UPDATED – The National Highway Traffic Safety Administration (NHTSA) has issued an Advance Notice of Proposed Rulemaking (ANPRM) for side underride guards on new trailers and semitrailers.

Regulatory agencies use an ANPRM to test out a proposal or solicit ideas before drafting a Notice of Proposed Rulemaking, which launches the actual rulemaking proposal. Here, NHTSA is responding to a mandate from Congress in the “bipartisan infrastructure law” to research the costs and benefits of side underride guards and to a petition from the Truck Safety Coalition.

NHTSA has jurisdiction over new vehicle standards, including trucks and trailers. If NHTSA adopts a regulation requiring side underride guards on trailers and semitrailers, the Federal Motor Carrier Safety Administration would follow with a rulemaking on the actual use of that equipment. Today, NHTSA is providing its research findings and assumptions and seeking public input and data in several areas.

NHTSA makes it clear that the side underride guards it is considering are not the “lateral protective devices” common in Europe. Carriers use those devices to prevent pedestrians and cyclists from entering the space under a truck trailer. The devices under consideration are also not the very light-weight airflow deflectors seen on semitrailers in the U.S. as a fuel efficiency measure. No other country requires side underride guards.

In the infrastructure law, Congress considered the impact of a passenger car traveling at 35 mph hitting the side of a trailer or semitrailer. The NHTSA ANPRM sets the bar at 40 mph, saying that prior tests of the only commercially available side underride guard in the U.S. showed no discernible difference between the two impact speeds.

Based on a 40 mph impact, NHTSA makes these assumptions:

  • An estimated 17.2 lives and 69 serious injuries would be saved annually if side underride guards were on today’s trailers and semitrailers. NHTSA thoroughly scrubbed several crash databases to arrive at that estimate. Based on those numbers, the annual safety benefits of side underride guards would range from $129 million to $166 million.
  • The cost of equipping new trailers and semitrailers with side underride guards, on the other hand, would range from $970 million to $1.2 billion annually. That includes the “lifetime fuel cost” in recognition of the added weight imposed.
  • NHTSA concludes that every analysis it performed resulted in a finding that “…the lifetime costs of equipping new trailers and semitrailers with side underride guards is six to eight times the corresponding estimated safety benefits.”

Case closed? No. The ANPRM asks for reaction to these NHTSA assumptions and calculations, as well as answers, backed by data, to questions such as:

  • Would the cost of side underride guards change if the sole U.S. manufacturer faced competition?
  • If advanced driver assistance technologies, such as automatic emergency braking, reduce side impact speeds, how would the safety benefits change? On the other hand, are there concerns about injuries or fatalities from impacts above 40 mph?
  • What are the costs, not considered in NHTSA analysis, of any necessary strengthening of trailer beams, frame rails and floors to accommodate side underride guards?
  • Are there practical issues in trucking operations with side underride guards, such as scraping road surfaces at rail crossings or difficulties in intermodal operations and at ports and freight docks?

Comments on this proposal were originally due by June 20, 2023, but NHTSA extended the deadline to July 20, 2023.

This blog was updated on June 9, 2023 due to NHTSA extending the comment period. 

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