When faced with the question of how to fix a dangerous street, the first instinct of many New Yorkers is to call for the most familiar symbols of regulating cars: the stop sign and the traffic light. Nothing, they think, could more effectively force dangerous drivers to stop speeding through their neighborhood than these familiar red symbols. Just this month a community group in Manhattan Beach, Brooklyn asked the city to remove a bike lane and zebra stripes from Oriental Boulevard — measures that have a real traffic-calming effect — and add a new traffic signal where the road intersects with Falmouth Street. But stop signs and traffic signals are usually ineffective, even counterproductive, if the goal is to make streets safer.