Modelling and simulating the assembly line supply by tugger trains

Tugger trains are an efficient and flexible material supply concept especially for mixed-model assembly lines. However, the performance and efficiency of a tugger train system are influenced by many external factors (e.g. material throughput) and internal interdependencies (e.g. cycle times, overtaking or stopping) making a discrete-event simulation necessary to prove the feasibility of the planned systems. We present the results of a simulation study carried out on behalf of the BMW Group. For this, we used a generic simulation model which was adapted to the unique requirements and elements of the planned system. We determined the security of supply and level of service and validated tugger train routes and schedules. The congestion on roads and intersections, space for overtaking and the number of trains passing and supplying a point of need were found to be the main influencing factors.