Like most people, I have these great ideas (I think so, at least) that never go anywhere. On the off chance that some Google will come across these pages, I'm going to write them up and post them.
My first one--the local HOV (high occupancy vehicle) lanes on Interstate 95 tend to attract criticism from people who are stuck in stop-and-go traffic in the regular lanes and look over to see cars whizzing by in the HOV. They protest--the lanes aren't being fully used, so why not open them to everyone?
Using the principle that feedback is often good, I'd suggest a traffic counter/display sign over each set of lanes. The count would be a running tally of the cars passing the point during the last hour, multiplied by an occupancy factor. For HOV-3, multiply each car times 3; for the regular lanes, multiply times 1. This means the signs would compare the effectiveness of the lanes in carrying people. Thus the signs would show whether or not the HOV lanes are working as they're supposed to.