Research Papers

Failure mechanisms of energy absorbing guardrail terminals

Filename 7A_Hildebrand.pdf
Filesize 2 MB
Version 1
Date added June 9, 2015
Downloaded 12 times/fois
Category 2015 CARSP XXV Ottawa
Tags Research and Evaluation, Session 7A
Stream/Volet Research and Evaluation
Author/Auteur Eric D. Hildebrand, Ryan W. Esligar

Slidedeck Presentation

7A_Hildebrand [V1]


A recent lawsuit in the U.S. resulted in a $175 million settlement against Trinity Industries Inc. in
connection with the ET-Plus energy absorbing guardrail terminal (EAGRT) system they manufacture.
This lawsuit has drawn attention to the in-service performance of EAGRTs that were assumed to
perform satisfactorily given that they met U.S. Federal Highway Administration (FHWA) testing
standards. Many U.S. states and Canadian provinces have suspended the use of the popular ET-Plus
system pending further testing by regulators.
This study synthesizes the real-world crash performance of a sample of 25 high-speed collisions
between passenger vehicles and an EAGRT conducted over a 5-year period. In-depth analyses and
reconstruction of the study cases provides an insight into failure mechanisms associated with these
systems. Findings indicate that for those collision configurations that fall within the boundaries of the
FHWA testing regime, crash outcome is often satisfactorily mitigated. Unfortunately, most real-world
collision configurations were not well represented by the FHWA test configurations, often resulting in
poor crash performance of these units. A total of 14 (of the 25) cases were shown to yield either mixed
or undesirable crash results. Examples of deficiencies in crash outcomes are highlighted including
vehicle intrusion/penetration, rollover, redirection of vehicle into adjacent lanes, and failure of the
EAGRT to gate when struck from the side. Although the results show that the EAGRT systems
absorbed on average 52% of total crash energy, the overall crash performance raises questions
whether alternative (including non-energy absorbing) systems may eventually prove to be more cost effective.

Eric D. Hildebrand, Ryan W. Esligar