GB2428725A

GB2428725A - Roadside traffic barrier

Info

Publication number: GB2428725A
Application number: GB0515891A
Authority: GB
Inventors: Michael Richard Lawrence; Aled Mon Roberts; Harold Lewis Collins; Martin Jeffrey Batchelor; Christophe Bastien; Matthew Austen Harriman
Original assignee: Corus UK Ltd
Current assignee: Corus UK Ltd
Priority date: 2005-08-02
Filing date: 2005-08-02
Publication date: 2007-02-07
Also published as: GB0515891D0

Abstract

The traffic barrier comprises an elongate length of rail 16a-d supported by posts 24a-d,26a-b set into the ground beneath with the rail having a terminating end that is set into an area of level ground adjacent the roadside. A post 26b is preferably attached to the terminating end, the post being set into the ground below the terminating end. Preferably a second post 26a is also set into the ground below the rail at a point where at least some of the rail is still beneath the surface of the ground. The rail preferably rises at an acute angle of less than 10 degrees. The posts are preferably attached to the rail so that the highest point of the rail is below the highest part of the rail at the attachment point, with the post preferably being directly attached to the rail. The rail supported in its section that is entirely above ground is preferably supported by at least three posts with varied spacing between them. Also claimed is a method of installing a roadside barrier.

Description

Vehicle Safety Barrier End Terminal

FIELD OF THE INVENTION * **

:.: The present invention relates to a vehicle safety barrier end terminal. S... * .

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.

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 verge protection of a stone or concrete wall or ditch, lighting column or sign gantry protection; if a vehicle were to leave the roadway and impact the obstruction 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.

It is not practical to place barriers continuously along the entire length of every road. Accordingly, the barriers must start and end at some point.

Particularly in respect of the starting point (relative to the traffic flow direction in the jurisdiction concerned), commonly known as the approach end terminal, there is a risk that the end terminal will create a further dangerous structure if it were to be hit by an errant vehicle. Thus, care is taken to ensure that the barrier commences with a structure that offers an appropriate level of crashworthiness. Departure end terminals also pose a risk to vehicles, especially where there are contra flow operations in place on dual carriageways, or crossover impacts on single carriageways.

In respect of barriers for areas that may suffer incidents involving vehicles at relatively low speeds, it is common in the UK for the barrier rail to be lowered to approximately a third of its usual height and terminated within or behind a concrete block (or fairing) formed in situ or installed as a preformed component.

This can present an increased risk to vehicles and occupants. Many European countries have a barrier detail where the final end terminal beam is partially :.:. buried below ground level, thereby eliminating the requirement for a fairing S.

.. detail. However, these terminal details have not been specifically designed or tested to withstand high speed ramped impacts or close side impacts at * 100km/h or greater. ..DTD: In areas at risk of incidents involving vehicles at relatively higher speeds, S.....

:." such as motorways, autoroutes, etc, a fairing detail of this type presents an * S unacceptable hazard. As a result, telescopic structures with full height collapsible mechanisms are typically installed. This is a deformable structure that absorbs at least part of the impact energy of a vehicle in a controlled manner. These systems have been specifically designed to withstand high speed head on and ramped impacts, but can sometimes be less effective than ramped ends at anchoring the barrier run. These systems have also been developed as a reaction a general perception that ramped end terminals are unsafe and cannot be designed to safely perform during high-speed head on impacts.

SUMMARY OF THE INVENTION

The present invention seeks to provide a barrier termination that is acceptable for use in areas at risk of higher speed incidents but which is simpler and hence more economic to install.

It therefore provides an installed roadside barrier comprising an elongate length of rail supported by posts set into the ground beneath, the rail having a terminating end that is set into an area of flat ground adjacent the roadside.

Such a termination to the barrier is capable of safely absorbing high speed ramped impacts and close side impacts by small and large cars. It does so with a simple and therefore economic construction.

It is preferred that there is a post attached to the terminating end, set into the ground below the terminating end. It is also preferred that there is a second post set in the ground below the rail, attached to the rail at a point along its length where at least some of the rail is still beneath the surface of the ground. These two posts provide effective end anchorage, and anchor the : .*. terminal beams during impacts. In addition, they provide an effective anchor to :::*:. standard full height runs, which can therefore be connected to the terminal.

Generally, the rail will rises from the ground at an acute angle such as 100 or less. However, the angle is preferably small such as below 5 , or as low as about 2 to 4 .

