Patent Application
20230407584
The field of application of this invention concerns the installation of road safety barriers (hereinafter also referred to as “guardrails”).
Said barriers are an essential element in ensuring road safety. In fact, in addition to clearly delimiting the edge of the road, they are intended to significantly reduce the consequences of accidents involving vehicles leaving the road.
Specifically, a “guardrail” must prevent vehicles from exit the road and their overturning, to avoid dangerous collisions with other vehicles and/or elements outside the road. At the same time, it must be able to absorb and dissipate all, or part of, the kinetic energy possessed by the vehicle at the moment of impact, reducing, in a controlled way, the decelerations induced by the collision to the occupants of the vehicle, and allowing its gradual return to the carriageway by stopping its travel, possibly near the roadside. These behaviors of the “guardrail” can be achieved in different ways, focusing on the stability of the installation, providing that the uprights of the “guardrail” deform, but do not detach from the ground, or also providing that some of these uprights detach from the ground. These different strategies may depend on the terrain on which the “guardrail” is installed, but also on the required safety requirements: it is clear that a road located on the edge of a precipice or on the embankment of a watercourse should favor the objective of preventing off-road exits, while a road with free land on the sides can be safer if vehicles affected by an accident are allowed to stop their run off the carriageway.
Therefore, the real safety requirements and, consequently, the rules that should guarantee these requirements, can be respected in many ways: what must be assessed is the overall result, which has to do with the safety of a road as a whole, equipped with appropriate safety barriers.
The common practice, based on the known technique, does not adequately consider these aspects concerning safety, and it is frequent that, in the event of an accident, the authority which is responsible of the management of the road is responsible also for the consequences of this accident.
It is quite frequent that the “guardrails” installed along the roads do not normally meet the technical safety requirements, because their installation does not reflect the certification conditions, with serious risk for the consequences of any accidents.
After all, the huge variety of installation conditions makes it very difficult to build roads in which the installation conditions of the “guardrail” are homogeneous.
In summary, it can be stated that the known technique is satisfactory from the point of view of the materials and elements that are used for the realization of the “guardrail” as a stand-alone product, (intended as a system certified by authorized laboratories), while it still remains substantially unresolved the aspect concerning its installation, which often does not replicate the certification conditions of the “crash-tests”.
In conclusion, a good number of installed “guardrails” do not meet the real safety requirements, due to installation differences.
A typical situation in which the installation doesn't meet safety standards is considered below, more in detail. This is the very common case in which the uprights of a “guardrail” are planted into the ground by a maneuver performed with a so-called “pile driver”. This maneuver consists in vertically positioning the upright of the “guardrail” at the point where it must be driven into the ground, after which, with a mechanically operated hammer, it is beaten and driven into the ground (normally at a depth more or less equivalent to the part emerging from the ground).
This technique has its main advantage in the speed and simplicity of installation. The upright has a very linear structure consisting of a piece normally with a constant profile in the buried part.
On the other hand, the tightness of the installation largely depends on the compactness and characteristics of the ground that, if not particularly compact, modifies the behavior of the road barrier in the event of a vehicle collision: in this case, in fact, being the uprights not well stable in the ground, following the impact of vehicles, they will tend to rotate rigidly in the ground, instead of flexing, reducing their deformation capacity and therefore the capacity to absorb and dissipate the necessary amount of kinetic energy; but, above all, the uprights fixed on the ground normally exhibit very different behaviors depending on the trait of road in which they are planted, with consequent different performances with respect to the safety they can guarantee.
Some solutions provide for the use of uprights whose part to be fixed to the ground has an appropriate shape to ensure greater sealing, for example by using uprights associated with an enlarged plate that makes a greater quantity of soil collaborate with the upright seal, when the “guardrail” is subjected to a violent impact caused by an accident.
These solutions based on the use of uprights, whose shape of the buried part, has an appropriate shape, make the seal more secure, but do not solve the problem of installation unevenness; they also provide particularly improved performance only when the ground is compact; and they end up to produce an almost negligible effect precisely in the cases in which such improved performance would be needed most, i.e. in installations on less compact ground.
