The importance of speed limits cannot be overstated. They are not arbitrary numbers on signs, but rather, crucial safety measures put in place to prevent unnecessary loss of life. Unfortunately, many drivers ignore these limits, resulting in tragic consequences. In 2023, speeding was a contributing factor in over 44,000 fatalities in the U.S., accounting for 29% of all motor vehicle deaths that year.
But there is hope. Trucking companies hold the key to mitigating speed-related truck accidents and curbing this statistic. While quick deliveries may boost profits, slower speeds offer substantial fuel efficiency benefits. Many trucking companies already use speed limiters—also known as speed governors—to cap their fleet’s speeds, but many more do not.
To truly enhance safety, the trucking industry must embrace and mandate safety measures like speed-limiting technologies. After all, there’s never a need for an 80,000-pound semi-truck to be driving 80 miles an hour down the highway.
In today’s world, two of the most popular technologies used to regulate speed in the trucking industry are speed limiters and ISA devices. While both have a similar result, their technology, cost, and functionality are quite different.
So, what are they and how do they differ?
What other advancements can we expect from the trucking industry to mitigate the epidemic of speeding tractor-trailers? Dive into the details of these speed-reducing technologies and how they work to save lives on our roads.
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What Are Speed Limiters?
A speed limiter, or speed governor, is a piece of technology that limits a truck’s top speed. Trucks aren’t the only vehicles with speed limiters in them. Most passenger vehicles have speed limiters installed, too.
Speed limiters use sensors to detect how fast the vehicle is moving and then send that information to the engine’s computer. If the vehicle reaches the top speed set by the limiter, the engine’s computer will start to restrict the flow of air and fuel to the engine. This stops the driver from exceeding the maximum speed set. If you see a semi built after 2003, chances are it has a speed limiter in it. But just because it’s installed doesn’t mean it’s turned on.
Some semi-truck manufacturers by default will set a max speed on their governors when building their tractor-trailers, but trucking companies have the ability to overwrite these defaults and set their fleet’s max speed or turn the speed limiter off entirely.
Many commercial trucking companies do, in fact, limit the speeds of their vehicles because it not only helps them avoid traffic violations and costly accidents, but it saves on overall fuel costs.
Speed governors also carry a secondary benefit of protecting the tires and other parts of the vehicle that aren’t built to be subjected to the kind of stress that goes along with an 80,000-pound vehicle traveling above the speed limit for prolonged periods of time.
What are ISA Devices?
Intelligent speed adaptors or intelligent speed assistance, much like speed limiters, are designed to curb speeding and cap the driving speeds of a vehicle. But just like the name implies, it does so in an intelligent way.
Where speed governors limit the top speed of a vehicle to a predetermined speed, ISAs use GPS to determine a vehicle’s location and compare that with local speed limit data. It then uses onboard cameras to gauge the speed at which the car is driving to determine if the car is traveling faster than the local speed limit.
From there, the computer takes a specific action depending on the type of ISA device installed.
Types of ISA devices include:
- Open system: This type of ISA device simply alerts the driver when they are speeding. This may include showing the speed limit on the dashboard, verbal warnings that the driver is speeding, vibration warnings, or haptic feedback through the acceleration pedal.
- Half-open: Here, the driver will experience accelerator resistance that will make speeding more difficult (though still possible). It operates much like cruise control or lane assistance technology, applying resistance and making it difficult to exceed the posted speed.
- Mandatory speed compliance: Much like a speed limiter, this type of ISA automatically prevents the driver from driving above the posted speed limit. It cannot be turned off or overridden.
What Are the Differences between Speed Limiters and ISA Technology?
At their core, both speed limiters and ISA devices are meant to keep drivers from traveling at excessive speeds, making roads safer and limiting emissions. That being said, there are a few key differences between the two. Knowing the pros and cons of each technology can help truck drivers and trucking companies determine which safety solution is best for them:
Speed Limiters
Pros:
- Speed limiters tend to be inexpensive to buy and install. And because virtually all semi-trucks on the road have a governor already installed in them, it would take ZERO dollars for the trucking industry to implement a maximum speed limit via speed limiter –whether that’s on the fleet or federal level.
- They prevent drivers from driving at excessive speeds above a predetermined limit, which is not tied to the speeds of the local area.
Cons:
- They can’t adapt to different speed limits, so if a speed limiter is set to 65 mph, someone could drive 65 miles per hour in a 25-mile-per-hour zone.
