Driving Safety DataSection 5-8

Driving Safety Data

The dashboard of your car gives you a lot of information about your car’s ability to go

It gives no information about your car’s ability to stop

How long do you think it takes just to switch from the gas pedal to the break pedal?

Driving Safety Data

The average, alert driver takes approximately ¾ of a second to 1 ½ seconds to switch from the gas pedal to the break pedal.

This time is called the reaction time.

How far does a car traveling 55 mph travel during this reaction time?

Driving Safety Data

How many feet are there in a mile? 5,280 ft = 1 mile

How many feet does a car traveling 55 mph travel in 1 hour? (5,280 ft) x (55 mph) =

How many feet does a car traveling 55 mph travel in 1 minute? (290,400 ft) ÷ (60 min.) =

290,400 ft

4,840 ft

Driving Safety Data

How many feet does a car traveling 55 mph travel in 1 second? (4,840 ft) ÷ (60 seconds) =

If your reaction time is 1 second, then in the time it takes you to realize you have to break your car will travel approximately 81 ft

80.67 ft

Driving Safety Data

Finding the distance traveled during reaction time

1. Find the distance traveled in feet in one hour1. Multiply mph by 5,280

2. Find the distance traveled in feet in 1 second1. Divide step 1 by 3,600

3. Multiply step 2 by the reaction time

Driving Safety Data

A car is traveling at a speed of 65 mph. The driver of the car has a reaction time of 1.5 seconds. How far will the car travel during the driver’s reaction time?

1) Find the distance traveled in feet in 1 hour:

→ (65 mph) x (5,280 ft) =343,200 ft

Driving Safety Data

A car is traveling at a speed of 65 mph. The driver of the car has a reaction time of 1.5 seconds. How far will the car travel during the driver’s reaction time?

2) Find the distance traveled in feet in 1 second:

→ (343,200) ÷ (3,600 ) =95.33 ft

Driving Safety Data

A car is traveling at a speed of 65 mph. The driver of the car has a reaction time of 1.5 seconds. How far will the car travel during the driver’s reaction time?

3) Find the distance traveled during the reaction time:

→ (95.33) x (1.5 ) =143 ft

Driving Safety Data

A car is driving on a rural road at a speed of 40 mph. The driver has a reaction time of 0.75 seconds. Find the reaction distance.

1) (40 mph) x (5,280) =

2) (211,200 ft) ÷ (3,600) =

3) (58.66) x (0.75) =

211,200 ft

58.66 ft

44 ft

Driving Safety Data

Page 272, Numbers: 1-3, 7 & 8

Driving Safety DataSection 5-7

Driving Safety Data

Previously, we covered two main topics:

1) Reaction time1) The time it takes you to realize you need to brake

2) Reaction distance1) The distance traveled during your reaction time

Driving Safety Data

What major factor do neither the reaction time or reaction distance account for?

Note, both of those statistics just cover how long and how far the car travels before you realize you have to brake

They do not take into account how long it takes your car to break

Driving Safety Data

The distance a car travels while braking to a complete stop is called the braking distance

What is the difference between braking distance and reaction distance?

Driving Safety Data

Why can braking distance vary depending on time of year, location, etc.?

The general formula we will use for braking distance is:

where “s” represents the speed of the car

20s B.D.

2

Driving Safety Data

Find the braking distance of a car traveling 48 mph.

It will take this car approximately 115.2 ft to come to a complete stop.

20s B.D.

2

48 s

20(48) B.D.

2

20

2,304 115.2

Driving Safety Data

Find the braking distance of a car traveling 65 mph.

It will take this car approximately 211.25 ft to come to a complete stop.

20s B.D.

2

65 s

20(65) B.D.

2

20

4,225 211.25

Driving Safety DataSection 5-7

Driving Safety Data

So far, we have covered two major concepts:

1) Reaction Time/Distance1) The time or distance you travel before you realize you

need to brake2) Average between 0.75 and 1.5 seconds

2) Braking Distance1) The distance your car travels from the time you start

braking and when your car comes to a complete stop

Driving Safety Data

Today, we will cover the final piece to these concepts

Total Stopping Distance The distance a car travels from the moment a driver

realizes the need to stop to the time that the car comes to a complete stop

Driving Safety Data

Total Stopping Distance The formula for this is just the sum of the reaction

distance and braking distance

= s

Where s is equal to the speed of the car

20s

2

Driving Safety Data

You are driving 65 mph on the highway. What is your total stopping distance?

20s

2

65 + 2065

2

= 65 + 211.25 = 276.25

You have a total stopping distance of 276.25 ft

Stopping Distance = s

Driving Safety Data

You are driving at 55 mph on a highway. You see an accident directly ahead of you about 200 feet away. Will you be able to stop in time?

Stopping Distance = s +

=

20s

2

55 + 2055

2

= 55 + 151.25 = 206.25

You will not be able to stop in time

Driving Safety Data