It is a rainy day on Broadway, and you have been waiting in line for three hours to buy tickets to Groundhog Day: The Musical. Just as your turn arrives, you notice that somebody has decided to form a new line to your left even though the only ticket window open is the one you are standing in front of. “The line is way back there,” you tell him. He smiles and says, “I’m just going to merge in front of you.”

Once you recover from the shock caused by his insolence, you explain that that’s not how it works. “We’ve all been waiting here since this morning; you can’t just cut in front us,” you tell him, as dozens of weary Groundhog Day fans behind you join in the rebuke. But a few other late arrivals like the idea of a “late merge,” and the new line begins to grow. Those in the long, original line sense the walls of society crumbling and instinctively form a human barrier to prevent the merge from happening. There is pushing and shoving – and there is rage. What was an orderly, albeit slow-moving queue becomes chaos.

Any ticket-buyer who decided to use a “late merge” in this manner would be widely, and properly, condemned for what amounts to cutting in line. But should this social rule extend to traffic situations?

For those who travel west on Interstate 393 in Concord every day, you may have noticed that the highway is reduced to one lane where work on the Portsmouth Street bridge is under way. You may also have noticed that when drivers see the orange signs saying “Left Lane Ends,” they begin to move to the right ASAP. They do this reflexively, even when a large electronic sign posts messages such as “Use Both Lanes” and “Take Turns.”

Although states such as Minnesota, Washington and Kansas have embraced the “zipper merge” as safer and more efficient than the traditional early merge in certain traffic situations, its use on I-393 is a brand new approach for New Hampshire, according to Bill Boynton of the state Department of Transportation.

The theory behind the zipper merge is simple: When traffic is light, the early merge is still the way to go. But when traffic is heavy, filling up both lanes and taking turns at the point of merger can significantly improve flow. In fact, zipper merge pioneers in Minnesota say the technique can reduce backups by about 40 percent.

But there is a catch. It’s effective only when drivers work together – and that’s going to take some reconditioning.

Traffic tie-ups are frustrating and mergers can be stressful – and that’s a good recipe for road rage. For the zipper merge to work properly, drivers must be willing to use both lanes and then cooperate with each other at the point of merger. When both lanes are filled equally and moving in tandem toward the point where two lanes become one, the perception that people are rudely merging late will disappear.

So if you find yourself westbound in the left lane on I-393 this week, with traffic crawling and an electronic sign urging drivers to “Use Both Lanes,” feel free to stay left until you run out of road. And if you find yourself in the right lane, just realize that while the zipper merge may be obnoxious in a Broadway ticket line, it can be a great way to keep traffic moving on the highway.