Discrete event simulation of bus terminals

Therese Lindberg, Licentiate Thesis, Linköping May 2019

Public transport is important to society as it provides spatial accessibility and reduces congestion and pollution in comparison to other motorized modes. To assure a high-quality service, all parts of the system need to be well-functioning and properly planned. One important aspect for the system's bus terminals is their capacity. This needs to be high enough to avoid congestion and queues and the delays these may lead to. During planning processes, various suggested designs and solutions for a terminal need to be evaluated. Estimating capacity and how well the suggestions will function is a challenging problem, however. It requires analysis of complex interactions and behaviour of the vehicles. This sort of analyses can preferably be carried out using microsimulation. Furthermore, a discrete event simulation approach can make use of the fact that the path of a vehicle through a terminal can readily be described by a sequence of events (such as arriving, starting to drive to a stop etc.). The overall aim of this thesis is to investigate how discrete event simulation can be used to evaluate bus terminal design and traffic control policies. The main contribution is the development of a method for bus terminal simulation. As a first step, a discrete event simulation model of a combined bus and tram stop is formulated. The model is tested on a real system where the current design is compared to an alternative one. The test shows that a model developed with a discrete event approach can be used to evaluate the situation at a stop and compare design alternatives. In the next step, a general discrete event simulation model of bus terminals is formulated. A modular approach is introduced, where a terminal can be constructed from a set of module building blocks. Another important contribution of the model is its spatial resolution that allows for queues and blockages to occur throughout the terminal. By applying the simulation model in a case study, it is shown that the model can be used to evaluate and compare various scenarios related to the layout, number of passengers and the outside traffic situation. Lastly, the bus terminal simulation model is used in a second case study in order to compare model output with empirical data. This study identified a number of factors that may have had an influence on differences between observations and simulation results and that is of interest to look further into. This includes the actual adherence to terminal rules and the effects of model parameters.

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