More interesting are the solutions that involve the use of anchors that grip the ground below the road surface.
The interest derives from the fact that the ground under the road surface is normally compacted in order to avoid the subsidence of the roadway due to the weight of the vehicles in transit. It is evident that such an inconvenience (i.e. the subsidence of the roadway) must be absolutely avoided, and therefore the surface on which the roads are built is always suitably prepared and, in particular, is pressed so as to make it very compact.
A solution of this type is taught in the patent application n. PCT/162019/050262-“Reinforcement element for fixing at the base, in ground, the uprights of roadside safety barriers” (by the same authors of the present patent application), which describes an upright connected, through a connecting element which works in tension, to one or more plates buried under the road surface. This solution, in its generality, is conceptually quite simple, but in its actual implementation it poses a series of problems, and requires further refinements, both to solve some installation problems, and to achieve a real quantitative control of the performance of the “guardrail”, as a system, in the event of an accident. Another solution, which is based on the exploitation of the greater compactness of the ground under the roadway, is taught in WO 2019/008525 A1-“Device for anchoring safety road barriers poles to the ground”. This is a solution that provides for a helical element, the cost of which is presumably very significant compared to the cost of the other elements of the “guardrail”; this element is suitable for being inserted into the ground by means of a screwing maneuver. Also this solution presents the problems of the previous one and, in addition, requires specific instrumentation for the installation, making the installation costs even more onerous, since it cannot be carried out with the instrumentation normally supplied to companies operating in the sector.
Furthermore, the anchoring system taught in WO 2019/008525 A1, in cases where it is most needed (i.e. when the roadside is not very compact, and does not offer adequate resistance), must penetrate deep enough into the ground below the roadway, in a zone that is often occupied by underground services. It is definitely preferable that the “road system” as a whole, including the appropriately installed safety barriers, does not invade the ground below the road substrate (approximately up to a depth of the order of one meter): this in order to decouple, as much as possible, the management of underground services (often associated with road layouts) from the road management.
In fact, there are sections of road where the priority objective of a safety barrier is to avoid going off the road: for example, due to the presence of a precipice, or a watercourse, or to protect what there is outside the street itself. In other sections, however, it is preferable that the vehicles involved in an accident go off the road, and what matters most is that their kinetic energy is dissipated, avoiding violent crashes against the barrier itself.
In fact, there are different types of road barriers, characterized by resistance parameters that allow them to be classified according to the behavior they must assume during accidents, defining the forces they must resist before bending or breaking; but there are no barriers where these parameters can be easily adjusted even during installation. Normally, a certain type of barrier, defined by the project, is installed in long stretches of road without variations, and the diversity of behavior depends only on the ground on which the installation takes place.
In other words, variable performances are obtained in a substantially random way, without the possibility to exercise a real control of the performances that this barrier should guarantee, so that they depend only (as it should be) on the real security needs that are required in the different road traits.
It is observed that the treatment and preparation of the ground where a road is built is part of the construction process of the road itself: indeed, it is one of the most important phases of road construction. A well-made substrate guarantees the durability and integrity of a road perhaps more than the laying of the surface, which, in any case, is an operation for which a periodic refurbishment must be envisaged for maintenance purposes; while the preparation of the substrate is a job that must be done at the beginning, once and for all.
Among the known art documents, which are considered somehow relevant for the purposes of the invention described below, it's worth mentioning also WO 2020/157074 A1 (“Road restraint system with elements for anchorages of the poles to improve performance”—Bruni M. et al. [IT]-6 Aug. 2020).
In addition, these safety requirements must be able to be defined even during construction, without necessarily requiring a detailed design of safety barriers for the entire length of a road.
In particular, the safety barrier indicated in the invention must be able to be installed in such a way as to react both through plastic deformations, and through programmed breakages of some elements, being such reactions decided during the installation operation.
