US 3417965 A
Description (OCR text may contain errors)
Dec. 24, 1968 .1. H. GRAY VEHICLE GUARD RAIL 2 Sheets-Sheet l Filed May 25. 1967 INVENTOR. JAMES HARVEY GRAY BY/vydgaad) m H 1.' TQRNEYa Y Dec. 24, 1968 J. H. GRAY VEHICLE: GUARD RAIL 2 Sheets-Sheet 2 Filed May 25. 1957 .,x... w 1 Il bwvvts,...
i rm, f N Y c v u m n HTToRNEY United States Patent Oice 3,417,965 Patented Dec. 24, 1968 3,417,965 VEHICLE GUARD RAIL James H. Gray, 75840 Altamira Drive, Palm Desert, Calif. 92260 Filed May 25, 1967, Ser. No. 641,244 3 Claims. (Cl. 256 13.1)
ABSTRACT F THE DISCLOSURE A vehicle guard rail assembly particularly for erection alongside a highway or between divided highways which is capable of positively but yieldably arresting the lateral travel of vehicles which hit it, and support their return to the traic lane. The guard rail is pivotally supported, and a torque tube resists pivoting upon impact of a vehicle.
BRIEF SUMMARY OF THE INVENTION In general, the guard rail assembly of this invention comprises a plurality of inclined arm members pivotally mounted on anchor posts driven into the ground. The anchor posts are spaced along the side of a highway, or on a median strip. Any conventional type of railing or steel cable can 'be attached to the extended arms of the assemblies to face the highway. The rail is the part of the assembly that is struck by the vehicle. Under impact loads the rail pivots vertically on the assembly, permitting a torque tube, which is connected to each inclined arm member, to twist and resist pivotal movement of the inclined arm.
By contrast, the use of springs, hydraulic shock absorbers, or similar devices, on each arm supporting the rail will have the effect of concentrating and localizing the impact loads instead of giving them the spanwise distribution achieved by the torque tube. In this case the individual arms and rail segments are subject to greater stresses as higher loads are put on the posts. Under such conditions the rail is far more apt to exceed its elastic limits, and pocket, thus permitting the front wheel of the vehicle to come in contact with a post. In such cases the car will probably spin and possibly roll. As the vehicle leaves the rail in this manner a following car collision is a high probability in heavy trailic.
The use of springs, or similar devices, on the individual arms will require a rail of impractical weight and rigidity to achieve the performance obtainable with standard rail and torque tube. With the locally concentrated energy storage a vicious rebound may be expected. In the event of post damage and distortion, a compressed spring may be released from its seating and become an extremely dangerous projectile.
Hydraulic systems would be safer than springs, but less reliable because of temperature effects on the uid. Under extreme winter conditions they may fail to yield due to very high viscosity. Conversely, the low viscosity caused by high summer temperatures may prevent them from absorbing a significant measure of the impact energy.
Such systems would present prohibitive maintenance problems, in addition to excessive initial costs.
BRIEF DESCRIPTION OF THE DRAWINGS FIGURE l is a generally diagrammatical top plan view showing two spans of the guard rail assembly;
FIGURE 2 .is a similar front elevation view of the guard rail assembly of FIGURE l;
FIGURE 3 is a similar rear elevation view of two spans of the guard rail assembly of FIGURE l;
FIGURE 4 is a fragmentary front elevation view on an enlarged scale of the guard rail and post construction;
FIGURE 5 is a view partly in section taken along the line 5 5 of FIGURE 4, with the guard rail assembly in normal position;
FIGURE 6 is a view in section taken along the line 6 6 of FIGURE 4;
FIGURE 7 is an enlarged fragmentary top plan view as viewed from above FIGURE 4;
FIGURE 8 is a view similar to FIGURE 5, taken on the line 8 8 of FIGURE 2;
FIGURE 9 is a view in section to that of FIGURE 6 but showing the guard rail in a partially yielding position under impact with a vehicle;
FIGURE 10 is a view in section similar to that of FIGURE 8, but showing the guard rail in a fully yielding position; and
FIGURE 1l is a view in section similar to that of FIG- URE 6, but showing a modiication of the invention.
