GB2426539A

GB2426539A - Sleeper

Info

Publication number: GB2426539A
Application number: GB0510513A
Authority: GB
Inventors: Andrew Raymond Foan
Original assignee: Balfour Beatty PLC
Current assignee: Balfour Beatty PLC
Priority date: 2005-05-23
Filing date: 2005-05-23
Publication date: 2006-11-29
Anticipated expiration: 2025-05-23
Also published as: GB0510513D0; CN1868794A; TW200706739A; HK1093228A1; GB2426539B

Abstract

A sleeper for supporting two parallel rails. The sleeper comprises a hollow elongate body having a slot 9 in an upper surface of the body for receiving cables. The slot extends at an angle to the length of the sleeper such that a first end of the sleeper has a relatively wide portion on a first side of the slot and a relatively narrow portion on an opposite second side of the slot, and a second end of the sleeper has a relatively wide portion on the second side of the slot and a relatively narrow portion on the first side of the slot. Each relatively wide portion is provided with a rail fastening member 19a,19b adapted to fasten a respective different rail to the sleeper. The sleeper is formed from metallic sheet material, and the upper surface is reinforced beneath each rail fastening member by an angled bracket running the length of the rail fastening member.

Description

SLEEPER This invention relates to a sleeper for supporting railway track. More particularly, this invention relates to a sleeper for supporting railway track and through which cables may be routed. Railway systems conventionally comprise railway track supported on sleepers. Sleepers are elongate lengths or timber of concrete that are set into a bed of ballast and provide a level surface onto which the rails of the railway track are mounted. The sleepers are positioned perpendicular to the rails and are spaced at regular intervals along the railway track. There is a requirement in railway systems for electrical cables to cross the railway track at regular intervals. For example, electrical cables carrying control signals for a railway signal often have to cross a railway track from a control box. Such cables may cross the railway track either above or below the rails. Where cables cross the railway track above the rails, it is necessary to provide a bridge for the cables so that they do not interfere with the passage of railway traffic. However, cable bridges are expensive and are susceptible to damage. Where cables cross the railway track under the rails, it is necessary to provide a passage for the cables without affecting the stability of the of the rails. Ideally, such cable passages should include sufficient clearance to allow the cables to be replaced easily during maintenance activities. It is known to provide a sleeper having a hollow bore and through which cables may be routed. However, during installation, the cables have to be fed through the bore from one end of the sleeper to the other end of the sleeper. This is inconvenient, especially in situations where the cables are laid out before the railway track is installed. According to the invention, there is provided a sleeper for supporting two parallel rails, the sleeper comprising a hollow elongate body having a slot in an upper surface of the body for receiving cables, wherein the slot extends at an angle to the length of the sleeper such that a first end of the sleeper has a relatively wide portion on a first side of the slot and a relatively narrow portion on an opposite second side of the slot, and a second end of the sleeper has a relatively wide portion on the second side of the slot and a relatively narrow portion on the first side of the slot, wherein each relatively wide portion is provided with a rail fastening member adapted to fasten a respective different rail to the sleeper. Because of their function, the rail fastening members have to be a certain minimum size. Consequently, the rail fastening members, or the upper surface of the sleeper onto which they mount, restricts the width of the slot. However, by providing rail fastening members on opposite sides of the slot for respective different rails, the rail fastening members are spaced apart along the length of the sleeper. In this way, the invention provides a sleeper having a slot that is able to receive large cables along an oblique route defines by the slot. By providing rail fastening members on opposite sides of the slot for respective different rails, the loads on the sides of the sleeper are balanced. Preferably, only one rail fastening member is provided on each side of the slot. However, in certain embodiments, two or more rail fastening members may be provided on one side of the slot. For example, an embodiment for supporting the rails of a multiple gauge railway track may have a plurality of rail fastening members on one side of the slot. Preferably, each relatively narrow portion is provided with a rail supporting member adapted to support a respective different rail. In this way, a rail fastening member and a rail supporting member may be provided on each side of the slot. Each rail may then be fastened to the sleeper on one side of the slot and supported by the sleeper on the other side of the slot. A width of the rail support members is preferably much than a width of the rail fastening members, so as not to restrict the width of the slot. The sleeper is preferably formed from metallic sheet material, such as 12mm thick sheet steel. In this case, the body of the sleeper is defined by the sheet material. The slot in the upper surface is preferably an oblique slot having substantially parallel sides, and the upper surface of the body then includes substantially triangular, or tapered, portions on either side of the slot. The parallel sides of the slot may be at an angle of a few degrees, for example between 1 and 5 degrees, to the parallel sides of the sleeper. In a preferred embodiment, the body is reinforced beneath each rail fastening member. In this way, the large loads that are transmitted to the sleeper when a rail vehicle travels along the railway track may be accommodated, and durability of the sleeper improved. The reinforcement is preferably provided by angled reinforcement brackets attached to an inside of the body, each bracket running at least the length of a respective rail fastening. Because the brackets are angled, their intrusion into the space for cables is minimal. The invention also provides a railway track arrangement comprising two spaced parallel rails, a plurality of sleepers supporting the rails and at least one cable, wherein at least one of the sleepers is a sleeper as described above having the at least one cable routed through its slot. Also provided is a method of forming the sleeper described above, comprising: forming a first fold in a pre-shaped sheet of