EP1419299A1

EP1419299A1 - Stanchion for steel-rope barrier

Info

Publication number: EP1419299A1
Application number: EP02740063A
Authority: EP
Inventors: Peter Nilson
Original assignee: Allmaco Saferoad AB
Current assignee: Allmaco Saferoad AB
Priority date: 2001-01-12
Filing date: 2002-01-10
Publication date: 2004-05-19
Also published as: SE516599C2; WO2002063103A1; SE0100103L; SE0100103D0

Abstract

The invention is a stanchion for a steel-rope barrier. Existing stanchions generally consist of vertical section, asymmetrical with regard to bending resistance, that have components such as flanges and other parts attached, which in various circumstances could hook onto and rip open vehicles, motorcyclists, etc., that collide with it. There is thus a risk of suffering great damage or injury. The same currently applies to round stanchions, which have protruding components mounted on the sides for holding the ropes in place. Using vertical tubular section (1) as a stanchion, and inserting a vertical notch (6) from the stanchion's (1) top, in which the barrier's ropes (5) run, results in a stanchion (1) without any protruding components and attached parts that could cause further damage or injury when collided with. So that the stanchion's (1) rope-holding and other functions are not impaired because of the placement of the notch (6), the parts of the stanchion (7, 8) affected by the notch (6) are reinforced with surface-mounted rings (9) and/or connecting devices (11). The placement of the ropes (5) in the notch (6), based on the same purpose, has also been taken into account in the invention.

Description

STANCHION FOR STEEL-ROPE BARRIER

This invention is a stanchion (post) designed to hold the ropes of a steel-rope barrier in the position intended, while simultaneously acting as an energy absorber, for example when impacted by a vehicle.

The rope barrier is chiefly used as a safety feature in the centre or along the sides of roads and streets in order to prevent, or at least diminish, a vehicle's deviation from its own lane, thereby reducing the risk of personal injury, caused by the vehicle slewing off the roadway, or of a collision between meeting vehicles or other mobile or fixed objects, for example.

In the main, a rope barrier consists of tensioned steel ropes, which are suspended on stanchions located at regular intervals along the stretch of road in question. In order to obtain and maintain the tension in the ropes, they are normally fitted with a tensioning device and the ends of the ropes are anchored in the ground in some way.

When a vehicle impacts a rope barrier, the ropes are stretched at the same time as resistance forces are mobilised. The vehicle is then slowed down and its direction of travel changes. The vehicle's impetus is also affected by the absorption of motive energy, which the stanchions bring about when they are impacted and deformed by the vehicle. Even the friction against and deformation of the vehicle itself, which occur on contact with the barrier, affect its impetus to a certain extent.

Normally, a rope barrier should meet certain criteria in order for the highway authorities to approve it for installation. The criteria applicable to such a rope barrier could, for example, apply to the risks of personal injury and the maximum lateral stretch when impacted at specific speeds, track angle, etc., for specified vehicle types.

The rope barrier's stanchions should hold the ropes as long as possible at the intended height and lateral positions, until the instant the vehicle collides with the stanchion. The vertical resistance should make it impossible for the vehicle to "crawl under" or "climb over" the barrier. Established standards for the maximum permissible lateral stretch of the ropes mean that the function of the stanchions as stays for the ropes is vital. If the stays give way laterally, the ability of the ropes to mobilise resistance is reduced and the lateral stretch increases substantially.

Once the vehicle collides with the stanchion, during vehicle-slowing energy absorption, the stanchion should bend in an incision at ground level, in order for it to collapse as fast as possible to a position parallel with the ground surface. This is so that the stanchion will not be a harmful obstruction to the vehicle. For example, an erect stanchion could damage the vehicle's chassis, fuel tank, etc., resulting in serious consequences. In addition, the stanchion, or important parts of it, must not break off because of the risk such an object poses to the surroundings.

With regard to the stanchion bending on vehicle impact, it must "release" the ropes so that they retain their intended level of efficiency and do not fall to the ground with the stanchion. If this does not happen, there is a risk that the vehicle will scale the barrier.

Today, mostly various types of steel section are used for the steel-rope barriers' stanchions. These could be U-or I-beams and round, tubular sections. With regard to the U- and I-beams, these are usually placed so that their normally weaker bodies are at right angles to the direction in which the ropes run.

Ordinarily, the ropes are secured symmetrically against the sides of the stanchion with the help of surface-mounted supports in the form of bolts, or welded-on hooks or brackets. If necessary, one or two ropes can be installed on the top of the stanchion. There is currently also an I-beam stanchion on which the ropes are located in a notch in the centre of the beam's body. The notch extends from the top of the stanchion downwards. The lower rope lies at the bottom of the notch and the other ropes are placed at regular intervals upwards in the notch, separated by plastic spacers.

Certain adverse factors exist concerning the stanchion types currently in use and described above, which involve unnecessary potential safety risks.

