The overall aim of the research is to develop a better understanding of the likely effect on policy appraisal of the increasing use of advanced discrete choice models of mixed multinomial logit (MMNL) and extended generalised extreme value (GEV) form. An investigation will also be carried out into the extent to which heterogeneity of tastes, complex substitution patterns and income effects would, if present and detected by such models, affect the appraisal of transport policy measures (relative to current MNL/NL approaches).<?xml:namespace prefix = o ns = 'urn:schemas-microsoft-com:office:office' />