From average travel time budget to daily travel time distributions: an appraisal of two conjectures by Koebl and Helbing and some consequences Jean-Paul Hubert and Philippe L. Toint Report TR05/05, 2005 Groupe de Recherche sur les Transports Facultés Universitaires Notre-Dame de la Paix Rue de Buxelles 61, 5000 Namur, Belgique An analysis of three travel surveys (in Britain, Belgium and France) is used to investigate conjectures by Koebl and Helbling (2003) relating mode choice and energy expenditure as well as distribution form. The analysis shows the link with energy expenditure to be questionable, but also provides alternative views of travel time analysis. In particular, weekly travel time budgets are shown to present different characteristics than the more commonly used daily ones, reinforcing the argument for inclusion of weekly regularities in travel behaviour analysis and modelling.