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   Common sense and human behaviour are two concepts that, when seen in concert, should be looked upon with some skepticism.  Take for instance the idea that when there is road construction and one lane is closed you should get over to the other lane ASAP as to not cause traffic congestion.  Seems like common sense, no?

Well it is wrong.

“Leon James, professor of driving psychology at the University of Hawaii, says the notion that “merging early is better” is responsible for the typical congestion caused by lane reductions on highways and roads.

“A lot of drivers think that if they merge into the open lane as early as possible, that they are helping to keep traffic moving. But all it really does is create an empty lane without any cars in it, and a crawling, grid-locked lane opposite,” says James.

“People think it’s courteous and makes them feel good without realizing that they are in fact causing a lot of trouble for everybody on the road.”

Merging hundreds of metres before a construction zone begins can result in a chain reaction of drivers in the open lane having to slam their brakes, thus generating what researchers call a traffic wave.

Traffic waves can impact driving conditions up to 30 kilometres before the actual merging point on busy highways, says James.

Sadly, this is completely my behaviour on the road.  I would rather switch earlier and go slower than deal with trying to get into the correct lane at the last second.

The Minnesota Department of Transportation introduced the zipper merge in 2002 and has been expanding its use throughout the state every year. Additional signage is added for several miles prior to a major construction site that tells drivers to stay in both lanes and when it is time to merge.

Extra warning and clear instructions a farther distance from the construction site is key to the system, says James. “It gives drivers the time they need to prepare mentally for the changes ahead” rather than being thrown into disarray by a sudden need to merge.

According to their website, it has reduced congestion by up to 40 per cent on Minnesota’s busiest freeways and helped to reduce traffic accidents in construction zones.

It seems like sound idea, plus I hate the lane cheaters that gun it in the open lane and then try and get in, that is just annoying.  I wonder if the zipper merge system addresses that problem?

“Previously, we had most of the people in one lane in a big, long line and you would have the odd person racing up to the front and trying to cut in at the last minute. It’s that difference in speeds that has proven to cause traffic jams and be unsafe,” says Gardiner.

The city is working with regional police to ensure that drivers who are not allowing other cars to merge at the proper time are ticketed or at least warned that they are legally required to do so.

No statistical data was collected on the original project, but Gardiner says the city is starting a new project at a different construction site that is expected to last weeks or months, giving the city enough time to measure how well the zipper merge is working.

Fascinating stuff.  As an additional benefit it plays well into how I am used to driving, so it looks zipper merging at least for me, is the way to go.