Back in 2016, the Federal Motor Carrier Safety Administration, along with the National Highway Traffic Safety Administration, floated a proposal to mandate speed limiters on trucks. As is often the case when the agency is in the beginning stages of a new regulation, this initial notice of proposed rulemaking for mandatory speed limiters was rather vague.

Yes, it called for mandatory speed-limiting of new commercial vehicles. Yet despite a decade-long push by trucking and safety advocates for such a mandate, the 2016 proposal was silent on what that limit should be. The Department of Transportation said only that the NPRM “discusses the benefits of setting the maximum speed at 60, 65, and 68 mph, but the agencies will consider other speeds based on public input.”

It also placed the onus on truck makers by mandating that speed limiters be installed and set at the factory — thus NHTSA’s involvement.

Early last month, FMCSA announced that it was putting the stalled rulemaking back into gear by working up a supplemental notice of proposed rulemaking to gather information from fleets that use speed limiters voluntarily.

The key difference is this time it will be a separate motor carrier-based rule. The agency placing the requirement on carriers will ensure compliance with the rule and potentially avoid confusion over who is responsible for implementing it.

Alas, another critical element is the same as before: This supplemental notice also makes no mention of a defined maximum speed. Not surprisingly, given this is early days, it also does not offer a timeline to adoption.

Back to the ball being lobbed into the fleets’ court. In this new SNPRM, FMCSA proposes that interstate carriers running commercial motor vehicles with a GVWR of 26,001 pounds or more that are fitted with an electronic engine control unit “capable of governing the maximum speed” will be required to limit the CMV “to a speed to be determined by the rulemaking” and to maintain that ECU setting for the service life of the vehicle.

So, again, an actual speed limit is still up in the air. No wonder that at press time, with a few weeks remaining for public comment on the mandatory speed limiter proposal, FMCSA was already showing that over 5,400 comments had been filed. And that despite the agency stating it wanted to hear about and receive data “regarding the adjustment or reprogramming of ECUs,” not about what the speed limit should be.

A half-hour ramble through the comments yielded almost all demands that the rulemaking be entirely dropped or, at the very least, not dictate split speed limits for trucks and cars. (Major organizations such as the American Trucking Associations, which supports a speed-limiter mandate with caveats, often don’t submit comments until near the end of the comment period.)

“This rule will cause more accidents not less,” starts out one commenter, who describes himself as a “21-year veteran” of trucking. “The State of Ohio just recently increased the truck speed limit from 55 to 70 because there was zero proof after 20 years+ that the split speed limit between cars and trucks was helpful! Frankly, the FMCSA is creating a bigger problem here… Reconsider dropping this and rely on your state patrol, weigh stations, and so on to enforce the laws already on the books.”

“Limiting truck speed causes more congestion and is more of a safety hazard than anything,” commented a logistics operator. “You have someone going up a hill faster than the other; when they reach the top, you have two trucks side by side for the next 15 miles with 4 miles of traffic behind them because they cannot pass one another.”

And this from a motor carrier: “Speed limiting devices are unsafe for public roadways…Restricting [truck] speed not only clogs highways and interstates, [but] it also generates more unsafe passing practices… Causing giant rolling roadblocks does nothing more than agitate the general public. Do not restrict trucks!”

This commentary first appeared in the June 2022 issue of Heavy Duty Trucking.