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New Mexico driving lesson · Communicating & Managing Space

Following, merging & crossing space

A 3-minute lesson from the New Mexico course. Read the rules and examples, follow the handbook page references, and check your understanding before you move on.

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Read time
3 minutes
Course unit
Communicating & Managing Space
Checkpoint questions
6
Source pages
26, 27

The more space you keep around you, the more time you have to react. Think of it as a safety cushion. Rear-end crashes are very common and are caused by following too closely to stop when the vehicle ahead suddenly stops.

Three-second rule

A way to check following distance that works at any speed: count the seconds from when the vehicle ahead passes a fixed point until you reach it.

Handbook p. 26 ↗

Using the three-second rule:

  • Watch the rear of the vehicle ahead pass a sign, pole or other fixed point
  • Count "one-thousand-one, one-thousand-two, one-thousand-three"
  • If you pass the mark before you finish, you're too close
  • Drop back and count again until you're no closer than three seconds
Handbook p. 27 ↗

Use four seconds or more:

  • On slippery roads
  • When following motorcycles
  • With a heavy load or pulling a trailer
  • When following emergency vehicles
  • When approaching railroad crossings
  • When stopped on a hill or incline
Handbook p. 27 ↗

Know the rule

To help keep drivers behind at a safe distance, keep a steady speed and signal early when you must slow or turn, such as stopping for passengers, parallel parking or driving slowly.

Handbook p. 27 ↗

Space to the side:

  • Make room for vehicles entering a road with two or more lanes
  • Keep extra space between you and parked cars
  • Give extra space to pedestrians and bicycles, especially children
Handbook p. 27 ↗
4 seconds

Gap needed to merge, change lanes or enter a roadway

Handbook p. 27 ↗

Know the rule

Moving into the middle of a four-second gap leaves both you and the vehicle now behind you a two-second following distance. Don't merge into a gap that's too small, and cross several lanes one at a time.

Handbook p. 27 ↗

Space to cross or enter:

  • You need room to get all the way across, or to turn and then get up to speed
  • Turning left, make sure no vehicles or pedestrians block your path
  • Even on green, don't start across if vehicles block your way
  • At railroad tracks, be sure you can cross without stopping on them
Handbook p. 27 ↗

Know the rule

Don't count on time to pass several vehicles at once. As a general rule, pass only one vehicle at a time.

Handbook p. 27 ↗

Put it into practice

On a wet morning you're following a motorcycle. The rear wheel passes a pole and you reach it at "one-thousand-three." That's fine in dry weather, but here you need four seconds, so drop back.

Check your understanding

Read the question, decide on an answer, then open it to check the explanation. These are Roadwise study questions based on the source handbook.

What is the normal following distance rule for a safe gap behind the vehicle ahead?
  1. Three-second rule
  2. The one-second rule
  3. The five-second rule
  4. The ten-second rule

Answer: Three-second rule

The three-second rule tells you if you're following too closely, and it works at any speed.

Handbook p. 26 ↗
When should you increase to a four-second following distance instead of three?
  1. Only on interstate highways
  2. Slippery roads or behind motorcycles
  3. When driving in a school zone
  4. Only above 65 mph

Answer: Slippery roads or behind motorcycles

Use a four-second following distance on slippery roads, behind motorcycles, with a heavy load, behind emergency vehicles, near railroad crossings, or stopped on a hill.

Handbook p. 27 ↗
About how large a gap do you need to safely merge into traffic?
  1. About one second
  2. About eight seconds
  3. About two seconds
  4. About four seconds

Answer: About four seconds

You need a gap of about four seconds whenever you merge with other traffic.

Handbook p. 27 ↗
How do you know you're following too closely using the three-second rule?
  1. You pass the point before counting to three
  2. You can't see the vehicle's brake lights
  3. Your speed is above 50 mph
  4. The vehicle ahead signals a turn

Answer: You pass the point before counting to three

You are following too closely if you pass the mark before finishing the three-second count.

Handbook p. 27 ↗
Which of these situations calls for a four-second following distance?
  1. Following a car on a dry, level road
  2. Approaching a railroad crossing
  3. Driving in light daytime traffic
  4. Following a passenger car at night

Answer: Approaching a railroad crossing

You may need a four-second following distance when approaching railroad crossings, among other situations.

Handbook p. 27 ↗
If you merge into the middle of a four-second gap, what following distance do you and the car now behind you have?
  1. About one second
  2. About two seconds
  3. About three seconds
  4. About four seconds

Answer: About two seconds

If you move into the middle of a four-second gap, both you and the vehicle behind have a two-second following distance.

Handbook p. 27 ↗
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