Note: Descriptions are shown in the official language in which they were submitted.
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ROADWAY
FIELD OF THE INVENTION
The present invention concerns a roadway having a rail
installed in it . Such roadways are used in particular f or j oint
use by road vehicles and railway vehicles especially light
railway vehicles.
BACKGROUND OF THE PRESENT INVENTION
The rails for a railway are I-beams supported by
transverse sleepers on a bed of ballast on a prepared base.
Where a road crosses a railway, the surface of the road is level
with the tops of the rails and the space between the rails is
then built up. These rails have a high profile in that the
width of the rail is very much less than the depth. For street
railways or tramways a similar high profile rail is used. Thus
tramways used a so-called phoenix rail which is generally an
I-beam but with a groove for flanges of the vehicle wheels
formed in the upper flange. To install such a rail in a road,
it is necessary to excavate the road surface to a depth of at
least 50 centimetres to provide for a sleeper or bed of concrete
under the rail which itself would be 18 centimetres depth. Such
a deep excavation entails re-routing underground services such
as water and electricity mains and destroys the integrity of the
road construction. Ways of reducing the depth of excavation
have been developed in Dresden in the late 50' s wherein the rail
was cast in concrete panels about 20 centimetres deep (but this
involved shortish lengths of rail which had to be welded
together) and in Budapest by Dr. Zahummensky in which rails are
inserted in steel-lined channels in concrete panels with the
rails being 7 centimetres deep and the panels 18 centimetres
deep. A snag with such panel systems is that the panels have a
tendency to settle or rock, in the Dresden system this is
resisted by the rigidity of the phoenix-type track. In
International Patent Publication WO 84/00391 there is described
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a phoenix-like rail consisting of an I-beam with a small foot
and a large head. This is said to lead to a reduction in the
number of sleepers and other bed structures because flanges
forming the head take substantially or essentially all the
loading onto the roadway which is of crushed stone structure
possibly bound by a surface coating of bitumen. It is said that
the depth of excavation needed to install the rail is reduced
but as illustrated it shows that the excavation is more than
twice the depth of the rail. It would seem moreover that the
rail has to be rather deep since crushed stone would tend to
settle unless the stiffness of the rail resisted such settling.
U.S. Patent 3,089,650 shows a rail with flanges towards the top
but these flanges are to provide a suitable area moment in a
weighing device. This rail would not be suitable for use in a
roadway since the groove is large being intended to receive the
entire wheel width and not merely a wheel flange and such a
large groove would tend to trap road vehicle wheels and be
dangerous.
SUMMARY OF THE PRESENT INVENTION
The present invention provides a roadway having a
recess in which is installed a rail, which rail has an upper
surface for supporting vehicle wheels, a groove in that surface
for receiving wheel flanges of those wheels, a bar portion
providing that surface and that groove, and a pair of flanges
extending integrally from the bar portion to spread the rail's
wheel loading over part of the roadway's surface characterized
in that the rail has a depth substantially less than its width
and in that the recess, whilst shallow, has a depth such that
the rail can settle into the recess so that the rail is
effectively suspended from the flanges.
More specifically, there is provided in a first aspect
of the invention, a roadway for rail and road vehicles having a
pair of rails recessed into a road surface, each of which rails
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consists of a central squat bar portion and a pair of flanges
extending integrally sideways from the top of the bar portion,
the bar portion serving to provide a groove in an upper surface
of the rail for supporting road wheels of a rail vehicle, which
groove is for receiving flanges of the wheels, characterized in
that each rail has a depth substantially less than its width and
has its bar portion installed in a relatively shallow recess
preformed in the road surface to a depth so as to receive the
bar portion with the flanges effectively supporting the rail.
According to a second aspect of the invention, there is
provided a method of constructing a roadway for rail and road
vehicles comprising a pair of rails recessed into the road
surface proper by forming a road surface with shallow performed
recesses and then inserting the rails which have central squat
bar portions, each defining an upper surface for wheels of the
rail vehicles and a groove for flanges of said wheels and
flanges extending integrally sideways from the top of the said
bar portion, and each rail having a depth substantially less
than its width and each recess being sized so as to receive the
bar portion of the rail with the flanges supporting the rail in
the recess.
Modern roads in cities where light railways are more
likely to .share a road with road traffic are built to high
standards capable of carrying 40 tonne vehicles with 11 tonne
wheel loadings. These roads are expensive to construct and the
present invention minimizes the amount of excavation needed to
install rails. The flanges serve the functions of spreading
vertical loading, gripping the roadway to resist cross-loading,
and to minimize damage to the roadway due to water seeping down
the sides of the bar portion. The flanges can have ridges to
bite into the roadway and/or a sealant can be used to provide a
water seal and to absorb sideways loading. Where sideways
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loading is expected to be very large, sections of phoenix track
can be used.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a section of a rail fitted in a roadway,
Figure 2 is a perspective view of a pair of rails
fitted in a roadway, and
Figure 3 is a perspective view showing a rail
intersection.
