When I worked in the school district, one strategy they taught us for helping kids obey rules was letting the kids know why the rules existed. If kids were empowered with information, it seemed, they were more likely to abide by the rules created from that information.
So with that in mind, I'd like to submit the following proposal to the City of Cambridge:
Please install postings detailing the reasoning behind each intersection at which:
1) Right turns on a red light are not permitted.
2) Left turns are prohibitted.
Below that a small sign that reads: Oncoming traffic does not stop. OR Heavy Pedestrian Traffic.
If the city implements this plan, I promise (cross my heart and hope to die) to obey all such traffic postings. (Not that I didn't already, of course.)