GB2457444A

GB2457444A - Vehicle crash barrier

Info

Publication number: GB2457444A
Application number: GB0802552A
Authority: GB
Inventors: Paul Clifford
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-02-12
Filing date: 2008-02-12
Publication date: 2009-08-19
Also published as: GB0802552D0

Abstract

The vehicle crash barrier, primarily for security round buildings and the like, comprises at least one cable with loops at each end which is formed into a lasso which is secured to an anchor and then suspended across the road. The cable preferably has a larger loop and a smaller loop, both formed with solid steel elliptical cores, such that the smaller loop can be passed through the larger loop to form the lasso. The barrier may be formed using two anchors between which one or more cables may be secured, and the anchors may comprise reinforced concrete blocks, sand-filled gabions or trees.

Description

Background

A crash barrier is a device that prevents an unauthonsed vehicle from driving through a vehicle entrance. Crash barriers are commonly used where there is a threat from car bombs and as such are located some distance (typically 30 to 50-rn) away from the highly occupied building being protected.

Crash barriers have many different types of design, including those illustrated in drawing two.

The most important feature of a crash bamer is its ability to stop an attacking vehicle (this is achieved by absorbing energy). To calculate a barriers ability to absorb energy is difficult as it involves dynamic stresses and so a reputable supplier will normally test their crash barrier by crashing a vehicle into it of known weight and speed and therefore award it an energy absorption rating'. For this reason, if I user wishes to be confident that a crash barrier will stop an attacking vehicle it is normal to purchase a rated crash barrier from a reputable supplier. Rated crash barriers typically cost several tens of thousands of US$.

Virtually all crash barriers are supplied in a fixed width and configuration which cannot be changed by the user during installation. An exception to this is the retractable bollards (shown in the bottom right of the above diagrams) which have some flexibility on the distance allowed between them during installation, however, these are not normally suitable for circumstances * , where the barrier needs to be opened and closed many times an hour due to the mechanism ***,* required for operation.

*... When packed for shipping or storage a typical rated crash barrier takes up a lot space.

Hence, typical crash barriers have a fixed width, cost tens of thousands of US$ and are large, so * ** that purchasing them before having an actual need and storing them for a possible future : * * application is not very practical.

* : * However, in organisations that need to respond quickly to urgent events (such as the military or the United Nations) the time it takes to purchase and install a crash bamer is often critical. For the United Nations it typically takes at least two months to carry out a competitive procurement * *. process, the supplier typically takes one or two months to manufacture the barrier, the shipping firm typically takes one or two months to deliver it and the installation will typically take at least : one month. Hence, for the United Nations to deploy a crash barrier it can typically take more than six months.

As a temporary quick measure unrated crash barriers are often implemented, i.e. crash barriers which may or may not be capable of stopping the perceived threat. A typical, temporary, quick and unrated crash barrier is a cable barrier' and consists of: * Two reinforced concrete blocks which each have a loop of reinforcement protruding from the surface (used as a lifting lug).

* A high t.nsiIp steel cable that at one end is passed thrcgh the fthg g of one of the concrete blocks and joined to itself using friction U'-grips in a similar way as indicated in the drawing 3. The other end of the cable is typically joined-to a small crane type hook in a similar way, thus enabling this end of the cable to be hooked onto a lifting lug of the adjacent concrete block and the cable to be suspended at about waist height across the road.

A cable barrier of this type can be varied in width simply by undoing the friction U-grips at one end, reducing the distance between the loops located at either end of the steel cable and moving the concrete blocks closer together.

The main disadvantage with a cable bamer of this type is that the friction grips are expected to fail before the cable and at a load that is not possible to accurately determine. To achieve a rated loop at the end of a steel cable typically requires the a solid steel elliptical core to form the loop with the cable being wrapped around it and the individual strands of wire within the cable being interwoven within itself using specialist equipment that would not be available to an end user in

the field.

The invention presented provides an inexpensive rated cable type crash barrier that is easily stored and whose width can be varied. Hence, an organisatiori like the United Nations could have a large quantity in stock and the installation time of a rated crash bamer reduced from months to days.

Statement of Invention

A vehicle crash barrier which incorporates at least one cable with loops at each end which are rated (both the cable(s) and the loops) to withstand a specified load and where at least one cable is formed into a lasso (for example, by one of its loops being larger than the other and the smaller one being passed through the larger one); at least one such cable lassoing an anchor (such as a large reinforced concrete block) and then being suspended across the road to form the main part of a vehicle bamer where the end user can control the length of the cable suspended across the road by wrapping the cable around the anchor more than once before passing one cable loop through the other to form the lasso.

It is expected that parts that are easily manufactured throughout the world (such as the reinforced concrete blocks) would not be supplied with the bamer.

An Example Embodiment of the Design An example embodiment of the design is shown in drawing one, where: Item 1 Are the anchors, in this case, two identical blocks of reinforced concrete. The anchors are shown * *. with large bases to resist tipping and upper cylindrical pieces to ensure the cable cannot slide off even if they do turn over during an attack. If these blocks were located on a flat surface the force * required to drag them could easily be calculated and as long as this is less than the force to break the cables the barrier would not be expected to break. The maximum distance that the barrier could be pushed back could also be calculated based on the coefficient of frication and the mass of the blocks.

Other anchors could be used by the end user, such as part of a sand filled gabion wall or a large * * tree. If the anchors are not expected to move the energy absorption would mostly derive from the deformation of the attacking vehicle.

Item 2 *. Is one of the two steel cables. It has been lassoed' around the concrete block on the left and is * being held tight around the blocks inner cylindrical core by means of a U' shaped friction grip (item 6).

The entire cable (including the loops at both ends) would be guaranteed by the manufacture to withstand the appropriate load. To achieve this it is normal for each loop to Incorporate a solid steel elliptical core. To enable the cable to be lassoed' around the concrete block the loop at one end of the cable is larger than the loop at the other end, therefore enabling the smaller loop to be passed through the larger one to form the lasso.

The main r.gth,f tha aiia is suspended across the roao ana is tfleretore the part which would be hit by an attacking vehicle.

If the end user wishes to reduce the width of the barrier opening, item two can be wrapped around the cylindrical core of the concrete block additional time(s) before being passed through the loop to form a lasso. Another variation would be to lasso a central core of reinforcement before pouring the concrete (the width of the barrier could be controlled by weaving the cable around specific sections of the reinforcement before pouring the concrete).

Feature 3 The loop of the cable (item 2) at the far right of the diagram loops over item five.

Item 4 Is the second steel cable. It has been wrapped around the other reinforced concrete block and has been joined to itself using item five.

Item 5 Is a crane type lifting hook that is guaranteed by the manufacture to withstand the same load as the cables. This item incorporates a typical removable pin on the non-hook side which enables it to be joined to loop(s) of the other cable (item 4). Item five could also incorporate a spring loaded latch on the hook side to retain the loop whatever direction the load is applied to the cable from during an attack. This latch could have holes in it and the surrounding structure that enable a padlock to be attached in order to prevent unauthorized opening.

This item could be held upright during normal use by a small metal plate that is bolted to the concrete block. * S. * . * * .. S... * . S... S. SI S. S * .

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