An integrated real time transit signal priority control for high frequency transit services

Bus bunching affects transit operations by increasing passenger waiting times and its variability. In order to tackle this phenomenon a wide range of control strategies have been proposed. However, none of them have considered together both station and interstation control. In this study we tackle this problem aiming to determine the optimal vehicle control strategy for the various stops and traffic lights in a single service transit corridor that will minimize the total time users must devote to making a trip taking into account delays for both transit and general traffic users. Based on a high frequency capacity constrained and unscheduled service (no timetable) were real time information about bus position (GPS) and bus load (APC) is available, this study focuses, on strategies for traffic signal priority in the form of green extension, considered together with holding buses at stops and limiting passenger boarding at stops. The decisions regarding transit signal priority are taken based on a rolling horizon scheme where effects over the whole corridor are considered in every single decision. The proposed strategy is evaluated in a simulation environment under different operational conditions. Results shows that the proposed control achieve excess delay reductions for transit users close to a 61.4% compared to no control while general traffic only increases a 1.5%.

The intermittent bus lane signals setting within an area

Intermittent Bus Lane (IBL) used for bus priority is a lane in which the status of a given section changes according to the presence or not of a bus in its spatial domain: when a bus is approaching such a section, the status of that lane is changed to BUS lane, and after the bus moves out of the section, it becomes a normal lane again, open to general traffic. Therefore when bus services are not so frequent, general traffic will not suffer much, and bus priority can still be obtained. This measure can be operating at a single city block, but if all related control parameters along bus lines are considered together, more time gains can be obtained. In this paper, the basic structure and operation of IBL around a single intersection are briefly introduced, then the construction of an objective function and its relationships with the related priority control parameters along one bus line and their simplifications are described. Finally the calculations of the priority control parameters when there are several connected bus lines within an area and some simulation results are discussed.