Effects of the passenger weight on the train running times and related implications on service frequencies

Although rail and metro systems are traditionally assumed to operate without congestion (i.e., transportation system performance is not influenced by travel demand), this study investigates how passenger volume affects train running times. Indeed, the passenger number significantly alters train dynamics, particularly when trains are fully loaded, and boarding passenger number depends on service frequency, creating a fixed-point problem between boarding passengers and train running times. An analysis of Line 1 of the Naples (Italy) metro system demonstrates these variations and highlights criteria for establishing a cycle time that remains stable despite fluctuations in demand.