The goal of the project is to develop a methodology for modelling, evaluating and simulating urban freight transport. To do so, an approach for increasing the sensitivity of a practicable, small-scale commercial transport model will be developed and tested. Selected traffic planning measures with their cause-and-effect connections are modelled as system dynamic models (System Dynamics, SD). The focus is on low-emission zones. Therefore, the fleet composition in commercial traffic and its change as a result of access regulations is analysed and modelled on the basis of registration data from the central vehicle register regarding pollutant emissions. The system dynamic model is linked to a macroscopic transport demand model in order to be able to depict the driving performance and resulting emissions of commercial transport.