and impact attenuating burner
system
may be modified for use on roadways or other types of racing tracks and
integrated
with other structures. Whereas multiple cable safety barriers of prior art do
not utilize
impenetrable barrier sections placed in front of the cables to firstly
interact with an
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CA 02406361 2002-10-15
impacting vehicle or racecar, in the application of the exemplary embodiment
described
herein, the impenetrable barrier sections are required to prevent an incident
vehicle or
racecar from penetrating between cables and having the cables cause damage to
the
vehicle or racecar and driver or occupants.
Each barner section 11, 12, 13, 14, 15 is suspended in a generally vertical
alignment with
respect to the roadway or racing surface by a plurality of suspended steel
cables 6
generally parallel to and at different heights with respect to the roadway or
racing surface
whose diameter and core structure are dependent on the required tension,
elasticity and
breaking strength for a specific application, each suspended steel cable 6 of
which is held
in position by a plurality of cable support rings 3 at different heights with
respect to the
roadway or racing surface in which the suspending cables are free to move. The
inner
surface of the cable support rings 3 may be reinforced and lubricated to
facilitate such
movement. The plurality of cable support rings 3 are fixed to the barrier
sections 11, 12,
13, 14, 15 by stove head bolts 4 or similar fixing hardware that will not
intrude on the
smooth surface of the barner system to form abutments. The impenetrable
barrier
sections 11, 12, 13, 14, 15 are placed external to an energy absorbing medium
or media 8
in the preferred embodiment to face incident racecars. However, the steel
cable
suspended energy absorbing and impact attenuating barrier system 10 of this
invention
may also be used in applications not associated with existing concrete barners
9 to
replace existing fixed steel or metal guardrail systems such as Armco fencing
on
roadways or in road racing circuits. In the latter embodiment of the present
invention, an
energy absorbing medium or media 8 may not necessarily be associated with the
application and the energy absorbing response of the steel cable suspended
energy
absorbing and impact attenuating barrier system 10 largely is due primarily to
the
displacement of the barrier section or sections against the tension or elastic
stretching of
the suspending steel cables. The impenetrable barrier sections 11, 12, 13, 14,
15 may
overlap to form a linear or curved continuous burner.
The impenetrable barrier sections 11, 12, 13, 14, 15 are made of an
appropriate material,
core, thickness, and structure suitable for the strength required, for example
plate steel,
CA 02406361 2002-10-15
rectangular, round or other shaped metal tubing or beams, metal fencing or
guardrails.
Regardless of the material, the impenetrable barner sections 11, 12, 13, 14,
15 must form
a continuous barrier surface without any significant abutments or openings.
The
impenetrable barrier sections 11, 12, 13, 14, 15 are anchored to the existing
concrete
barrier 9 by steel cables 5 generally horizontal to and at different heights
with respect to
the roadway or racing surface whose diameter and core structure are dependent
on the
required tension, elasticity and breaking strength for a specific application
and are fixed
on the one end to the cable support rings 3 and on the other end to anchors 21
imbedded
within the existing concrete barners 9 or by other means.
The impenetrable barner sections have a leading segment 31 which is that area
extending
from top to bottom of the barrier section at the end of the barrier section
farthest along
the section with respect to the direction of travel of the vehicle or racecar,
and a trailing
segment 32 which is that area extending from top to bottom of the barrier
section at the
end of the barner section nearest on the section with respect to the direction
of travel of
the vehicle or racecar. The impenetrable barrier sections have a leading edge
33 which is
that cross-sectional surface at the end of the barrier section farthest along
the section with
respect to the direction of travel of the vehicle or racecar, and a trailing
edge 34 which is
that cross-sectional surface at the end of the barrier section closest along
the section with
respect to the direction of travel of the vehicle or racecar. The impenetrable
barrier
sections 11, 12, 13, 14, 15 have a plurality of overlap stops 7 fixed
generally at the
leading segment 31 at different heights on the internal surface of the barner
section to
butt against the overlapping trailing edge of the subsequent barrier section
to prevent
forward displacement (i.e., displacement in the direction of the traffic
direction) of the
impenetrable barrier sections 11, 12, 13, I4, 15 upon impact and maintain the
integrity of
the continuous barner surface formed by the overlapping impenetrable barrier
sections
11,12,13,14,15.
Generally, the steel cable suspended energy absorbing and impact attenuating
barrier
system 10 will be considered to have three states as shown generally in FIG. 2
for the
purposes of this description: resting, impact or compression, and rebound.
