Service Regularity Loss in High-Frequency Feeder Bus Lines: Causes and Self-Driven Remedies

An agent-based model of a single bus line is de- signed to assess quality of service in terms of regularity and occupancy. Agents represent buses moving on a linear network of stops, where passengers (summarized by counts) get on and off. Three performance-loss factors are considered: distances between stops, drivers' behavior, and influx of users along the line. We show that service regularity is less impacted by sec- tion lengths and bus speeds than by demand. Two solutions are tried: increasing the number of buses through a higher de- parture frequency, and improving the exchange of passengers with all-door boarding instead of the usual one-door scheme. These solutions are self-driven since no central supervision is required. We defined a measure of regularity based on the distribution of "headways" (time intervals) betwen buses. Ac- cording to our model, higher frequencies do not improve reg- ularity, whereas all-door boarding does for large numbers of incoming passengers. We describe a case study based on real data collected from a "feeder" service of the Parisian regional train network. It is highly unbalanced, as it serves opposite commuting directions during the morning and evening peaks, making it an especially interesting example.