Pernetti, Mariano (Ilva Pali Dalmine S.r.l. Via Terragneta, 90 Torre Annunziata, I-80058, IT)
| 1. | 1) A semirigid, positioncorrectable, collision energydissipating guardrail comprising a number of posts (3), and a shaped strip (5) connected to each of said posts (3) by a corresponding connecting assembly (6); said connecting assembly (6) comprising an energy dissipator (13) located between said strip (5) and a spacer (13) connected to said post (3); said spacer (13) having a group of cam slots (27,28) cooperating with. a group of engaging members (29,30) carried by said post (3); said cam slots (27,28) being such as to provide for a substantially rigid connection at an initial stage in the collision of a vehicle, and for a position correction of said strip (5) at a subsequent stage in said collision; and said engaging members (29,30) engaging a release body (41) for releasing said strip (5) from said post (3) at a final stage in said collision; characterized by comprising strengthening means (33,58) for limiting deformation of said post (3) and/or said connecting assembly (6) and/or said strip (5). |
| 2. | A guardrail as claimed in Claim 1, characterized in that said strengthening means (33,58) comprise a frame (33) connected to said spacer (13) and to said post (3). |
| 3. | A guardrail as claimed in Claim 2, characterized in that said frame (33) is defined by said engaging members (29,30), by two connecting members (31,32) connecting the ends of said engaging members (29,30), and by two oblong plates (52) connected to the ends of one of said engaging members (29,30). |
| 4. | A guardrail as claimed in Claim 3, wherein said spacer (13) comprises two lateral walls (16); and wherein said dissipator (21) comprises two corresponding lateral walls (24) connected to the lateral walls (16) of said spacer ^ (13); each lateral wall (16) of said spacer (13) being connected to said post (3) by two cam slots (27,28) cooperating with said engaging members (29, 30); and said connecting members (31,32) being positioned vertically; characterized in that said two oblong plates (52) are positioned horizontally, and are fitted at one end (53) to said engaging member (30), and at the other end (54) to said lateral walls (16) of said spacer (13). |
| 5. | A guardrail as claimed in Claim 4, wherein said release body (41) is movable telescopically with respect to said post (3); and wherein said engaging members are defined by two bolts (29,30) spaced vertically on said release body (41); said two cam slots (27,28) also being spaced vertically; characterized in that each of said two oblong plates (52) is fitted to the bottom bolt (30) of the two bolts (29,30). |
| 6. | A guardrail as claimed in Claim 5, characterized in that at least one of said connecting members (31,32) has a downward extension (34); said extension being connected directly to said post (3). |
| 7. | A guardrail as claimed in one of the foregoing Claims, characterized in that said strengthening means (33,58) comprise a strut (58) fitted to said spacer (13) and for opposing deformation of said strip (5) in the course of said collision. |
| 8. | A guardrail as claimed in Claim 7, wherein said strip (5) is of the type having three ridges; characterized in that said strut (58) slopes downwards to oppose deformation of the bottom ridge of said strip (5). |
| 9. | A guardrail as claimed in Claim 7 or 8, characterized in that said strut (58) is defined by a channel having two wings connected to the lateral walls (16) of said spacer (13). |
| 10. | A guardrail as claimed in one of the foregoing Claims, characterized in that the connecting assemblies (6) of said posts (3) are connected by diagonal struts (63) lying substantially in a plane perpendicular to the axes of said posts (3); said diagonal struts (63) sloping towards the center of the road in the traffic direction and being parallel with one another so as to exert traction in theevent of collision by a vehicle. |
| 11. | A guardrail as claimed in Claims 4 and 10, characterized in that each of said diagonal struts (63) is fitted with one end between a chain (45) and a bracket (46) of said spacer (13) of a first of said posts (3); another end of said diagonal strut (63) being fitted at a fastening point of a ridge (4) of said shaped strip (5); and said fastening point being located on an intermediate wall (25) of the ! dissipator (21) of the post (3) downstream from said first post (3) in said traffic direction. |
BACKGROUND ART Guardrails of the above type are known in which a shaped strip is connected to a number of posts by means of respective connecting assemblies, each comprising a spacer and a collision energy dissipator. In one known type of guardrail, the spacer is connected to the post by means of a pair of cam slots engaged by a pair of bolts, and which provide for substantially rigid connection at the initial vehicle collision stage, and for position-correcting the rail at a subsequent collision stage via rotation and translation of the post and spacer. One of the bolts is sheared at a further vehicle collision stage, and a telescopically movable body in the post releases the shaped strip from the post
at the final collision stage.
