EP0708206A1

EP0708206A1 - Semirigid position-correctable road barrier for controlled impact energy dissipation

Info

Publication number: EP0708206A1
Application number: EP95116362A
Authority: EP
Inventors: Antonio Pellecchia
Original assignee: CENTRO ACCIAI SpA
Current assignee: CENTRO ACCIAI SpA
Priority date: 1994-10-17
Filing date: 1995-10-17
Publication date: 1996-04-24
Also published as: ITTO940822A0; ITTO940822A1; IT1268127B1

Abstract

A semirigid road barrier (1) wherein a rail (5) is connected to a number of posts (3) by respective connecting assemblies (6), each presenting a spacer (13) and a connecting device (14) for connecting the spacer (13) to the respective post (3); the connecting device (14) presenting a first (25) and second (26) cam guide assembly presenting respective cams (27) (28) on the relative spacer (13), and respective stop members (29) (30) associated with the relative post (3); the cams (27) (28) being defined by respective guide slots (31) (35), and presenting respective first portions (32) (36) cooperating with the respective stop members (29) (30) and with each other to define a substantially rigid connection of the spacer (13) and the respective post (3) at the initial impact stage wherein the post (3) is still substantially upright.

Description

The present invention relates to a semirigid, position-correctable road barrier for controlled impact energy dissipation.
More specifically, the present invention relates to a semirigid road barrier of the type described and illustrated in European Patent Application n.93101729.7 filed on 4 February, 1993, by the present Applicant, and comprising a number of posts, a shaped metal rail extending crosswise to the posts, and a number of connecting assemblies for connecting each post to a respective intermediate portion of the rail.
Each connecting assembly of known barriers of the above type is an energy absorbing assembly, and normally comprises a varying number of breakoff plates which, upon a vehicle colliding with the rail, are severed to dissipate, relatively sharply, part of the impact energy of the vehicle.
Known connecting assemblies also comprise substantially plate-like members connected on one side to the rail and on the other to the post, and which, upon impact, rotate in relation to the post about an instantaneous hinge axis to prevent a variation in the inclination of the impact surface of the rail in relation to the road surface. The plate members are also connected to the post in such a manner as to move, in relation to the post and in a direction parallel to its axis, between two limit axial positions, and so permit the post to bend freely and partly backwards, i.e. outwards of the road.
Though widely used and doubtless highly effective in preventing the formation of ramps, the above method of connecting the plate members to the posts fails to provide for absorbing the impact energy and retaining the vehicle in controlled manner.
In fact, upon impact, the breakoff plates are first severed and the plate members shifted in substantially uncontrolled manner parallel to the axis of the post; and the rail then drops in relation to the road surface, by virtue of it being permanently connected to and hence forced to accompany the post which, in many cases, is knocked into an almost horizontal position.
In known barriers of the above type, permanent connection of the rail to the posts is further reinforced by a traction belt or chain connected to the surface of the post facing away from the rail, to prevent free and complete deformation of the posts. Tests have shown, however, that undeformed posts connected to the rail seriously impair the retaining action of the barrier.
It is an object of the present invention to provide a semirigid road barrier designed to overcome the aforementioned drawbacks, and which in particular provides for gradual, constant absorption of impact energy throughout the period of interaction between the barrier and vehicle.
According to the present invention, there is provided a semirigid, position-correctable road barrier for controlled impact energy dissipation, the barrier comprising a number of posts with respective axes; at least one shaped rail extending crosswise to the posts; and, for each post, a connecting assembly for connecting the post to a respective intermediate portion of the rail; each connecting assembly in turn comprising a spacer interposed between the rail and the relative post, and connecting means for connecting the spacer to the relative post; characterized in that said connecting means comprise a first and second cam guide assembly in turn comprising respective cams on one of either said spacer or said post, and respective stop members associated with the other of either said spacer or said post; said cams presenting respective first portions cooperating with the relative said stop members to define a substantially rigid connection of the spacer and relative post at the initial impact stage in which the relative post is still substantially upright.
Said connecting means of the above barrier preferably also comprise release means associated with the post, and for automatically detaching the rail from the post as the post is deformed.
