A constraint model for scheduling train trips on a network of tracks used in both directions, using a headway abstraction is described. We argue that a generalisation of a straightforward job-shop scheduling formulation using sequence dependent task extensions can decrease the required resolution of network representation and hence problem size. A geometric interpretation of the model of the constraints that can be used to visualise schedules is presented. Preliminary ideas on search heuristics are presented with performance results and a set of examples