Originally conceived as a systems dynamic model to strategically assess European transport policy, ASTRA (Assessment of Transport Strategies) has been developing since 1997. The European version now covers 29 countries and 25 economic sectors. Renewable energies have been included since 2005. The version for Germany was developed in 2012. Currently, ASTRA Germany is being used for the research projects ImpRES and Climate Protection Scenarios 2050 as well as for two dissertations.
The ASTRA model is made up of different components: a population module, transport modules and macroeconomic modules and an illustration of the interdependencies. ASTRA is used for the analysis of scenarios running from 1995 to 2030 (conditionally until 2050) with a calibration period from 1995 to 2007 with annual time steps. In the ASTRA model, the population and transport modules are divided into 39 administrative districts. Where necessary, the regional distribution of the macroeconomic modules has been done top-down, otherwise aggregated values are used. A regional economic module of the model is being developed within the scope of ImpRES. In ASTRA Germany, 57 economic sectors are illustrated.
In the ASTRA model, a number of existing models are linked to an overall model and implemented with “System Dynamics”, a method used for the holistic analysis and simulation of complex and dynamic systems. This approach makes it possible to model a future development based on codes of conduct and conditions in the past. “System Dynamics” is particularly suited to modelling feedback effects with high temporal resolution. As a result, not only direct effects (impulses) on different actors (households, economic sectors, government) can be integrated into the model and illustrated, but second-round effects and macroeconomic net effects (model output such as net employment, disposable income, gross value added per economic sector) are also revealed.
Figure 3 shows the considered structural characteristics (income groups, economic sectors, regions where possible), the integrated impulses, the modelling mechanisms and the model output and/or the estimated net effects by area of investigation. It is obvious that the impulses (inputs) are differentiated by income group, economic sector and region, that the mechanisms include both negative and positive effects and that the net effects (output) can be depicted for economic sectors and income groups by regions.