Citation

Hirsch TJ, Buth CE, Nixon JF, Hustace D, Cooner H. Transp. Res. Rec. 1977; 631: 68-76.

Copyright

(Copyright © 1977, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

A relatively simple method has been found to modify the turned-down ends of highway guardrails to eliminate or minimize the probability that a vehicle impacting them will ramp and roll over. To modify the standard quardrail, the 5/8-in diameter bolts are removed from the first five posts. With these bolts removed, the rail will drop to the ground if the turned-down terminal section is struck by a vehicle, which eliminates ramping of the vehicle. To hold the rail at its proper height (69cm (27in) in Texas) before and during a vehicle impact along the length of need, backup plates are bolted to the first five posts. The action of this modified guardrail terminal is simple. When a vehicle tire or bumper pushes down on the turned-down terminal, the rail drops from the first five posts, which allows the vehicle to pass over the rail. If the vehicle bumper impacts the rail on the length of need and pushes it laterally against the backup plates on the posts, the rail is held at its proper height and the vehicle is redirected. The test program included the four crash tests for longitudinal barrier terminals. All of the test were successful, and no vehicles rolled over.