- A Mobility Allowance Shuttle Transit (MAST) system is an innovative concept that merges the flexibility of Demand Responsive Transit (DRT) systems with the low cost operability of fixed-route bus systems. It allows vehicles to deviate from the fixed path so that customers within the service area may be picked up or dropped off at their desired locations. In this paper, we summarize the insertion heuristic presented by Quadrifoglio et al. (2007) for routing and scheduling MAST services, and we carry out a set of simulations to show a sensitivity analysis of the performance of the algorithm and the capacity of the system over different shapes of the service area. The results show that a slim service area performs better in general, but also that the positive effects of a proper setting of the control parameters of the heuristic is much more evident for wider service areas. In addition, a performance comparison shows that MAST systems can provide a better service to customers than fixed-route ones even for a slim service area. 2008 Springer-Verlag Berlin Heidelberg.