What is a zipper merge?
A zipper merge is a traffic technique where drivers use both lanes up to the defined merge point, and then take turns merging into the open lane, like a zipper. It's also called a late merge.
How it works?
Drivers use all available lanes up to the defined merge point. Drivers in the open lane then let drivers in from the ending lane. Back and forth. The best way to merge is for drivers in the ending lane to reach the barricade, wait for one car to proceed, and then zip in. This means the vehicle in the open lane needs to stay alert, reduce speed at the merge point, and allow one car in before continuing.
Why it works?
Using the zipper merge helps move traffic more efficiently through lane reductions, reducing congestion and the length of traffic backup. It also helps balance the speeds between the two lanes with all drivers maintaining speed up to the merge point. By changing this one driving behaviour, we can improve safety and traffic flow through busy construction zones.
