A model to predict bus commercial speed

摘要

Commercial speed is defined as the average journey speed of public transport services between two points, including any delay at stops. Based on previous studies, a model is proposed that relates the bus commercial speed to the frequency and duration of stops. The form of the proposed model is a negative exponential function. The model was calibrated with data collected at bus routes in Santiago de Chile by means of instrumented vehicles. The model shows a good fit and sensitivity to various characteristics: vehicle technology, peak and off-peak periods, and direction of travel (to and from the city centre). It is postulated that the model is a better explanation of the observed bus speeds than the speeds derived from the Strategic Urban Transport Model of Santiago (ESTRAUS), which tries to relate bus speeds to car speeds. The commercial speed is one of the main factors in evaluating the level of service of the public transport. A better estimation of the public transport speed will allow the planners an improved assessment of bus priorities and vehicle technology, which is the final aim of this paper.