Traffic jams on highways are often triggered where two lanes must merge into one. Lanes of cars cannot merge if there are no large gaps between cars. Therefore, drivers who create large gaps between cars will ease this type of traffic jam.

SIMPLE, EH?

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To ease this type of jam: Maintain a large space ahead of your car.

Never "punish" late-merging drivers by closing your gap. It's illegal, and for good reason.

Encourage one, two even three cars to merge ahead of you.

As you approach the final merge point, open your space wider and wider.

If traffic slows to a complete stop, KEEP TWO CAR-LENGTHS OF SPACE OPEN AHEAD OF YOU.

Fed Hwy Admin says: merge at the last minute. Early merging is the cause of jams.

MnDOT: Do The Zipper Merge (vid)

MnDOT on proper merging (vid)

Other suggestions Amazingly enough, it is not necessary that EVERYONE do this. If only a few drivers will maintain extra-large gaps during heavy traffic, then merging traffic is not forbidden, and the situation in the left-hand diagram can be prevented.

The "zipper flow" is counterintuitive. It's created by proper late-merging at the last minute. It's destroyed by early merging. For this reason, the Fed Highway Admin has specific recommendations for proper driver behavior. They (and the various state highway groups) also have found the best road signage for smoothing the flow: "STAY IN LANE UNTIL MERGE POINT." Then at the last minute, another sign: "MERGE HERE, TAKE TURNS." Early merging ruins everything. Any drivers who encourage early merging, but who tailgate to punish late merging, they've fallen for faulty reasoning. The situation is counterintuitive. The ideal behavior is the exact opposite of drivers' early-merge and "cheater-punisher" beliefs: keep everyone in their lanes, no early merging allowed. No empty lanes, so 'cheating' is stopped. Then take turns merging *only* at the last minute. Anything else is a recipe for hot-headed tailgaters and jam-triggers.

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Yes you're right, you cannot eliminate every problem by simply making a big gap in front of your car. When there are too many cars on the road, traffic slows down. But if we use these special driving habits, the smaller jams can be erased, and stop-and-go traffic can be smoothed out. Since many traffic jams are caused by merging lanes, many traffic jams can be improved by the actions of just one driver.