A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a front view of a portion of a preferred embodiment of a semirigid road barrier in accordance with the teachings of the present invention;
Figure 2 shows a top plan view of the Figure 1 barrier;
Figure 3 shows a larger-scale section along line III-III in Figure 1;
Figure 4 shows a section along line IV-IV in Figure 3;
Figure 5 shows a larger-scale view, with parts removed for clarity, of a detail in Figure 3;
Figure 6 shows a larger-scale view of an intermediate portion of Figure 4;
Figure 7 shows a view in perspective of the Figure 3 detail;
Figure 8 shows an exploded view of a detail in Figure 7;
Figure 9 shows an exploded view of a first variation of the Figure 8 detail;
Figures 10 and 11 are similar to Figure 6, and show sections, with parts removed for clarity, of a further two variations of the Figure 9 detail;
Figure 12 is similar to Figure 3, and shows a double median strip barrier in accordance with the teachings of the present invention;
Figure 13 shows five different operating positions of the barrier in Figures 1 to 11.

Number 1 in Figures 1 and 2 indicates a semirigid, position-correctable road barrier for controlled impact energy dissipation, commonly known as a guardrail, and installed along the edge of a road 2.
Barrier 1 comprises a number of posts 3 with respective vertical axes 4 (Figure 3); a shaped (e.g. triple-ridge) rail 5 extending crosswise to posts 3; and, for each post 3, a connecting assembly 6 for connecting post 3 to a respective intermediate portion of rail 5.
Each post 3 comprises a metal channel section with its concavity facing the adjacent post 3, and in turn comprising two lateral walls or wings 7 parallel to each other and to rail 5, and an intermediate wall or core 8 perpendicular to rail 5. Each post 3 comprises a bottom end portion 9 fitted into the ground in known manner; and a top end portion 10 connected to rail 5 and presenting an upper slot 11 open at the top end, and a lower slot 12, which slots 11 and 12 are formed in wall 8 and aligned with each other parallel to the axis 4 of post 3.
As shown in Figures 3 and 7, each assembly 6 provides for dissipating at least part of the impact energy to which rail 5 is subjected, and comprises a spacer 13 interposed between rail 5 and post 3, and a connecting device 14 for connecting spacer 13 to post 3.
More specifically, spacer 13 comprises a substantially parallelepiped box body 15 extending crosswise to post 3 and perpendicularly to rail 5, projecting on either side of post 3, and partly engaged by portion 10. Body 15 comprises two parallel plates 16 perpendicular to rail 5, located on either side of post 3, and each presenting an integral top and bottom outer tab 17, 18 perpendicular to rail 5 and to plate 16.
On the side facing rail 5, body 15 also comprises an end wall 19 with two openings 20, and supports a projecting metal shell 21 extending between wall 19 and rail 5 and which is deformed gradually by a load less than that required to bend post 3. In the example shown, shell 21 comprises two cylindrical half shells 22 presenting generating lines parallel to axis 4, and each extending from a respective plate 16 to which it is connected by a respective connecting tab integral with half shell 22, and by means of a pair of through bolts 23. Opposite the ends connected to the respective connecting tabs, half shells 22 present respective end portions superimposed and connected to each other and to rail 5 by a pair of bolts 24.
As shown in Figures 3 to 7, connecting device 14 comprises a first and second cam guide assembly 25 and 26 for continuously imposing a predetermined connection of spacer 13, and hence rail 5, to post 3 during the period of interaction between the vehicle and barrier 1, i.e. during the period in which the impact energy of the colliding vehicle is absorbed.
Guide assemblies 25, 26 comprise respective cams 27, 28 on spacer 13, and respective stop members cooperating with respective cams 27, 28 and defined by two bolts 29, 30 associated with post 3, and of which bolt 30 is smaller in diameter than bolt 29.
