EP2260147A1

EP2260147A1 - A rail track system

Info

Publication number: EP2260147A1
Application number: EP09714611A
Authority: EP
Inventors: Colin Davies; Mick Large; Shreekant Jaiswal; Dave Farrington; Les Hodgson; Farzad Neysari
Original assignee: Corus UK Ltd
Current assignee: Tata Steel UK Ltd
Priority date: 2008-02-29
Filing date: 2009-02-27
Publication date: 2010-12-15
Also published as: WO2009106346A1; GB0803824D0

Abstract

The invention relates to rail track system comprising a frame for supporting the rails and a solid base for distributing the load on the frame into the ground. The invention also relates to railway comprising said rail track system and the use thereof.

Description

A RAIL TRACK SYSTEM

The invention relates to a rail track system and a railway comprising said rail track system. There are two main types of rail track system known, ballasted track and slab track.

In ballasted track, sleepers or other rail support members sit on a bed of crushed rock (ballast).

Ballasted track is inexpensive to install, but requires constant maintenance as the condition of the track changes with time. Extensive machinery has been developed for lifting the track, and reinstating the necessary level of ballast. This is often combined with partial "cleaning" of the ballast to adjust the size profile. This results in additional costs, and can cause problems where access is difficult. In slab track, the rail support members are embedded in a concrete slab.

Embedding the rail support members in concrete prevents the condition of the track from changing with time. This means that slab track is essentially maintenance free. However, it also means that it is not possible to correct for ground movement. The tracks must therefore be built on ground which has been treated to prevent ground movement.

This is done by excavating the soil, and replacing it with "improved" soil or by more expensive combinations of soil and other materials such as cementitious material to give added strength, resistance to water ingress and frost protection. This means that, although the cost of maintaining slab track is low, the cost of installing slab track is high.

Moreover, in the transition from ballasted track to slab track, it becomes necessary to maintain "springiness" in the response of the system to vehicle forces, so that transient interfacial wheel to rail forces continue to be attenuated. This leads to the use of specialised rail support systems which allow greater movement of the rail without excessive lateral movement of the head. This is particularly difficult to arrange when S&C (switches and crossings) are mounted on slab track as the relative positioning of different components has to be maintained despite increased movement at the rail level. This means that using slab track with S&C is complicated.

In addition, slab track has the disadvantage that it cannot be used until the concrete has fully cured. It is an object of the invention to seek to mitigate the problems which are met with ballasted track and slab track.

Accordingly, the invention provides a rail track system comprising a frame for supporting the rails and a solid base for distributing the load on the frame into the ground. This system can be used to carry both plain line and S&C. The individual members of the system may be made adjustable in any direction by the provision of slotted holes in the attachment points. The separation of the system into 2 parts, the frame and the base, means that height adjustment is made feasible and relatively simple both at installation and in later life.

The term "solid base" as used herein means a base which does not alter its shape over time, and remains in substantially the same position as that in which it was originally installed.

In the rail track system of the present invention, the rails are carried by a frame, rather than being embedded in concrete. This means that the rail track system is able to be adjusted if there is ground movement, with the result that only minimal preparation of the ground is necessary before installation of the system. Installation costs are therefore much lower than is the case for slab track.

Moreover, because the rails are supported on a frame, the system maintains "springiness" in its response to vehicle forces without the use of specialised rail support systems, with the result that the rail track system of the present invention is easier to use with S&C than slab track. Moreover, for S&C the frame may be adapted by drilling or cutting to allow the mounting of machinery or actuator arms or electrical cable etc, within the boundaries of the frame. If necessary the longitudinal members may be interspersed and not continuous within the overall structure.

In addition, because the load is distributed into the ground through a solid base, rather than through ballast, the shape and position of the base does not change with time, meaning that less maintenance is required than is the case with ballasted track. Resilient elastomeric material may be provided between the frame and the solid base.

Also, the inherent strength of the frame may be used to act as a bridge over short distances optionally supported by bespoke foundations that would eliminate effect of weak grounds. This would speed up the site erection, hence reducing cost and erection time considerably.

An advantage or tne system accorαiπg to tne invention is tnat wnoie or part assemblies may be created and carried to the installation site, to be installed together instead of as individual components.

The frame may be supported on one or more feet which are in contact with the ground. The feet will assist in transferring load to the ground. The vertical loads of the system may be carried by "stools" which are seated on the lower flanges of the longitudinal members. The frame may be supported on one or more feet which are in contact with the base and/or the ground.

The frame and/or the base may be carried by piles driven into the ground beneath the frame and/or the base.

The frame may comprise a plurality of transverse members for carrying the rails. The rails may be mounted on the system, preferably on the transverse members, using direct fixings or resilient baseplate systems.

The transverse members may be supported on one or more longitudinal members.

