GB2439081A

GB2439081A - Vehicle safety barrier with angled anchor construction

Info

Publication number: GB2439081A
Application number: GB0611629A
Authority: GB
Inventors: Michael Richard Lawrence; Christophe Bastien; Martin Jeffrey Batchelor; Aled Mon Roberts; Harold Lewis Collins
Original assignee: Corus UK Ltd
Current assignee: Corus UK Ltd
Priority date: 2006-06-13
Filing date: 2006-06-13
Publication date: 2007-12-19
Also published as: GB0611629D0; WO2007144141A1; EP2032765A1; EP2032765B1

Abstract

The vehicle safety barrier comprises a length of rail 12 supported by posts 14 and, at the end of the rail, an anchor 21 comprising first 22 and second 24 uprights connected by bracing 28, the anchor being orientated such that the line defined by the first and second uprights is at an acute angle to the line defined by the posts, with the rail extending past the first upright to a point of connection with the second upright. The bracing preferably comprises at least one inclined strut extending between the uprights, preferably upwardly from the first to the second upright. One upright is preferably provided with a bracket to which the rail is attached, the bracket comprising an element for accepting the rail at an acute angle and a spacer element between the rail and anchor. The spacer may be a hollow or solid section and may be trapezoidal. A truss may extend from the rail to one of the anchor or the ground. Also claimed is a vehicle safety barrier with an anchor located behind the line of the posts of the barrier.

Description

Vehicle Safety Barriers

FIELD OF THE INVENTION

The present invention relates to vehicle safety barriers.

BACKGROUND ART

Vehicle safety barriers for road use typically comprise one or more horizontal rails supported by posts spaced along the roadside. If a vehicle leaves the roadway for some reason, it impacts the rail and is restrained. Such barriers are a common sight on roads (etc) and are often referred to generically as "Armco"(RTM).

Extensive testing has been carried out in respect of such barriers in order to ensure that they withstand impact and redirect the vehicle safely. As a result, such barriers are used extensively where there are sensitive or dangerous structures or areas near to the roadway. An example is a support for a bridge over the roadway; if a vehicle were to leave the roadway and impact the bridge support then a potentially serious incident could result. A barrier serves to deflect the vehicle away from a course that would otherwise result in an impact.

Different types of hazard call for lesser or greater levels of restraint on the part of the barrier, and different designs have been developed corresponding to these different levels. It is, from time to time, necessary to join different types of barrier, such as where a simple W-section barrier meets a stiffer barrier protecting (for example) a bridge support. These joins must also anchor the W-section barrier, since these operate in tension and therefore require either an effectively infinite length or a firm anchor at the end.

SUMMARY OF THE INVENTION

The present invention therefore provides a vehicle safety barrier, comprising a length of rail supported by posts and, at the end of the rail, an anchor comprising first and second uprights and bracing therebetween, the anchor being oriented such that the line defined by the first and second uprights is at an acute angle to the line defined by the posts, and the rail extending past the first upright to a point of connection with the second upright.

We have appreciated that the anchor is in fact a potential risk point.

Vehicles that impact at or shortly before the anchor meet what is in effect a rigid object in their path. Angling the anchor to the direction of travel allows an impacting vehicle to be more smoothly deflected past the anchor.

In preferred embodiments, the bracing comprises at least one inclined strut extending between the uprights. The inclined strut can extend upwardly from the first upright to the second upright; in this way it is best able to withstand forces in the rail that are transferred to the anchor, while minimising the overall height of the anchor.

In a further aspect of the invention, we provide a vehicle safety barrier, comprising a length of rail supported by posts and, at the end of the rail, an anchor comprising first and second uprights and bracing therebetween, the anchor being located behind the line defined by the posts. Existing anchors are built in line with the posts supporting the rail and therefore present a sudden increase in the transverse stiffness of the barrier that adversely affects the performance under impact of the barrier. Positioning the anchor behind the general line of the rail allows the anchor to be taken out of some impacts completely, and for the crash performance of the barrier under more severe impacts to be tailored to take into account the presence of the barrier.

To assist in connecting the rail to the anchor, the end of the rail can be angled inwardly relative to the posts. To further protect impacting vehicles from the anchor, the rail can extend past the first upright to a point of connection with the second upright.

The rail is preferably a W section. This can be reinforced, at least in its end section. Reinforcement allows the rail to exert a greater returning force on a vehicle to deflect its path away from the anchor with greater urgency. A suitable reinforcement for both the rail and for a W-section deflector bar comprises a length of C-section behind the W-section, such that the free edges of the C-section extend into the two recesses of the rear of the W-section. This is particularly straightforward to manufacture and to install. The central peak at the rear of the W section can sit in the channel defined by the C section and the two can be attached to a post using the same fixing. No further join need be provided, although the two could evidently be welded or otherwise joined along their length if this were felt worthwhile.

