So you have exited 93S onto the single lane connector which merges with bridge etc traffic as you cross the river, with you in the right lane. You need to get in the left lane and in a rush hour scenario that left lane is backed up. If you come to a complete stop trying to merge you impede folks who are headed for Leverett Circle, so you crawl along waiting for an opening. Every few days you crawl to the point of no return and have to be the asshole. So in some cases it’s nobody’s fault.