DESCRIPTION OF AN EXEMPLARY EMBODIMENT
Figure 1 illustrates on a large scale a rail 11 in a
shallow recess 12 in a roadway 14. The recess can be, for
example 4 centimetres deep and 10 centimetres wide. The rail
has a central bar portion 15 which is generally a regular
trapezium in section but with a groove 16 for a vehicle wheel
flange in the wider surface which in use is the uppermost
surface of the rail. Extending integrally sideways from the bar
portion, there is a flange 17 on each side of the rail. The
recess is preferably cut out by suitable cutters such as disc or
other cutters cutting the sides of the recess and such as a
plane or other cutters removing the material remaining between
the cut sides of the recess. The recess is then partially
filled with a suitable material 18 so that when a rail is
inserted in the recess the rail can be settled into the material
18 so that the vertical loading is effectively taken by the rail
being suspended from the flanges. The rail can be of steel,
iron or another material rolled, extruded or otherwise
fabricated into the squat T-shape illustrated. The rail can be
secured in place by mechanical or other means such as an
adhesive bond which preferably has a degree of resilience as is
provided by Corkelast. It is possible to provide ribs or a
shallow groove in the underside of each flange to improve the
sealing and the resistance of the rail to sideways movement.
Rails can be welded or otherwise joined end-to-end to form a
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continuous track and can be laid under tension to avoid thermal
expansion problems. As shown in Figure 2, a pair of rails will
normally be used and a pair of recesses can be cut
simultaneously using ganged cutters to ensure correct spacing.
Cross ties not illustrated can be provided at intervals to form
gauge defining devices and these can be recessed below the
roadway surface .
To avoid crossing road traffic and in particular two-
wheeled vehicles such as pedal and motor cycles being
inconvenienced by the smooth metallic bumps formed by the rails,
the space between the rails 11 is built up to the top of the
rails by .a thin layer of tarmac 20 or other road facing
material. It would be possible to recess the flanges slightly
in the road surface so that they are substantially flush with
the roadway and then merely fill the seam alongside the flanges
with tarmac or the like. It would also be possible to have the
flanges slightly down from the top of the rails with tarmac or
other material on top of the flanges to minimize the amount of
metal exposed.
Figure 3 illustrates a junction piece which would be
cast or otherwise formed and comprises two rails 21 and 22
crossing at an angle with the grooves in the two rails extending
across the central intersection 23. Where more complicated
arrangements are involved such as junctions, special provisions
might be made such as the provision of sections of conventional
phoenix tracks but a suitable adaptation of Figure 3 is
possible.
The present invention is mainly for use where road
vehicles and track vehicles share road space. Such situations
arise where there are tramways or light urban railways. The
invention can be used even when such tramways or urban light
railways run on segregated tracks and even for mainline
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railways. Where segregated tracks or mainline railways are
involved the roadway in which the rails are laid can be made of
heavy concrete or stone slabs or panels or even on a continuous
concrete bed laid in situ; with such concrete roadways there
would have . to be expansion j oints but the recesses can be formed
during manufacture or laying wet concrete. For example the
recesses can be formed by a slip-form paviour or other machine.
The low profile rail according to the present invention offers
advantages due to the reduction in rail height over traditional
railway track especially when a track is being adapted for
electrification or gauge conversion since it would not be
necessary to lower an existing track bed possibly exposing wall
foundations in existing tunnels.
The rails can be used for signalling or electric power
supply if the rails are insulated. However it is probably not
possible to supply sufficient power to drive a vehicle in this
way but only to use the rails has a return path and then it
would be desirable to bond the rails to a low resistance earth
cable at intervals to avoid earth leakage currents interfering
with other services.
The cross-section of the rails depends on the use. The
groove is shaped to suit the intended traffic and can for
example not only engage those wheels supporting a vehicle but
also steering wheels which engage the groove and transmit
steering information to the supporting wheels. The central bar
portion would be deep enough to provide an adequate groove and
typically would be about 7 centimetres deep with 4 centimetres
recessed in the roadway, and would be typically 10 centimetres
wide with the flanges extending further out by sufficient
distance bearing in mind the substrate load-bearing capacity to
suspend the rails from the roadway so the vertical and
horizontal loading on the rails is taken on the upper surface of
the roadway without appreciable settlement unlike the previous
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systems where the vertical loading was taken to the bottom of
the rails.
Even when the flanges are offset or recessed down the
bar portion and the flanges as well as the bar portion are
recessed in the roadway, the vertical loading is taken near to
the top surface of the roadway. It is thought that having the
flanges recessed into the roadway will only be practical when
the recesses are preformed during roadway laying or when the
rails can ~be laid during roadway construction with the final
surfacing burying the flanges without raising the intended level
of the roadway.