- They don’t collect and store data to be analyzed after a crash.
Truck Drivers Weigh In
Some truck drivers believe that speed limiters hinder them from keeping up with the flow of traffic, especially when traffic is moving faster than the posted speed limit. They argue that not being able to keep up with speeding traffic is, itself, what creates a hazard.
However, based on our conversations with truck drivers, this argument is somewhat facile. Trucking companies that use speed limiters typically set their truck’s max speed with variances in traffic flow in mind.
It’s also important to remember that at some point, it becomes unnecessary and extremely dangerous for a trailer to exceed a certain speed, even if doing so would allow them to keep up with speeding traffic.
Intelligent Speed Adaptors
Pros:
- ISAs adapt to speed limits in different areas, assuring that, at the very least, a truck driver is alerted to the fact they are speeding –if not prevented from speeding altogether.
- ISAs can store travel data including speed history that can be analyzed by police, insurance companies, and trucking companies to determine if the driver was speeding at the time of the truck accident. This data can also be used to help trucking companies monitor the driving behavior of their truck drivers, allowing them to address unsafe driving behavior before a truck accident happens.
Cons:
- These devices are more expensive than speed limiters, so trucking companies might be less likely to adopt them. However, the expense is not as much as the cost of a truck accident lawsuit from a crash resulting in a death or serious injury. If their use were mandated at the federal level, rolling this out to the trucking industry would certainly face more bureaucratic hurdles than speed limiters.
- Because most vehicles do not come with ISA devices preinstalled, this technology would likely need to be retrofitted into a semi-truck, which can be complex and expensive.
What Other Benefits Does Speed-Limiting Technology Have?
Whether you’re using a speed limiter or an ISA device, there are many benefits that extend beyond limiting a vehicle’s speed and the likelihood of causing a fatal crash.
Limiting a vehicle's speed also results in using less gas, which keeps fuel costs low and limits exhaust. This, of course, curbs the carbon footprint of a company — something that is top of mind for many Americans.
Driving at a reasonable speed also results in less vehicle wear and tear, so companies using a speed-limiting device may see lower maintenance costs over time.
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How Effective Are ISA Devices and Speed Limiters?
In a study conducted by the United States Department of Transportation, it was determined that trucks using speed limiters were in half as many high-speed collisions as those not using speed limiters. The technology has proven to be effective since the 1990s, which is why it has been adopted by many trucking companies.
If you see a semi built after 2003, chances are it has a speed limiter in it.
But just because it’s installed doesn’t mean it’s turned on.
Though speed limiters are commonly used in the U.S., ISA technology is relatively new and doesn’t have as much stateside data to support its efficacy. However, limited trials have been done with promising results.
In 2022, New York City conducted an ISA trial program where these devices were installed on 50 city-owned buses. The early results were overwhelmingly positive with fleet operators complying with speed limits 99% of the time and instances of hard braking were reduced by 36%.
Europe, however, has more experience testing ISAs. In 2015, ISAs were installed on London buses. Prior to installation, the buses exceeded speed limits 15% to 19% of the time. After ISA installation, that figure fell to 1% to 3%.
Starting this year, the European Union mandates that all new vehicles include ISA technology. The European Transport Safety Council estimated that the move will eventually cut road deaths by 20%.
In both the EU and NYC studies, not every vehicle on the road was equipped with ISA devices. However, the hope is that having a portion of vehicles on the road equipped with ISAs will serve to calm traffic and force other vehicles to maintain the speed limit. This would, in turn, reduce the frequency of speed-related fatalities. In fact, the National Highway Traffic Safety Administration and the Federal Motor Carrier Safety Administration found that limiting the speed of heavy vehicles to 65 mph would save 63 to 214 lives annually.
The Case for Speed-Limiting Technology
With speed-related fatalities on the rise, it’s time that trucking companies and our government take action. Speed-limiting devices are key to reducing traffic fatalities, and much like with seatbelts and airbags, public education and government mandates could pave the way for a safer future.
Though ISA is a more advanced solution, cost and accessibility make it a harder sell for a nationwide speeding solution. Speed limiters, however, can be activated with the flip of a switch. So, while people become more familiar with ISA technology, speed limiters are a great option for large commercial vehicles. The technology is free, and it’s proven to save lives.
Learn more about how The Law Firm for Truck Safety is working to get speed limiters installed in every truck on the road, and what you can do to help.
Learn More about Other Safety Initiatives the Law Firm for Truck Safety Is Working to Address
