Negotiating Highways and Interchanges

Crashes on highways are the most severe because traffic is moving at a high speed. You are at greatest risk at highway interchanges, when you are changing lanes, and when traffic unexpectedly slows or stops, due to congestion.

Entering Highways

Your first critical decision when entering a highway is to make sure you do not turn onto the exit ramp by mistake and drive head-on into other traffic. The exit ramp will be marked with ONE WAY signs as well as DO NOT ENTER and WRONG WAY signs. Sometimes, but not always, the entrance ramp will have a green sign that says HIGHWAY ENTRANCE. If you see a white line on your right and a yellow line on the left, you are headed in the right direction.

Some highway entrances and exits are very close together with only a short "weaving lane" in between. Traffic entering and exiting the highway must share the weaving lane. A potential threat is posed by two drivers who want to use the same space at the same time. If you are the driver entering the highway, you must yield to the exiting driver. 

Entrance ramps for highways often have acceleration lanes. These lanes run beside main traffic lanes and should be long enough to allow you to accelerate to the speed of traffic before you enter the highway itself. When looking for a gap while driving on a highway entrance ramp, look over your shoulder and in your side mirror.

Exiting Highways

Get in the proper lane for exiting well in advance. Do not slow down until after you have moved into the exit lane. 

If you miss your exit, take the next one. 

• Do not stop or back up on the highway. 
• Do not swerve across several lanes to try to make the exit at the last second. 
• Do not cross over the median to try to turn around. 

These maneuvers are illegal and can be extremely hazardous to your health and safety. 

Exit ramps have a warning sign to let you know the maximum safe speed.

Traveling On Highways

Half of the fatal crashes on highways involve vehicles that have run off of the road as the result of speeding and/or driver fatigue. 65 mph is almost 100 feet per second; it takes less than one second to run off of the road.

When you change lanes to pass a slower-moving vehicle on a highway, only change lanes one lane at a time, use your turn signal every time you change lanes, and turn it on in plenty of time for other drivers to see it.

If you see a vehicle about to enter the highway from an on-ramp, a common courtesy is to change lanes to allow the driver to enter the highway more easily. Even though the entering driver is required to yield the right-of-way to you, such courtesy on your part keeps traffic moving smoothly. But, first, check to make sure it is clear around your vehicle.

Another risk when driving on highways is inattention due to "highway hypnosis." This happens when you stare straight ahead at the roadway for long periods of time and stop actively scanning ahead, behind, and around your vehicle. If you "zone out" in this way, you are very likely to crash into traffic slowing or stopping ahead of you. Of fatal crashes on highways, 20 percent involve rear-end collisions. Driver inattention and following too closely account for most of these crashes.