We prefer that one of the uprights is provided with a bracket for attaching a barrier rail, the bracket comprising an attachment means for accepting the rail at an acute angle to the anchor and a spacer element between the rail and the anchor. Under an impact, the attachment means can absorb longitudinal forces in the rail, while the spacer element can resist rotation of the rail about its point of attachment to the anchor.

The spacer element can be a hollow section such as a trapezoidal section.

It is preferably located between the rail and the bracing. The attachment means (or part of it) can also extend between the spacer element and the rail, so that the spacer element is crushed between the attachment means and the anchor bracing.

A truss can extend from the rail to the anchor or to ground, to assist further in stabilising the barrier under impact.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Figure 1 shows a perspective view of a vehicle safety barrier including an anchor according to the present invention; Figure 2 shows the barrier of figure 1 from above; Figure 3 shows the barrier of figure 1 from behind; Figure 4 shows the anchor of figure 1 from the front; Figure 5 shows a perspective view of the anchor; Figure 6 shows the reinforcement of a W-section; Figure 7 is a perspective view of the joint between the anchor and the rail; Figure 8 is a view from above of the joint between the anchor and the rail; Figures 9 to 11 show end, top and perspective views (respectively) of the bracket responsible for that joint; and Figure 12 shows an alternative bracket.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 shows a safety barrier termination according to the present invention. This is described and claimed in our two copending applications filed simultaneously with this application and each entitled "Vehicle Safety Barriers" and "Rail for Vehicle Safety Barriers", and the disclosures of which is hereby incorporated by reference. A standard W-section safety barrier 10 is shown, which consists of a W-section rail 12 supported by posts 14. Each post 14 is set into a socket 16 that is embedded in to the ground surface 18; other means of securing the posts are also known, such as driving the socket directly into the ground. In the arrangement shown in figure 1, the barrier 10 needs to be terminated prior to an obstruction in the form of a vertical concrete block 20.

It should be emphasised that the design parameters for the termination shown in figure 1 were that it should not intrude or otherwise be supported by the vertical concrete block 20. Thus, the result is a universal safety barrier termination which does not rely in any way upon support provided by the obstruction 20 in order to meet the necessary testing requirements. A vehicle impacting the barrier within the parameters of the test requirements will be guided to safety without impacting the obstruction 20. Thus, in real life, the obstruction 20 could be replaced with any other form of barrier or obstruction.

This means that validation of this design will enable it to be used as a termination for a new or existing W-section barrier at an interface with any other form of barrier or parapet. Likewise, with suitable modification, the principles of this invention can be applied to terminate any other form of vehicle safety barrier prior to an obstruction or interface.

The termination 21 consists of first upright 22 and second upright 24, both formed of I-section struts. When viewed in the direction of traffic flow 26, the first upright 22 is before the second upright 24. A bracing structure 28 is provided between the first and second upright 22, 24, and consists of an inclined box section running between the I-section uprights, from a low point at its connection with the first upright 22 to a highest point at its connection with the second upright 24. Other sections such as C-or I-sections could also be used.

Given that (as will be explained later) most forces and moments exerted on the termination 21 will be applied via the second upright 24, the inclining of the bracing structure 28 assists in absorbing these forces. Furthermore, the fact that the bracing structure 28 attaches to the first upright 22 at a relatively low height means that the first upright 22 can be relatively short, shorter than the second upright 24. Given that approaching vehicles meet the first upright 22 early, this can improve the impact profile of the termination 21.

A deflector (or "kicker") bar 30 extends from the first upright 22 to the second 24 and beyond, and is held in place at securing points on each upright.

The deflector bar 30 is generally positioned at a level slightly above ground level 18 affixed at the top of the first upright 22. It extends generally alongside the direction of travel 26, past the front of the second upright 24 and in front of the vertical concrete block 20. In total, the length by which the deflector bar extends beyond the second upright, alongside the vertical concrete block 20, is slightly more than the distance between the external faces of the uprights, i.e. the spacing of the uprights including their thicknesses.

The total length of the deflector bar is dictated by the context of the anchor. A shorter deflector bar, such as the length between the internal sides of the uprights (i.e. their spacing not including their widths), or one half of the spacing (on either basis) might be useful in other situations. In extremis, the deflector bar might not extend beyond its attachment to the second upright at all.

Figure 1 also shows that the W-section rail of which the deflector bar 30 is formed and later sections 32 of the W-section rail 12 forming a part of the safety barrier 10 are reinforced with a C-section reinforcement 34. This will be described in more detail later.

