A new study of accidents involving highway guardrails has found shortcomings in several different manufacturers’ W-beam end caps in certain types of crashes.
The report, from a Federal Highway Administration and American Association of State Highway and Transportation Officials task force, also calls for fully implementing AASHTO’s 2009 Manual for Assessing Safety Hardware (MASH) guidelines for crash-testing new installations of guardrail terminals.
But the report doesn’t recommend new crash tests for existing guardrail equipment under an older set of criteria, contained in National Cooperative Highway Research Program Report 350 (NCHRP], because the devices’ limitations lie outside of those criteria’s test “matrices.”
FHWA Administrator Greg Nadeau said in a statement, “Now, after months and months of analysis, one thing is clear: we must fully implement the next-generation criteria as part of our roadside safety efforts.”
Highway guardrails have been in the spotlight in recent months because of controversy over the ET Plus guardrail end caps made by Trinity Industries, Dallas. In June, a federal district court directed the company to pay a $663-million judgment for allegedly defrauding FHWA. Trinity has denied the allegation.
The FHWA-AASHTO report, released on Sept. 11, says that it found end cap “performance limitations” in several types of vehicle-guardrail accidents—side impacts, head-on impacts from a shallow angle, impacts at a vehicles headlight area, and head-on shallow-angle impacts at high speeds. It said several types of the hardware, including the ET Plus, had the shortcomings.
Chris Poole, Iowa DOT safety programs engineer, told reporters in a conference call the team found that “the design of this class of device was vulnerable to certain impact conditions—typically those involving either offset or shallow-angle impacts where the forces between the rail and the impacting vehicle weren’t aligned with each other.”
Poole, a task force co-chair, said that as a result, “the offset of these forces tended to bend the rail ahead of the impact head and buckle the rail, rather than allowing the energy-absorbing capabilities of the impact head to function as demonstrated in head-on crash testing.”
Jeff Eller, a Trinity spokesman, said in a statement that the report’s data and conclusions “reinforce what we have always stated: We have confidence in the ET Plus System as designed and crash tested.” He added that the equipment “is a robust end terminal system that performs as designed pursuant to NCHRP 350 criteria when properly installed and maintained.”
He also said that the system continues to be eligible for federal reimbursement to states that permit its use and “remains accepted for use on the nation’s roadways today.”
Eller said that the Virginia DOT has told the company that it plans further tests of the ET Plus soon. Virginia’s attorney general, Mark Herring, filed suit last December in a Richmond court against Trinity. Herring contends that the company sold guardrails that had not been tested properly to ensure safety.
Virginia DOT and many other state transportation agencies last year suspended use of the ET Plus.
Poole said that among the study’s conclusions was that all extruding W-beam terminals had performance limitations and they "are not unique to the ET Plus four-inch terminals.” In addition, he said, the panel found that more crash tests under NCHRP 350 “would not be informative.”
Poole said, “Report 350 has worked well for over 20 years and the time has come for the resources of the roadside safety community to instead be directed toward full implementation of MASH and the safety benefits it provides.’ "
Bud Wright, AASHTO executive director, said in a statement that the recommendations “are key steps in the ongoing process of developing the next generation of roadside hardware.”
Jeff Paniati, FHWA executive director, said that the agency and AASHTO have already taken steps to carry out the task force recommendations.
Mike Griffith, director of FHWA’s office of safety technologies and the study’s other co-chair, noted that the number of fatalities resulting from guardrail crashes dropped by 53% to 258 in 2013 from 548 in 1979. Fatalities from crashes involving the guardrail ends declined 12% from 2005 to 2013, he added.
Story changed on 9/15/15 to correct name of National Cooperative Highway Research Program