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Everything To Know About Truck Speed Limiters

Updated on: 1/2/2023

There are few things more frightening on America’s interstate highways than a speeding semi truck. The potential risk of one of these commercial vehicles barreling down at 80 mph is massive, and the collisions involving these trucks are usually severe.

Data from the Insurance Institute for Highway Safety shows that even a lightly loaded semi-truck – around 40,000 pounds – has 13 times the energy of a passenger vehicle traveling the same speed. That amount of energy is a recipe for trouble.

In 2007, the Federal Motor Carrier Safety Administration released a study titled “The Large Truck Causation Study.” It is the first report to examine the causes of commercial truck crashes. In the 967-crash sample, speeding was found to be a cause in 23 percent of accidents. 

Everyone would like to see a decrease in large truck crashes. Excessive speed is obviously a large factor. In the last decade, “speed limiters” have been posed as one solution to the problem. Let’s explore the issue.

What Is A Truck Speed Limiter?

First, let’s understand what a semi-truck speed limiter really is. Also known as a “speed governor,” speed limiters are devices that limit a vehicle’s speed using the engine’s computer and electronic sensors. When the truck reaches a certain maximum speed, sensors will tell the internal computer to keep the truck from going faster. This is done by controlling the air flow, fuel intake and sparks needed for internal combustion. 

Many trucking companies have speed limiters in place. This is done for insurance reasons, as well as safety. Different truck engines also have their own pre-determined speed-limiters.

Speed Limits In the United States

Speed limits in the United States vary widely. They range from 35 mph in urban areas to 85 mph in rural areas, where there’s less risk of accidents. Many highways have posted truck speed limits lower than those for passenger vehicles. In Washington state, the truck speed limit is 60 mph – that goes for rural interstates, urban interstates and other limited access roads. 

Speed limits have been increasing steadily in the United States for the past 20 years. From 1973 through 1995, a federal law required states to adopt 55 mph as their maximum speed limit to receive their share of highway funds. That was repealed in 1995 – as fuel became more available – and states have been adopting higher and higher limits. In 2018, 41 states have speed limits of 70 mph or higher on some roads. 

Adrian Lund, president of the Insurance Institute for Highway Safety, wrote that the agency’s research shows that 33,000 deaths between 1993 and 2013 can be attributed to speed limit increases. 

Yes, drivers across the country need to slow down. But what effect would speed limiters have on commercial truck crashes? It’s a hot-button issue among truck drivers, insurance companies, personal injury attorneys, as well as legislators and lobbyists in Washington, D.C. There’s no consensus on these devices, and no shortage of opinions on the matter.

Positives Of Truck Speed Limiters

The No. 1 reason for the proposal of speed limiters is safety. Commercial trucks are responsible for about 18 percent of all fatal crashes. Reducing crashes seems like an idea everyone can get behind, though the idea of a federally-mandated speed-limiter is controversial. 

As discussed above, national speed limits have increased in almost every state over the past 20 years. But large trucks still take a long time to stop compared to passenger vehicles. At 65 mph, a passenger vehicle will take 316 feet to stop, while a semi-truck takes about 525 feet to stop. And the risk of damage is huge – a semi-truck going 80 mph has 50 percent more energy to manage in an emergency than if it were going 15 mph slower, according to the IIHS.

Advocates for speed limiters on trucks say the devices would decrease the amount of accidents. They also claim speed limiters would:

Improve fuel efficiency: The IIHS says that a large truck reducing its speed by 1 mph will benefit from fuel savings of about 1 percent. Simply put, slower speeds = less wind drag, meaning less fuel is burned.

Reduce emissions: As stated above, the faster a truck goes, the more fuel used. Lowering fuel consumption means less carbon dioxide produced and released into the environment. 

iihs logoNegatives Of Truck Speed Limiters

Those against speed limiters on commercial trucks say the devices can cause real problems. For example, a truck passing another truck at similar speeds – 65 mph vs. 64 mph – would create a rolling roadblock and create traffic problems. 

Those against also say a string of five semi-trucks traveling one behind another is dangerous. Someone passing in the left lane would have to go long distances in close proximity to the trucks, a potential risk.

There’s also research sponsored by the AAA Foundation for Traffic Safety that found no safety value for differential speed limits on trucks (different limits for trucks vs. passenger vehicles). 

A decade-long push to implement speed limits on large trucks has gained momentum in recent years but stalled in July 2017. A nationwide decrease in federal regulations likely spelled the end – at least for the near future – on the U.S. Department of Transportation’s rule to mandate speed limiters on large trucks.

Truck Speed Limiters Reduce Crashes In Canada

While the debate rages on in the United States, one Canadian province has seen positive results from speed-limiter legislation. The Ontario Ministry of Transportation looked at pre-legislation (2006-08) and post-legislation (2010-12) large truck crash data. The study, conducted between 2014-15, found that:

  • After 2009, large truck drivers were involved in fewer at-fault speed collisions.
  • The crash rate of speeding trucks dropped by 73 percent after the speed-limiter rules were implemented.
  • Passenger cars and other vehicles, which also got speed-limiters, had a decrease of around 30 percent.

Contact A Truck Accident Attorney

Regardless of what you believe caused your semi-truck accident, you may benefit from speaking with attorney Chris Davis and the team at Davis Law Group, P.S. You have nothing to lose with our free case evaluation offer. Thousands of dollars in compensation, closure after your accident, and a sense of justice may all await you. Mr. Davis and his staff want to help you and your family after a tragic trucking collision.

The team at Davis Law Group is ready and awaiting your call. We believe in aggressive representation and are willing to take cases to trial if necessary. We don’t shy away from complex or difficult cases, and we have the financial and legal resources to win your case. Call (206) 727-4000, use the chat feature below or fill out the form on this page to get started.

Chris Davis
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Chris Davis is the founder of Davis Law Group, P.S. in Seattle, WA.
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