Figure 2 shows the safety barrier 10 and termination 21 from above. It can be seen that the front face of the safety barrier 10 that is to be terminated defines a straight line 36, and that the termination structure 21 is located entirely behind that line. Furthermore, the first upright 22 is situated further back than the second upright 24 so that, from the point of view of an approaching vehicle moving in the direction of the assumed traffic flow 26, the termination structure 21 is tilted slightly to face the traffic. The fact that the termination structure 21 is set back behind the front face of the barrier 36 means that the rail 12 can continue past the first upright 22 and then, via a small kink 38 be bought back for connection to the second upright 24.

A small kink 40 in the deflector bar 34 allows one end of the deflector bar to be positioned alongside the first and second upright 22, 24 and the remaining length of the deflector bar 34 to be alongside the vertical concrete block 20.

This is assumed to be parallel to the front face of the safety barrier 36 and set back therefrom, in line with the requisite standards for the safety barrier 10.

Figure 3 shows barrier 10 and the termination structure 21 from the rear, and it can be seen that the deflector bar 34 is located generally below the barrier rail 12. Thus, in the event of a vehicle impacting the barrier in this general area, the deflector bar 34 can provide an additional point of contact with the vehicle to deflect it forwards and away from the vertical concrete block 20. Figure 4 shows a corresponding view from the front.

Figure 5 shows the termination structure 21 standing alone, without the accompanying safety barrier 10. Together with figure 6, it shows in more detail the nature of the W-section deflector bar 30 which, viewed from a front face 42, has two protruding ridges 44, 46 between which there is a defined valley 48. A C-section reinforcement 34 is disposed behind the W-section rail 30 with the open part of the C-profile receiving the valley 48. Thus, the two edges of the C-section 34 extend into the W-section behind the ridges 44, 46. This can be secured to the W-section rail without any further apparatus. Normally, a W-section is secured to posts by a bolt which passes through a slot formed in the valley 48. A corresponding slot at the centre of the C-section 34 can receive the same bolt, which will then retain both profiles in place. No welding or other fastenings are (strictly) necessary, allowing galvanised profiles to be used without difficulty.

Other forms of reinforcement for the rail are shown in our copending application referenced above and entitled "Rail for Vehicle Safety Barriers".

In use, a vehicle that impacts the safety barrier 10 some distance from the termination structure 21 will generally bend or deform the posts 14 and deflect the rail 12 backwards away from the vehicle carriageway. As it does so, the rail 12 is stretched and the tension therein exerts a force on the vehicle restoring it towards the carriageway. Friction between the side of the vehicle and the rail 12 also decelerates the vehicle, and these two factors together therefore restrain its rate of departure from the carriageway. This effect relies on there being a tensile force in the rail 12.

For impacts closer to the end of the barrier, the effect of the end needs to be catered for. Clearly, if the rail 12 simply terminated at a free end, then for impacts near the end of the barrier 10 there would little restraining force and the vehicle could simply pass through the barrier and beyond. The termination structure 21 therefore should provide an anchor point to exert the necessary tensile force in the rail 12 at locations further back along the safety barrier 10.

In addition, the termination structure 21 needs to resist rotation of the rail 12, as a free rotation about the end point will allow the rail 12 to deform excessively under impact.

In impacts closer to the end of the safety barrier 10, the vehicle will meet the reinforced section 32, in which the C-section reinforcement 34 is placed behind the W-section rail 12. In this area, the restoring forces exerted by the rail 12 will be greater and therefore the vehicle should intrude by a lesser distance behind the front face 36. This will assist in preventing the vehicle from impacting the vertical concrete block 20. There will still be some rotational forces in the rail, but this can be expected to become less severe as the impact point approaches the kink 38.

In impacts still closer to the end of the safety barrier 10, the vehicle may meet the termination structure 21. Instead of this acting as a rigid post, as was previously the case, the deflector bar 34 will provide an additional point of contact with a vehicle below the rail 12, and will exert a still greater restoring force on the vehicle to return it towards the carriageway and arrest its motion towards the vertical concrete block 20.

Whilst it is, in general, preferable to minimise the forces exerted on the vehicle, at the end of the rail 12 this is outweighed by the need to deflect the vehicle away from the vertical concrete block 20.

Previous full height anchors have employed deflector bars, but these have not extended significantly beyond the second upright 24 and have been in line with and parallel to the front face 36 of the rail 12. As a result, they have not generally been effective in deflecting the vehicle forwards since from the point of view of the approaching car they simply form part of the upright post. The fact that the deflector bar 34 is set back from the front face 36 and angled towards the oncoming traffic assists it in deflecting the vehicles forwards around the corner of the vertical concrete block.

