摘要:AbstractThis paper provides a mathematical model and a contribution to the discussion of the problem of queues and waiting times at loading/unloading ramps as a part of transportation networks. As a central point, the paper investigates how the waiting time can be reduced by adding additional empty trailers to the logistics system, and under the assumption that the trailers can be exchanged by the drivers. The proposed model can be used for further investigations and estimates in the cost benefit analysis, on the reduction of CO2emission and other related issues.