metallic material; forming four parallel folds in the sheet to define a base, the sides and the upper surface of the sleeper, wherein the first fold maintains an open structure of the sheet to facilitate the subsequent folding operations; and removing the first fold from the sheet to provide a closed sleeper structure. For example, the first fold may be formed along a portion of the sheet that will become the base of the sleeper. Four right angled folds defining the four surfaces of the sleeper are then formed in an opposite direction to the first fold. The first fold maintains an open structure during the folding step, so that conventional tooling can be used. Once the four right angled folds have been formed, the first fold is removed to provide the closed sleeper structure. Preferred embodiments of the invention will now be described, by way of example only, with reference to the following drawings in which: Figure 1 is a plan view of a sleeper according to the invention; Figure 2 is a side view of the sleeper shown in Figure 1; Figures 3, 4 and 5 are cross-sectional views of the sleeper shown in Figure 1 taken across lines A-A, B-B and C-C respectively; and Figure 6 is a railway track arrangement according to the invention. It should be noted that the drawings are not to scale, and certain features have been emphasised for the sake of clarity. It should also be noted that the crosssectional views shown in Figures 3 to 5 include elements that do not form part of the sleeper, in particular cables 11. In the drawings, dashed lines indicate hidden detail. The invention provides a sleeper in which a slot is formed in an upper surface thereof. The slot defines an oblique passage for cables crossing a railway track supported by the sleeper. The oblique angle of the passage maximises the cable capacity of the slot. Rail fastening members are provided on opposite sides of the slot for different rails of the railway track. By providing the rail fastening members on opposite sides of the slot, loads transmitted from rail vehicles to the sleeper are balanced. Referring to the drawings, the sleeper 1 according to the invention is a folded structure formed from 12mm thick sheet steel. The sleeper structure comprises a base 3, two sides 5a, 5b, and an upper surface. The overall dimensions of the sleeper structure are approximately 2500mm length, 280mm width and 185mm height. The sleeper 1 is galvanised to provide protection from corrosion. The upper surface of the sleeper structure is defined by two portions 7a, 7b separated by an elongate gap 9. The elongate gap 9 has a constant width along most of the length of the sleeper, the edges of the gap 9 defining an oblique angle of 2.5 degrees with the sides 5a, 5b. At the ends of the sleeper 1 the edges of the gap 9 diverge slightly, one of the edges of the gap 9 being parallel with the sides 5a, 5b. The portions 7a, 7b of the upper surface provide respective wide surfaces at the ends of the sleeper 1. A wedge shaped rail fastening member 19a, 19b is attached to each of these wide surfaces. The rail fastening member 19a, 19b are positioned for fastening the spaced apart rails of the railway track (not shown). The rail fastening member 19a, 19b are welded to the sleeper structure and each has a pair of holes formed therein for fastening the rails to the sleeper 1. The portions 7a, 7b of the upper surface also provide respective narrow surfaces at the ends of the sleeper 1. A wedge shaped rail supporting member 21 a, 21 b is attached to each of these narrow surfaces. The rail supporting members 21 a, 21 b are much smaller than the rail fastening members 19a, 19b and provide support for the rails without any fastening function. The rail supporting members 21 a, 21 b are welded to the sleeper structure. Thus, in the above described arrangement, the portions 7a, 7b of the upper surface each include a rail fastening member 19a, 19b at one end of the sleeper 1 (the wide end) and a rail supporting member at the other end of the sleeper 1 (the narrow end). One rail fastening member 19a, 19b and one rail supporting member 21 a, 21 b are provided for each rail. The sides 5a, 5b and the portions 7a, 7b of the upper surface of the sleeper 1 together define an elongate slot for accommodating cables 11, for example, signalling cables. By providing portions 7a, 7b having a wide end and a narrow end, sufficient space may be provided (at the wide end) for attaching the rail fastening members 19a, 19b. The oblique angle of the gap 9 also maximises the size of cables 11 that may be laid in the elongate slot. Reinforcing brackets 23a, 23b are provided directly underneath each of the rail fastening members 19a, 19b. The reinforcing brackets 23a, 23b each comprise a piece of steel sheet bent at a right angle and of similar thickness to the sleeper structure. The reinforcing brackets 23a, 23b are each positioned such that the side of the bracket defining the right angle faces into the slot, and the limbs of the bracket 23a, 23b bridge the corners of the sleeper structure, as shown in the cross-sectional views of Figures 3 and 5. The brackets are each approximately 400mm long and run at least the length of the respective rail fastening plate 19a, 19b positioned directly above. The reinforcing brackets 23a, 23b provide additional bracing in the region of the rail fastening members 19a, 19b, which is where stresses in the sleeper 1 are greatest. However, the angled design of the brackets 23a, 23b ensures that they do not protrude into the elongate slot excessively. The base 3 has a number of holes 15 formed therein to allow moisture to drain from the inside of the sleeper structure. End plates 17a, 17b are also welded to the ends of the sleeper structure. The end plates 17a, 17b do not substantially restrict the passage of the cables 11. Figure 6 shows a railway track arrangement 25 comprising the sleeper 1 described above. In use, the sleeper 1 is installed in a bed of ballast (not shown). Cables 11 are then laid from above directly into the slot of the sleeper 1. The structure of the sleeper 1 maximizes both the individual size and the total volume of cables 11 that may be laid in the sleeper 1. Rails 27 are then fastened to the sleeper 1. When a rail vehicle travels over the rails 25, stresses are transferred into the sleeper through the rail fastening plates 19a, 19b. The reinforcing brackets 23a, 23b help to absorb these stresses. The sleeper and railway track arrangement described above are specific embodiments of the invention. Various modifications and changes, within the scope of the claims, will be apparent to the skilled person. For example, the sleeper described above is formed from sheet steel. However, in certain embodiments, the sleeper may be moulded from other materials, such as concrete.

