EP1108090B1

EP1108090B1 - Barrier for calibrating the decelerations of "light" vehicles upon impact

Info

Publication number: EP1108090B1
Application number: EP99926741A
Authority: EP
Inventors: Gabriele Camomilla; Stefano Bruschi
Original assignee: Autostrade Concessioni e Costruzioni Autostrade SpA
Current assignee: Autostrade SpA
Priority date: 1998-08-13
Filing date: 1999-06-09
Publication date: 2003-08-27
Anticipated expiration: 2019-06-09
Also published as: ES2205835T3; ITRM980549A1; ITRM980549A0; AU4390199A; ATE248257T1; EP1108090A1; WO2000009812A1; DE69910798T2; DE69910798D1; PT1108090E; IT1302438B1

Abstract

A device (9) used in steel-made road safety barriers comprising a band or strip (2) and posts (1), wherein the device may be mounted on a lateral barrier or on a traffic divider. The device (9) is located in an intermediate position between the base of the posts and the upper spacer, which is designed to absorb the impact due to heavy goods vehicles, and the device connects a longitudinal rail (2) to the posts themselves (1). The device forms a spacer (9) specifically designed for light vehicles, and moves rearward under the impact force by sliding transversally; the device calibrates and gradually absorbs the impact force and therefore the decelerations transmitted to the vehicle and to its passengers.

Description

Technical Field

The present invention relates to a road safety barrier, comprising a device mounted on the posts of the road barrier, to act as a spacer for the lower longitudinal rail of the barrier, in order to calibrate the decelerations which are transmitted to "light" vehicles during impact.

The barrier belongs to the category of metallic road safety barriers including a band or strip, and posts, and is intended for use as lateral barrier or traffic divider, wherein said device forms a spacer and/or a lower energy absorbing device for automobiles.

Background Art

As known in the field of safety barriers and in particular those to be installed on traffic dividers of motorways, very high retention levels - of the order of 600 kJ - are required in order to prevent vaulting by a goods vehicle of more than 40 tons and with a high center of gravity.

Barriers with high resistance are consequently very rigid, and for this reason, with respect to an impact caused by a light vehicle (automobiles with a weight of between 800 and 1500 kg), even at very high speeds and energies up to 70 KJ, no problems of vehicle retention arise, but the decelerations transmitted in this case to the passengers may be very high and fatal.

In many cases of accidents involving automobiles, the relatively low energies involved are not sufficient to "trigger" the barrier displacement so as to reduce and calibrate the decelerations.

On the other hand, it is anyway obvious that in the field of safety barriers for roads and especially in the field of traffic dividers, the most important problem is that of obtaining protection and preventing vaulting for the whole variety of vehicles circulating on the road, which have masses, sizes and velocities which are extremely different.

Barriers suited to retain heavy goods vehicles, with a weight between 3 and 44 tons, may represent a fatal obstacle (due to their rigidity) in case of impacts by vehicles with a weight between 800 and 1500 kg.

In particular, in the field of metallic barriers including a band or strip and posts, that is in the case of guardrails, said high absorption energies are obtained by means of a blade having a triple wave configuration, and upper spacers which are more and more wide, heavy, and not easily deformable, connected to each other through diagonally arranged tubes, and said posts are becoming more and more high and close to each other.

The current metallic barriers comprise a lower rail - the so-called "wheelguard" - in an intermediate position between the upper spacer and the base of the posts, which prevents a "highly localized" impact by an automobile against a post, that is the immediate stop of the vehicle and the consequent extremely high peak of the decelerations, not bearable by the passengers.

The main problem of many current high resistance barriers is due to the fact, that the upper spacers have a noticeable transversal dimension (with respect to the row formed by the posts), so that, in practice, the automobile hits the barrier on the triple wave and on the upper spacer at the level of the windshield (see Fig. 1), but said components are designed to resist to impacts by heavy vehicles, so that the automobiles will be seriously damaged and the passengers will be seriously injured; in practice, the automobile does not hit the lower rail or "wheelguard".

