The final report focusing on injury and fatality risk of different energy absorbing guardrail end terminal designs based on data from two states has been released.
The study examined eight years of severe injury and death data for crashes that occurred in Missouri and Ohio involving five different guardrail end terminal designs. While the data are limited, the study found that the ET-Plus design, manufactured by Trinity Industries, Inc., was a statistical outlier in injury and fatality crashes.
The initial release of the study in September entitled, “In-Service Evaluation of FHWA-Accepted Guardrail Terminals” has been revised to reflect comments from three independent reviewers as well as its sponsors. As a result, the title of the study was changed. The final report, released this week, entitled, “Relative Comparison of NCHRP 350 Accepted Guardrail Terminals” containing reviewers input has increased the impact severity from 1.36 times more likely to produce a severe injury to 1.95 and from 2.86 times to 3.95 more likely to produce a fatality than the ET-2000 end terminal design.
Further, following the release of the initial study, Trinity Industries’ expert released an unsigned review of the study’s methodologies and results. The University of Alabama author, Kevin Schrum, considered Trinity’s analysis of the initial report, sought input from credentialed reviewers, and released the following rebuttal, “Rebuttal to a Review of In-Service Evaluation of FHWA Accepted Guardrail Terminals”
Guardrail energy absorbing end terminals are designed to lessen the severity of a crash, by allowing the striking vehicle to ride down the crash forces safely, without deflecting the vehicle back onto the roadway. Since the 1960s, guardrail end designs have evolved from blunt-end terminals, which often acted like spears, penetrating the vehicle compartment, to twist turn-down designs that served as a ramp, causing vehicle rollovers. Today, the W-Beam guardrail with an energy absorbing end is the most commonly used energy absorption system. In this design, the end terminal rail is deformed away from the striking vehicle, either by flattening, cutting or kinking the rail.
The study, sponsored by The Safety Institute and the Missouri Highways and Transportation Commission, analyzed single-vehicle ran-off-road crashes that occurred in Ohio, between 2005-2013, and Missouri, between 2005-2014, in which contact with the guardrail end was identified as the Most Harmful Event.
The crash performance of four designs was assessed against that of the ET-2000, the first crashworthy energy-absorbing end terminal, also manufactured by Trinity.
- Flared Energy Absorbing Terminal (FLEAT) and the Sequential Kinking Terminal (SKT), both produced by Road Systems, Inc., in which the guardrail is forced through the head and sequentially kinked to dissipate energy.
- Slotted Rail Terminal (SRT), a Trinity Product, which features strategically-placed slots in the rail to reduce the rail’s stiffness in the event of a head-on impact.
- The ET-Plus, which extrudes the guardrail into a flat metal ribbon.
Sample sizes in this two state study were insufficient to reliably assess the comparative safety performance of the FLEAT, SKT and SRT designs, but there was a sufficient sample size to compare the performance of the ET-Plus against that of its predecessor.
The researchers caution that further study is needed, and that “the results and conclusions pertinent to one state are not necessarily pertinent to any other state.”
The Safety Institute supported the study to address the lack of sufficient reliable data on the in-service performance of highway guardrail end terminals. The mission of The Safety Institute is to support evidence-based research aimed at reducing injuries and improving product safety.
Recently, The Safety Institute and the Center for Auto Safety filed a motion to intervene in United States ex rel. Harman v. Trinity Industries, alleging the government was defrauded when it purchased modified guardrail end terminals. The plaintiffs sued Trinity under the qui tam provisions of the False Claims Act, in which a private individual can sue federal contractors on behalf of the government, alleging fraud. The lawsuit claims that Trinity instituted a dimensional change to the feeder chute of the ET-Plus end terminal that causes the guardrail to lock up instead of attenuating the energy in a crash, but failed to notify the agency about the change as it is required to do. These allegations have been reported by the news media and are the subject of civil and fraud litigation.
Represented by Public Justice, the two advocacy groups sought public access to sealed court records, but the motion was denied. The Safety Institute and the Center for Auto Safety appealed the decision this week. The Safety Institute motion filed in the qui tam case in District Court for the Eastern District of Texas, Marshall Division stated:
The Safety Institute and its Board Members feel strongly that documents filed under seal in this action are of immediate importance to the motoring public. Motorists operate their vehicles on roadways nationwide upon which these terminals are equipped. We have an opportunity and an obligation in support of our organization’s mission and on behalf of the motoring public and their passengers to protect them from undue harm. If these records shed any light on the safety record of the ET-PLUS, the public has a right to know, and the Institute is committed to ensuring that any such information is used to shed light on this important public safety issue.
The Safety Institute will continue to pursue this information and conduct objective research to assess the safety and efficacy of highway equipment on which motorists depend.