Figures 7 to 11 show the connection between the anchor 22 and the barrier rail 12 in more detail. The rail 12 connects to the second upright 24 via a bracket 50 shown separately in figures 9 to 11, figure 9 being a view along the direction of arrow IX in figure 10. This has an C-section 52 comprising a vertical backplate 54 and upper and lower plates 56, 58 (respectively). On the rear of the backplate 54 (i.e. extending in the opposite direction to the upper and lower plates 56, 58), a trapezoidal section 60 is attached to the C-section 52. This is a generally box-shaped section albeit with one side narrower than the opposing side. Thus, the sides connecting these are (in this example) non-parallel. It is attached to the backplate 54 via one of the non-parallel sides, with the edge between that side and the longer parallel side aligned with the open edge of the backplate 54.

The remaining open edge of the C-section 52 is chamfered along a line that is generally aligned with the remaining non-parallel side of the trapezoidal section 60. As a result, the backplate 54 is essentially cut short and the upper and lowerplates 56, 58 have triangular extensions. The space thus created adjacent the backplate 54 is closed off with a connection plate 62.

Figures 7 and 8 show how the bracket is fitted. The connection plate 62 is attached to the second upright 24 at the level of the rail 12, with the C-section 52 extending back along the path of the rail 12. The size of the C-section 52 corresponds to that of the reinforcement 34 behind the rail 12 such that the C-section 52 fits outside the reinforcement and can be connected to it by welding, bolting, etc. This connects the rail 12 (via the reinforcement 34) to the second upright 24.

The trapezoidal section 60 is then located between the reinforcement 34 and the bracing structure 28, as the chamfer to the C-section 52 is aligned with the edge of the trapezoid. A small clearance may exist between them of, say 2-15mm.

In an impact that deforms the rail 12 adjacent the anchor 21, the rail 12 and reinforcement 34 are likely to be subject to forces tending to cause rotation at the point where they are connected to the anchor 21. If unconstrained, this rotation will allow the rail 12 to buckle and allow the vehicle to escape too far from the roadway. However, the above-described trapezoidal section 60 will then be trapped between the reinforcement 34 and the bracing structure 28, and will serve to constrain the reinforcement 34 and hence the rail 12 against further rotation. The degree of resistance offered by the trapezoidal section 60 can be tailored by adjusting the wall thickness, material strength, precise wall shapes, section profile, etc. Figure 12 shows a slightly modified bracket 50'. It differs in that the trapezoidal spacer 60' is solid instead of being hollow in section. This means that the spacer will be correspondingly less willing to deform under an impact, causing the bracket to offer greater resistance to rotational forces in the rail. In this way, and/or by changing the cross-sectional shape of the bracket, the action of the anchor under impact can be tailored to the requirements of the intended installation site.

To assist further in preventing such rotation, there could alternatively (or in addition) be a truss extending from the rail 12 to the anchor 21 or to ground.

It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.

Claims

CLAIMS

1. A vehicle safety barrier, comprising a length of rail supported by posts and, at the end of the rail, an anchor comprising first and second uprights and bracing therebetween, the anchor being oriented such that the line defined by the first and second uprights is at an acute angle to the line defined by the posts, and the rail extending past the first upright to a point of connection with the second upright.

2. A vehicle safety barrier according to claim 1 in which the bracing comprises at least one inclined strut extending between the uprights.

3. A vehicle safety barrier according to claim 2 in which the inclined strut extends upwardly from the first upright to the second upright.

4. A vehicle safety barrier, comprising a length of rail supported by posts and, at the end of the rail, an anchor comprising first and second uprights and bracing therebetween, the anchor being located behind the line defined by the posts.

5. A vehicle safety barrier according to claim 4 in which the end of the rail is angled inwardly relative to the posts.

6. A vehicle safety barrier according to claim 4 or claim 5 in which the rail extends past the first upright to a point of connection with the second upright.

7. A vehicle safety barrier according to any one of the preceding claims in which an upright is provided with a bracket to which the barrier rail is attached, the bracket comprising an attachment means for accepting the rail at an acute angle to the anchor and a spacer element between the rail and the anchor.

8. A vehicle safety barrier according to claim 7 in which the spacer element is a hollow section.

9. A vehicle safety barrier according to claim 7 in which the spacer element is a solid section.

10. A vehicle safety barrier according to any one of claims 7 to 9 in which the spacer element is trapezoidal in section.

11. A vehicle safety barrier according to any one of claims 7 to 10 in which the spacer element is located between the rail and the bracing.

12. A vehicle safety barrier according to any one of claims 7 to 11 in which part of the attachment means extends between the spacer element and the rail.

13. A vehicle safety barrier according to any one of the preceding claims in which a truss extends from the rail to one of the anchor and the ground.

14. A vehicle safety barrier substantially as described herein with reference to and/or as illustrated in the accompanying figures.