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  3. Traffic lights are crucial tools for regulating traffic flow. They are not, however, perfect. Drivers exchange the gridlock that

Traffic lights are crucial tools for regulating traffic flow. They are not, however, perfect. Drivers exchange the gridlock that

admin2014-12-31  72
问题     Traffic lights are crucial tools for regulating traffic flow. They are not, however, perfect. Drivers exchange the gridlock that would happen at unmanaged junctions for a pattern of stop-go movement that can still be frustrating, 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 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 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.
What does the passage mainly concern?
选项 A、Traffic lights turn out to be not perfect all the time.
B、Phones with SignalGuru can be a great aid to drivers.
C、Drivers are often struck at unmanaged junctions.
D、Cities in the developed countries need SignalGuru badly.
答案B
解析 主旨题。通读全文可知，这篇文章主要讲述SignalGuru这款手机应用软件的作用，为司机提供很大帮助。故选项B正确。
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