At 45 mph, how long will it take to notice a hazard and come to a complete stop?

When driving at 45 mph, a driver typically needs to account for perception time, reaction time, and braking distance to come to a complete stop.

At this speed, perception time, which is the time it takes for a driver to notice a hazard and begin to react, is usually around 1.5 seconds. During this time, the vehicle will continue to travel forward. The distance covered during perception time while driving at 45 mph is approximately 99 feet (1.5 seconds at 45 mph is about 66 feet).

After perceiving the hazard, the driver enters the reaction phase, which also includes the time taken to physically press the brake pedal. This reaction time is often estimated at around 0.75 seconds, which adds about 50 feet to the distance traveled before the brakes are fully engaged.

Once the brakes are applied, the car will continue to travel a certain distance before coming to a stop, which varies based on road conditions, the vehicle's braking efficiency, and other factors. Stopping distance at 45 mph can be roughly estimated to be around 100-150 feet.

Adding all these components together—perception distance, reaction distance, and braking distance—brings the total stopping distance to