Jan Gerrit Tuinenga is senior researcher at Significance BV in Leiden. He has a background in Operations Research / Econometrics. His main area of interest at Significance is in the design, development and implementation of transportation model systems, which are used in analysing and forecasting multi-modal transportation demand. Jan Gerrit is and was involved in the specification, implementation, documentation, application and validation of a range of transport model systems like the Antonin model (Paris region), LMS (for the Dutch Ministry of Infrastructure and the Environment), and ProMiSe (for the Dutch railway company). He has substantial programming experience in Pascal and in more dedicated (transport planning, estimation and other) software.