More specifically, and as shown in Figure 5, cam 27 is defined by a pair of shaped slots 31 formed facing each other in respective plates 16 and partly at slot 11 formed in post 3. Each slot 31 comprises a first and second portion 32, 33; the first portion 32 extending towards tab 18 and shell 21 from a portion of respective plate 16 close to tab 17; and the second portion 33 extending towards tab 18 and shell 21 from the bottom end of first portion 32. Portions 32 and 33 form with each other an obtuse angle A, and form respective angles B and C, of which angle B is greater than angle C, with a plane P along axis 4 and perpendicular to plates 16.
As shown in Figure 5, cam 28 is defined by a pair of shaped slots 35 formed facing each other in respective plates 16 and partly at slot 12 formed in post 3. Each slot 35 is narrower than slot 31, and presents a length M, measured in said vertical plane P, shorter than the length L of slot 31 measured in the same plane P.
Each slot 35 extends between slot 31 and bottom tab 18, and comprises a first and second curved portion 36, 37; first portion 36 extends beneath and presents its concavity facing portion 32 of corresponding slot 31; and second portion 37 extends towards tab 18 and shell 21, and presents a portion extending beneath second portion 33, its convexity facing second portion 33, and a radius of curvature greater than that of first curved portion 36.
As shown in Figures 3 to 7, bolts 29 and 30 extend perpendicularly to plates 16, and respectively engage in sliding manner slots 11, 31 and slots 12, 35. Bolts 29 and 30 also engage in sliding manner respective slots 38 and 39 (Figures 3, 5, 7) formed in the central wall 40 of a tubular U-shaped body 41 extending inside portion 10 of post 3 to close the channel section. Slots 38 and 39 are formed in line with each other parallel to axis 4 and corresponding with or facing respective slots 11 and 12 in post 3.
To prevent bolts 29, 30 from jamming inside respective slots 31, 35, device 14 also comprises a pair of spacer plates 41a, each fitted outside a respective plate 16 and presenting holes engaged by the shanks of bolts 29, 30.
As shown particularly in Figures 6 to 8, tubular body 41 is fitted telescopically to portion 10, and is held frictionally inside portion 10 by a pair of through bolts 42 extending through respective holes in walls 7 of post 3, and each engaging in sliding manner a respective longitudinal slot 43 formed in a respective lateral wall 44 of body 41 contacting respective wall 7, and extending parallel to axis 4 from the bottom edge of body 41.
As shown in Figures 3, 4 and 7, barrier 1 also comprises one or two traction belts or cables 45, each defined by a metal strip extending on the opposite side of posts 3 to rail 5, and connected integral with each body 15, at the opposite end to that fitted with shell 21, by means of a U-shaped bracket 46 to which it is fitted integrally by a bolt 46a. More specifically, bracket 46 presents a central wall 47 closing respective body 15, and two lateral walls 48 extending outside respective plates 16 and connected integral with plates 16 by means of respective bolts 49.
With reference to Figures 3 and 7, barrier 1 also comprises a further rail or wheel guard 50 extending parallel to and beneath rail 5, and defined by a channel section with its concavity facing posts 3. Rail 50 is connected to each post 3 by a respective connecting device 51 defined by a channel section 52 extending perpendicular to post 3 and parallel to body 15, and connected at one end to rail 50 by a bolt 53, and at the opposite end to wall 8 of post 3 by a bolt 54 engaging in sliding manner a longitudinal slot 55 formed in the central wall or core of section 52. Slot 55 extends perpendicular to axis 4, and presents a first portion 56 of a width approximately equal to but no less than the diameter of bolt 54, and a second portion 57 extending from rail 50 and narrower than the diameter of bolt 54. Alternatively, according to a variation not shown, slot 55 is of constant width, and bolt 54 comprises a spherical head, and a quadrangular-section underhead portion engaging slot 55.
Operation of barrier 1 will now be described, for the sake of simplicity, with reference to a portion comprising one post 3, and as of the condition in which both post 3 and rails 5, 50 are undeformed (Figures 3, 13a), bolts 29, 30 are located at the top end of respective portions 32, 36 of respective cams 27, 28, and bolt 54 engages portion 56 of slot 55 to maintain rail 50 in the extracted position.
