Many motorists complain about traffic congestion, especially during the busy summer road construction season, so here is something you can do about it.

Other drivers might flip you the bird or honk their horn if you use the zipper or late merge. Relax, while it's not the law, the practice is encouraged by law enforcement and the Colorado Department of Transportation.

A "zipper merge" is when drivers in the lane ending at a lane reduction point on the road merge with vehicles in the thru-lane in alternating fashion, like a zipper.

"We all learned in kindergarten not to cut in line, and there are lots of people who think zipper merging is cutting in line,'' said Joe Olson, city of Fort Collins traffic engineer. "Zipper merging is for the greater good, but people still don't see it that way.''

CDOT says zipper merging can reduce delays by up to 40 percent in heavily congested areas.

Zipper merging is encouraged when coming upon construction zones, crashes, on interstate on-ramps and city streets where lanes merge from two to one.

Olson said there are two busy areas of Fort Collins where zipper merging would greatly benefit all drivers, if people actually used it. Because they don't, he said traffic lights must be set longer to allow vehicles to clear the stacked-up lane, which makes other drivers at the intersection wait longer.

He said southbound Lemay Avenue and Horsetooth Road is one area. There are two left turn lanes on Lemay at the intersection. Most often, drivers stack up on the inside left turn lane so they can take a quick right on Lemay Avenue where it jogs around Warren Park. Far fewer drivers are in the far left turn lane.

If more drivers filled the far left lane to equal out the two lanes and then were allowed to zipper merge to continue south on Lemay Avenue, Olson said the turn light could be shortened, allowing for better traffic flow.

Another area where zipper merging is encouraged is on eastbound Prospect Road at Timberline Road. Eastbound Prospect narrows from two to one lanes several blocks east of Timberline. The stretch is especially busy during the school year and during the evening rush hour.

Olson said CDOT has used signage to encourage zipper merging with limited effectiveness.

So next time you encounter a zipper merge situation, know you aren't being a jerk, just a motorist who wants to make the best of a bad traffic situation.

How to zipper merge

Vehicles should fill both lanes as long as possible.

At the merge point, those in the thru-lane have the right of way and aren't required by law to let you merge.

Use your blinkers to indicate you wish to merge and make eye contact with the driver of the thru-lane vehicle to make sure they are willing to let you merge.

If allowed to merge, do so smoothly and at the pace of traffic.

A courtesy thank-you wave never hurts.

Benefits of the zipper merge

Reduces lane speed differences.

Improves traffic flow, even in heavily congested areas.

Reduces congestion on highway exchanges.

Reduces crashes in construction zones.

Sources: Various highway safety organizations

Miles Blumhardt looks for stories that impact your life — be it news, outdoors, sports, you name it he wants to report it. Have a story idea, send it his way. Email him at milesblumhardt@coloradoan.com or find him on Twitter at @MilesBlumhardt. If you find value in these stories, support Miles and the other journalists at the Coloradoan by subscribing atColoradoan.com/subscribe