S.....

:.: We also propose that the posts are attached to the rail with the highest * point of the post below the highest part of the rail at the attachment point. This is unusual. In the UK, posts typically protrude above the top of the barrier rail edge, to support the barrier edges during vehicle interactions. Many European systems such as those common in the Federal Republic of Germany incorporate reduced height posts alongside a yoke', whose purpose is to support the barrier rail across its height using a two-point support contact, and allow for a shorter height post. We propose a reduced height post without yokes. Barrier behaviour is not compromised by this detail - in fact ramped end interactions are significantly safer with less opportunities for vehicle snagging on the barrier during impact. We therefore prefer that the posts be attached directly to the rail.

A further preferred aspect of the present invention is for the rail to be supported in its section that is entirely above ground by at least three posts, an nth post closest to the terminating end followed by an (n+l)th and an (n 2)th post, in which the spacing between the (n l)th and the (n 2)th post is less that the spacing between the nth and the (nfl)th post. This reduction in spacing can be between 25 and 75%, more preferably between 40 and 60% of the spacing between the nth and the (n+1) th post. We also prefer that there is an (n+3)th post spaced from the (n+ 2)th post by a distance in accordance with the spacing between the (n+l) th and (n+2)th post, preferably the same as that spacing.

These three or four posts serve to absorb direct side impacts in both forward and rear directions.

The present invention further provides a method of installing a roadside barrier including the steps of preparing a recess in the ground adjacent the roadway, inserting a rail into the recess and filling the recess around the rail to level the ground and up to at least the height of an end of the rail. *4S

Generally, the rail will be set into the ground to an extent sufficient to ensure that, at the terminating end, the upper edge of the rail is not significantly above the ground level.

In referring to flat ground into which the rail is set, we intend to exclude . the presence of above-ground structures designed to shield or cover the terminating end. Instead, the rail descends into and is at least substantially buried in the local ground level. Whilst that ground may well not be geometrically planar, it is ideaHy flat in the sense that ground alongside roadways is in general flat.

Preferred aspects of the method provided by the invention reflect the preferred aspects of the installed roadside barrier.

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 is a view of an embodiment of the invention from above; and Figure 2 is a view of the embodiment from the side.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to figures 1 and 2, a safety barrier system 10 comprises a length of safety barrier 12 (that can be conventional in nature) that is terminated with an end terminal structure 14 according to the present invention.

Figure 1 shows that the system is straight when viewed from above.

Some barrier systems curve away from the traffic at the end terminals, but that is not necessary in this case and installation can therefore be made more straightforward.

As shown in figure 2, the end terminal structure comprises a length of rail 16 that is made up of a series of rail sections 16a, 16b, 16c and 16d to provide the requisite length. Each section is joined to an adjacent section via joints 18b, 18c and 18d. An initial joint 18a connects the end terminal structure to the safety barrier 12.

Posts are used to support the rails 12, 16. Posts set into a prepared holes supports the safety barrier rail 12 in the conventional manner. A total of six posts 24a, 24b, 24c, 24d, 26a and 26b (respectively) support the rail 16 in the end terminal structure 14.

Each of the posts 24a, 24b, 24c, 24d, 26a and 26b is set successively deeper in the ground than the previous post. This means that within the end terminal structure 14, the rail 16 is inclined downwardly at a shallow angle of about 2.5 to 3 . In this example, the posts are generally the same length, although posts of different length may be appropriate in socketed versions of the design. Generally, posts may be installed by driving them into the ground by appropriate means, or by means of a post dropped into a socket that is cast in a concrete foundation, or by being cast In-situ in a concrete foundation below. All concrete foundations are preferably below ground level.

The end post 26b is attached to the rail 16 at its end and is thus almost entirely submerged beneath the ground. The adjacent (2) post 26a is attached approximately 4 metres along the rail 16 at a point where the rail is partly above the surface and partly beneath, typically half submerged. These two posts serve to provide an effective end anchorage. They anchor the terminal beams during impacts, and provide an effective anchor to the standard full height run 12 connected to the end terminal structure 14.

The remaining 4 posts are spaced along the rail 16. The next successive (3rd) post 24d is 3 metres from the 2 post 26a and is attached to the rail at the point where it if just fully clear of the ground level. The 4th post 24c is attached 4 metres from the 3td post 24d, and the 5th and 6th posts are attached to the rail 2 metres from the 4th post and 2 further metres from the 5th post, respectively.