The transverse members and/or the longitudinal members may have one or more feet which are in contact with the ground and/or the base. The attachment of the transverse member of the frame to the base or elongate members therein may include a resilient or spring type fixing. The purpose of this would be to enable, through friction from the clamping force, the transfer of longitudinal forces into the solid base whilst accommodating the desired movement in other directions. The feet may be reinforced to facilitate transfer of load through the feet into the ground, e.g through the attaching or placing of steel plates under the feet

The transverse members may comprise means to facilitate transfer of load to the base, for example through built in adjustable screws.

The base may be positioned beneath the transverse members and in between the feet.

Provisions may be made for expansion to relieve stresses in the longitudinal members used as feet, typically at joints between such members.

The base may comprise concrete. If the frame comprises feet which are in contact with the ground, the track system may be used by rail traffic even during the period in which the concrete base is curing, because the feet will transfer load into the ground. Once the concrete has cured, the position of the frame on the base can be adjusted using jacks or screws in order to facilitate transfer of load into the ground via the base. The position of the frame can also be adjusted to obtain the correct geometry. Provisions may be made for inspection of the lower parts of the longitudinal members by restricting the width of the concrete base.

The concrete base may be reinforced.

The reinforcement for the base may be surrounded by concrete. This will protect the reinforcement from corrosion. Any suitable reinforcement may be used. In the described embodiment, the reinforcement comprises a plurality of elongate members. These are made from steel.

The base may comprise a metal, preferably steel. For example, the base may comprise a plurality of elongate steel members. The steel may be protected from corrosion.

The base may be concrete-free.

A shock absorbing material may be positioned between the frame and the concrete base. This may be the resilient elastomeric material described above. This will cushion wheel loads and will also ensure that the transverse members are uniformly supported.

The frame may comprise a thermally insulating material, and/or a noise insulating material.

According to a second aspect, a railway comprising the rail track system in accordance with the invention, and the use thereof is provided.

The invention will now be illustrated by way of example with reference to the following drawings of which:

Figure 1 shows a prior art ballasted track system; Figure 2 shows a prior art slab track system;

Figure 3 shows a side cross-sectional view of a rail track system according to the invention; Figure 4 shows a perspective view of the frame of the rail track system shown in Figure 3; and

Figure 5 shows a side cross-sectional view of a rail track system according to the invention showing the attachment of the transverse member of the frame to the base with a resilient or spring type fixing. Figure 1 shows a prior art ballasted track system. The rails 1 are carried on Y shaped steel sleepers 2 which sit on a bed of ballast 3.

Figure 2 shows a prior art slab track system. The rails 4 are carried on a series of concrete tubes 5. The ground 6 beneath the concrete tubes has been excavated and replaced with a mixture of soil and a cementitious material 7. The rail track system of the present invention shown in Figures 3 and 4 comprises a steel frame 8 and a concrete base 9 for distributing the load on the frame 8 into the ground.

The frame 8 comprises two parallel, spaced apart longitudinal members 10 connected together by a plurality of parallel, spaced apart transverse members 11 for supporting the rails 12. Each longitudinal member 10 comprises a load bearing H beam or asymmetric beam having a top flange 13 and a bottom flange 14 separated by a central web 15. The bottom flanges 14 of the longitudinal members 10 rest on the ground, and act as feet for the frame 8. A number of blocks 16a, 16b, 16c are attached to the underside of the transverse members 11 to assist with transferring the load on the frame 8 into the ground. A block 16b is provided in the centre of each transverse member 11 and a block 16a, 16c is also provided at each junction between a transverse member 11 and a longitudinal member 10. The blocks 16a, 16c are cubic in shape and are of such a size that they can be positioned with one side abutting the lower surface of the top flange 13 of the longitudinal member 10, one side abutting the upper surface of the bottom flange 14 of the longitudinal member 10, and one side abutting the central web 15 of the longitudinal member 10. The blocks 16b are also cubic in shape. The frame 8 may include in its interstices a thermally insulating material (not shown) to provide frost protection. The frame 8 may also include in its interstices a noise absorbing material (not shown).

The frame 8 may be protected against corrosion.

Load distribution may be further improved by inserting reinforcing bar, carbon fibre wire or a similar material as perpendicular stiffeners.

The frame 8 is supplied in sections which included connecting flanges (not shown) to enable the sections to be connected together using either bolts or grooved locking pins. These flanges may include expansion capability to reduce thermal effects. The rails 12 are mounted on a baseplate 17 with an elastomeric pad 18 underneath it. The softness of the pad 18 and the mass of the baseplate 17 are selected to reduce noise and vibration.