As of the above condition, upon a vehicle colliding with rail 5, the impact energy transmitted by the vehicle gradually deforms and is partly absorbed by rail 5 and shell 21 (Figure 13b); and at the initial impact stage, post 3 remains practically upright, and bolts 29, 30 slide along respective portions 32, 36 with which they define a substantially rigid connection of spacer 13 and post 3. That is, at the initial impact stage, post 3 remains substantially undeformed, shell 21 is deformed completely (Figure 13b), and bolts 29, 30 continue to engage respective portions 32, 36 to form an initial support for spacer 13 for substantially as long as post 3 remains upright.
At the end of the initial impact stage, post 3 starts to bend (Figure 13c), so that bolts 29, 30 slide out of respective portions 32, 36 and engage respective portions 33, 37; and, as post 3 bends further (Figures 13c, 13d), bolts 29, 30 slide along respective portions 33, 37 to so control the mutual displacement of spacer 13 and post 3 that the position of rail 5 in relation to road 2 remains substantially unchanged, thus preventing the formation of ramps capable of "launching" the colliding vehicle.
At this point, on account of the different lengths of slots 31, 35 and the different diameters of bolts 29, 30, upon bolt 30 reaching the bottom ends of slots 35 and/or the top ends of slots 12 as post 3 bends further, bolt 30 is severed whereas bolt 29 continues sliding along slots 31. As post 3 is deformed even further, body 41, which by now is only connected to body 15 by bolt 29, begins withdrawing from portion 10 of post 3 in opposition to the retaining action of bolts 42 which, as body 41 and post 3 shift in relation to each other, slide along respective slots 43. Body 41 continues withdrawing, i.e. shifting in relation to post 3, until it is fully detached from portion 10 of post 3, at which point, bodies 15 and 41 shift together with rail 5 and metal strip 45. By virtue of being integral with bodies 15, strip 45 continues to be subjected to pulling stress and to resist deformation of rail 5, which therefore continues to effectively absorb the impact energy and effectively retain the vehicle; whereas, post 3, which by now is fully disconnected, is free to bend, even into the fully horizontal position.
At the initial impact stage, part of the impact energy of the vehicle is also absorbed by rail 50, which withdraws gradually towards post 3 into a limit position in opposition to the varying resistance of device 51. More specifically, upon impact, bolt 54 first travels along portion 56 of slot 55, and the reaction exerted by section 52 on rail 50 is determined solely by the tightening torque of bolt 54. Subsequently, bolt 54 engages portion 57, and the smaller width of portion 57 as compared with the diameter of bolt 54 results in additional friction which, added to the tightening torque of bolt 54, provides for further resisting displacement of rail 50 and hence, increasing the amount of impact energy absorbed.
Rail 50 functions differently depending on the type of vehicle involved. More specifically, in the event of a truck colliding with the barrier, rail 50 acts as a wheel guard to prevent the wheels of the truck from engaging posts 3, and at the same time cooperates with rail 5 to absorb the impact energy of the truck. In the event of a car colliding with the barrier, in addition to absorbing part of the impact energy, rail 50 also prevents the car from becoming wedged inside the gap between the road surface and rail 5.
Figures 9 and 10 show a C-section post 58, which differs from post 3 by comprising two small lateral walls 59 extending parallel to rail 5, and a large lateral wall 60 perpendicular to rail 5. Wall 60 presents a slot 61 extending from the top edge of and parallel to the axis of post 58, and of a width comparable with that of walls 59.
The top end portion of post 58 houses a tubular body 62, which differs from body 41 by comprising two channel sections 63, 64 of different sizes with their concavities facing each other; the lateral walls of section 63 are positioned facing and superimposed on the lateral walls of section 64, and are connected integral with the lateral walls of section 64 by means of respective bolts 65; and the shank of each bolt 65 projects from the respective lateral wall of section 63, and engages in sliding manner a respective slot 66 formed in a respective wall 59 and extending from said top edge of post 58.
Body 62 also differs from body 41 by comprising a pair of slots 38 and a pair of slots 39; the slots in each pair are the same shape and positioned facing each other; and, in use, body 62 is withdrawn from post 58 together with bolts 29 and 30.
In the Figure 11 variation, body 62 comprises two sections 63, 64 of the same shape and size.
