WO1987004477A1

WO1987004477A1 - Rail crossing panel

Info

Publication number: WO1987004477A1
Application number: PCT/GB1987/000035
Authority: WO
Inventors: Howard Peter John Taylor
Original assignee: Dow Mac Concrete Limited
Priority date: 1986-01-20
Filing date: 1987-01-20
Publication date: 1987-07-30
Also published as: GB2185510A; GB8601281D0; EP0258286A1; AU6892387A

Abstract

The railway level crossing panel (10) comprising polyester concrete, coffers or recesses (14) in the underside of the panel and reinforcing rods (22, 24) in the upper surface, in the ribs (20) defined by the recesses (14) and in lateral projections (12) from two opposed edges of the panel. The lateral projections (12) fit into hard rubber wedges which themselves engage side flanks of the rails of the railway or railroad.

Description

RAIL CROSSING PANEL

This invention relates to panels incorporated in railway or railroad level crossings.

Some years ago a novel and much improved design of level crossing structure was introduced into the United Kingdom and has been widely adopted by British Rail as the construction is relatively straightforward to instal and if correctly carried out gives a far smoother passage for road traffic.

Such level crossings comprise a number of pre-cast concrete components of which the largest and heaviest are the panels which are mounted above the sleepers of the rail track and extend between and are mounted on the side flanks of the rails. Other panels forming parts of the crossing assembly are also liable to be heavy enough to render weight-saving desirable. Such crossings are disclosed in GB-A-1 281 940 and GB-A-1 494 667 and in various equivalent patents elsewhere.

It will be understood that these panels are subject to heavy loadings, sometimes involving impact and it follows that substantial amounts of steel reinforcement have been included and furthermore an external frame of metal has been provided to add to the overall strength of the panel. A typical panel of the kind in question ay weigh 265 Kg or even more and this generally involves the use of mobile cranes with resultant increased cost, not only from the expense of hire or depreciation of the crane but because the crane can often present an impediment to other work being carried out on site.

With the objective of reducing the weight while retaining adequate strength for the onerous task involved it has been proposed to use polyester concrete which has a higher tensile strength for a given weight, than conventional Portland cement-based concrete and this has resulted in a reduction in weight, but not to a sufficient degree to enable easy manhandling of the panels on site. At least a part of the weight reduction has been made possible by omission of the external frame hitherto used. The remainder of the weight saving has been achieved in this relatively recent proposal by the use of polyester concrete and a slight reduction in thickness of the panel.

A partial weight reduction for a given size of panel is, however, not of real value either technically or commercially since the speed of installation on site is not materially increased, mobile cranes still being required and as a_. result hindrance to other work which could otherwise be carried out simultaneously. It must, of course be remembered, that site work on railway lines is often restricted because of the need to maintain rail services while at the same time enabling road traffic either to continue use of the crossing or to be disrupted for diversions for as short a time as possible.

Thus the provision of panels which can be manhandled will result in shorter possession time of the crossing, reduced labour costs and a lower equipment cost.

According to the present invention there is provided a concrete panel for incorporation in a rail level crossing structure, the panel comprising polyester concrete with recesses in the undersurface and appropriate reinforcement at least at or adjacent the top and bottom surfaces.

The invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which:

Figure 1 is a plan view of a concrete panel in accordance with the present invention;

Figure 2 is a fragmentary section illustrating an edge portion of the panel of Figure 1 and in vertical section;

Figure 3 is a fragmentary view illustrating one feature of the present invention;

Figure 4 is a plan view, to an enlarged scale, illustrating a portion of the panel shown in outline in Figure 1;

Figure 5 is a partial side view also illustrating the internal reinforcing rods; and

Figure 6 is an end elevation also indicating the locations of internal reinforcements.

Referring now to the drawings, a concrete panel in^' accordance with the invention generally referenced 10 is rectangular in plan view but has four ears or lateral projections 12 by which opposed edges of the panel are supported by the opposed flanks of the rails of the associated railway track though the intermediary of hard rubber wedges (not shown) . The underside of the panel has six recesses 14 with the objective of reducing the overall weight of the panel which is in addition to the weight saving enabled by the omission of the conventional outer steel frame and the use of polyester concrete. The recesses 14 in the undersurface are trapezoidal in both orthogonal sections and extend towards the upper surface so that at maximum depth the panel has a thickness of approximately one quarter the maximum depth at the ribs or lands 20, between the recesses.

As shown six recesses, or coffers are shown, but a greater or lesser number may be incorporated. It is not likely that less than four will be used.

The panels are so constructed that they follow, on the undersurface, the shape of a conventional prestressed concrete -railway sleeper although_m there is no contact between the sleeper and the undersurface. Fig. 3 illustrates this feature. In a panel for use in the United Kingdom the edge portion 15 of the panel is as shown in Figures 2 and 3 120 mm thick while the central portion or rib 20 where the recesses are provided is 135 mm thick, and this provides an important advantage from the point of view of improved tensile strength by the inclusion of reinforcement rods see Figures 4 to 6 at a lower level in relation to the load-receiving upper surface than would be possible if the undersurface were plane over its whole extent. The shape in this respect also ensures that the highest strength is available where the stresses are highest. The need for greater depth, particularly at the central area of each panel results from the lower modulus or stiffness of polyester concrete.

The ears or projections 12 are generally conventional and as shown in Figure 2 are provided on the undersurface with a recess 16 and on the upper surface with a chamfer 18, the recess and the chamfer being adapted generally to the cross-sectional shape of the wedge (not shown) engaged against the flank of a conventional rail.

It is conventional practice to incorporate in a level crossing a cattle grid which also serves to deter at least unauthorised pekrsons from straying on to rail tracks. By the use of polyester concrete it becomes possible to make the sharply upwardly pointed grids of concrete in place of timber.