This type of guardrail is highly effective in preventing vehicles from running off the road, and provides for dissipating large amounts of energy. As such, however, the component parts must be extremely strong, thus increasing the weight of the rail.
As is known, guardrails are normally of modular design, each module being defined by a shaped rail segment of standard length. Each module also comprises a number of posts, e. g. three, spaced a given center distance apart and to which the shaped strip segment and other rail module components are fitted. The above known guardrail has a module of 4.50 m in length, and a center distance between the posts of 1.50 m.
DISCLOSURE OF INVENTION It is an object of the invention to provide a guardrail of the above type, which, for a given degree of energy dissipation, provides for reducing the number of and increasing the center distance between the posts, and for reducing the total weight of the guardrail with no increase in the size of the posts or connecting assemblies, and with no change in the vehicle-retaining, collision-energy-dissipating or position-correcting performance of the guardrail.
According to the present invention, there is provided a semirigid, position-correctable, collision- energy-dissipating guardrail comprising a number of
posts, and a shaped strip connected to each of said posts by a corresponding connecting assembly; said connecting assembly comprising an energy dissipator located between said strip and a spacer carried by said post; said spacer having a group of cam slots cooperating with a group of engaging members carried by said post; said cam slots being such as to provide for a substantially rigid connection at an initial stage in the collision of a vehicle, and for a position correction of said strip at a subsequent stage in said collision; and said engaging members engaging a release body for releasing said strip from said post at a final stage in said collision; characterized by comprising strengthening means for limiting deformation of said post and/or said connecting assembly and/or said strip.
BRIEF DESCRIPTION OF THE DRAWINGS A preferred, non-limiting embodiment of the invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a front view of a preferred embodiment of a semirigid guardrail featuring the improvements according to the invention; Figure 2 shows a top plan view of the Figure 1 guardrail; Figure 3 shows a larger-scale section along line III-III in Figure 1; Figure 4 shows a larger-scale top plan view of
Figure 3; Figures 5 and 6 show two larger-scale sections along lines V-V and VI-VI in Figure 3; Figure 7 shows a view in perspective of a detail in Figure 3; Figure 8 shows an exploded view in perspective of a detail in Figure 3; Figure 9 shows a top plan view of a variation of the guardrail.
BEST MODE FOR CARRYING OUT THE INVENTION Number 1 in Figures 1 and 2 indicates as a whole a semirigid guardrail of the type installed along an outer edge of a road 2. Guardrail 1 comprises a number of posts 3; and a shaped strip 5 connected to each post 3 by a connecting assembly 6. More specifically, strip 5 (Figure 3) is a known type comprising three ridges- separated by two grooves 4, and is defined by segments of standard 4.88 m length. The guardrail is of modular design, in which each module M (Figure 1) is 4.50 m in length.
Each post 3 (Figures 3-6) is defined by a metal channel with the concavity facing one of the two adjacent posts 3; each channel comprises two lateral walls 7, and a flat intermediate wall 8 perpendicular to strip 5; and each wall 7 terminates with a partial wall 8'parallel to wall 8.
Each post 3 has a bottom portion 9 reinforced by
two plates 9' ; portion 9 is fitted into the edge of road 2 so that the axis of post 3 is vertical; each post 3 comprises a top end portion 10 in which assembly 6 is fitted; at portion 10, wall 8 has two axial openings 11 and 12 (see also Figure 8) separated by a partition 14; and another partition 14 ! closes opening 11 at the top.
Connecting assembly 6 (Figures 3 and 4) comprises a spacer 13 carried by post 3, and an energy dissipator 21 located between strip 5 and spacer 13. Spacer 13 is defined by a metal sheet, bent into a U to form two parallel walls 16 contacting walls 8 and 8'of post 3; and the two walls 16 each have a top and bottom tab 17, 18 facing outwards, and are connected to each other by an intermediate wall 19 at the front of post 3.
