May 1, 2017
Driving Reaction Time

Our Perception When Stopping

It might surprise you to know that when you are driving at 60 miles per hour you are moving at roughly 88 feet per second! Perception/Reaction times (PRT) to can be critical in certain auto accident lawsuits. Whether it be a pedestrian, tractor trailer, car or motorcycle; time and distance calculations can tell the story.

There are experts who deal with perception and reaction times. A human response to something auditory, visual, or tactile stimuli can be timed.

While 1.5 seconds is often used as a benchmark in accident cases, there are several factors and components that make up PRT:
1. Perception Time and Mental Processing: here the driver might detect a truck is turning across the roadway directly ahead, and decide to brake.
2. Time of Motor Movement: Once selected, the required muscle movement is not as instant as one might expect. The time spent lifting one’s foot off the accelerator, and moving it across to the brake pedal, then to apply the brakes.
3. Mechanical Movement Time: The brakes apply friction to the rotors, slowing the tires which work to offset momentum, inertia and other physical forces.

Speed: PRT + Braking = Total Stopping Distance
20mph 20’ + 20’ = 40 feet (3 car lengths)
30 mph 29’ + 46’ = 75 feet (6 car lengths)
40 mph 40’ + 80’ = 120 feet (9 car lengths)
50 mph 53’ + 122’ = 175 feet (13 car lengths)
60 mph 60’ + 180’ = 240 feet (18 car lengths)
70 mph 70’ + 245’ = 315 feet (24 car lengths)

Note that a Tractor Trailer may take over 400 feet to stop from 60 mph!

If testing shows that a driver was intoxicated and therefore did not take proper steps to avoid an accident, having an expert to show that the driver acted with appropriate reaction time can negate the inference of negligence due to intoxication. If, however, reaction time seemed delayed or prolonged, it is more likely the driver would be blamed for comparative negligence.

Stay alert on the roads.

Mr. Peel seeks justice for those injured in motorcycle, truck and car accidents, disability and medical malpractice. He often addresses churches, clubs and groups without charge. Mr. Peel may be reached through wherein other articles may be accessed.

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