As the summer road-construction season hits full swing, so too do traffic tie-ups, and the debate over the etiquette for merging from two lanes into one.
Signs at the construction zone around the intersection of Lasalle Boulevard and Notre Dame Avenue in Sudbury call for drivers to use both lanes right up to the merge point.
But south of the border, in Minnesota, road crews are going further to help people learn the so-called zipper technique for merging in traffic.
Minnesota is trying a special system that uses sensors in the road to trigger signs with instructions on how merge.
"When you have that long queue, and people perceiving other people as cheaters, we've got behaviours that can lead to accidents," said Ken Johnson, a Minnesota state work-zone engineer.
Johnson said research shows traffic moves at least 40 per cent faster when both lanes of the road are used until the necessary merge point.
He said some people don't realize it's legal to drive in both lanes until it's time to merge.
"There are a lot of people who feel they should move over early, because they feel that's the polite thing to do, and when we have backups that is what causes problems," Johnson said.
Sudbury police say people who intentionally block both lanes to prevent cars from using both lanes until a merge point can be ticketed for failing to share the roadway.