You are driving on a divided highway with two lanes on your side going the same direction. You are in the left of those two lanes. You can see that a mile or so ahead, due to highway construction, the left lane ends, requiring drivers in your lane to merge into the right lane. Long before the merge point, like most drivers in the left lane, thinking yourself courteous, you start merging into the soon-to-be-stationery right lane.  

Feeling self-satisfied, you glance over and see a driver from behind you speed down the now open left lane to the front merge point. You feel enraged by the driver’s cheating, taking advantage of your courtesy to get ahead of you. You shake your fist at the cheater, give the guy the finger, or, if you are from Texas, hold your AR-15 out of your window in a threatening manner. Further up the line, a few brave drivers pull over to block the cheater’s progress, and when the now complete outcast finally gets to the merge point, no one will let the guy in. Group morality triumphs.

Sound familiar?

The problem is that the overtaking driver, whatever their motivations, is doing precisely what traffic experts recommend they should do. Study after study have shown the best way to merge is for the left lane drivers not to gradually merge into a stationary right lane, but instead to drive all the way to the front, and then alternate with the right lane letting each other in. Traffic experts call this, “zipper merging”.

Zipper merging results in 40% faster overall traffic flow. It also results in much less stress for drivers in both lanes: the left lane not having to figure out whether they can merge into the right, and the right lane, whether to let the buggers in. Less stress ultimately leads to fewer minor collisions, scrapes, and, in Texas, road-rage discharges from AR-15s.

Despite folk morality’s massive inefficiencies in this case, it seems to be winning out over the greater good. Given that this moral instinct arises from our deep mind, it is unlikely to respond to utilitarian arguments from the puny rational mind. So, the only solution is for the traffic authorities to start educating drivers on the zipper method and put up a plethora of signs ahead of a merger point telling drivers in the left lane not to try to merge into the slowing right lane but to go all the way to the front and then alternate with the right lane entering the resulting single lane. 

Which is exactly what most traffic authorities are starting to do.

So, at your next traffic merger, be sure to read the signs carefully.