**1. Introduction**

Transit-Oriented Development (TOD) has been widely considered as a wise approach to make the public transit more attractive. Transit Signal Priority (TSP) is a promising and key tool in support of TOD strategies. The first research about TSP dates back to the 1970s [1]. TSP has evolved, together with its application tested and implemented through the advances in intelligent transportation technologies. TSP is an operational treatment that facilitates the movement of public transit,

**Figure 1.** *Transit signal priority framework.*

either busses, tramways, or streetcars, through signalized intersections without the interruption of red signal lights when possible (see **Figure 1**). It can be an effective strategy for lowering transit vehicle delays at signalized intersections as well as passengers delays, reducing fuel consumption and vehicle emissions, preventing bus-bunching, and significantly enhancing transit reliability which results in transit with lower passenger waiting time and operating costs (smaller transit fleet size).

The Transit Capacity and Quality of Service Manual [2] described bus preferential treatments at intersections including transit signal priority, queue jumping, curb extension, and boarding islands. Among the stated transit treatments, TSP has the lowest cost and can easily be implemented in dense urban transportation networks, while other treatments require more capital and physical spaces to be considered. In practice, transit agencies are more interested in making use of limited resources in an efficient manner and TSP could satisfy such needs. However, the impact of TSP will prove more effective with the use of extensive evaluation, ongoing performance monitoring, and adjustment after the initial implementation [3]. By 2015 [4], 109 cities around the world, mostly in North America and Europe, have implemented TSP. However, the majority of attempts used simple and easy-to-implement logics in practice. Portland, Los Angeles, Chicago, and New York City in the United States have been the pioneer cities in implementing TSP in order to enhance their transit system. Various technologies have been deployed for TSP including: the Loopcom System in Los Angeles, CA, the Amtech System in Seattle, WA, the TriMet in Portland, OR, and wireless local area network in Minnesota, MN and in New York City, NY [5–7].
