You’re probably familiar with the laws that require drivers to give semi trucks extra space on the road. These laws exist for the safety of everyone involved. While ordinary cars can brake in a couple hundred feet, big rigs can take over twice that distance to come to a stop, especially if they’re fully loaded.
The reason for this lies in the laws of physics. A passenger car is smaller and weighs significantly less than a semi. Big trucks are huge compared to most cars, and to top it off, they’re often loaded with several tons of cargo. At a given speed, it takes an object with a larger mass much longer to stop moving than a smaller object. If a driver tried to brake the truck quickly, he would risk flipping the vehicle.
Semi brakes are also differently designed than ordinary car brakes. While cars operate with a hydraulic brake system (which responds instantly to driver signals), big trucks use air brakes. Air brakes have a slight delay in between the driver’s signal and the actual brake application, because the air must flow out and reach all parts of the truck before the brakes are applied. This further adds to the time it takes to bring a semi to a halt.
Because of this, big trucks can’t just stop on a dime in the same way that cars can. Drivers must anticipate their stops several hundred feet in advance and brake carefully to make sure that they’re able to stop in time. Drivers are often forced to plow through yellow lights or rush past slower traffic, because they simply cannot slow the vehicles quickly enough.
All of this means that you should give trucks lots of space on the road. If you’re trying to pull out into traffic, don’t pull out in front of a truck. Don’t cut in front of a semi-truck on the highway, especially if there’s a red light or stop sign coming up. While you might be able to stop your car in time, chances are that the truck won’t be the same. The driver is doing everything he can to operate his truck safely, but there are some things that are just beyond his control, and physics is one of them. Help keep the roads safe, and give trucks the space and time they need to come to a complete stop.