You see a sign in the road ahead of you warning that your lane is dropping. You wonder, what’s the best way to merge safely when a lane drops? Should you immediately merge into the lane that is continuing? Or should you drive in your lane as far as possible and then switch over? This is known as the early merge vs. zipper merge debate. Studies have shown that the zipper merge, or late merge, is more efficient for traffic. Below you’ll find out what these merging situations are and when to use each.

How-to: Merge Safely When a Lane Drops: Early Merge vs. Zipper Merge

Situations Where You Might See a Lane Drop

Your lane might be dropping for any number of reasons. Construction zones and road narrowing are the most common reasons. But you could need to merge due to a crash or any sort of obstacle in the road. When you come upon these situations, know how to merge safely when a lane drops. If you’re in the lane that is not dropping, then luckily you can simply stay put.

The Early Merge

The early merge happens when drivers see a lane closure sign ahead and immediately slow down and try to move to the continuing lane. Many consider this the “polite” thing to do. In contrast, the drivers who wait until the last minute are “cutting”. Sometimes this can even lead to road rage and accidents. Drivers have been known to try and block cars from attempting to “cut in” because as they see it, they’ve already waited their turn. The early merge is a way to merge safely when a lane drops, but it may not be the most efficient.

Zipper Merge

In contrast to the early merge, the zipper merge is another way to merge safely when a lane drops. In a zipper merge, cars continue in their lane as far as possible and then take turns with the continuing lane when they reach the point of the lane dropping. This taking turns from each lane resembles the teeth of a zipper fitting together. Studies have shown that this form of merging is actually more efficient. Merging early means that there is open space in one lane that’s not being utilized. With the zipper merge, both lanes hold as many cars as possible and there’s no wasted space. However, many drivers see this as “cutting” in line.

The Bottom Line

The bottom line is that either the zipper merge or the early merge is a way to merge safely when a lane drops. However, the zipper merge is most efficient. But of course, this is only when all cars are in agreement. If some drivers attempt to block the dropping lane cars from moving over, traffic will stall. Moreover, the zipper merge is most effective with heavy stop and go traffic. In contrast, if traffic is moving swiftly, an early merge keeps all cars moving quickly and efficiently.

If you’re trying to merge safely when a lane drops, either the early merge or zipper merge should be safe. Slamming on breaks to change lanes is not safe. Studies have shown that the zipper merge is most effective in standing traffic. However, it is not as well known and is considered rude by many drivers. Whether you’re merging because of a bottleneck in the road or a construction site, make sure that you are aware of other traffic on the road when you switch lanes.