Hugh Pickens writes writes: "Tracy Loew and Elida S. Perez report that at least 16 US cities, including Austin, Denver, Minneapolis, San Francisco, Seattle and Washington DC, have now installed bicycle-specific traffic signals that pop up alongside the traditional round red, yellow and green signals controlling intersections. The reason for the new signals? Bicyclists can be at risk when entering an intersection on a yellow light that allows enough time for cars to clear the intersection, but not for bikes and even traditional green lights may not allow enough time for a bicyclist starting from a stopped position to make it across. Bicycle signals can also help prevent collisions when a motorist is turning right and a cyclist is going straight, by allowing the cyclist a few seconds head start. "It's a lot quicker and easier to make my way through that intersection now," says Joel Cleland, 39, who rides his bike two miles to and from work each day. "I've never waited more than 20 seconds for the new light to turn green." Portland, Oregon, installed one-of-a-kind active warning sign last fall, requiring drivers turning right at a busy intersection to look over their shoulders and yield to cyclists passing through in the bike lane. The sign, triggered by a sensor, flashes only when a bike is approaching. California passed laws setting out rules and regulations for bicycle traffic signals in the early 2000s and last year Oregon lawmakers approved Senate Bill 130, adding bicycle-only signals to the state's list of traffic control devices. "At some point they will appear in our national standards," says traffic engineer Gary Obery, "but that process involves trying things out and seeing what works best.""