* These stanchion types (except I-beam type with notch in body for rope placement) have the above-mentioned rope-support components, which when impacted by a vehicle can cause unnecessary damage and/or injury. This is particularly evident, for example, when a motorcyclist collides with or merely grazes a stanchion.

• An I-beam's bending resistance is greatest against loads that act at right angles to its flanges, and lowest against loads that act at right angles to its body. This means that an I-beam could react uncontrollably and perform differently, depending on the angle at which a vehicle collides with it. With an increased angle of impact in relation to the direction in which the ropes run, the risk increases of the stanchion not bending low enough in order to prevent the I-beam's protruding and angular parts from causing serious damage to the vehicle's chassis. Furthermore, in these cases the stanchion could present such great bending resistance that the resultant braking effect is so powerful that this in itself can cause personal injury. A similar line of argument can also be applied to the other stanchions with asymmetrical bending resistance, for example the U-beam type.

The bending resistance of a round, uniformly thick tubular stanchion does not depend on the vehicle's angle of impact, however. With suitably chosen tube dimensions, for example with regard to tube diameter and material thickness, it is easier than for other stanchion contours to control the stanchion's bend and its braking effect on impacting vehicles. Moreover, the tube in itself does not have any protruding or angular parts such as U- and I-beams have.

The purposes of this invention are that:

• The stanchion holds the barrier's steel ropes in the intended vertical and lateral positions up until the instant the vehicle impacts it. This should apply irrespective of the angle at which the vehicle collides with the barrier.

• The ropes are "released" as quickly as possible when the vehicle soundly impacts the stanchion, so that they are not dragged down with it to the ground.

• On vehicle impact, the stanchion, as quickly as possible and predictably, without breaking off or loosening, plus under "reasonable" vehicle-braking energy absoφtion, bends sufficiently along an incision in it at ground level, so that the risk of injury to the vehicle occupants and persons in the vicinity because of the stanchion's reaction and design is completely avoided or is lessened to the greatest possible extent. • As far as possible, the stanchion itself is shaped without protruding components such as flanges, etc. that could snag , for example, in a vehicle or unprotected driver/passengers, thereby causing further damage and/or injury.

• As far as possible, the stanchion is without protruding parts, such as bolts, hooks and brackets that could snag , for example, in a vehicle or unprotected driver/passengers, thereby causing further damage and/or injury.

The invention

This invention, as described below and featured diagrammatically in Figures 1 and 2, meets the purposes cited.

The main part of the stanchion is comprised of a uniformly thick tube (1), which is fitted into a matching hole in a fixed base in the ground (2). The base could consist of different material, vary in shape and itself have the purpose, or in co-ordination with the surrounding ground material (3), without moving to any great extent itself, of mobilising adequate and stable resistance when a vehicle collides with the stanchion (1), so that the stanchion bends close to the upper side of the base.

The stanchion's vertical height above ground level (4) depends on the desired placement level of the ropes (5). From the stanchion's (1) top downwards, through the stanchion's (1) vertical centre line, there is a notch (6) in which the barrier's ropes (5) run at different levels parallel to the ground. The notch (6) is made by placing two slits (7) in the wall of the tube in a straight line with each other, i.e. 180° apart, on either side of the stanchion's (1) centre line. The width and length of the slits (7) depends on the diameter of the ropes (5) and the vertical placement of the ropes (5) respectively.

Since the slits (7) are made in the wall of the tube, the stanchion's (1) bending resistance is weakened considerably in the position of the notch (6). This means that in all probability the stanchion's (1) remaining material at the lower edge of the slits (7), i.e. at the bottom of the notch (6), will not hold up to the bending moment caused by the lateral energy of the ropes, which occurs when a vehicle collides with the rope barrier. This, in principle, "half-moon-shaped" part of the tube (8), which actively supports and braces against the ropes' (5) lateral tendency, will give way and release them. Thereby, the stanchion (1) loses its function as a stay for the ropes (5), upon which their ability to withstand and stop the vehicle's sideways movement is impaired. The result will thus be inferior barrier performance.

It is possible to fully or partially eliminate this slit drawback by modifying the dimensions of the stanchion tube (1), for example by increasing the thickness of the material. In this case, however, there is a great risk that the stanchion's (1) bending resistance will become too great, producing undesired effects on vehicle-braking and from the upright barrier stanchion (1). Consequently, the stanchion's (1) dimensions, such as tube diameter and material thickness, are chiefly governed by requirements for the stanchion's (1) cross-section and function at ground level (4).

