Commercial Trucks And Required Stopping Distances

Because of how large and heavy semi trucks are, the state and federal governments have strict regulations in place governing the industry. Among those regulations, truckers must follow hours of service rules. These rules limit such things as the number of hours a driver can drive every day, how many miles they can go and when they have to take breaks. Commercial trucks can weigh up to 80,000 pounds. When they are in accidents, the sheer weight and size of these large vehicles can involve strong physical forces, making the accidents potentially deadly. It is also much more difficult to stop large trucks, which means truck drivers have to take additional precautions to make certain they have enough distance to stop in time.

Scientific Data

For smaller vehicles such as passenger cars or small pickup trucks, it takes an average of 316 feet for drivers to come to a stop after they realize they need to do so. By contrast, a large truck will require an average of 525 feet to stop after the driver realizes he or she needs to do so. When a truck is involved in a wreck, there may be questions about whether the driver had enough time to stop or if the driver was following too closely. Accident reconstructionist hired by your semi truck accident lawyer may be used to reconstruct what happened and make the determination. They use various factors to calculate the involved vehicles’ stopping distances.

Distance to React

When a driver recognizes an impending danger, they normally will begin braking. This action will take a passenger vehicle driver around 1.5 seconds to first recognize danger and then to react. Truck drivers also take about 1.5 seconds to recognize dangerous situations and then react by applying the brakes.


The time it will take for a passenger vehicle or a large truck to stop is the vehicle’s weight. Because semi-trucks can weigh up to 80,000 pounds, they are equipped with larger brakes. Despite this, it still takes them a lot longer to come to a stop because of that large amount of weight. By comparison, passenger cars only weigh around 5,000 pounds on average, making it easier for them to stop in a shorter period of time. This means that a passenger car will require about 124 feet of stopping distance when they are traveling at a speed of 40 miles per hour. At the same speed, truck drivers will take about 169 feet of stopping distance after the driver recognizes the upcoming danger.


In order to calculate the stopping distance of a vehicle, knowing how fast the vehicle was going just prior to the collision is necessary. The faster the speed of the car, the longer it takes to come to a stop. For example, at a speed of 65 miles per hour, a passenger car will take an average of 316 feet to come to a complete stop after the driver recognizes a danger. A truck driver will need around 525 feet to stop when they are traveling at a speed of 65 miles per hour.

Height and Perception

The height of a vehicle can also factor into stopping distances. Since semi-truck drivers are perched much higher up than drivers of passenger vehicles, they are able to see much further. This may make it easier for them to spot potential dangers sooner than can passenger car drivers. This may be an advantage because the truck driver may be able to take steps earlier in order to avoid the danger. If trucks and passenger vehicles are traveling too closely behind other vehicles, the drivers are unable to recognize potential dangers coming up in front of them. This means they will have less time to react.

Other Factors

A number of other factors can also affect the stopping distance of commercial trucks, including the weather conditions. Rain, ice or snow on roads can all increase the required braking distance significantly. The condition of the road itself can also play into the stopping distance. Finally, the tread depth of the tires and how the brakes are applied can also affect the truck’s stopping distance. If a driver is distracted or there are other factors affecting his or her ability to perceive the danger, those can also affect how the reconstructionist completes the calculation.

Onboard Computers

A majority of modern commercial vehicles have onboard computers that keep data about the commercial trucks. Data that is stored may include such things as the truck’s speed and the time the brakes were applied before the accident. This information can then be used to help better understand the moments and what happened immediately before the accident. The available data will vary depending on the manufacturer and the specific onboard computer that is installed.

Legal Assistance

If you have been injured in an accident with a commercial truck, you will want to speak with the personal injury attorneys at Cantor Crane. Your attorney may be able to talk about whether or not an onboard computer was used. They may also explain how the braking distance could be determined for the commercial truck. An attorney may then look at the various factors that could have an impact depending on the particular facts and circumstances of the particular incident.

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Attorney Matthew L. Nebeker provides strong and aggressive legal representation for DUI cases in Salt Lake

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