Some patent applications have solved this technical problem in different ways.

For example EP-A-0 708 206 discloses a semirigid road barrier comprising several posts, and connecting assemblies for an upper rail. The connecting assemblies present a spacer and first and second cam guide assemblies, in order to ensure that when the post starts bending, at the end of the initial impact stage, connecting bolts can slide along respective portions of said cam assemblies, to ensure that the position of the upper rail remains substantially vertical, as may be seen in Figs. 13 a)-d) of this cited patent application.

Moreover, the road barrier of EP-A-0 708 206 also includes a wheelguard extending beneath the upper rail.

The wheelguard protrudes towards the carriageway along a distance comparable to that of the upper rail and the associated connecting assemblies. Moreover, the wheelguard comprises a connecting device defined by a channel section extending perpendicular to the posts, and connected at one end to the lower rail by a bolt, and at the opposite end, to the wall of the post, by means of a bolt engaging in sliding manner a longitudinal slot formed on the central wall of said section. The slot may have a portion which is narrower than the bolt diameter. Upon impact, the channel section may rotate by an angle.

US-A-5,657,966 discloses a metallic guardrail comprising a sustaining post and a spacing member.

The spacing member is secured at one side to the sustaining post and carries the upper rail at the other end. The spacing member includes a window and one or more holes are provided on the spacing member in proximity of the vertexes of the quadrilateral window. In case of crash of a colliding vehicle, a pin will tear an area of the spacing member, which is weakened by holes. This system allows to maintain the spacing member in a vertical position, thereby preventing vaulting of the vehicle. A beam, which is actually a wheelguard, has in this metallic guardrail a size (in the direction perpendicular to the rail) which is much smaller than the dimension of the spacing member in the same direction. This wheelguard is "stationary", because it does not include a device allowing its sliding upon impact, and serves only to avoid any dangerous interference of the forecarriage of the colliding vehicle with the sustaining posts.

DE-U-1 944 842 discloses a spacer for a guardrail, wherein the guardrail forms a traffic divider, and the spacer comprises an intermediate tubular body and two external tubular bodies, fitted partly inside the intermediate tubular body.

The external tubular bodies are fixed to the intermediate tubular body by means of rivets which break under a shearing force, thereby allowing the retraction (sliding) of the external tubular body inside the intermediate tubular body.

This utility model is applied to the upper spacer, not to the wheelguard itself. Moreover, after the shearing of the rivets, only the friction between the tubular bodies serves to calibrate the decelerations, and there are no other means provided for this function. As opposed to the present invention, the reaction force tends therefore to decrease and not to increase, during sliding of the external tubular body.

EP-A-0 810 325 discloses a high performance deformable steel guardrail, with a longitudinal rail comprising a pair of metal section irons and a double wave. This system involves no sliding and is totally different from the present invention.

Disclosure of invention

An object of the present invention is to realize a road safety barrier with a device which connects the lower rail or "wheelguard" to the posts, having a transversal dimension comparable to that of the upper spacer, in such a way as to be able to protect the automobile from a direct impact against the upper spacer, which is very rigid because it is designed and constructed so as to absorb the impact produced by goods vehicles.

Another object of the present invention is to calibrate the decelerations of the automobile (light vehicle) which hits the device, by providing a "sliding" system in the device of the invention, so that the device can absorb part of the energy while moving rearwards.

This further object of the present invention therefore amounts to transforming the current barriers of the guardrail type into "bivalent" barriers, that is, to adapting them to absorb not only impacts produced by heavy goods vehicles, but also those caused by automobiles, without giving rise to unacceptable decelerations acting on the passengers.

The invention solves the above problems by providing a barrier according to claim 1.

Preferred embodiments of the invention are defined independent claims 2-6.

