Most of those lights can be triggered by a push-button (for pedestrians); many have spots painted on the road which indicate an area more sensitive to metal/weight so a bicycle can be detected. Otherwise... I treat the most bicycle-oblivious lights as a flashing red, essentially: stop, proceed with caution, any other traffic has the right of way. In other words, I don't necessarily follow the law to the letter, but I sure don't ignore those lights.