Abstract for: Bringing distributed software development to SD modelling with Vensim

Maintaining one of the most complex System Dynamics model ASTRA with a group of more than 5 economists, we were facing two main problems. First, collaboration was difficult because all developers had to work with different files and changes had to be manually transferred into one model. Second, calibration was time consuming, since the complete model needs various minutes for only one run even on high end computers. We found a solution to these problems in transferring techniques from distributed software development to SD modelling. We split our complex ASTRA model into more than 40 modules, developed standards for these modules to be able to run them inde-pendently and to enable automatic merging of any amount of modules to one model, developed a tool for automatically executing this merge in order to run the complete ASTRA model and we set up a version controlled repository accessible by all developers via internet to manage the simultaneous development work of our modelling team which is spread out over three institutes in two countries. In this paper, we would like to present in detail the individual task as described above and conclude with our experiences after this major transformation of our ASTRA model.