[originaltext] Controlling traffic is a complex and high cost problem in man

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. They are developing a system that helps traffic managers, planners, emergency workers and businesses plan and react better. They say the system is important to help emergency workers, or first responders, reach an accident area faster. 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. Scientists say the goal is to help develop an intelligent system of road signals that will communicate with each other and with vehicles on the roads.
Questions 5 to 7 are based on the news report you have just heard.
5. Why does controlling traffic become more difficult and costly?
6. What is the importance of the system according to the news item?
7. What is the goal of the scientists at CATT of the University of Maryland?