Changing lanes looks simple. You signal, you move over. But a surprising number of crashes happen during lane changes, almost always because a driver moved into a space that wasn't empty. On a road test, it's also one of the most closely watched maneuvers, because it shows whether you actually look before you act.
This article covers how to set your mirrors to shrink your blind spots, the step-by-step routine examiners want to see, and how to judge whether a gap is big enough.
Start with your mirrors
A safe lane change starts before you even get on the road, with mirrors set up properly. Most people set their side mirrors so they can see a good chunk of their own car. That feels reassuring, but it means the side mirrors mostly show the same view as the rear-view mirror, and leaves large blind spots beside the car.
A widely recommended alternative is to set the side mirrors further out:
- Rear-view mirror: Sitting normally, adjust it to frame the whole rear window.
- Left mirror: Lean your head toward the driver's window, then adjust the mirror until you can just barely see the side of your car.
- Right mirror: Lean your head toward the center of the car, then adjust the right mirror the same way.
When you sit back up, you won't see your own car in the side mirrors at all. Instead, a car passing you should move from the rear-view mirror into the side mirror, then into your peripheral vision, with less of a gap in between. It takes some getting used to, and it doesn't remove blind spots completely, so you still need a shoulder check. But it makes them much smaller.
The lane-change routine
Driving instructors use different names for it, and some teach it with the acronym SMOG: Signal, Mirrors, Over the shoulder, Go. Whatever you call it, the order matters.
1. Check your mirrors and plan
Before signaling, glance in your rear-view and side mirrors to get a picture of what's around you. Is there a gap in the lane you want? Is anyone coming up fast?
2. Signal
Turn on your signal and give other drivers a few seconds' warning before you move. A signal is a request, not a command. It tells others what you'd like to do, but it doesn't give you the right to move over.
3. Check mirrors again
Look again. Traffic changes in a few seconds. Make sure the space you saw is still there, and that nobody in the lane beyond it is about to move into the same space.
4. Shoulder check
Quickly turn your head and look over your shoulder into the blind spot on the side you're moving to. Keep it quick, under a second, so your eyes aren't off the road ahead for long. On a road test, make it clear enough that the examiner can see you do it.
5. Move smoothly
If it's clear, steer gently into the new lane. Don't slow down. Keep your speed steady or match the speed of the new lane. Cross the line in one smooth movement instead of drifting along it, and settle into the center of the lane.
6. Cancel your signal
Once you're in the new lane, make sure your signal turns off. A signal that keeps blinking tells other drivers you're about to move again.
How big a gap do you need?
A good rule is that you shouldn't make the car behind you in the new lane brake. Some practical checks:
- You can see both headlights of the car behind you in the new lane in your rear-view mirror. That usually means there's a car's length or more of space.
- Time, not just distance. Aim for at least a few seconds of space both ahead and behind you once you're in the new lane, the same gap you'd want when following.
- Watch closing speed. A car far behind you but going much faster can close the gap before you finish. If its mirror image is getting bigger quickly, wait.
If you're not sure, the answer is no. Wait for the next gap. There always is one.
Common lane-change mistakes
- Signaling and moving at the same time. The signal needs to come first, so others have time to react.
- Skipping the shoulder check. This is the single most common lane-change error on road tests.
- Slowing down to change lanes. On a highway, this forces the cars behind you to brake. Keep your speed up or match the new lane.
- Changing lanes in an intersection. Many places prohibit it, and it's dangerous everywhere. Wait until you're through.
- Crossing several lanes at once. Move one lane at a time, with a fresh signal and check before each one.
- Drifting across slowly. Spending a long time straddling the line leaves drivers in both lanes unsure what you're doing.
- Cutting in too close. Pulling in right in front of another car after passing it takes away their following distance.
Merging onto a highway
Merging is a lane change with an added challenge: you have to get up to speed first. Use the on-ramp and acceleration lane to match the speed of highway traffic, signal, check your mirrors and blind spot, and find a gap. Avoid stopping at the end of the ramp unless you truly have to, since joining fast traffic from a standstill is much harder and more dangerous. Drivers already on the highway are expected to make room when they safely can, but you're the one responsible for finding a safe gap.
Practicing in The Driver Tester
The Driver Tester's Changing Lanes scenario scores each lane change the moment you settle into the new lane. You earn the full 40 points for completing it only if your signal was on at least half a second before you started moving over. Without a proper signal, it's worth just 10. You get up to 20 more for the gap to other traffic (three seconds or more scores best), up to 20 for being centered in the new lane, and up to 20 for crossing the line promptly, in 1.2 seconds or less. Straddling the line for more than three seconds costs points.
In the 3D cockpit view, the mirrors show live traffic behind you, including cars sitting in your blind spot. Press A or F to look over your left or right shoulder. Use Z and C for the turn signals. Practicing the full routine with those keys, in order, every time, is a good way to make it automatic before you're in a real car.