Dissipator 21 is defined by another metal sheet bent into a U to form two lateral walls 24 connected by an intermediate wall 25 by means of rounded edges; the two walls 24 are connected to the two walls 16 of spacer 13 by two bolts 20 inserted inside two spacer sleeves 22; the dissipator has a horizontal opening 26 extending at least the whole length of intermediate wall 25; and spacer 13 is connected to post 3 by a group of cam slots 27,28 cooperating with two engaging members defined by two bolts 29,30 sliding inside slots 27,28.
More specifically, each wall 16 comprises two cam slots 27 and 28 separated vertically; bolts 29 and 30 extend perpendicularly to walls 16 and also engage in
sliding manner openings 11 and 12 in wall 8 of post 3; bolts 29 and 30 are kept apart by two vertical spacer plates 31 and 32 (Figure 7) with which bolts 29 and 30 form a frame indicated as a whole by 33; the two plates 31 and 32 (Figure 5) are located between walls 16 and walls 8 and 8' ; and plate 32 is located on the wall 8 side, and has an extension 34 (Figure 3) extending downwards a given distance beyond bolt 30 for the purpose explained later on.
Bolts 29 and 30 engage in sliding manner two vertically aligned slots 36 and 37 (Figure 8) formed in a central wall 40 of a body 41, which slides telescopically in top portion 10 of post 3. Body 41 has a U-shaped section comprising two walls 42 on either side of wall 40, is positioned with wall 40 adjacent to partial walls 8'of post 3, and is retained frictionally inside portion 10 by two bolts 44 tightened by respective nuts. Each bolt 44 engages a hole formed in the corresponding wall 7 of post 3, and an open-bottomed longitudinal opening 43 formed in the corresponding lateral wall 42 of body 41.
Slots 27 and 28 (Figure 3) are so formed as to provide for substantially rigid connection at the initial stage in the collision of a vehicle with strip 5, and for position-correcting strip 5, via rotation and translation of post 3 and spacer 13, at a subsequent collision stage. At the final collision stage, bolts 20
and 30 shear the two partitions 14 and 14'of post 3, and body 41 is released from post 3 to enable release of strip 5 from post 3, substantially as described in Italian Patent Application T094A000822 filed by CENTRO ACCIAI S. P. A.
Wall 25 of dissipator 21 has the usual holes for connection by means of bolts to the two grooves 4 of strip 5; dissipator 21 may have strengthening ribs 38; and each wall 16 of spacer 13 may have a strengthening rib 39, substantially as described in Italian Patent Application T098A000044 filed by the present Applicant.
Guardrail 1 also comprises a chain 45 defined by a flat metal section and fitted to a series of U-shaped brackets 46, each fitted to walls 16 of each spacer 13, by a bolt 47 inserted inside another spacer sleeve 48 located between the two walls 16. Finally, guardrail 1 also comprises a wheel rail 50 extending parallel to and below shaped strip 5, and which is fitted to a series of C-shaped supports 51, each fitted to one of posts 3.
Both chain 45 and wheel rail 50 are defined by segments of a length corresponding to a module M; and the strip 5, chain 45 and wheel rail 50 segments of each module M are connected to those of the two adjacent modules M by bolted overlapping portions located at the end posts 3 of modules M.
According to a variation of the invention, each strip 5 segment is connected to only three posts 3 with
an exceptionally long center distance, which may advantageously be 2.25 m, so that each module M comprises only two spans between posts 3. To strengthen guardrail 1, while maintaining the same energy- dissipating performance, guardrail 1 is provided with strengthening means for limiting deformation of post 3, of assembly 6, and of shaped strip 5. Which strengthening means comprise frame 33 (Figure 7), which is provided with a further two plates 52 and is connected by additional bolts to spacer 13 and to post 3.
More specifically, each plate 52 is fitted at one end 53 to the bottom bolt 30 of frame 33, and at the other end 54 to a wall 16 of spacer 13 by a bolt 56.
