This paper demonstrates the application of Simulink to building a discrete event model that simulates the operation of urban public transport services. An important feature of the model is the explicit tracking of change of passenger demands at a transport station along a given route, including the passengers coming to the station to board (and alighting) a transit vehicle (e.g. a bus or a train), the passengers boarding the vehicle, and the passengers remaining at the station for next services. This feature enables the formulation of average waiting time of passengers at a station, which differs from many of its type found in the literature by accounting for the fact that passengers may miss a number of vehicles (due to high demand) before successfully boarding one. To demonstrate the potential of the model in assisting operational planning for urban public transport services, the paper presents simulation results from a parametric study that uses the model to investigate the correlation between operation parameters (e.g. cycle time) and key performance indicators of a shuttle bus route in Wollongong City (New South Wales, Australia). The discrete event model together with sample input datasets and post-processing codes of simulation results are available at https://github.com/smart-facility/PTSim.