It is clear that the control of some mechanical requirements during installation cannot be based on the installation of different barriers depending on the requirements to be obtained, because this solution would pose substantial problems when ordering the materials; Instead, it is desirable to have a single barrier, which has suitable adjustment elements to allow the control of mechanical requirements.
The installation must be able to be carried out with instruments typically supplied to operators in the sector, without requiring them to be equipped with specific equipment, built specifically for a particular type of “guardrail”. Typical equipment allowed are the so-called “pile driving machines”, tools for cutting asphalt and the equipment necessary for sealing cracks in the asphalt.
Still in the context of maintenance, it should be noted that the installation of road barriers that require the positioning of some elements under the road surface should not interfere (in a problematic way) with the routine maintenance of the road surface itself.
In general, the “road system”, including special safety barriers, must be associated with an innovative method of installation and maintenance, which is not significantly more onerous than the methods currently practiced for the installation and maintenance of simple road barriers, in which the fixing of the uprights to the ground takes place simply by driving them into the ground through the use of a “pile driver”.
These objectives are achievable in a “road system” which includes a road with a stabilized road substrate on which a road surface is laid, that is a road with a road substrate consisting of ground with known compactness characteristics; and said road is equipped with a road safety barrier comprising a plurality of uprights, infixed in the roadside as in the known art; moreover, said road is characterized in that said safety barrier comprises, in turn, at least the elements listed below.
And said junction element comprises parts with programmed breakage such that said junction element breaks when said connecting tie exerts a traction force higher than a predetermined threshold, and lower than the force that would damage said connecting tie rod or the force that would produce a displacement of said vertical plate system with respect to the road substrate in which it is infixed, and when said junction element breaks, said “guardrail” upright is no longer connected to said vertical plate system.
This “road system”, including special safety barriers, is suitable for being built even when the road, without a safety barrier, is already in place and the asphalt surface is already laid over the roadway, using a method of installing a road safety barrier as described above; and such installation method includes at least the steps listed below.
In fact, the elements that break first are always the junction elements, which are located near the uprights, and therefore on the roadside, in a position of easy access.
The main advantage of the present invention consists in the fact that any upright for “guardrail” installed according to the teachings of the present invention satisfies all the main requirements for which it was conceived, designed and certified.
Moreover, this invention also has further advantages, which will become more evident from the following description, from some examples of practical embodiments which illustrate further details, from the attached claims which form an integral part of the present description, and from the attached figures in which:
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The uprights 110, in a typical and widespread installation method, are fixed to the base by driving them into the ground. The number 200 indicates the land where the “guardrail” is installed, in the cases considered by the present invention.
The numbers indicate the same elements as in
Another feature, which can be appreciated from the view of
There are various ways in which the performance of a “guardrail” can be tested: ranging from tests carried out in the laboratory to real tests in which a true vehicle simulates an accident and hits the “guardrail”. The tests performed by simulations with real vehicles are certainly the most significant, as they clearly show whether the “guardrail” performs its main function, which is the containment of a vehicle that is getting out of the road and stops its run in a point that minimizes the dangerous consequences of a simulated accident. This containment function always requires the complete dissipation of the kinetic energy of the vehicle involved in the accident, and this dissipation can occur in many ways: through the plastic deformation of the “guardrail”, or through the breaking of parts thereof. In some cases it is required that the “guardrail” does not detach from the ground where it is installed, while in other cases, some uprights may also detach from the ground and the containment takes place due to the holding of the horizontal blockout bar which remains attached to a plurality of uprights, some of which, when stressed by an impact of a mass having a reduced momentum, do not detach from the ground.
Ultimately, the “optimal guardrail” is the one that performs its function in the best possible way, and its behavior depends not only on the “guardrail” as such, but also on the type of road and the characteristics of the ground on which it is fixed to the ground. Finally, in
Another feature of the road substrate 201 is that (at least in roads at the state-of-the-art) it is homogeneous and should not host the presence of underground utilities (e.g. ducts or pipes) which should therefore be located below it.