Figure 12 shows a double metal barrier 65a, which differs from barrier 1 by comprising two parallel rails 5 on either side of posts 3, and a connecting assembly 66 for connecting rails 5 to each post 3. Each connecting assembly 66 comprises a spacer 67 in turn comprising two spacers 68 substantially similar to spacer 13 and extending in opposite directions on either side of post 3. More specifically, measured perpendicularly to post 3, spacers 68 are shorter in length than spacer 13 of barrier 1, and the respective end portions opposite those fitted with respective shells 21 are integral with each other and so formed that first portions 32, 36 of respective cams 27, 28 are substantially coincident with each other, and second portions 33, 37 of respective cams 27, 28 extend symmetrically on either side of plane P.
Barrier 65a also differs from barrier 1 by comprising two wheel guard rails 50 beneath and parallel to respective rails 5, and connected to the posts by a connecting assembly 69 comprising two devices 51, the channel sections 52 of which are of different sizes and connected telescopically to each other.
Barriers 1 and 65a as described above therefore provide for a high degree of reliability and efficiency, by absorbing the impact energy transmitted by the vehicle to rails 5, 50 with substantially no change in the position of the impact surface of the rails in relation to road 2, thus presenting the formation of ramps, and by absorbing the impact energy of the vehicle gradually and in controlled manner throughout the period of interaction between the vehicle and rails 5, 50.
This is substantially due to the particular design of devices 14 connecting spacers 13 to posts 3, 58, and in particular to cam assemblies 25, 26 which provide for optimum controlled displacement of rail 5 in terms of impact energy absorption. At the initial impact stage, in fact, the design of portions 32 and 36 provides for a substantially rigid connection of spacers 13 and respective posts 3, 58, so that the impact energy of the vehicle is initially absorbed by rail 5, and by shells 21 which are deformed totally before posts 3, 58 start to bend; and, following the initial impact stage, the design of portions 33 and 37 provides for continuously rotating and simultaneously translating rail 5 in relation to posts 3, 58.
Moreover, upon posts 3, 58 bending, bodies 41, 62 connected telescopically to the free ends of the posts provide, as compared with known barriers, for tripling the travel of rail 5 in relation to the posts 3, 58 and for gradually detaching rail 5 from the posts, so that, on reaching a given bend angle, the posts are detached from the spacers and free to deform without affecting rail 5 which continues its retaining and arresting function with substantially no change in height in relation to road 2 (Figure 13e). The retaining function of rail 5 is further enhanced by belt/s 45, which in any case cooperate directly with the rail as opposed to the posts 3, 58 as in known solutions.
Finally, the location and sliding connection of rail 50 to posts 3, 58 provide for effectively and gradually absorbing the impact energy transmitted to the barrier by the vehicle wheels.
Clearly, changes may be made to barriers 1 and 65a as described and illustrated herein without, however, departing from the scope of the present invention.
In particular, changes may be made to the posts and spacers, to cam assemblies 25 and 26, to cams 27 and 28 described by way of example, and to the devices for connecting rail or wheel guard 50 and bodies 41, 62 to the posts; and shells 21 may be formed in one piece, and need not necessarily be cylindrical.

Claims

A semirigid, position-correctable road barrier (1; 65a) for controlled impact energy dissipation, the barrier (1; 65a) comprising a number of posts (3; 58) with respective axes (4); at least one shaped rail (5) extending crosswise to the posts (3; 58); and, for each post (3; 58), a connecting assembly (6) for connecting the post (3; 58) to a respective intermediate portion of the rail (5); each connecting assembly (6) in turn comprising a spacer (13) interposed between the rail (5) and the relative post (3; 58), and connecting means (14) for connecting the spacer (13) to the relative post (3; 58); characterized in that said connecting means (14) comprise a first (25) and second (26) cam guide assembly in turn comprising respective cams (27) (28) on one of either said spacer (13) or said post (3; 58), and respective stop members (29) (30) associated with the other of either said spacer (13) or said post (3; 58); said cams (27) (28) presenting respective first portions (32) (36) cooperating with the relative said stop members (29) (30) to define a substantially rigid connection of the spacer (13) and relative post (3; 58) at the initial impact stage in which the relative post (3; 58) is still substantially upright.
