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　　進入專題：2015年聽力風暴來襲，英語四級每日一聽！

　　Controlling traffic is a complex and high cost problem in many developed countries. It becomes more difficult and costly with the ever-increasing number of cars on the roads. But scientists and students at the Center for Advanced Transportation Technology, or CATT, at the University of Maryland are working to solve this problem. They are using simulation technologies to help government and private business control and react to changing traffic conditions.

　　The online economics magazine Forbes.com says traffic congestion cost Americans $124 billion in 2014. It says that number could rise to $186 billion by 2030.

　　But scientists at the CATT laboratory are trying to reduce those costs. They are developing a system that helps traffic managers, planners, emergency workers and businesses plan and react better. Michael Pack is CATT director. He says the system is important to help emergency workers, or first responders, reach an accident area faster.

　　"For every one minute that a lane on the freeway is blocked, the chances of another accident occurring goes up about 3%. So, if we can get a first responder out to the scene even a minute quicker and get them to clear the accident a minute quicker, that reduces overall delays and congestion significantly."

　　The CATT Lab collects information from many sources, including roadside devices, GPS - or global positioning system - equipment and wireless phones.

　　About 60 students and 30 software developers observe traffic flow and manage the computer servers at all times. They also work to develop software and applications that can help traffic run smoother and safer. Some of them turn the information gathered into so-called "visualizations." These visual representations help emergency workers better understand what is happening.

　　The center shares its findings with firefighters, police, transportation departments and the military. They also share information with universities and transportation companies. The technology company Google uses the data for its traffic-related websites. Michael Pack says the information is then shared with anyone who wants to help traffic run more smoothly.

　　"Our tools not only tell you what's going on at the scene, like there's an accident and it's involving a tractor-trailer truck, they tell you who has been notified to get to the scene, it tells you how long it took them to get to the scene, when they arrived, how long they were there, what did they do on the scene."

　　Mr. Pack says the goal is to help develop an intelligent system of road signals that will communicate with each other and with vehicles on the road.

　　I'm Jonathan Evans.

　　VOA's George Putic reported this story from Washington. Jonathan Evans adapted it for Learning English. Caty Weaver was the editor.

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