456 CHAPTER 11 . NETWORK MODELS Case Study Southwestern University Traffic Problems Southwestern University (SWU), located in the small town of 35,000 per hour, and the number of cars that may pass through Stephenville, Texas, is experiencing increased interest in its nodes 5, 6, and 7 is even greater. Therefore, Dr. Lee has sug. football program now that a big-name coach has been hired. gested that the current capacity is 33,000 cars per hour. He has The increase in season ticket sales for the upcoming season also suggested that a recommendation be made to the city man- means additional revenues, but it also means increased com- ager for expansion of one of the routes from the stadium to the plaints due to the traffic problems associated with the football highway to permit an additional 2,000 cars per hour. He recom- games. When a new stadium is built, this will only get worse. mends expanding whichever route is cheapest. If the city Marty Starr, SWU's president, has asked the University Plan chooses not to expand the roads, it is felt that the traffic prob- ning Committee to look into this problem. lem would be a nuisance but would be manageable. Based on traffic projections, Dr. Starr would like to have Based on past experience, it is believed that as long as the sufficient capacity so that 35,000 cars per hour could travel street capacity is within 2.500 cars per hour of the number that from the stadium to the interstate highway. To alleviate the an- leave the stadium, the problem is not too severe. However, the ticipated traffic problems, some of the current streets leading severity of the problem grows dramatically for each additional from the university to the interstate highway are being consid- 1,000 cars that are added to the streets. ered for widening to increase the capacity. The current street ca- pacities with the number of cars (in 1.000s) per hour are shown Discussion Questions in Figure 11.34. Since the major problem will be after the game, 1. If there is no expansion, what is the maximum number of only the flows away from the stadium are indicated. These flows include some streets closest to the stadium being trans- cars that may actually travel from the stadium to the inter- state per hour? Why is this number not equal to 33,000, as formed into one-way streets for a short period after each game with police officers directing traffic. Dr. Lee suggested? Alexander Lee, a member of the University Planning Com- 2. If the cost for expanding a street were the same for each mittee, has said that a quick check of the road capacities in the street, which street(s) would you recommend expanding to increase the capacity to 33,000? Which streets would diagram in Figure 11.34 indicates that the total number of cars per hour that may leave the stadium (node 1) is 33,000. The you recommend expanding to get the total capacity of the number of cars that may pass through nodes 2, 3, and 4 is system to 35,000 per hour! FIGURE 11.34 Roads from Stadium to interstate 12 0 16 Stadium Interstate 0