How does reaction time impact the ability to stop a vehicle?
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What can a one-second advantage mean to your fleet drivers?
Everybody wants the gift of more time, but how valuable could just one measly, crummy second be to you? When it comes to using your vehicle's brakes on the highway, it could mean – well, a whole lot more than you might imagine.
Your reaction time plus stopping distance equals where your vehicle finally comes to a rest. Studies have shown that it takes the average driver from one-half to three-quarters of a second to perceive a need to hit the brakes, and another three-quarters of a second to move your foot from the gas to the brake pedal.
Everybody’s reaction times are different, but that’s up to a full one-and-a-half seconds between when you first start to realize you’re in trouble and before you even start to slow down. And what happens after you stop your vehicle is why this matters, often the difference between a crash and a safe stop.
This is fundamental – there’s no changing human physiology. But let’s look how that affects your ability to stop your car.
The table below shows the distances it takes an average car to come to a stop on dry pavement from different speeds, including the distance traveled for just one second of perception and reaction time:
Speed | Perception/Reaction Distance | Braking Distance | Overal Stopping Distance | Equal to Approx Number of Car Lengths (@15 feet) |
30 mph | 44 feet | 45 feet | 89 feet | 6 |
40 mph | 59 feet | 80 feet | 139 feet | 9 |
50 mph | 73 feet | 125 feet | 198 feet | 14 |
60 mph | 88 feet | 180 feet | 268 feet | 18 |
70 mph | 103 feet | 245 feet | 348 feet | 23 |
80mph | 117 feet | 320 feet | 439 feet | 29 |
Notice that when you double your speed – say, from 30 mph to 60, or 40 to 80 – your total stopping distance more than doubles: it triples!
When it comes to braking, always follow these three key defensive driving principles:
A classic study conducted in the 1980s found that 90% of all accidents could have been avoided if the driver had reacted just one second earlier. Using these tips for safe braking might just give you the one-second advantage you need.
Another added benefit of better brake use and understanding stopping distance? Improved fuel economy! By knowing when to push the pedal, when to coast and when to use your brakes you will increase your vehicle's fuel efficiency!
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