A simulation model of the flow of Intermodal Terminal Units (ITUs) among inland intermodal terminals is presented. The intermodal terminals are inter-connected by rail corridors. Each terminal serves a user catchment area via a road network. The terminal is modelled as a set of platforms, which are served by a number of gantry cranes and front lifters. Given the schedule of train connections among the terminals, an agent-based system, the Intermodal Transport Planner (ITP) books ITUs on trains and assigns trucks to deliver them to the source terminal and to pick them up in the destination terminal. The terminal and rail corridor simulation software has been implemented as a discrete-event simulation model, using MODSIM III as development tool. The ITP has been implemented on the basis of the TELETRUCK system. This research has been developed within the PLATFORM project, funded by the Directorate General VII of the European Community.