The rails 12 may be provided with additional damping means to reduce noise radiation. The concrete base 9 comprises a plurality of elongate members 19 encased in concrete 20. Each elongate member 19 comprises two inclined side webs 21 separated by a central horizontal web 22, and is positioned so that it is parallel to the two longitudinal members 10. Each member 19 may include holes or projections (not shown) to enable the member 19 to bond with the surrounding concrete 20.

The concrete base 9 is positioned beneath the transverse members 11 and in between the longitudinal members 10 of the frame 8. There is a gap 23 between the upper surface of the concrete base 9 and the lower surface of the transverse members 11 to allow a shock absorbing material to be positioned between the frame 8 and the concrete base 9.

Channels (not shown) may be provided in the concrete base 9 to allow for drainage.

In order to install the rail track system, a plurality of parallel spaced apart elongate members 19 are positioned in the area where the track is to be laid. A section of the frame 8 is then deposited on top of the parallel members 19 so that the member 19 are positioned beneath the transverse members 11 and in between the longitudinal members 10 of the frame 8. There is a gap 23 between the upper surface of the members 19 and the lower surface of the transverse members 11. Finally, two rails 12 are mounted on a baseplate 17 carried on an elastomeric pad 18 on top of the transverse members 11 of the frame 8. Concrete 20 is then poured into the area beneath the transverse members

11 and in between the feet of the longitudinal members 10 to form the concrete base 9. Joints in the concrete base 9 may be achieved by staggering the ends.

Once the concrete has cured, a shock absorbing material is positioned in the gap 23 between the upper surface of the members 19 and the lower surface of the transverse members 11.

As the longitudinal members 10 are in contact with the ground, i.e. act as feet, the track system may be used by rail traffic during the period in which the concrete 20 is curing. The load on the frame 8 will be transferred to the ground via the longitudinal members 10 which are stiffened and strengthened by the blocks 16a, 16c. Once the concrete has cured, the blocks 16b on the transverse members 11 will also play a part in transferring load into the ground, via the concrete base 9. To facilitate transfer of load into the ground via the blocks 16b, jacks or screw bit taper packs are used to adjust the position of the frame 8 on the concrete base 9. The frame 8 is also adjusted to achieve the desired geometry.

As the rail track system of the present invention can be corrected for ground movement, only minimal ground preparation is necessary before installation. However, where the ground is not stabilised, it may need to be strengthened, for example by injecting columns into the ground which can be directly connected to the frame 8. S&C can be supported directly by the frame 8, in which there is increased space for the drivegear and signalling.

If it is desired to increase mass in areas requiring low vibration, the whole rail track system may be embedded in concrete.

Figure 5 shows a side cross-sectional view of a rail track system according to the invention showing the attachment of the transverse member of the frame to the base with a resilient or spring type fixing 24.

The above embodiment is described by way of example only. A number of possible modifications will be apparent to the skilled person without departing from the scope of the claims.

Claims

1. A rail track system comprising a frame for supporting the rails and a solid base for distributing the load on the frame into the ground.

2. A rail track system according to claim 1, wherein the frame is supported on one or more feet which are in contact with the ground.

3. A rail track system according to claim 1 or claim 2, wherein the frame comprises a plurality of transverse members for carrying the rails.

4. A rail track system according to claim 3, wherein the transverse members are supported on one or more longitudinal members.

5. A rail track system according to claim 3 or claim 4, wherein the transverse members and/or the longitudinal members have one or more feet which are in contact with the ground.

6. A rail track system according to any preceding claim, wherein the feet are reinforced to facilitate transfer of load through the feet into the ground.

7. A rail track system according to any of claims 3 to 6, wherein the transverse members comprise means for facilitating transfer of load to the base.

8. A rail track system according to any of claims 3 to 7, wherein the base is positioned beneath the transverse members and in between the feet.

9. A rail track system according to any preceding claim, wherein the base comprises concrete.

10. A rail track system according to claim 9, wherein the concrete base is reinforced.

11. A rail track system according to claim 10, wherein the reinforcement for the base is surrounded by concrete.

12. A rail track system according to claim 10 or claim 11, wherein the reinforcement for the base comprises a plurality of elongate members.

13. A rail track system according to any of claims 1 to 8, wherein the base comprises a metal, preferably steel.

14. A rail track system according to claim 13, wherein the base comprises a plurality of elongate members.

15. A rail system according to claim 13 or claim 14, wherein the base is concrete-free.

16. A rail track system according to any preceding claim, wherein a shock absorbing material is positioned between the frame and the base.

17. A rail track system according to any preceding claim, wherein the frame comprises a thermally insulating material.

18. A rail track system according to any preceding claim, wherein the frame comprises a noise absorbing material.

19. A rail track system substantially as described herein or as shown in Figures 3 and 4 of the drawings.

20. Railway comprising the rail track system in accordance with any one of claims 1 to 19.

21. Use of the railway according to claim 20.