16
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The resting state of the exemplary steel cable suspended energy absorbing and
impact
attenuating barrier system 10 is shown generally in FIG. 2A. The barner
sections 11, 12,
13, 14, 15 are suspended in a generally vertical alignment with the roadway or
racing
track by anchor cables S having a diameter, core structure, tension,
elasticity and
breaking strength appropriate for the application with an energy absorbing
medium or
media 8 of appropriate density, compressive strength or strengths, and height,
width and
thickness interceding between the existing concrete barrier 9 and the barner
sections 11,
12, 13, 14, 15. Note that by adjusting the length of the upper, mid and lower
anchor
cables 5 that the barner sections may have a positive or negative camber with
respect to
the racing surface should such a camber provide an improved energy absorption
or
impact attenuation. The anchor cables 5 hold the barrier sections 1 l, 12, 13,
14, 15 in
intimate association with the energy absorbing medium or media 8. Thus the
barrier
sections 11, 12, 13, 14, 15 are maintained in a generally vertical alignment
with respect to
the roadway or racing surface on the one side by the energy absorbing medium
or media
8 and by the length and tension of the anchor cables S.
The barrier sections 1 l, 12, 13, 14, 15 overlap one another at their leading
segments 31
and trailing segments 32 by an appropriate length depending on the strength
and
maximum displacement of the barrier sections such that the leading segment 31
of one
section is positioned in front of (i.e., towards the roadway or racing surface
facing
incident vehicles or racecars) the trailing segment 32 of the next panel with
respect to the
direction of travel of the roadway or racing surface. The overlap length must
be
appropriate related to the strength of the barrier sections 11, 12, 13, 14, 15
such that an
impact at one section may flex the impacted barner section but will not cause
the
impacted barner section to deform permanently rather than transfer the impact
energy to
displace the trailing segment 32 of the next subsequent section. The overlap
length must
be appropriate related to the maximum displacement of the barner sections such
that at
maximum displacement of one panel with respect to it's previous or subsequent
barrier
section, that a continuous barrier surface is maintained with respect to the
travel of the
vehicle or racecar without creating an abutment or loss of integrity of the
barrier surface.
17
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The trailing edge of each the barrier sections 11, 12, 13, 14 butt against the
plurality of
overlap stops 7 fixed to the internal surface (i.e., facing away from the
roadway or racing
surface, or towards the energy absorbing medium or media 8) of the leading
segment of
barrier sections 12, 13, 14, 15.
The suspending steel cables 6 form a multiple cable safety barner and also
serve to
maintain the barrier sections 11, 12, 13, 14, 15 in their prescribed
overlapping fashion to
form a continuous impenetrable barner and have a diameter, core structure,
tension,
elasticity and breaking strength appropriate for the application and to also
function as a
multiple cable safety barrier. The suspending steel cables 6 have an amount of
tension or
slack per barrier section appropriate for the maximum displacement of the
barner
sections such that upon impact the barner sections 11, 12, 13, 14, 15 are
capable of
displacing an appropriate amount in the direction of the impact against the
taking up of
the slack, tension and elastic stretching of the suspending steel cables 6.
In the impact or compression state of the exemplary steel cable suspended
energy
absorbing and impact attenuating barrier system 10 shown generally in FIG. 2B,
the
barrier section 13 is impacted by an incident racecar 25 in an oblique
collision. The front,
right portion of the racecar 25 impacts barrier section 13 such that the
trailing segment of
barner section 13 more readily displaces and compresses the energy absorbing
medium
or media 8 because the leading segment 32 of barrier section 13 overlaps that
of barrier
section 12 in front (i.e., towards the roadway or racing surface) of barner
section 12, thus
requiring barrier section 12 to also be displaced against the tension of the
steel
suspending cables 6 and compression of the energy absorbing medium or media 8.
Forward displacement of the impacted barrier section 13 (i.e., displacement of
barner
section 13 in the direction of traffic towards barrier section 12 in oblique
collisions) is
prevented by the plurality of overlap stops 7 fixed on the internal surface of
the leading
segment 31 of barrier section 13 that butt against the trailing edge 34 of
barner section
12. The barrier section 13 displaces in the direction of the impact, trailing
segment 32
more so than leading segment 31, causing the incident racecar 25 to be
redirected back to
the racing surface in the direction of travel after impact and causing the
slack of the steel
18
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suspending cables 6 to be taken up, tension to increase and possible elastic
stretching
depending on the severity of the impact in the steel suspending cables 6
thereby causing
displacement of neighbouring sections 12 and 14 against the energy absorbing
medium or
media 8. The anchoring cables 5 of barrier sections 12, 13, 14 have slackened
while the
anchor cables 5 of other barrier sections will be at tension holding the
barrier sections
from pulling away from the concrete barriers to which they are attached due to
the
increased tension or potential elastic stretching of the steel suspending
cables 6. The
displaced barrier sections 12, 13, 14 will compress the associated energy
absorbing and
impact attenuating medium or media 8 to varying degrees, generally more so in
the
region of the trailing segment 32 of the impacted section 13. The barrier
sections 12, 13,
14 remain in an overlapped condition with one another even while displaced to
maintain
a continuous impenetrable barrier surface with respect to the travel of
racecar 25 without
creating an abutment or loss of integrity of the barrier surface.
