The Research On The Critical Demand Density Of Mobility Allowance Shuttle Transit(MAST)

In recent years,with the rapid development of public transportation service,citizens have higher requirement on the quality of transit,and the form of public transport also presents the trend of diversification.In this context,the various types of demand responsive transit become more and more attractive and favorite.In this paper,Mobility Allowance Shuttle Transit(MAST)belongs to the category of Para transit,but it is also a typical form of Demand Responsive Transit(DRT).It is an innovative concept that merges the flexibility of Demand Responsive Transit systems with the low cost operability of Fixed-route Transit(FRT)systems and has a high-level "door-to-door" service capability.MAST has good adaptability and wide application prospect in the area of non-central city and other area with relatively low demand.In this paper,we mainly study the critical demand density of MAST.First of all,this paper reviews and evaluates the research status of DRT and MAST.Secondly,this paper introduces the operation principle of MAST system,and analyzes the service characteristics of the MAST system and the travel characteristics of the passengers.And two scheduling models of one-vehicle and multi-vehicle MAST system are described.Then,from the user point of view,passenger travel utility models of FRT system and one-vehicle MAST system are proposed in this paper based on customer walking time,waiting time and riding time.And on those bases,the critical demand density model is developed to switch between FRT system and one-vehicle MAST system.At the same time,from the system point of view,three travel utility models of one-vehicle MAST system,two-vehicle MAST system and three-vehicle MAST system are built based on vehicle running time,customer waiting time and riding time.Then,based on those three utility models,the critical demand density models are developed to switch between one-vehicle MAST system and two-vehicle MAST system and between two-vehicle MAST system and three-vehicle MAST system.Finally,we design two analytical and simulation experiments.Firstly,we carry out a set of simulations to show a sensitivity analysis of the performance of FRT system and one-vehicle MAST system over different shapes of the service area and different modeling parameter 1?.Secondly,we compare the utility function values generated by the two methods for the one-vehicle MAST system,the two-vehicle MAST system and the three-vehicle MAST system.And a sensitivity analysis is conducted to find out the impact of a key modeling parameter 1? on the critical demand density for switching between one-vehicle MAST system and the two-vehicle MAST system and between two-vehicle MAST system and the three-vehicle MAST system.The two sets of experiments have obtained the anticipated results.