The remaining drawback concerning the wealcened slits (7) when the stanchion tube's (1) dimensions have been established, can be remedied by the following measures, either individually or jointly:

* The ropes (5) are placed at levels as close to the bottom of the notch (6) as possible in order to reduce the bending moment, which arises from the lateral energy of the ropes that occurs when the vehicle collides with the rope barrier. For the stanchion's cross section with slits (7), the bending moment is at its greatest at the base of the notch (6). When the position of the ropes (5) is decided upon, the requirement for adequate spacing in the levels between the ropes (5) must be taken into consideration, however, so that "good interception" of the vehicle is achieved, i.e. that the amount of rope damage to the vehicle (5) is acceptable.

* One or several rings (9) of any shape are placed around the outside, tightly fitting the remaining parts of the tube (8) and the two slits (7) in order to transfer parts of the laterally directed energy resulting from collision with the barrier from the actively resistant part of the tube (8) to the passive part (8). Because of this, in principle the cross section surface is doubled, thus contributing with bending resistance. The rings (9) can be placed under, between or above the ropes (5) and can consequently even have the task of acting as spacers between them (5). One requirement for the rings (9) is that they must have a combined tensile strength so that their (9) unified and energy- transmitting effect is not lost before the bending moment in the stanchion (1) at ground level (4) forces it (1) to bend. Another requirement is that the rings (9), without themselves causing personal injury, leave the stanchion (1) so that the ropes (5) are given "safe passage" out of the notch (6) when the stanchion (1) bends on being directly impacted by the vehicle. The rings (9), however, must be prevented to the greatest possible extent from leaving the stanchion (1) before the vehicle impacts it (1). Through friction between the stanchion (1) and the ring (9) and/or through at least vertically anchoring the upper ring (9) in the stanchion (1), for example with a spring, bolt, clamp or similar (10), any upwardly directed energy that the vehicle could generate in the ropes (5) on impacting the barrier is counteracted. In general, the rings (9) could be made from various materials and be different in shape, thickness, width, etc.

* One or several devices (11), such as springs (11), bolts (11), pins (11) or similar (11) of any shape, join the remaining parts of the tube (8) together in order to transfer parts of the laterally directed energy resulting from collision with the barrier from the actively resistant part of the tube (8) to the passive part (8). By this, and like the ring concept described, in principle the cross section surface is doubled, thus contributing with bending resistance. The devices (11) can be placed under, between or above the ropes (5) and can consequently even have the task of acting as spacers between them (5). One requirement for the devices (11) is that they must have combined tensile strength so that their (11) unifying and energy-transmitting effect is not lost before the bending moment in the stanchion (1) at ground level (4) forces it (1) to bend. Another requirement is that the devices (11), without themselves causing personal injury, leave the stanchion (1) or give way so that the ropes (5) are given "safe passage" out of the notch (6) when the stanchion (1) bends on being directly impacted by the vehicle. The devices (11), however, must be prevented to the greatest possible extent from leaving the stanchion (1) or from giving way before the vehicle impacts the stanchion (1), thereby counteracting any upwardly directed energy in the ropes (5) that the vehicle could generate in them (5) on impacting the barrier. In general, the devices (11) could be made from various materials, have different shapes, thickness, widths, etc.

Claims

PA T E N T C LA IM S

1. Stanchion for steel-rope barrier characterised by it (1) consisting of an upright tubular section (1) without potentially harmful protruding components and parts that could grip or hook onto an object. From its (1) top, for a limited distance downwards, it has a notch (6), formed by two slits (7) in the wall of the tube, placed symmetrically 180° apart on either side of the stanchion's (1) centre line, on which the barrier's ropes (5) run parallel to the tubular section's (1) cross section and the foundation's surface (4).

2. Stanchion as per patent claim 1, characterised by one (9) or several rings (9) of any shape and height being placed around and tightly fitting the remaining parts of the tube (8) and slits (7), in order to transfer parts of the energy originating in the ropes, when collision with the barrier occurs, from the actively resistant part of the tube (8) to the passive part (8), for the purpose of increasing the stanchion's (1) bending resistance and ability to absorb energy in the section affected by the slits (7).

3. Stanchion as per either of the previous claims, characterised by at least one of the rings (9) being anchored in the stanchion by means of friction and/or another device (10), such as a spring, bolt, clamp or similar, in such a way that it allows the ropes (5) to leave the notch (6) and the stanchion (1) only when the last-mentioned (1) is impacted by a vehicle.

4. Stanchion as per any of the previously detailed claims, characterised by one (11) or several devices (11) such as springs (11), bolts (11), pins (11) or similar (11) of any shape and at any height being placed in a way that connects the remaining parts of the tube (8) with regard to the notch (6) and the slits (7), in order to transfer parts of the energy originating in the ropes, when collision with the barrier occurs, from the actively resistant part of the tube (8) to the passive part (8), for the purpose of increasing the stanchion's (1) bending resistance and ability to absorb energy in the section affected by the slits (7).

5. Stanchion as per any of the previous claims, characterised by placement of the ropes (5) in the notch (6) being as close to its (6) bottom as possible in a way that takes into account acceptable rope (5) damage to the vehicle that collides with the barrier.