In the rebound state of the exemplary steel cable suspended energy absorbing
and impact
attenuating barrier system 10 shown generally in FIG. 2C, the barner section
13 rebounds
after impact from the incident racecar 25 which has now been redirected and
traveled .
further along the racing surface. Subsequent to barrier sections 12, 13, 14
reaching their
maximum displacement due to the impact energy, steel suspending cable 6 is at
tension
and possibly stretched elastically depending on the severity of the impact due
to the
displacement of barner sections 12, 13, 14, and the energy absorbing medium or
media 8
is compressed to varying degrees more so in the region of the trailing segment
32 of
burner section 13. The steel suspending cable 6 tensioning and possible
elastic stretching,
and elasticity of the compressed energy absorbing medium or media 8 will cause
a partial
rebound of barrier sections 12, 13, 14 to their resting state positions after
the impact
depending on the severity of the impact. The barrier sections 12, 13, 14
maintain overlap
with one another even while rebounding to maintain a continuous impenetrable
barrier
surface that is maintained with respect to the travel of racecar 25 without
creating an
abutment or loss of integrity of the barrier surface. The barrier sections 12,
13, 14 are
then completely restored to their resting state positions quickly and easily
by repair
crews. The mufti-phase energy absorbing and impact attenuating module 10 is
designed
19
CA 02406361 2002-10-15
to be sufficiently resilient to accommodate multiple impacts and resist
incapacitating
damage that will cause it to lose integrity or function during a racing event.
Further details of the exemplary steel cable suspended energy absorbing and
impact
attenuating barner system 10 are shown generally in FIG. 3, FIG. 4, FIG. 5 and
FIG. 6.
Conceivably, those persons knowledgeable in this field of endeavor will, upon
studying
this disclosure, consider various modifications and/or improvements to the
inventive
concept presented, but still within this concept. Though primarily designed
for the
preferred embodiments and aspects as mentioned herein, this in no way limits
the use of
the invention. In fact, steel cable suspended energy absorbing and impact
attenuating
barrier systems may be useful in a wide variety of applications in which
energy
absorption and impact attenuation of a vehicle or racecar are desired.
Therefore, the
invention herein is not to be limited to the preferred embodiments and aspects
set forth as
exemplary of the invention, but only by the scope of the claims and the
equivalents
thereto.
CA 02406361 2002-11-27
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of an exemplary steel cable suspended energy
absorbing and impact
attenuating barrier system wherein said barrier system is an impact-absorbing
barrier for race tracks
or roadways.
FIG. 2 is a top view of an exemplary steel cable suspended energy absorbing
and impact attenuating
barrier system wherein said burner system is impacted by an incident racecar.
Figure 2 consists of
three sub-figures representing the dynamics of the crash and response of the
exemplary steel cable
suspended energy absorbing and impact attenuating barrier system.
FIG. 2A demonstrates an incident racecar and said exemplary steel cable
suspended energy
absorbing and impact attenuating barrier system in its resting state.
FIG. 2B demonstrates the impact of an incident racecar with said exemplary
steel cable suspended
energy absorbing and impact attenuating barrier system and exhibits the
response of said exemplary
steel cable suspended energy absorbing and impact attenuating barrier system
in the impact or
compression phase.
FIG. 2C demonstrates the re-direction of the impacting racecar back onto the
racetrack by
preferential deflection of the trailing segment of the impacted barrier
section and the response of
said exemplary steel cable suspended energy absorbing and impact attenuating
barrier system after
the impact during the rebound state.
FIG. 3 is a detailed top view of an exemplary steel cable suspended energy
absorbing and impact
attenuating barrier system in its resting state isolating the overlapping
joint of t:he barrier sections,
steel suspending cables, anchor cables and cable support rings of an exemplary
steel cable
suspended energy absorbing and impact attenuating barrier system in its
resting state.
FIG. 4 is a side view of an exemplary steel cable suspended. energy absorbing
and impact
attenuating barrier system in its resting state.
CA 02406361 2002-11-27
FIG. 5 is a top view of an alternate embodiment of an exemplary steel cable
suspended energy
absorbing and impact attenuating barrier system in which the energy absorbing
medium or media is
placed between the anchor cables of the leading segment of one impenetrable
barrier section and the
anchor cables of the trailing segment of the subsequent impenetrable barrier
section.
FIG. 6 is a side view of an alternate embodiment of an exemplary steel cable
suspended energy
absorbing and impact attenuating barrier system in which the upper anchor
cable is anchored to
withstand the potentially higher tension created when an open wheel racecar
(e.g. IRL or CART
racecar) impacts the impenetrable barrier section lower to the racing surface
in comparison to a
closed wheel car (e.g., NASCAR car).
CA 02406361 2002-11-27
[DRAWINGS]
Figure 1 Figure 2A
Figure 2B Figure 2C
Figure 3 Figure 4
Figure 5 Figure 6