These four posts have been specifically located to absorb direct side impacts in both forward and rear directions. Their spacing assists in doing so. a.. *

All six posts differ from conventional posts in that the top of the post has been lowered to minimise vehicle snagging during ramped impacts.

:. Traditionally, UK system posts protrude above the top of the barrier rail edge.

This is to support the barrier edges during vehicle interactions. Many European systems incorporate reduced height posts alongside a yoke'. The purpose of the S.....

: * yoke' is to support the barrier rail across its width using a twopoint support contact. The presence of the yoke also allows for a shorter height post. We propose a reduced height post without yokes. Barrier behaviour is not compromised by this detail - in fact ramped end interactions are significantly safer with less opportunities for vehicle snagging on the barrier during impact.

This detail is achieved by connection the top of the post directly to the centre section of the rail. Arranging for the post to terminate below the beam top height assists end terminal safe performance, as well as providing a reduced snagging detail for cars and motorcyclists etc. Thus, our sloping high speed end terminal includes such features as; - a reduced height post - Shallow angle for high speed redirection of ramped impacts A post pattern aimed at close anchorage impact - catering fro forward and rear impact orientation.

- A close impact anchorage By way of background, it is European Standard DD ENV 1317-4:2002 issued which lists testing methods and performance categories for end terminals.

In general, end terminal testing has been limited across various countries. Many national terminals have little or no testing. Limited testing is carried out in respect of other terminals, some of which are approved to "P1" class for speeds of 80km/h or below.

P1 class tested end terminals and untested end terminals commonly terminate to ground over 4 to 16 metres in 1 to 4 beams, with a structure to shield the free end of the rail. P1 class terminals only need to pass one test, namely a quarter offset 80 km/h ramped end impact. No consideration of close * *.* side impacts is made for P1 and traditional terminals.

There are only two or three P4 class terminals currently in existence. All are based upon a full height collapsible barrier principle with energy absorbing nose and controlled barrier collapse mechanisms. P4 class terminals are SSa*S * designed and tested for high speed, quarter and half offset head on impacts, as :* well a forward and reverse side impacts in close proximity to barrier end.

Our novel P4 terminal described above is specilically designed for high speed ramped impacts by small and large cars, together with close side impacts, again by small and large cars.

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

1. An installed roadside barrier comprising an elongate length of rail supported by posts set into the ground beneath, the rail having a terminating end that is set into an area of level ground adjacent the roadside.

2. An installed roadside barrier according to claim 1, including a post attached to the terminating end, the post being set into the ground below the terminating end.

3. An installed roadside barrier according to claim 2 including a second post set in the ground below the rail, attached to the rail at a point along its length where at least some of the rail is still beneath the surface of the ground. * **

::.:

4. An installed roadside barrier according to any one of the preceding claims in which the rail rises from the ground at an acute angle. * a.

5. An installed roadside barrier according to any one of the preceding claims in which the rail rises from the ground at an angle of less than 10 .

:

6. An installed roadside barrier according to any one of the preceding claims in which the posts are attached to the rail with the highest point of the * post below the highest part of the rail at the attachment point.

7. An installed roadside barrier according to claim 6 in which the posts are attached directly to the rail.

8. An installed roadside barrier according to any one of the preceding claims in which the rail is supported in its section that is entirely above grounds by at least three posts, an th post closest to the terminating end followed by an (n+1)th and an (n+2)th post, in which the spacing between the (n l)th and the (n 2)th post is less that the spacing between the th and the (n l)th post.

9. An installed roadside barrier according to claim 8 in which the spacing between the (n+l)th and the (n+2)th post is between 25 and 75% of the spacing between the th and the (n+l)th post.

10. An installed roadside barrier according to claim 8 in which the spacing between the (n+l)th and the (n+2)t1 post is between 40 and 60% of the spacing between the th and the (n+l)th post.

11. An installed roadside barrier according to any one of claims 8 to 10 in which there is an (n+3)th post spaced from the (fl 2)t post by a distance in accordance with the spacing between the (n l)th and (n+2)th post.

12. An installed roadside barrier according to any one of the preceding claims that is straight when viewed from above.

* ,.

13. A method of installing a roadside barrier including the steps of preparing a recess in the ground adjacent the roadway, inserting a rail into the recess and filling the recess around the rail to level the ground and up to at least the height of an end of the rail. * * S ** *. * S S * *