A common complaint that Lawrence drivers may have regarding the commercial trucks and big rigs that they share the road with is that not only do these massive vehicles take up a lot of space, but they’re also slow. For safety reasons, semi-truck drivers are strongly encouraged to watch their speeds. However, the demands of meeting strict delivery schedules and the perceived need to travel as many miles per day as possible can often lead drivers to exceed safe highway speeds.
The danger posed by speeding trucks is that the sheer size of these vehicles makes them much more difficult to maneuver and stop on the road. Stopping distance takes into account three factors:
- Perception distance
- Reaction distance
- Breaking distance
When scanning the road, the ideal perception time for drivers is said to be 0.75 seconds. Unfortunately, The Federal Highway Administration reports that normal perception times can actually be up to 1.5 seconds. The national interstate speed limit in the U.S. is 70 mph. Thus, a vehicle going only 5 mph over that speed limit will travel 175 ft. before its driver perceives an object on the road. The typical reaction time for most drivers is, in fact, 0.75 seconds. At 75 mph, the aforementioned vehicle will travel a further 83 ft. before the driver reacts.
It’s in breaking distance where speeding heavy trucks present so more danger than traditional vehicles. The Centers for Disease Control and Prevention reports that at 75 mph, the breaking distance for a heavy truck is 422 ft., as opposed to only 289 ft. for a standard vehicle. Thus, the total stopping distance of a truck traveling at 75 mph would be 690 ft., compared to 547 ft. for smaller vehicles. Put into context, that’s a difference of nearly one-half of a football field.