Of all of the reasons for traffic snarls, impending lane closures bring out a particularly brutal combination of road rage and etiquette confusion. Most drivers know the pain of approaching two lanes in this situation; the left one is backed up much further because the right one will close in less than a mile thanks to, say, construction.

Which lane should a driver pick in this scenario? Steer to the left as soon as you see a closure notice and you'll almost certainly go slower; stay in the right and you'll catch stink-eye, honks, and even swerving drivers. Everyone is upset that you're about to essentially cut in line—an act that will require a tense, last-minute merge of your own.

Most driving schools and transportation departments in Canada don't instruct drivers on how to handle this situation or whether they must merge within a certain mileage, leaving this kind of merge up to the grace of your fellow, angry commuters.

Last week, however, Saskatchewan Government Insurance (SGI) released an updated version of their Driver's Handbook and they made sure to include a section on zipper merging.

In the case of road congestion, zipper merging can reduce backups by a whopping 40% on average, since both lanes approach the merge with equal stake in maintaining speed.

"A zipper merge is basically the best way to ensure the smooth flow of traffic when you're entering a work zone or any other situation where two lanes become one," stated Tyler McMurchy, SGI's Media Relations Manager. "It allows drivers to use both lanes until the closing lane ends and then alternate in a zipper fashion into the open lane making traffic flow more quickly and efficiently."

Say you're driving along in the center lane on a traffic-filled highway, and the left lane is ending in a few hundred yards, due to construction or the way the road is built. The polite drivers in that left lane put their blinkers on right away, and move over as soon as someone lets them in. The rude drivers zip to the end of their lane-passing you and many other drivers in the center lane. Then they merge in as soon as they can, effectively cutting in front of you and other center-lane drivers in the process.

You might be annoyed enough to respond to one of those rude drivers with an obscene gesture. But guess what? A lot of studies show those rude drivers are helping traffic flow better. It makes sense if you think about it. Those apparently rude drivers are putting more of the roadway to use and thus helping speed things along, in much the same way that water flows faster through a funnel than through a straw.

As Canadians, it’s our natural instinct to line up and be patient. Nobody likes seeing other people race past them. But if all drivers use the zipper merge, all drivers benefit. In other words, if everyone is using both lanes equally, nobody is cheating.

"So if I'm in the lane that's continuing, I let one driver in and then I proceed. If you're in the lane that's ending you proceed right to the merge point, you signal your intention, you shoulder check, you make sure that one driver is letting you in and you proceed into that continuing lane," McMurchy added.

Tips for performing a safe and successful zipper merge (when conditions allow):

• Drive consistently. Don’t rush ahead, only to slam on your brakes later.

• When ready to move over, signal your intent and merge in an alternating fashion.

• If there is no bottleneck and an early merge makes sense, feel free to do so.

• The zipper merge works best in traditional congestion situations like construction zones. If a lane closure is due to a crash or breakdown, reduce your speed and move over as soon as possible to avoid endangering emergency workers and/or tow truck operators.

Other new information added to the SGI Driver's Handbook:

•Tougher impaired driving and cellphone laws that came into effect this year.

•The most effective steering wheel hand positions.

•Changes to rules around tow truck lights and speeds when passing a truck with flashing lights.

•Changes to which family members are allowed to ride with new drivers.

•Right of way in parking lots.

The handbook is updated and reprinted each fall and the updated version is available online or at most SGI licence issuers and driver-exam offices.