The time it takes you to recognize a problem and act on it is called reaction time. Think about if you are driving and you need to suddenly stop your vehicle. How quickly could you do so? In this activity, you will explore reaction time in traffic situations.

The Workers' Compensation Board of Alberta estimates that a fighter pilot must keep track of about 300 different things when flying a routine mission. A driver on the road during rush hour, on the other hand, has to pay attention to about 3,000 different things! It won't do for drivers to let their attention wander when behind the wheel! 

Even if you are paying close attention and react very quickly, there are many factors that affect your ability to stop your vehicle. Your car might have had bald tires or poor brakes. The road may have been slick with ice. As a result, you might have slid into the car in front of you, even though you had been watching closely. Some drivers have a bad habit of following too closely, and they do not always have enough room to stop if the car in front stops suddenly.
 
 A distraction is anything that takes your attention away from what you are supposed to be doing. You can't stop distractions from occurring outside your car, but you can control the distractions inside your vehicle. One major distraction is using a cell phone. Statistics suggest that cell phone usage can definitely slow reaction times.

Another factor that contributes to a delay in reaction time is fatigue. It has been reported that about 15% of people say they have fallen asleep while driving. If you are very sleepy, you are a serious danger to yourself and others because you can't pay enough attention to the road and the demands of traffic. Sleepy drivers may:

• run off the road
• roll their vehicle into a ditch
• cross the centre line and drive into oncoming traffic, possibly killing other people and themselves
  

Sleep is the only cure for fatigue. Pull over to a safe parking place and take a nap.

 
From your understanding of momentum, you know that stopping a vehicle in a short period of time is more difficult than coming to a gradual stop. If you are distracted and not paying attention to the road in front of you, you might lose precious seconds when you have to put on your brakes to try to avoid a collision. In an upcoming activity, you will look at how alcohol and drugs can impact reaction time. 

 More about Reaction Time

When driving, reaction time is the time it takes between the driver seeing the need to stop and applying the brakes.

 You may find when you take a driver education program that you are asked to do an exercise on a closed course. You are first asked to drive around the course at 60 km/h. Then, when the instructor gives a signal, you hit the brakes. What do you think will happen?

 The vehicle will travel several metres before stopping. The distance that a vehicle travels after the driver applies the brakes is called braking distance. Stopping distance includes the distance travelled during reaction time plus the braking distance. Look at the example below.

What if you have to react to a sudden obstacle in the road that is only 10 metres ahead of you? If your speed is 60 km/h, it would be impossible to stop immediately. Yellow traffic lights are set to last different lengths of time depending on the speed limit of the road. This is to make sure people have enough warning to see the light change, react, and stop their vehicle before the light turns red.

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 If you follow too closely behind others, you are at a higher risk of having a collision. Even if your reaction time is very quick, a vehicle takes a certain time and distance to stop. The faster you are moving, the longer it will take to stop. To be safe, you should keep a following distance of two seconds behind the car in front of you. That means that when the car in front of you passes a road sign, it should be two seconds before you pass the same sign.