Last week, the Federal Motor Carrier Safety Administration (FMCSA) and the National Highway Traffic Safety Administration (NHTSA) announced that it withdrew its 2016 proposal to require heavy vehicles with a GVWR of 26,000 pounds or more to be equipped with a speed limiting device.

FMCSA also cancelled its May 4, 2022, proposal that the same vehicles equipped with speed limiters must set a speed limit and maintain that setting for the life of the vehicle. 

The original intent was based on data of the time suggesting that limiting the speed of these heavy vehicles would reduce the severity of crashes involving those vehicles. However, the agencies were not able to estimate the effects of speed reduction on the number of crashes, and the proposal did not include estimated costs or benefits related to crash reductions or increases. 

In 2016, over 7,000 comments were received in regard to the rule; some drivers in light vehicles applauded the move, perceiving it as a safety win. Others were concerned about the potential speed difference and felt that it could lead to increased risky driving behavior by light vehicles trying to pass the slower, heavier vehicles and overall highway slowness as heavy vehicles passed one another. The Insurance Institute for Highway Safety (IIHS) supported the rule, stating that lowering speeds would also lower the kinetic energy of crashes, thus reducing injuries, and that speed differentials already existed between trucks and cars on the highway. 

The 2016 rule was never fully adopted, and since, NHTSA and FMCSA determined that it lacks a sufficiently clear and compelling safety justification for its implementation and raises significant concerns regarding federalism. 

"In light of significant policy and safety concerns and continued data gaps that create considerable uncertainty about the estimated costs, benefits, and other impacts of the proposed rule," the federal register filing stated. Furthermore, they said the public comment process did not provide the necessary information to proceed with a final rule. 

The agencies noted that there have been considerable advancements in crash avoidance technologies such as automatic emergency braking (AEB) and and forward collision warning, which are being adopted at an increasing rate. FMCSA and NHTSA now say that a portion of the crashes that they assumed would be mitigated by speed limiters may also be mitigated by these new systems.