The road substrate 201 therefore represents the ideal ground for anchoring the uprights 110 for the installation of safety barriers. Anchors of this type are known, for example from patent application no. PCT/162019/050262-“Reinforcement element for fixing at the base, in ground, the uprights of roadside safety barriers”, or from WO 2019/008525 A1-“Device for anchoring safety road barriers poles to the ground” (both already mentioned previously); however, in the known solutions some problems remain unsolved, such as the control of the mechanical performance of the guardrail, and its consequent behavior in the event of accidents, and the installation and maintenance problems, which are very onerous in the known solutions.
With reference to the mechanical performance, the trick taught in the present invention consists in the particular composition of the anchoring system, which must be composed of several parts, among which at least the three parts listed below must be present:
Said system of vertical plates 153 is designed to be infixed vertically in the road substrate 201, where this is more compact, in an area below the road surface 210, possibly not too close to the edge of the road.
The infixion must take place so that its upper part remains near the upper limit of the road substrate 201 and does not cross it completely downwards, so as to minimize the risk of breaking any underground services during the infixion maneuver (remember that the underground services are normally made to pass under the road substrate). Furthermore, they must not protrude excessively above the road substrate 201, in order not to interfere with the remaking of the above road surface 210 which, from time to time, are carried out for the road maintenance.
Another characteristic of said system of vertical plates 153 (not clearly visible in
Said connecting tie rod 152 is an element which works in tension being connected to said system of vertical plates 153 on one side and to an upright 110 on the other, even if, as will be clarified below, the connection with the upright 110 is not a direct connection. The function of said connecting tie rod 152 is to hold the upright 110 to which it is connected in the installation position, when the latter is stressed by an impact force, again indicated with the number 400, and coming from the road.
The junction between an upright 110 and a connecting tie rod 152, as already mentioned, is not a direct junction: the teachings of the present invention provide that it is implemented through said junction element 151. The functions of said junction element 151 are more than one: in fact, in addition to guaranteeing the junction between an upright 110 and a connecting tie rod 152, it allows to use uprights of very simple manufacture, such as those typically used in implementations according to the known art, which can be installed by driving through the use of a pile-driving machine, and which do not require particular conformations to hook onto said connecting tie rod 152.
Furthermore, and this is perhaps the most important characteristic of said junction element 151, it is an element of rather limited dimensions which is located near the base of the uprights 110, in an area not covered by the road surface (so that the maintenance operations are easy), and which can be sized to break when stressed by predetermined forces.
Basically, said junction element 151 must break before said connecting tie rod 152 breaks and before said system of vertical plates 153 moves due to a particularly high impact force 400 which, acting on the upright 110 towards the outside the road could drag the whole system of vertical plates 153.
Not only that, the programmed breakage of said junction element 151 can be decided, according to the case, so as to hold the upright 110 in position to determining the deformation of the upright 110 at its base, or it can be sized to break before this deformation happens, letting the post 110 rotate without deforming, or deforming only to a small extent. It is clear that when said junction element 151 is broken, the connection between the vertical plate system 153 and the upright 110 is also lost.
In short, it is possible to concentrate on said junction element 151, all the adjustments on the mechanical performances that are intended to be obtained with regard to the behavior of a “guardrail” in the event of an impact.
It is also emphasized that, in addition to regulating the mechanical performance of the “guardrail”, the use of a junction element 151, with a programmed and predetermined break, allows to preserve the integrity of the roadway in the event of particularly violent accidents that involve heavy vehicles, avoiding that the impact forces may be such that the system of vertical plates 153 can be torn off the road substrate.
Said junction element 151 can be made according to many variations. In fact, it can be a simple horseshoe-shaped element that wraps the upright 110 made with a thickness such as to give it the desired resistance, or it can be assembled with a higher resistance part completed with a lower resistance bar, closed or hooked to the connecting tie rod 152, by means of screws or pins with programmed break. In short, what is important is that said junction element 151 wraps around the base of the upright 110 and has a predefined strength, so that it breaks when a predetermined stress is reached, or it never breaks before the upright is bend over.