Brief Description of Drawings

The present invention will now be explained in more detail by means of a preferred embodiment, which is given only for illustrative and non-limitative purposes, and which is shown in Fig. 6 of the annexed drawings, wherein:

Fig. 1 is a schematic view of a traditional metallic barrier comprising a triple wave, wherefrom it is possible to obtain the relative sizes of the automobile as compared to the barrier components, and thereby understand the objects of the present invention;

Fig. 2a is a side view of a device, not according to the present invention, in its simplest realization, before an impact (initial condition), but which helps to illustrate the invention;

Fig. 2b is a side view of the device of Fig. 2a, after the impact (final position);

Fig. 3a is a side view of a second device not embodying the invention, formed by two elements, fixed to the post and in the initial condition;

Fig. 3b is a side view of the device of Fig. 3a in the final position after the impact;

Fig. 4 is a side view of the device of Fig. 3a, according to a variant comprising a box-like rail;

Fig. 5 is a view similar to that of Fig. 4, in the initial device position, wherein the rail is a double blade;

Fig. 6 is a side view of a safety barrier according to the present invention, comprising adjustment means for the sliding movement of the wheelguard during the impact, and therefore also of the decelerations involved, the adjustment means being provided by holes;

Fig. 7 is a side view of a modified prior art device, which is mounted on a metallic traffic divider;

Fig. 8a is a top view of the device of Figs. 3a, 3b;

Fig. 8b is a rear side view of the device of Figs. 3a, 3b;

Fig. 9a is a cross-sectional view and a front view respectively, of the first (stationary) element of the device of Figs. 3a and 3b;

Fig. 9b is a cross-sectional view and a front view, respectively, of the second (movable) element of the device of Figs. 3a and 3b;

Fig. 9c is a front sectional view showing the insertion of the second movable element of the device inside the first stationary element of the same device, and their mutual connection;

Fig. 10a is cross-sectional view and a front view respectively, of the first (stationary) element of the device according to a different embodiment;

Fig. 10b is a cross sectional view and a front view respectively, of the second (movable) element of the device according to the embodiment of Fig. 10a;

Fig. 10c is a front sectional view showing the insertion of the second movable element of the device, inside the first stationary element of the device, and their mutual connection, according to the embodiment of Figs. 10a and 10b.

Best Mode of carrying out the Invention

Fig. 1 shows a traditional metallic traffic divider comprising a triple wave, including several posts 1, a wheelguard or lower rail 2 which is usually formed by a steel channel section, and an upper spacer 3' to which the band with a triple wave shape 3 is attached.

It can be noted that the transversal dimension and the height with respect to the ground, of the spacer 3', which is constructed so as to resist to impacts caused by heavy vehicles, are such that the automobile hits in fact directly against the spacer at the level of the windshield whereas the "wheelguard" is not involved; for this reason, serious consequenses are to be expected.

On the other hand, according to the present development in the field, the barrier comprises posts which are very closely arranged, and spacers having a remarkable transversal size, a high weight and a high rigidity, connected to each other by diagonal tubes (not shown), with the aim to retain goods vehicles.

The following figures show how the problem may be solved, in particular according to Fig. 6, which shows an embodiment of the invention.

In the following, we will describe two barriers (Figs. 2a, 2b and 3a, 3b respectively) which may be considered variants of the prior art (e.g. EP-A-0 708 206), but which help in understanding the present invention, shown in Fig. 6. In Figs. 2a and 2b, a deformable cushioning element is formed by a single movable element 4, fixed in a position between the base of the post 1 and the upper spacer (the latter being omitted in the figures following Fig. 1). This movable element 4, realized in the shape of a steel channel section, comprises two slots 8 for the sliding movement instead of one.

The two clamping bolts 5, are used to "fix" the movable element 4 to the post 1; said clamping bolts are introduced in the two slots 8 of Fig. 2a, which are obtained on the greater side of the movable element 4. The bolts 5 are also driven in the post 1, specifically inside two holes of the respective post.

At its left end in Fig. 2a, the movable steel channel section 4 forms a front wall 6, which serves for fixing a longitudinal rail 2 by means of a round-headed fixing bolt 7.