Oblong plates 52 are advantageously positioned perpendicular to the axis of post 3 and just below rib 39, and provide for delaying rotation of post 3 and the spacer upon vehicle impact.
The strengthening means also comprise the downward extension 34 of spacer plate 32, which extension is connected to wall 8 of the corresponding post 3 by means of a further bolt 57. Upon initial impact, extension 34, so connected, prevents upward movement of the two bolts 29 and 30 until bolt 57, or the end portion of extension 34, is sheared, thus delaying the telescopic upward movement of body 41.
Finally, the strengthening means comprise a strut
58 for opposing deformation of shaped strip 5. Strut 58 is defined by a channel segment, the wings of which are connected by two pairs of bolts 59 to the two walls 16 of metal sheet 15 of spacer 13; and the two bolts 59 in each pair are offset vertically so that strut 58 is inclined with a free end 60 behind the bottom ridge of strip 5.
Guardrail 1 operates as follows.
Upon a vehicle colliding with strip 5, deformation of the bottom ridge of strip 5 is limited by struts 58, thus reducing the impact energy of the wheels against wheel rail 50; strip 5 tends to move connecting assemblies 6 towards post 3, which in turn tends to bend outwards ; but the above movement is delayed by bolt 57 connecting post 3 to extension 34 of spacer plate 32.
If the impact energy is sufficient to shear bolt 57, connecting assembly 6 begins to back up (rightwards in Figure 3); and slots 27 and 28, acting on bolts 29 and 30, move release body 41 upwards and rotate spacer 13 to keep strip 5 substantially parallel to itself and so redress guardrail 1.
Upon impact, slots 27 and 28 of the two walls 16 tend to slide differently on the two bolts 29 and 30, so that spacer 13 tends to rotate with respect to post 3; which rotation tendency is reduced by the two plates 52 strengthening the two walls 16 of spacer 13. Finally, if the impact energy is not yet dissipated, bolts 29 and 30 shear partitions 14'and 14, so that body 41 is released from post 3, together with assembly 6 and strip 5.
The advantages, as compared with known guardrails, of guardrail 1 according to the invention will be clear from the foregoing description. In particular, guardrail 1 provides for increasing the center distance of posts 3, thus reducing its own total weight, while at the same time maintaining the same vehicle-retaining, collision- energy-dissipating and position-correcting characteristics. Furthermore, by limiting deformation of the bottom ridge of strip 5, struts 58 reduce the risk of the vehicle wheels jamming beneath strip 5. And finally, frame 33 tends to delay both rotation of connecting assembly 6 and/or post 3, and release of strip 5 from posts 3.
As shown in the Figure 9 variation, if considerably greater collision energy absorption is required, the center distance between posts 3 may be reduced, e. g. halved, with respect to that of the Figure 1 and 2 variation ; in which case, each module M comprises four 1.125 m spans between posts 3.
Furthermore, each connecting assembly 6 may be connected to that of the adjacent post 3 by a diagonal strut 63 lying in a horizontal plane, i. e. perpendicular to the axes of posts 3. Diagonal strut 63 may be defined by a flat bar having two bent ends, one of which is fitted between chain 45 and bracket 46 of spacer 13 of
one post 3, and the other of which is fitted, at the fastening point of top ridge 4 (Figure 3) of shaped strip 5, on intermediate wall 25 of dissipator 21 of the adjacent post 3.
Diagonal struts 63 (Figure 9) advantageously slope towards the center of the road in the traffic direction, so that they are also parallel to one another, and so that, in the event of vehicle impact, act as ties, making maximum use of the tensile strength of the steel.
Clearly, changes may be made to the guardrail as described herein without, however, departing from the scope of the accompanying Claims. For example, spacer 13 and/or dissipator 21 may have no strengthening ribs; wheel rail 50 (Figure 3) of guardrail 1 may be replaced by a wheel rail located just below the bottom edge of shaped strip 5, and which may be defined by a section having a vertical central wall, a horizontal top wall, and a subvertical bottom wall, substantially as described in Italian Patent Application n. T098A000143 filed by the present Applicant.
Frame 33 may also be connected to spacer 13 by means other than oblong plates 52; and finally, both spacer plates 31 and 32 may have a downward extension 34 for connection to post 3.