The junction element thus composed is very simple. Its shape allows the use of normal uprights designed to be infixed in ground, which, when the “guardrail is installed, are inserted into the concavity of the” U″ shaped element 151.1.
Bar 151.3 allows to install the overall system by wrapping the uprights of the “guardrail” even if the “guardrail” itself is already assembled. Finally, the screws 151.2 allow you to close the junction element 151 as a whole.
In a variant very similar to that shown in
As mentioned, an essential feature of said junction element 151 is given by the fact that it must be able to split (thus opening the ring that holds the base of the upright 110) by effect of a predetermined and controllable stress force.
The programmed break can be obtained by acting on the dimensioning of the thickness of the material with which said “U” shaped element 151.1 is made, or by acting on the choice of screws 151.2, or on the tightness of their thread.
The programmable break can also be adjusted in the field, and very easily, for example by making a hole on said bar 151.3 as shown in
Breakage can be controlled:
Ultimately, the junction element 151 shown in
Each of said uprights 110 is surrounded by a joining element 151.
Well inside the street 300, the shapes of the section of three systems of vertical plates are highlighted, again indicated with the number 153.
Finally, each upright 110, through the junction element 151 and a connecting tie rod 152 is connected to at least one system of vertical plates 153.
Although a simple connection scheme is practicable, in which each upright 110 is connected to a single system of vertical plates 153, it can be observed that there may be some convenience in connecting each upright 110 to a pair, or even to three, vertical plate systems. In this way, when an upright 110 is hit by an impact coming from inside the road, and which would therefore tend to push the upright towards the outside of the road itself, the resistance to this movement would be exerted not only by the resistance of a single system of vertical plates 153, but by the strength of two, or three of these. In the example of
Regardless of the connection scheme, which can be chained as shown in
In fact, an essential feature of the system of vertical plates 153 is that it has a thin horizontal section, and this allows to drive said system of vertical plates 153 into the road substrate, without removing the asphalt of the road surface, but simply by cutting it according to a shape as that of the vertical plate system 153. In the case of the example shown in
Once the correct shape has been cut, the system of vertical plates 153 is driven into the road substrate by means of a pile-driving machine commonly supplied to operators in the sector.
The connecting tie rod 151 also has a thin shape that allows it to be inserted under the road surface through a cut in it.
It is noted that the cutting of the road surface is a relatively simple operation, which does not require special tools (it is commonly found among the equipment supplied to operators in the sector, like pile-driving machines).
Among the road surface restoration operations, one of the simplest is precisely the sealing of the cuts. Therefore, through this sealing operation, the road surface is restored and made accessible so that the road can be traveled.
The installation operations described above can also take place if the vertical plate system 153 has a section with enlargements (for example in the center). In this case, in addition to cutting the asphalt, it is also necessary to carry out a core drill to remove a small part of the road surface in order to make a hole in the road surface itself, to accommodate any enlargement of the vertical plate system 153. It is here observed that the core drilling of asphalt for the removal of small asphalt layers is a simple operation and can be carried out with generic equipment, therefore there are no problems with respect to the general objectives of the invention which aim to seek a solution that can be implemented by a large multitude operators without placing requirements on the instrumentation they must have at their disposal, posing potential discrimination in the choice of operators to whom to assign the work.
In this latter case, the restoration of the road surface is slightly more complex, because we do not have to limit ourselves to sealing a cut, but it is also necessary to plug the hole made with the coring; however, for small holes, even this maneuver is relatively simple and can be performed with cold worked material.
It is clear that the restoration of the road surface is important to quickly restore the viability of the road 300, but, obviously, the asphalt paving remains marked by the interventions carried out. However, at the first maintenance of the asphalt resurfacing, every trace disappears, and the buried underground system is designed to last over time.
At this point, it is reiterated that both said vertical plate systems 153 and said connecting tie rods 152, when installed, are in contact with the road substrate 201 (the vertical plate system 153 is immersed in the road substrate), and possibly immersed only in a small part in the bottom part of the road surface 210, so that even maintenance which requires the removal of the road surface, for the subsequent reconstruction, can be carried out without interfering with the system described.
