This (the light stuff) is already state law and has been for aeons; the only difference is that Cambridge is re-stating it in a bylaw and actually enforcing it.

FWIW, I think most communities would be better served by just enforcing traffic law evenhandedly — and for cyclists that would mean stopping wrong-way riders and red-light runners, who get in way more than their fair share of the car/bike accidents.

Lisa W.