A real-time signal control strategy for mitigating the impact of bus stops at urban signalized intersections

Buses stopping at transit stops reduce the capacity of signalized intersections, which can lead to excessive delays for all users. In order to avoid such phenomena, signal control strategies can be utilized. This article presents a real-time signal control strategy to mitigate the impact of bus stop operations on traffic operations along an undersaturated approach. The objective of the proposed strategy is to ensure that any residual queues due to a bus stopping are fully dissipated as soon as possible by increasing the green time for the bus stop approach as soon as the bus departs. In addition, this strategy ensures that the cross-street approaches do not become oversaturated. Kinematic wave theory is utilized to track the formation and dissipation of queues and determine the green extension (or red truncation) for the subject approach. The benefits achieved from the proposed strategy are illustrated through simulation tests at a single intersection for a variety of bus stop and bus operation characteristics. Average delay and average queue length for the bus stop and cross-street approaches, as well as for the whole intersection, are used to assess the performance of the strategy. The tests performed indicate that the signal control strategy can achieve substantial reductions in delay for the bus stop approaches and the intersection as a whole without adversely affecting the cross street operations, when the demand at those cross streets is low.     

Analyzing the structure of informal transit: The evening commute problem

Through the use of a profit-maximizing continuum approximation model, this paper systematically analyzes the development and structure of informal transit systems as a function of the network, user, and modal characteristics. This study examines the evening commute problem along a linear corridor where passengers originate uniformly from a central business district and have destinations uniformly distributed along the corridor. Informal transit drivers who are profit-maximizing will be compared against the traditional case of coordinated, government service that aims to maximize the total welfare. Policies, such as fare regulation and vehicle licensing schemes, will be presented to help rationalize informal transit service using a government-operated service as the baseline.