Transit service reliability is important to both passengers and transit agencies. Slow and unreliable transit service may increase transit user costs in the short term and reduce transit mode share and ridership in the long term, which in turn may lead to higher levels of congestion, emissions, energy consumption, and car dependency in urban areas. In addition, bus travel time is important to schedulers because excessive variability forces schedulers to add excess slack or layover time to transit schedules. Therefore, transit agencies want to reduce bus travel time and its variability. In practice, there are many factors that affect bus travel time and its variability, such as uncertain passenger demand, traffic conditions, driver behavior, signal delay at traffic lights and bus-stop locations, road geometry, vehicle incidents/accidents, weather, etc. (Turnquist, 1981; Levinson, 1991; Ceder, 2007). Transit agencies generally try to reduce bus travel time and improve service reliability. Transit signal priority (TSP) is one of the strategies that can help buses reduce travel time delay across an intersection. Although some studies evaluated TSP system performance using simulation techniques (Balke et al., 2000; Dion et al., 2004; Shalaby et al., 2003), practical assessment of the TSP system showed that TSP benefits are not consistent across intersections (Albright and Figliozzi, 2012a) or across routes and time periods (Kimpel et al., 2005). Previous studies did not have access to detailed TSP phase data. The novelty of this research arises from the fine granularity of the analyses (intersection level) as well as the integration of new data sources including bus AVL/APC data; SCATS signal phase log data (including TSP phases); and SCATS intersection traffic count data. The integration of these three data sources makes it possible to evaluate TSP system performance at a high level of detail that is novel. The objectives of this study are to (1) develop an algorithm to integrate bus AVL/APC data, SCATS signal phase log data and intersection traffic count data; and (2) evaluate TSP system performance by evaluating TSP phase effectiveness, as well as bus and passenger time savings and delay.