Once the vertical plate systems 153 and the connecting tie rods 152 have been installed, the ends of the connecting tie rods 152 which are close to the uprights 110 must be connected to the uprights themselves: as already explained, this occurs through the junction elements 151.
From the installation point of view, it is important to observe how this coupling between the connecting tie rods 152 and the junction elements 151 can take place indifferently even if the uprights 110 are installed or before installing them. In this second case, the junction elements 151 are placed on the ground so that they surround the point where the upright 110 is to be infixed, and the latter can be driven in at a later time, as normally occurs with a pile driver. The installation is then completed by tensioning the connecting tie rod: this maneuver can also take place with one of the many known tensioning systems, for example with a screw system positioned on the junction element.
This installation sequence, that is the fixing to the ground of the uprights 110 of the “guardrail” after the installation of the vertical plate systems 153 and the connecting tie rods 152, is typical of the installations carried out during the construction of new roads, in which the complete road, with its mantle, is normally completed before the installation of the “guardrails”: in this case it is obviously convenient to install the vertical plate systems 153 and the connecting tie rods 152 as soon as the road substrate 201 is ready, before laying the road surface 210 (thus avoiding unnecessary cuts).
On the other hand, when it is necessary to reinforce an existing safety barrier, which is present on a complete road, the junction elements 151 must be coupled to the already fixed uprights 110: for this reason it is necessary that they are composed of several pieces that allow their opening, to wrap the base of the uprights 110, and a subsequent closing, around the base of the uprights 110, ending with a tensioning operation of the connecting tie rods, obviously pre-installed as already explained above.
A final observation, about maintenance aspects, concerns the access to the connecting tie rods 152, or to the vertical plate systems 153, when these elements are under a road surface 210, which has been redone after the installation of these elements, and therefore the signs of the cuts are not visible. Well, being the elements in question, in general, metal elements that are located at a depth of the order of ten centimeters, it is easy to find them using a metal detector, which is, for sure, able to identify the precise position where to make a cut for reaching the elements to be maintained.
In general, as seen from the previous description, the “road system”, according to the present invention, lends itself to numerous implementation variants, as well as the method to implement it, can be put into practice with some variants, provided that the essential steps indicated in the attached claims are maintained.
The provided description already highlights how many variations are possible. In fact, the possible forms for making the vertical plate systems 153 are innumerable, as well as the junction elements 151 and the connecting tie rods 152 can be implemented in many ways to connect them to the uprights 110 for “guardrails”.
With strict reference to the geometric shape of said vertical plate systems 153, it is worth underlining how the plates can assume all possible geometric shapes. All these variations of shape show that it is not the shape of the plates that is a characterizing prerogative, but rather the fact that these plates are a functional element designed in order to exploit a greater quantity of earth to increase the infixion strength of an upright for “guardrail” 110, when hit by a violent impact.
Regarding their shape, the only feature that seems recommendable is that they are flat, so that they can be driven into the road substrate 201 by inserting them into straight cuts and therefore easy to be done. It is evident that if these plates were obtained on wavy metal plates, the cutting of the road surface 210 to drive them into the road substrate 201 should also have a wavy shape, causing a useless installation difficulty.
Possible further variants may also depend on technological aspects concerning the individual components of the system, such as any additional consolidation and stiffening subsystems, but also on the materials that can be used to make each single part of the system.
These variants can offer further advantages over those already mentioned, and can be implemented by the man skilled in the art without thereby departing from the scope of the invention as emerges from the present description and the attached claims.
Furthermore, the invention itself can be implemented in a minimal or superabundant way, for example with plate systems composed of a single plate, or with a number of plates greater than two, and arranged in various ways and in different directions: even if the solution with two plates arranged in a cross (therefore with a four-branch system) appears to be the preferred form of implementation for simplicity of construction and installation (making two orthogonal cuts seems the simplest thing to do).
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IT2020/000075 | 11/9/2020 | WO |
