100% of the intersections I see that get backed up are backed up because someone blocks the box. Can we get more enforcement for that? They don't even need a patrol car. Just have an officer stand at the corner of Mercer and Westlake from 4pm to 7pm, and each time the light changes, walk out into the intersection and ticket the guy who's blocking it. You could write $1000 in tickets an hour, every night of the week.
Many intersections have threatening signs to this effect, but they don't do any good. I've never seen or heard of anyone getting ticketed for that.