Panels in accordance with the present invention are preferably made of polyester concrete and require no external frame. Reinforcement is entirely internal and because of the higher impact resistance of polyester concrete the risk of chipping at the edges during installation or subsequent use is substantially eliminated. The concrete may alternatively, although not preferably, be of the kind which is basically made of Portland cement and is impregnated with polymer after setting. The polymer may otherwise be added to the mix of cementitious concrete prior to setting. Normally the polymer will be a polyester. Polyester concrete gives rise to the additional advantage that the electrical resistance is higher than that of conventional concrete mixes and the omission of the external frame also gives rise to advantage of reduced risk of leakage currents. Because of the electrical resistance advantage it is desirable that all panels of a crossing should be made of polyester concrete.

Reinforcement details are illustrated in Figures 4 to 6 and in the plane, upper, portion of the panel will be in form of a grid with intersections of orthogonal rods 22,24 welded at their intersections. Each one of one set of rods 24 is located centrally above one of the ribs or lands 20 which define the longer sides of the recesses or coffers 14. The other set of rods 22, orthogonal to the first set will have some individual rods coincident with but spaced centrally above the ribs or lands 20 which define the shorter sides of the recesses or coffers. Other rods 22 will be spaced above the recesses 14.

Immediately adjacent the ears 12 at opposed edges of the panel a reinforcing rod loop 26 is provided towards the bottom of the panel and a plurality of U-shaped rods 28 are welded to these loops and extend into the ears 12 so that the bottoms 30 of the "U"s lie closely adjacent the free edge of a respective U. The adjacent limbs of adjacent U-shaped rods 28 may touch one another and the bottoms 30 may be interconnected by welding by a transverse rod 32. A further transverse rod 34 may be provided which is welded at mid-height of the Us. By means of these reinforcements strength in shear is enhanced.

Where the highest tensile loads are encountered, namely at and adjacent the lower edge of each land or rib 20, further, larger diameter, reinforcing rods 36 are incorporated. In the case of the rib defining the shorter sides of the coffers two larger diameter rods 36 will be incorporated but for the orthogonal ribs only one larger diameter rod will be incorporated.

The reinforcement at the edge portions extending orthogonally to the edges carrying the ears will take the form of two larger diameter rods 38,40 disposed substantially at the same depth location as the rods in the lands. As best shown in Figure 5, however, one rod 38 extends into one of the ears 12 while the other 40 is cranked and extends only into the edge portion itself.

In a modification, illustrated in chain lines in Figure 4 those recesses 14 lying opposite an ear 20 are tapered thus enabling an extension 31 of one limb of two U-shaped rods 28 to be accommodated. The extension 31 is cranked relative to the corresponding limb and thus provides excellent anchorage in the polyester concrete.

A standard internal panel for a level crossing as hereinbefore particularly described has been found to have a weight saving in relation to conventional panels of approximately 25%. This is sufficient to enable manhandling by three or four men without risk of back damage. Other panels of a crossing will also give a simil.ar weight saving, while still providing adequate strength. The use of polyester concrete gives a higher electrical resistance and the reduced weight also cuts transportation cost.

Claims

CLAIMS -

1. A concrete panel for incorporation in a rail level crossing structure, the panel comprising polyester concrete with recesses in the under surface and reinforcement means at least at or adjacent the top and bottom surfaces of the panel.

2. A concrete panel for incorporation in a railway or railroad level crossing structure, the panel comprising polymer concrete with recesses or coffers in the undersurface, ears or other lateral projections extending from two opposed edges of the panel for cooperation with rails of the track and reinforcement rods at pr adjacent the upper surface of the panel, at or adjacent the lower edge of the lands or ribs defining the recesses and within the lateral projections.

3. A concrete panel for incorporation in a railway or railroad track level crossing structure, the panel comprising polymer concrete with recesses or coffers arranged regularly in the underneath of the panel, each recess being of elongate form, ears or other lateral projections extending from two opposed edges of the panel for cooperation through resilient wedges with opposed flanks of the rails of the track, reinforcement rods extending at or adjacent the upper surface of the panel and in lands or ribs defining the coffers at or adjacent the lower edges thereof and multiple reinforcing rods extending from adjacent edge portions of the panel into each ear.

4. A panel according to claim 2 or 3, comprising four lateral projections at opposed edges of the panel by which the panel can be supported by the opposed flanks of the rails of the associated rail track.

5. A panel according to any one of the preceding claims wherein the recesses on the under surface of the panel are trapezoidal in both orthogonal sections .

6. A panel according to any one of the preceding claims wherein the recesses extend towards the upper surface of the panel so that at maximum depth the panel has a thickness of approximately one quarter the maximum depth of lands or ribs defined between the recesses.

7. A panel according to any one of the preceding claims wherein edge portions of the panel have a lesser thickness than those portions, lands or ribs of the panel where the recesses are provided.

8. A panel according to any one of claims 2 to 7 wherein each ear or projection i_s provided on its under surface with a recess and on its upper surface with a chamfer.

9. A panel according to any one of claims 3 to 8 wherein those recesses which lie opposite a said ear or lateral projection are tapered so that they become narrower adjacent that ear or projection and the reinforcing rods within the ear or projection are of U shape and two of which have one limb which is extended into the concrete defining the taper, this extension being cranked in relation to the corresponding limb and extending substantially parallel to one tapered face of the recess or coffer.

10. A panel according to any one of claims 3 to 9 wherein two reinforcing rods are provided adjacent the lower edge of each edge portion of the panel extending between the opposed lateral projections, one of the rods terminating within orthogonal edge portions from which the ears project and the other rod terminating within the ears themselves, the one rod being cranked at each end portion and the other rod being rectilinear throughout its length.