California Driver Handbook - Vehicle Positioning
Merging In/Out Of Traffic
Whenever you enter traffic, signal and be sure you have enough room to safely enter the lane. You have to share space with traffic already on the road, and you must know how much space you need to merge with traffic, cross or enter traffic, and exit out of traffic.
Enter the freeway at or near the speed of traffic. (Remember that the maximum speed allowed is 65 mph on most freeways.) Do not stop before merging into freeway traffic, unless it is absolutely necessary. Freeway traffic has the right-of-way.
Any time you merge with other traffic, you need a gap of at least four seconds, which gives both, you and the other vehicle, only a two-second following distance. When it is safe, go back to following the "three-second rule" (refer to the "Do not be a tailgater" section).
- Do not try to squeeze into a gap that is too small. Leave yourself a big enough space cushion.
- Watch for vehicles around you. Use your mirrors and turn signals. Turn your head to look quickly over your shoulder before changing lanes or merging in traffic. Leave three seconds of space between you and the vehicle ahead of you. Make sure you can stop safely, if necessary.
- If you need to cross several freeway lanes, cross them one at a time. If you wait until all of the lanes are clear, you may cause traffic delays or a collision.
Whenever you cross or enter city or highway traffic from a full stop, you will need a large enough gap (from vehicles approaching in either direction) to get up to the speed of other vehicles. You need a gap that is about:
- Half a block on city streets.
- A full block on the highway.
If you are crossing lanes or turning, make sure there are no vehicles or people blocking the path ahead or to the sides of your vehicle. You do not want to be caught in an intersection with traffic coming at you.
Even if you have the green light, do not start across the intersection, if there are vehicles blocking your way.
When turning left, do not start the turn just because an approaching vehicle has its right turn signal on. The driver may plan to turn just beyond you, or the signal may have been left on from an earlier turn. This is particularly true of motorcycles. Their signal lights often do not turn off automatically. Wait until the other driver actually starts to turn before you continue.
When you plan to exit the freeway, give yourself plenty of time. You should know the name or number of the freeway exit you want as well as the one that comes before it. To exit safely:
- Signal, look over your shoulder, and change lanes one at a time, until you are in the proper lane to exit the freeway.
- Signal your intention to exit for approximately five seconds before reaching the exit.
- Be sure you are at the proper speed for leaving the traffic lanenot too fast (so you remain in control) and not too slow (so the flow of traffic can still move freely).
Always signal before passing. Do not pull out to pass unless you know you have enough space to pull back into your lane.
Avoid passing other vehicles, including motorcycles and bicycles, on two-lane roads; it is dangerous. Every time you pass, you increase your chances of having a collision. However, when you pass a bicyclist, be patient. Slow down and pass him/her only when it is safe. Do not squeeze the bicyclist off the road.
At highway speeds of 50–55 mph, you need a 10–12 second gap in oncoming traffic to pass safely. At 55 mph, you will travel over 800 feet in 10–12 seconds; so will an oncoming vehicle. That means you need over 1,600 feet (or about one-third of a mile) to pass safely. It is harder to see and judge the speed of oncoming vehicles that are traveling one-third of a mile or more away from you.
You must judge whether or not you have enough room to pass whenever you approach:
- An oncoming vehicle.
- A hill or a curve.
- An intersection.
- A road obstruction.
Do not pass:
- If you are approaching a hill or curve and you cannot see if there is another vehicle approaching.
- Within 100 feet of an intersection.
Vehicles appear to move slower than they really are moving. A vehicle that is far enough away generally appears to be standing still. In fact, if you can see it moving closer to you, it is probably too close for you to start to pass.
Before you return to your driving lane, be sure you are not dangerously close to the vehicle you have just passed. One way to do this is to look for the vehicle in your inside rear view mirror. When you can see both headlights in your rear view mirror, you have enough room to return to your driving lane. Do not count on having enough time to pass several vehicles at once or that other drivers will make room for you.