2.7 Managing Space

To be a safe driver, you need space all around your vehicle. When things go wrong, space gives you time to think and to take action.

To have space available when something goes wrong, you need to manage space. While this is true for all drivers, it is very important for large vehicles. They take up more space and they require more space for stopping and turning.

2.7.1 Space Ahead

Of all the space around your vehicle, it is the area ahead of the vehicle--the space you're driving into --that is most important.

The Need for Space Ahead.

You need space ahead in case you must suddenly stop. Accord­ing to accident reports, the vehicle that trucks and buses most often run into is the one in front of them. The most frequent cause is following too closely. Remember, if the vehicle ahead of you is smaller than yours, it can probably stop faster than you can. You may crash if you are following too closely.

How Much Space?

How much space should you keep in front of you? One good rule says you need at least one second for each 10 feet of vehicle length at speeds below 40 mph. At greater speeds, you must add 1 second for safety. For example, if you are driving a 40-foot vehicle, you should leave 4 seconds between you and the vehicle ahead. In a 60-foot rig, you'll need 6 seconds. Over 40 mph, you'd need 5 seconds for a 40-foot vehicle and 7 seconds for a 60-foot vehicle. See Figure 2.12.

To know how much space you have, wait until the vehicle ahead passes a shadow on the road, a pavement marking, or some other clear landmark. Then count off the seconds like this: "one thousand-and-one, one thousand and­ two" and so on, until you reach the same spot. Compare your count with the rule of one second for every ten feet of length.

If you are driving a 40-foot truck and only counted up to 2 seconds, you're too close. Drop back a little and count again until you have 4 seconds of following distance (or 5 seconds, if you're going over 40 mph). After a little practice, you will know how far back you should be.

Remember to add 1 second for speeds above 40 mph. Also remember that when the road is slippery, you need much more space to stop.

Heavy Vehicle Formula

For timed interval following distance

  • 1 second required for each 10 feet of vehicle length at speeds under 40 miles per hour
  • Above 40 miles per hour use the same formula, then add 1 second for the additional speed
40 foot truck (under 40 miles per hours) = 4 seconds
40 foot truck
50 foot truck (above 40 miles per hour) = 6 seconds
50 foot truck
60 foot truck (under 40 miles per hour) = 6 seconds
60 foot truck

2.7.2 Space Behind

You can't stop others from following you too closely. But there are things you can do to make it safer.

Stay to the Right.

Heavy vehicles are often tailgated when they can't keep up with the speed of traffic. This often happens when you're going uphill. If a heavy load is slowing you down, stay in the right lane if you can. Going uphill, you should not pass another slow vehicle unless you can get around quickly and safely.

Dealing with Tailgaters Safely

In a large vehicle, it's often hard to see whether a vehicle  is close behind you. You may be tailgated:

  • When you are traveling slowly. Drivers trapped behind slow vehicles often follow closely.
  • In bad weather. Many car drivers follow large vehicles closely during bad weather, especially when it is hard to see the road ahead. If you find yourself being tailgated, here are some things you can do to reduce the chances of a crash.
    • Avoid quick changes. If you have to slow down or turn, signal early, and reduce speed very gradually.
    • Increase your following distance. Opening up room in front of you will help you to avoid having to make sudden speed or direction changes. It also makes it easier for the tail­gater to get around you.
    • Don't speed up. It's safer to be tailgated at a low speed than a high speed.
    • Avoid tricks. Don't turn on your taillights or flash your brake lights. Follow these suggestions above.