The lower rail 2 is fixed to the plurality of front walls 6 of the different movable elements 4 associated to the respective posts 1 of the barrier; said lower rail may form a continuos steel channel section, or a box-like configuration, or a double wave or other configurations (see Figs. 4 and 5).

In the case of a lower rail having a box-like configuration, the fixing operation to the movable element 4 requires a longer bolt (see Fig. 4).

As shown in Fig. 2b, the movable element 4 moves to the right upon impact, and the clamping bolts 5 will thereafter possibly be located at the opposite end of the slots 8, at the end of stroke position.

The lower (continuos) rail 2 will have the function to stop the motion of the colliding vehicle (in the first place an automobile), while the displacement shown in Fig. 2b will allow to "cushion" the impact force, thereby limiting and calibrating the decelerations. This is the reason for using the definition "a barrier for calibrating the decelerations".

Figs. 3a and 3b show a second solution, in which a movable element 9 is partially inserted inside the stationary element 4' fixed to the post 1, by means of the bolts 25. In this case the bolts 25 are introduced into circular holes of the stationary element 4' and through holes aligned with them, which are provided on the post 1. The movable element 9 slides upon impact by a vehicle, inside the stationary element 4', while the greater sides of these two elements remain in contact.

The bolt 10 is used for the purpose of mutually "fixing" the two elements 4' and 9 of the device, but it slides in the slot 8 during the impact (observe that in this solution a single slot is sufficient). This second solution is preferable; it prevents bending of the movable element 9, since the latter is constrained to slide inside the stationary element 4'.

Fig. 3b illustrates the displacement of the movable element 9 inside the stationary element 4' upon an impact by a vehicle.

The solution proposed by the present invention, which is shown in Fig. 6 differs from that according to Figs. 3a and 3b, in that a plurality of holes with "programmed" breakage 13 is provided instead of the slot 8.

Alternatively, the bolt 10 could be arranged inside a slot 8 located ahead (upstream) of the plurality of holes 13. Said holes 13 are useful for gradually decelerating the vehicle, due to the fact that the bolt 10 must successively break the thin walls of material located between adjacent holes 13. If a slot 8 is also provided, during the first displacement inside the slot 8 the device will oppose a reduced resistance, but afterwards the bolt 10 will have to "extrude" part of the sheet in the vicinity of the holes 13. The choice of the thickness of the wall between two respective holes (corresponding to some mm), is also a way to adjust energy absorption and therefore is a means to calibrate decelerations.

According to the embodiment of Fig. 6, once the movement of the movable element 9 has been "triggered", the slot 8 alone will first oppose a minimal resistance, and thereafter a condition is reached in which the resistance can be gradually increased in order to resist more and more to the motion of the vehicle advancing during the impact against the device.

Therefore, a constant mutual distance between the various holes 13 will lead to a gradually increasing resistance opposed by the different layers of interposed sheet steel, to the momentum associated to the collision.

This solution proposed by the present invention illustrates the principle on which the invention is based: that is, the principle of decelerating the vehicle in a gradual manner. This gradualness is firstly obtained by progressively reducing the impact force during the first period of the impact, - and this can be attained by means of the sliding movement of the movable element inside the stationary element -, and secondly by the increasing resistance opposed by the plurality of holes "extruded" by the bolt. In case of collisions involving even higher energies, during a second period the colliding vehicle will be decelerated because of the deformations of the spacer and of the post. The device must be calibrated with regard to impacts caused by automobiles, and it is obvious, therefore, that the device itself and the "wheelguard" will undergo considerable deformations and will break at certain spots, in case of impacts due to heavy goods vehicles.