A barrier as claimed in Claim 1, characterized in that the first portion (32) of one (27) of said cams (27) (28) is a substantially straight portion, and the first portion (36) of the other (28) of said cams (27) (28) is a curved portion.
A barrier as claimed in Claim 2, characterized in that said curved first portion (36) presents its concavity facing said substantially straight first portion (32).
A barrier as claimed in any one of the foregoing Claims, characterized in that said cams (27) (28) comprise respective second portions (33) (37) cooperating with the relative said stop members (29) (30) to simultaneously rotate and translate said spacer (13) in relation to said post (3; 58).
A barrier as claimed in Claim 4, characterized in that the second portion (33) of one (27) of said cams (27) (28) is a substantially straight portion, and the second portion (37) of the other (28) of said cams (27) (28) is a curved portion.
A barrier as claimed in Claim 5, characterized in that said curved second portion (37) presents its convexity facing said substantially straight second portion (33).
A barrier as claimed in any one of the foregoing Claims, characterized in that said cams (27) (28) present respective lengths, the projections (L) (M) of which in a plane (P) parallel to the axis (4) of the post (3; 58) and perpendicular to the rail (5) differ from each other.
A barrier as claimed in any one of the foregoing Claims, characterized in that said cams (27) (28) are defined by respective slots (31) (35) formed in said spacer (13).
A barrier as claimed in any one of the foregoing Claims, characterized in that said connecting means (14) also comprise release means (41, 42, 43; 62, 65) associated with the post (3; 58) and for automatically detaching the rail (5) from the post (3; 58) as the post (3; 58) is deformed.
A barrier as claimed in Claim 9, characterized in that said release means (41, 42, 43; 62, 65) comprise an elongated body (41; 62) connected telescopically to an end portion (10) of the post (3; 58).
A barrier as claimed in Claim 10, characterized in that said elongated body (62) is retained by friction inside the post (58).
A barrier as claimed in Claim 10, characterized in that said elongated body (41) is connected to the post (3) by at least one pin member (30) which is severed upon partial bending of the post (3).
A barrier as claimed in any one of the foregoing Claims, characterized in that said spacer (13) comprises shell type dissipating means (21) for gradually absorbing at least part of the impact energy.
A barrier as claimed in Claim 13, characterized in that said shell type dissipating means (21) are deformed gradually by a load less than that required to bend the post (3; 58).
A barrier as claimed in one of the foregoing Claims from 12 to 14, characterized in that said shell type dissipating means comprise a cylindrical tubular body (21) presenting generating lines parallel to said axis (4), and connected to said rail (5).
A barrier as claimed in any one of the foregoing Claims, characterized in that it comprises at least a further rail (50) extending parallel to and beneath said rail (5); and further connecting means (51; 69) for connecting each said post (3; 58) to said further rail (50); said further connecting means (51; 69), in use, permitting said further rail (50) to shift in relation to the relative post (3; 58).
A barrier as claimed in Claim 16, characterized in that said further connecting means (51; 69) comprise at least a guide and slide assembly (51, 54) for permitting said further rail (50) to shift in relation to the post (3; 58) in a direction crosswise to the axis (4) of the post (3; 58) and between two limit positions, one of which is an extracted position wherein the further rail (50) extends detached from the post (3; 58), and the other of which is a withdrawn position wherein the further rail (50) extends in contact with the post (3; 58).
A barrier as claimed in Claim 17, characterized in that the resistance of said guide and slide assembly (51, 54) to displacement of said further rail (50) increases alongside a variation in the position of the further rail (50) between said extracted and said withdrawn position.
A barrier as claimed in one of the foregoing Claims from 16 to 18, characterized in that said further connecting means (51; 69) comprise hinge means (52, 54) permitting rotation of said further rail (50) in relation to the post (3; 58) and about an axis crosswise to the axis (4) of the post (3; 58).
A barrier as claimed in any one of the foregoing Claims, characterized in that it comprises at least one belt member (45) acting as a tie and cooperating, in use, solely with said spacers (13).