DETAILED DESCRIPTION OF THE INVENTION The guard rail assembly 20, as shown in FIGURES 1 3, comprises a rail 21 supported from a plurality of post assemblies 22. Each post assembly 22 is constructed of a plurality of parts which will be described hereinafter.
The rail 21 comprises a channel member which extends along the side of a highway. The `channel member has the W-beam cross-sectional shape generally illustrated in FIGURE 5 (as two convex or C-shaped portions 24 and 25 joined together by a narrow ilat strip portion 26). The rail 21 `may be of other shapes.
The bases 27 of a plurality of U-brackets 28 are fastened by bolts 29 to the strip portions 26. The U-'brackets 28 have spaced parallel side flanges 30 and 31.
For each post assembly y22, there is a post 35 driven into the ground G alongside a highway. The posts 35 are positioned parallel to the highway.
Each post assembly 22 also includes -a downwardly extending, inclined H-beam member 38, provided with anges 39 and 40. The downwardly extending H-beam flanges 39 and 40 have lower ends 41 and 42 porjecting below the ground into which the posts 35 are driven. A metal U-shaped strap 43 is -wrapped about the post 35 if a wood -post is used (not required on steel posts), and the plates 39 and 40 are pivotally mounted to the post 35, with the U-shaped strap 43 around the back and sides of the post and between the H-beam anges and the post.
The pivotal mount for the H-beam member 38 comprises one end 44 of a tension-torsion rod 45. The end 44 of a tension-torsion rod 45. The end of the rod 45 has a nut 46 threaded against and welded to the anges 41 or 42 and welded to the rod 45. The other end 48 of the rod 45 extends through the side anges 30 and 31 of the bracket 28 and through the flanges 39 and 40 of the i11- clined H-beam member 38 of the next post assembly. A nut 49 is threaded onto the end 48 of the rod 45, and the rod end 48 is welded to the side flanges 30 and 31 to enable the rod 45 to function both as a tension and torsion member and to hold the rail in a generally vertical position. Thus the rods 45 act as tension members to keep the post assemblies 22 from bending over or rotating horizontally in the direction of travel of an automobile upon impact by a vehicle. Since each rod 45 is welded to the anges 39 and 40, the rod also provides torsion resistance to swinging of an inclined H-beam member 38 upon impact. With respect to assemblies 22 that have the end 44 of a rod 45 anchored in the post 35, the guard rail 21 is secured to the member 38 by means of a headed bolt 47 that extends through the side flanges of a bracket 28 and the flanges 39 and 40 of said arm member. A lock washer and nut are applied to the projecting end of the bolt, as shown in FIGURES 5 and 7. With respect to the post assemblies 22 that do not have the end 44 of a rod 45 anchored in the post 35, the lower end portion of the member 38 is pivot- 3 ally secured to the post by a similar bolt 47 that extends through the post and the flanges 39 and 40 of said arm member. A lock washer and nut are applied to the projecting end of the bolt, as shown in FIGURE 8.
An elongated steel torque tube 55 of circular crosssection is fastened to the inclined members 38 by a plurality of U-bolts 56. The torque tube 55 has flattened sections 57 where it is connected by the U-bolts 56 so that, when the nuts 58 are turned to tighten the U-bolts, the torque tube 55 cannot rotate relative to the inclined members 38. If the posts 3S are Wood, they have depressions 59 in them for accommodating the nuts 58 and ends of the U-bolts 56. If steel H-beam posts are used, such clearance is provided by the shape -of the post.
FIGURE 9 shows the partially pivoted position of the guard rail assembly upon impact with a vehicle, and FIG- URE 10 shows the fully pivoted position. The vehicle strikes the rail 21 as the vehicle veers off the highway. However, the vehicle instead of meeting a semi-rigid or rigid unyielding barrier, is met with a somewhat yielding barrier. As the vehicle strikes the rail 21, the inclined arms 38 near the point of impact pivot toward the position shown in FIGURE 9, but the weight and inertia of inclined members 38, 21 and 55 remote from the impact area keeps them in the inclined positions shown in FIG- URE 6, thereby causing twisting of the torque tube 55 and the tension-torsion rods 45. The torque tube 55 and the rods 45 yield, permitting the inclined members near the point of impact to pivot toward the position shown in FIGURE 8, but the resistanceto yielding is such that the barrier pivots to the position shown in FIGURE 9 with absorption of energy by the torque tube 55 and rod 45 and consequent reduction of shock forces. As the members 38 pivot, the rail 21 remains in a vertical position as illustrated in FIGURE 10, against the vertical side of the vehicle and places a torsion load on the rod 45. The web 50 between the flanges 39 and 40 of the H-beam member 38 has a lower end 51 separated from the flanges and bent at 45 and welded back on the flanges, acting as a stop to normally hold the inclined member 38 at a 45 incline relative to the post 35.