Even if the barrier of Fig. 6 relates to a lateral barrier to be installed on the side of the road, that is to a barrier protecting only one side, it can be understood that the device according to the invention - due to its versatility - lends itself to the use in a traffic divider too, which protects two sides at the same time. From the point of view of its construction, only a symmetrical reproduction of the structural components will be necessary, with the only exception that a single central supporting post 1 and a single stationary symmetric "double" element will be needed. For this application involving traffic dividers for the protection on two sides at the same time, the same principle applies with regard to the operation of the device, as has been extensively described previously, both with respect to the form of the rail and to the means used to finely calibrate the deceleration of the colliding vehicle.

In the same way, Figs. 10a, 10b, 10c show further embodiments of the movable element 9"' and of the stationary element 4"'; they illustrate the box-like sections of the respective two elements, when separated from each other, and the cross-section of the two elements, when one of them is introduced inside the other one.

In analogy to Figs. 9a, 9b, 9c, numeral 16"' now indicates the hole obtained on the movable element 9, for the introduction of the clamping bolt 10"' slidable inside the slot , while numeral 17"' denotes the hole on the bent wall or fin 6"', the latter hole being obtained on the movable element 9"' for the insertion of the clamping bolt 7"' rigidly connecting the movable element to the lower rail.

According to Fig. 10, the structural difference with respect to Fig. 9 obviously consists in providing a bolt 10"' which is sufficiently long to reach the opposite end of the element 4"', for the mutual connection of the two elements of the device.

The device mounted on a safety barrier according to the present invention, located in an intermediate position between the base of the posts and the (upper) spacer, allows to calibrate the decelerations of the colliding vehicle, both for high and low masses. It extends the possibilities of operation of the traditional "wheelguard" and it is also suited to be realized according to further interesting embodiments, due to its structural versatility, said further embodiments comprising instead of the steel channel sections connected by bolts and instead of the other realizations generally disclosed in the description, other functional elements with different cross-section, e.g. box-like elements, elements shaped like a parallelepiped, or otherwise shaped, which are steel-made or made of fiber glass, etc.

Claims

A road safety barrier made of steel or fiber glass and comprising a band or strip (3), posts (1), an upper spacer (3') connecting the strip (3) to a post (1), a wheelguard or lower rail (2), and a lower spacer (4',9) connecting the lower rail (2) to the post (1), characterised in that said lower spacer comprises a movable element (9) and a stationary element (4'), wherein said movable element (9) is partially inserted in said stationary element (4'), said lower rail (2) being fixed to the free end of the movable element (9) and said stationary element (4') being rigidly connected to the post (1) by means of bolts (25) introduced in circular holes (15) of the stationary element (4') and in corresponding holes provided on the post (1) and aligned with the circular holes (15), said movable element (9) being connected to said stationary element (4') by means of a clamping bolt (10) so that, before impact by a vehicle, the transversal size of said lower spacer is comparable with that of said upper spacer (3'), said movable element (9) being slidable, upon impact by a vehicle, inside said stationary element (4'), the greater sides of the stationary element (4') and of the movable element (9) remaining in frictional contact during the collision, when the movable element (9) slides inside the stationary element (4'), said stationary element (4') being laterally provided in its longitudinal direction with a row of holes (13) and possibly a slot (8) located upstream said row of holes (13), said clamping bolt (10) being introduced inside the first of said holes (13) or inside said slot (8) if present, and said holes (13) being separated from each other by thin walls, which are designated to be sequentially broken during the collision.
A barrier according to claim 1, characterized in that said movable element (9) and said stationary element (4') have the form of channel sections of steel, or have a parallelepipedal shape.
A barrier according to claim 1 or 2, characterized in that the lower rail (2) is formed by a continuous channel.
A barrier according to claim 1 or 2, characterized in that the lower rail (2) is formed by a continuous sheet with a configuration of a double wave.
A barrier according to claim 1 or 2, characterized in that the lower rail (2) is formed by a box-like structural steel, and the movable element (9) is attached thereto by means of a bolt whose length is greater than the cross-section of said lower rail (2).
Use of a barrier according to any of claims 1 to 5 as a lateral barrier or as a traffic divider.