Claims

1. A sleeper for supporting two parallel rails, the sleeper comprising a hollow elongate body having a slot in an upper surface of the body for receiving cables, wherein the slot extends at an angle to the length of the sleeper such that a first end of the sleeper has a relatively wide portion on a first side of the slot and a relatively narrow portion on an opposite second side of the slot, and a second end of the sleeper has a relatively wide portion on the second side of the slot and a relatively narrow portion on the first side of the slot, wherein each relatively wide portion is provided with a rail fastening member adapted to fasten a respective different rail to the sleeper.

2. The sleeper as claimed in claim 1, wherein only one rail fastening member is provided on each side of the slot.

3. The sleeper as claimed in claim 1 or 2, wherein each relatively narrow portion is provided with a rail supporting member adapted to support a respective different rail.

4. The sleeper as claimed in claim 3, wherein a width of the rail supporting members is less than a width of the rail fastening members.

5. The sleeper as claimed in any preceding claim, formed from metallic sheet material.

6. The sleeper as claimed in any preceding claim, wherein the hollow body is reinforced beneath each rail fastening member.

7. The sleeper as claimed in claim 6, wherein the hollow body is reinforced beneath each rail fastening member by a reinforcement bracket attached to an inside of the hollow body.

8. The sleeper of claim 7, wherein each reinforcement bracket runs at least a length of the respective rail fastening.

9. The sleeper as claimed in claim 8, wherein each bracket comprises a length of angled metallic sheet material.

10. A railway track arrangement comprising two parallel rails, a plurality of sleepers supporting the rails and at least one cable, wherein at least one of the sleepers is a sleeper as claimed in any preceding claim having the at least one cable received in its slot.

11. A sleeper substantially as hereinbefore described and/or as shown in the accompanying drawings.

12. A method of forming a sleeper as claimed in any preceding claim, comprising: forming a first fold in a pre-shaped sheet of metallic material; forming four parallel folds in the sheet to define a base, the sides and the upper surface of the sleeper, wherein the first fold maintains an open structure of the sheet to facilitate the subsequent folding operations; and removing the first fold from the sheet to provide a closed sleeper structure.