When the post assembly 22 is in the position illustrated in FIGURE 6, the lower end 51 of the downwardly extending member 50 of each post assembly 22 is positioned against the post 35. The weight of the inclined members 38 and the rail 21 biases the post assemblies 22 toward this position.
From the foregoing, it is apparent that the use of torque tubes as energy absorbing elements in the design of energy absorbing guard rail systems has several advantages. The torque tube produces a spanwise distribution of energy over several post assemblies in either direction from the point of impact. This lateral energy distribution results in a uniform curvature of the rail and tube that progresses, wave-like, with the vehicle, the point of contact remaining at the center of the curvature until contact is broken.
Interaction of the inclined members 38 permits the rail to yield as a smooth continuously curving surface, turning and guiding the vehicle back toward its proper traiic lane. This is accomplished without severe negative acceleration and with minimum transverse accelerations.
The spanwise distribution of energy also tends to prevent the rail from bending beyond its elastic limits and consequent permanent distortion.
As energy is absorbed by the torque tube 55, it is stored throughout its eiective length and, unless major damage has been incurred, will restore the rail to its normal static position as contact with the vehicle is broken. The energy is stored over a suicient length, or volume, of steel that there is little possibility of unacceptable rebound.
The torque tube 55 performs a dual purpose by providing additional safety in an energy absorbing guard rail system. The rail 21, being pivotally mounted on the inclined members 38, will rise as it recedes under impact. For conventional sized cars this is an advantage in preventing their jumping or rolling over the rail, a factor that is particularly necessary on median installations. In the case of small compact cars, however, the increase in clearance below the rail will permit them to pass under the rail, with usually fatal results to the occupants. The torque tube, in addition to its work in absorption and dissipation of energy, also functions as a rubbing rail, effectively preventing underpassing of small vehicles.
FIGURE 11 shows a slight modification of the invention. Here, the lower end 62 of the H-beam arm web 50 is extended well into the ground G. Also, the plates 39 and 40 have lower vertical extensions 63 extending into the ground and welded to the side edges of the lower end 62 of the plate 50. With these extensions into the ground, further resistance to pivoting of the inclined members 38 is provided.
Various changes and modifications may be made within the purview of this invention as will be readily apparent to those skilled in the art. Such changes and modiiications are within the scope and teaching of this invention as defined by the claims appended hereto.
What is claimed is:
1. A vehicle guard rail for erection alongside a highway comprising a plurality of posts adapted to be driven into the ground alongside the highway, an arm pivotally supported by each post, an elongated torque tube means, means for connecting the torque tube means to the arms and locking the torque tube means against rotation relative to the arms, whereby pivoting of an arm relative to other arms requires twisting of the torque tube means, `a guard rail strung between the arms, means for connecting the guard rail to the arms for free pivotal movements of the guard rail relative to the arms.
2. The vehicle guard rail of claim 1 including rod means connected between the lower end of one arm and the upper end of an adjacent arm to prevent the arms from being bent in directions longitudinal of the guard rails when hit by a vehicle.
3. The vehicle guard rail of claim 1 wherein the torque tube comprises a steel tube of circular cross-section to provide a spanwise distribution of energy and a smooth curvature of the guard rail under impact and prolonged loading.
References Cited UNITED STATES PATENTS 2,227,958 1/1941 Camp 25613.1 3,284,054 11/1966 St. Pierre 256-13.1
DAVID I. WILLIAMOWSKY, vPrimary Examiner.
DENNIS L. TAYLOR, Assistant Examiner.