How Long Does It Take an 18-Wheeler to Stop?

Semi-trucks are giants of the road that the nation relies on to transport most goods to consumers. While trucks are needed and should be respected, their drivers don’t have to be told twice that it takes a great deal of caution to navigate an 18-wheeler. Weighing as much as 80,000 pounds, trucks are 26 times heavier than the average vehicle on the road. This makes knowing how to safely stop a tractor-trailer an incredibly valuable—and potentially life-saving—skill.

How Much Longer Does a Semi-Truck Take to Stop Compared to a Car?

The average passenger vehicle is approximately 3,000-4,000 pounds with occupants. If a car weighs 4,000 pounds and was traveling at 65 mph, it would take 316 feet to stop. On the other hand, an 80,000-pound 18-wheeler would take 525 feet to stop in the same conditions.

Importantly, the scenarios mentioned above describe ideal conditions. Road conditions often mean that it can require even more distance to completely stop a loaded semi.

Factors That Determine the Stopping Distances of a Semi

The weight and quality of a truck’s brakes aren’t the only factors that influence how long it takes to stop it. There are three things that factor into how long it takes to stop a truck: perception distance, reaction time, and braking distance.

Perception Distance

Perception distance is how far a truck travels as a driver notices a situation that requires them to slow down or stop their vehicle. This step's length can vary based on how alert a driver is, the conditions on the road, and any other factors that can impact a driver’s reactions such as the influence of alcohol or drugs.

Reaction Time

Reaction time is how long it takes the driver to adequately react to a situation. As with perception distance, reaction time also depends on the individual, how alert they are, and external factors such as the influence of substances.

Braking Distance

Braking distance describes how long it takes the truck to physically stop after the driver applies the brakes.

Why Stopping Distance Factors Matter

It’s important to consider all three stopping distance factors because they can significantly impact how long it takes an 18-wheeler to stop. While the example above mentions that it takes about 525 feet to stop a truck, this figure only includes the braking distance of the truck based on its speed and weight. Perception distance and reaction time can add even more stopping distance, meaning that it could take hundreds of feet more to safely stop a truck.

What’s Semi-Truck Brake Lag?

Semi-trucks have a fourth factor that can make them harder to stop: brake lag. Passenger vehicles use hydraulic brake systems while 18-wheelers usually have air brakes. While hydraulic brakes begin to function as soon as the brake pedal is depressed, air brakes have a lag between when they’re activated and when they work.

When a truck driver applies brakes, air needs to build up throughout the system before the brakes activate. While this can only take a second, brake lag can be a significant influence on how long it takes for an 18-wheeler to stop and the severity of a collision.

Hurt Because of a Collision Caused by Unsafe Braking? Call Our Team.

While trucks are harder to stop than normal vehicles, it’s up to drivers to make sure they’re operating within the safe limits of their vehicles. When a driver fails to stop in time and collides with other vehicles, it’s often because they weren’t allowing enough distance to safely stop or were traveling too fast for conditions.

If you’ve suffered because of a preventable truck accident, call Arnold & Itkin today. Our truck accident lawyers have secured billions of dollars in settlements and verdicts on behalf of drivers. We fight for the answers people deserve after serious accidents and demand the compensation they need to rebuild, no matter what.

Your consultation with our truck accident law firm is free when you call (888) 493-1629.