Changing the duration of activities in resolving scheduling conflicts Toma ´s Ruiz a, * , Harry Timmermans b,1 a Department of Transport, School of Civil Engineering, Technical University of Valencia, Camino de Vera s/n, 46022 Valencia, Spain b Urban Planning Group, Faculty of Architecture, Building and Planning, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands Received 24 May 2005; received in revised form 21 September 2007; accepted 3 October 2007 Abstract There is a growing interest in the characterization and modelling of activity scheduling and re-scheduling behaviour. In this paper, a specific aspect of that research stream is studied: the resolution of activity scheduling conflicts. Using empir- ical data collected in an Internet survey, the modification of the pre-planned activities’ duration to accommodate a new activity in the schedule was analysed. That schedule adjustment was studied as an end-of-duration process using a para- metric hazard duration modelling approach. The results indicate that the process of lengthening/shortening the earlier pre- planned activity depends on the amount of modification of the pre-planned activity’s duration. But this is not the case of the later pre-planned activity, which is not a function of how much the duration was modified. The characteristics of both the implicated activities and the schedule modification are the most important factors that explain the process of schedule change. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Activity scheduling; Duration analysis; Travel behaviour 1. Introduction Understanding activity participation is a key issue in activity-based travel behaviour research (Bhat and Koppelman, 1999; Arentze and Timmermans, 2000). Recently, the investigation of scheduling and re-sched- uling behaviour has been recognized as playing a key role in future modelling efforts. The success of policies such as tolling, congestion pricing, and travel demand management depends on how people would adjust their daily activity and travel patterns to the enforced changes in their everyday lives (Axhausen and Ga ¨rling, 1992). The dynamic process of how individuals organize their activities and travel is often termed activity scheduling. Therefore, those models that attempted to specify the process of activity scheduling will be potentially more 0965-8564/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.tra.2007.10.007 * Corresponding author. Tel.: +34 96 387 73 76; fax: +34 96 387 73 79. E-mail addresses: truizsa@tra.upv.es (T. Ruiz), h.j.p.timmermans@bwk.tue.nl (H. Timmermans). 1 Tel.: +31 40 2472594; fax: +31 40 2475882. Available online at www.sciencedirect.com Transportation Research Part A 42 (2008) 347–359 www.elsevier.com/locate/tra