What Is The Stopping Distance Of A Semi-Truck?

by Sudarsan

The stopping distance of a semi-truck depends on many factors. The main factor is travel speed; this increases the chance that something will occur to cause the truck to stop quickly. A secondary factor is braking ability – and it affects both the stopping distance and stopping time (see below).

Lastly, weather plays a role: wet roads increase stopping distances, and poor visibility (because of fog or dust) can result in longer stopping distances. The stopping distance of a semi-truck is usually about 80 feet (25 meters) at 55 miles per hour (mph). At this speed, most drivers can stop within the distance of a football field.

The Stopping Time Of A Semi Truck

When the truck travels faster than 18 mph, it can brake in time. The stopping time is about three times the normal stopping distance. So at 55 mph, it will take about 165 feet (50 meters) to stop from that speed using a dead-stop.

In other words, if you were trying to stop a semi-truck in traffic, you would have to slam on your brakes and lock them so that they engaged immediately. It is the only way to stop when someone else does not.

And when it comes to coasting (reducing speed), trucks are very sluggish in doing so. They take about three times longer than cars in gaining speed, that’s why they need much more time getting up to speed. As a result of this slower acceleration, it takes a semi-truck much longer to reach its driving speed.

Longer Stopping Distance Equals Greater Risk

The greater stopping distance of a semi-truck is due to the sheer size and weight of these vehicles, making it harder for them to stop in time. If the brake system fails or there is a problem with the brakes, the truck’s stopping distance is even greater.

As a driver who is sharing the road with these massive vehicles, you must be aware of their additional stopping distance – and always maintain a safe following distance from them. This way, you can have enough time to stop your car if there is a problem with the truck’s brakes – helping mitigate the chance of a collision.

When it comes to tractor trailer stopping distance, you must think about physics: the longer the stopping distance, the longer it takes for one to come to a complete stop.

Three basic factors influence the stopping distance of a truck tractor trailer combination:

1. The speed at which one is traveling (including acceleration or deceleration)

2. The brakes on the truck

3. Weather conditions

The formula for stopping distance is [Speed x Speed] / [Braking ability + Rolling Resistance]. So, when you’re driving a 30-ton semi in a busy highway environment, how can you make sure you bring your rig to a stop in time?

Well, here’s the good news: you would only need to decelerate at about 10 feet per second (fps) to avoid a crash. If you are traveling at 55 mph, that means it will take just over 300 feet to stop safely.


The longer stopping distance of a semi-truck is something that every driver has to account for in their driving. You don’t want to get into an accident situation because you wouldn’t be able to avoid it if the truck doesn’t have enough braking power or time to come to a complete stop.

You may also like