The U.S. is one step closer to mandating speed limiters in commercial vehicles, although proposals have yet to establish what maximum speeds might be.

A Notice of Intent (NOI) filed on April 27 is designed to notify the public about plans to move forward with the speed limiter rulemaking process, the U.S. Federal Motor Carrier Safety Administration (FMCSA) said on its website.

Plans to mandate speed limiters have been in the works in the U.S. for years. A Notice of Proposed Rule Making (NPRM) was filed in 2016, although FMCSA acknowledges that some perspectives may have changed in the years since then.

“Studies and research have already proven what we were all taught long ago in driver’s ed classes, that traffic is safest when vehicles all travel at the same relative speed,” said Owner-Operator Independent Drivers Association (OOIDA) president Todd Spencer, in a related statement. “Limiting trucks to speeds below the flow of traffic increases interactions between vehicles which can lead to more crashes.”

Most crashes involving commercial vehicles also occur in areas where speed limits are below 55 mph (88 km/h), which mitigates the effect of any mandate, he added.

“What the motoring public should know is that when they are stuck behind trucks on long stretches of highway, those trucks are often limited to a speed well under the posted speed limit.”

The American Trucking Association welcomed FMCSA’s “constructive, data-driven approach” to the issue.

“We intend to thoroughly review FMCSA’s proposal, and we look forward to working with the agency to shape a final rule that is consistent with our policy supporting the use of speed limiters in conjunction with numerous other safety technologies,” said ATA president and CEO Chris Spear.

The association has supported speed limiters with maximum set speeds of 70 mph in trucks with Automatic Emergency Braking and adaptive cruise control. In trucks without those features, it supports a top set speed of 65 mph.

Canadian mandates

The technology is nothing new to carriers operating in two of Canada’s largest provinces. Ontario and Quebec have had mandated speed limiters set at 105 km/h since 2009.

An Ontario Ministry of Transportation (MTO) study determined that speed-related, at-fault collisions involving large commercial vehicles dropped 73% after mandatory speed limiter legislation took hold in the province.

The same study confirmed there was no evidence that speed limiters contributed to other collisions such as rear-end crashes. The share of truck drivers struck in the rear (10% of collisions) remained unchanged. Researchers compared data from 2006-08 to 2010-12, looking at fatalities, injuries, and police-reported property damage on high-speed highways.

The U.S. rules would apply to commercial vehicles with gross vehicle weights above 26,000 lb., and would require on-board diagnostics to identify the time and date settings were changed. Motor carriers would be required to maintain the speed limiters during the life of the vehicle.

Most heavy trucks have come with electronic control units since 1999, although some manufacturers were still installing mechanical controls through 2003, the U.S. National Highway Traffic Safety Administration (NHTSA) says.

“The agency is considering making the rule only applicable to [commercial motor vehicles] manufactured after a certain date, such as 2003, because this is the population of vehicles for which ECUs were routinely installed and may potentially be used to govern the speed of the vehicles,” FMCSA has said.

Comments collected through the NOI are to be included in a supplemental notice expected in 2023. From there, the rulemaking moves to the Office of Management and Budget Review before being published.

-This article has been updated to include comments from OOIDA and ATA.