A side underride guard installed on a truck. The equipment has been the source of much debate. (AirFlow Deflector)
The National Highway Traffic Safety Administration has denied a request seeking an investigation into whether side underride guards on trailers could reduce the severity of vehicle collisions with tractor-trailers.
“Currently, a Federal Motor Vehicle Safety Standard requiring side underride guards on semi-trailers does not exist,” NHTSA noted in a March 31 announcement in response to the petition, filed by the nonprofit Institute for Safer Trucking. “The petitioner contends that a failure to include side underride guards equates to a safety defect in the semi-trailer’s design, construction and performance.”
The agency noted that the broader question of whether trailers should be equipped with side underride guards — devices that critics say require further study — is already under review.
“NHTSA believes that the issues raised here are best addressed through its recent rulemaking and the ongoing actions under the Infrastructure Investment and Jobs Act,” the agency said, referencing an Advance Notice of Proposed Rulemaking it published as part of the Biden-era bipartisan infrastructure legislation. The ANPRM summarized and requested comment on a 2022 NHTSA report that contained analysis of potential issues with a requirement for side underride guards on new trailers and semitrailers. NHTSA’s Office of Rulemaking is reviewing more than 2,000 comments received on the ANPRM.
Also in accordance with the IIJA, on June 18, 2024, the NHTSA-formed Advisory Committee on Underride Protection issued its biennial findings to Congress and the secretary of transportation. The group issued two reports — one from the group’s majority, one from its minority — summarizing its efforts to provide advice and recommendations on regulations related to underride crashes. Though the committee’s charter was extended through June 2025, the committee concluded its work following the publication of the reports.
NHTSA previously announced other actions related to truck-trailer underride safety, including efforts to improve data collection on underride crashes by recommending inclusion of underride data in state crash data systems. It also has recommended providing educational materials to state and local police departments on identifying and recording underride crashes.
The agency’s Office of Defects Investigation also participates in Commercial Vehicle Safety Alliance events through which it has encouraged law enforcement to report underride crashes. It also proposed CVSA focus on underride guards during the 2024 International Roadcheck, an annual 72-hour safety blitz that takes place in the U.S., Canada and Mexico. The defects office also met separately with Utility Trailer Manufacturing Co. and the Auto Haulers Association of America regarding, respectively, Utility’s side underride guard design and the operational environment of low clearance vehicles, such as car haulers.
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A review of the office’s databases contained no injury or fatality trend specific to any make, model or model year trailer.
“Based on the information available to the agency, trailer manufacturers continue to pursue side underride guard technology, and at least one manufacturer is currently offering an optional guard,” NHTSA said.
Meanwhile, NHTSA said it is conducting research on rear impact guard designs that better protect occupants of passenger vehicles in rear underride crashes. In August 2022, the agency, in partnership with FMCSA, published and distributed to law enforcement a pamphlet that explains how to identify and record such crashes.
