The building of scenarios is a fundamental stage of any modelling activity aimed at the prediction of mobility demand. There are various factors determining mobility and the prediction of such factors is uncertain, with the possibility of the relative trends being conditioned by intervention policies.
For the building of the scenarios of the European model developed by the OPTIMISM project, the factors were identified characterised by greater importance in terms of impacts on mobility and by greater uncertainty. This activity was carried out by using expert opinions gathered in an online survey. The scenarios were then built on the basis of the combinations of the levels of the two factors evaluated as most important and uncertain, the price of fuel and the orientation of transport policies in favour of co-modality.