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  3. Traffic lights are crucial tools for regulating traffic flow. They are not, however, perfect. At unmanaged junctions, a pattern

Traffic lights are crucial tools for regulating traffic flow. They are not, however, perfect. At unmanaged junctions, a pattern

admin2012-12-13  30
问题     Traffic lights are crucial tools for regulating traffic flow. They are not, however, perfect. At unmanaged junctions, a pattern of stop-go movement can still be frustrating and burn 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 may help, but they have not been widely deployed. Now scientists have an idea that could make the process cheaper and more effective. Instead of a hardwired network of signs, they propose to use mobile-phone apps.
    For a driver to benefit, he must load a special software, dubbed SignalGuru, into his phone and then mount it on a special bracket attached to the inside of his car’s windscreen, with the camera lens pointing forwards. SignalGuru is designed to detect traffic lights and track their status as red, amber or green. It broadcasts this information to other phones in the area that are fitted with the same software, and—if there are enough of them—the phones thus each know the status of most of the lights around town. Using this information, SignalGuru is able to calculate the traffic-light schedule for the region and suggest the speed at which a driver should travel in order to avoid running into red lights.
    Tests in Cambridge, Massachusetts, where five drivers were asked to follow the same route for three hours, and in Singapore, where eight drivers were asked to follow one of two routes for 30 minutes, revealed that SignalGuru was capable of predicting traffic-light activity with an accuracy of 98. 2% and 96. 3% respectively, in the two cities. This was particularly impressive because in Cambridge the lights shifted, roughly half-way through the test, from their off-peak schedule to their afternoon-traffic schedule, while in Singapore lights are adaptive, using detectors embedded (嵌入) under the road to determine how much traffic is around and thus when a signal should change. Fuel consumption fell, too—by about 20%. SignalGuru thus reduces both frustration and fuel use, and makes commuting a slightly less horrible experience.
Roadside signs have not been widely deployed probably because______.
选项 A、they are less effective in bad weather
B、they cost more money to install
C、it is hard to wire them to traffic lights
D、it takes a lot of space to put them up
答案B
解析 推理判断题。定位句明确指出，路旁信号装置没有得到广泛使用，但是没有直接阐述原因，而是在下一句中通过描述科学家的一个办法暗示出来：现在，科学家们想出一个更便宜、更有效的办法。由此推断，路旁信号装置之所以没有得到广泛应用可能是由于费用过高、效果不理想，故B)“安装它们需要花费更多的钱”符合文意。
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