traffic lights are key tools for regulating traffic now.they are not, however, perfect. drivers exchange the traffic jams that would happen at unmanaged crossings for a pattern of stopgo movement that can still be annoying, and which burns more fuel than a smooth passage would.
creating such a smooth passage means adjusting a vehicle's speed so that it always arrives at the lights when they are green.that is theoretically possible, but practically hard.roadside signs wired to traffic lights can help get the message across a couple hundred metres from a crossing, but such signs are expensive, and are not widespread.margaret martonosi and emmanouil koukoumidis at princeton university, and lishiuan peh at the massachusetts institute of technology, however, have an idea that could make the process cheaper a资源难易程度:★★★★★★★★★★★★★★★
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