There is a sequential interaction of the modules. The sequential approach reduces the number of computation loops.
The chronological sequence a model run is as follows:
- The sequence starts with the Demography (DEM) module to produce demographic outputs for all forecast years (2015 to 2050).
- The Economic & Resources (ECR) module is run using the DEM results for a time step (t) and outputs from Vehicle Stock (VES) Passenger Demand (PAD) and Freight Demand (FRD) modules for the previous time step (t-1).
- Vehicle Stock (VES) module is activated using outputs from DEM/ECR (step t), and PAD/FRD (step t-1).
- PAD and FRD are run, using results from DEM/ECR/VES, and ECR/VES, respectively.
- Results from PAD, FRD and VES are delivered for all years to the Environment (ENV) module to compute the environmental impacts, and from PAD and FRD to Safety (SAF) to compute the safety impacts.
The base year is 2010. Thus, the first time step, 2015, is partly driven by 2010 results, and 2020 by 2015 results.