Simulation Test under Scenario 2. Analogously, simulation tests were conducted for Scenario 2. The 130-second-cycle signal plan was used, with early green and green extension time intervals fixed at 15 seconds for TSP system operations. The average delays and stops for transit along the corridor are illustrated in Table 10-4. However, simulation results showed that the TSP system introduced considerable negative impacts on transit operations under this test scenario. Transit vehicles with priority green time allocation experienced much longer delays than those operating under the regular signal control scheme when traveling along the entire corridor. Such data were observed from multiple simulation iterations, as shown in Table 10-4, indicating that the problem was less likely a result of the randomness of the simulation process. Table 10-4 Simulation Results of Delays and Stops for Transits along the Corridor for Test Scenario 2 from Ten Simulation Iterations Test Period 3 Hours AVD1 ANS2 Simulation Iterations TSP On TSP Off TSP On TSP Off 2 455.8 455.2 3.32 3.00 3 484.9 480.3 3.82 3.32 4 455.8 448.6 3.32 3.00 5 484.8 461.2 3.82 2.82 6 469.8 468.5 4.00 3.32 7 482.5 441.8 3.50 2.77 8 469.4 460.6 3.59 2.59 9 458.7 487.2 3.41 3.64 10 489.3 478.6 3.73 3.45 Average 473.5 465.7 3.70 3.17 Significance Test at the p=0.05 level Y Y 1 Denotes average vehicle delay; 2 denotes average number of stops; By decomposing transit operations at each intersection, further research was conducted. Detailed analysis demonstrated that although the TSP control scheme could reduce transit travel delays at isolated intersections, it could also lengthen transit travel times along a corridor under certain signal control conditions because of interrupted progression of traffic flow. For the entire corridor, signal control plans could be coordinated at each intersection, and disruption to traffic flow progression could be minimized by setting up a proper offset for each signalized intersection. However, the TSP system could potentially disrupt signal control coordination by allocating more green time to transit at upstream intersections, resulting in longer travel delays at downstream intersections. Three consecutive intersections were selected to further clarify this issue. Simulation data including average travel delays and stops for transit were collected from ten simulation runs, as shown in Table 10-5. Further observations of simulation operations were included for verification. At the upstream intersection of SR ...
