Near-Side Bus. Stops Many researchers have found that at intersections with a near-side bus stop and the transit detector upstream of the bus stop, the benefits from TSP decreases significantly (Xxxxx et al. 2002, Ngan 2003, and Xxxxx and Xxxxx 2004). The near-side bus stop makes it very difficult to accurately predict the travel time from the upstream transit vehicle detector to the stop bar. In addition to vehicle speed and the distance from the transit vehicle detector to the stop bar, several other factors affect travel time, such as the number of passengers to load and unload. These factors are typically random and are not known when a TSP treatment decision is made. TSP treatments based on wrong travel-time predictions will not only waste the valuable green time but also decrease the expected transit benefits from TSP. Furthermore, extra delays to transit vehicles may be introduced by TSP treatments in comparison with non-TSP intersections, under certain conditions. In this study, we proved that a near-side bus stop increases transit delays under certain conditions at TSP-enabled intersections, which seems to contradict our intuition. To evaluate the impacts of near-side bus stops on transit delay at intersections, Zheng et al. (2006) developed a theoretical model. The conditions studied in this research included an upstream check-in transit vehicle detector, two TSP treatments of green extension and early green (also called red truncation), and a fixed-time and uncoordinated traffic signal timing plan. Their approach compared bus movements with TSP on and off in time-space diagrams. Four scenarios were possible when a transit vehicle arrived at the stop line of a TSP-enabled direction: (1) the transit vehicle received a green extension and benefited from the treatment because it skipped the near-side bus stop; (2) the transit vehicle received a green extension but missed the treatment because of the dwell at the near-side bus stop; (3) the transit vehicle received an early green and skipped the near-side bus stop; (4) the transit vehicle received an early green and made a stop at the near-side bus stop. Transit delays were analyzed for all four scenarios. Xxxxx found that all the scenarios except number two benefited from TSP treatments. However, the expected delay might still be a net increase because the cost for missing a green extension would be high. Most of our theoretical results were backed up with simulation data. With this model, the extra cost from the ...
