Constraints affecting mode choices by morning car commuters Carolyn O’Fallon a, * ,1 , Charles Sullivan b , David A Hensher c a Pinnacle Research, P.O. Box 3058, Wellington, New Zealand b Capital Research, 31 Gloucester Street, Wilton, Wellington, New Zealand c Institute of Transport Studies, The University of Sydney, NSW 2006 Sydney, Australia Received 31 July 2002; revised 4 February 2003; accepted 30 March 2003 Abstract In New Zealand as elsewhere, there is an increasing interest in alleviating congestion on the road transport network to improve economic productivity, reduce pollution, and to use the transport network more effectively. Governments enact various policies to encourage car drivers to change their behaviour, but often find that the full impact is not reached. We propose that car drivers have constraints influencing their mode choice for the morning peak period trip (e.g. needing to transport children, needing a car for work during the day). A stated preference experiment conducted in the three largest New Zealand urban areas not only quantifies the likely impact of a wide range of policy tools (both ‘sticks’ discouraging car use, and ‘carrots’ encouraging alternative modes) for each area, but also identifies many significant constraints. q 2003 Elsevier Ltd. All rights reserved. Keywords: Driver behaviour; Travel behaviour; Stated preference; Constraints; Peak period; Mode choice; Urban; Policy; Demand management 1. Introduction In New Zealand, as elsewhere internationally, there is an increasing interest in alleviating congestion on the road transport network, thereby improving economic pro- ductivity (by reducing the amount of productive employee time spent sitting in traffic), reducing air pollution, particularly carbon monoxide and CO 2 emissions, lessening noise and water run-off impacts, and making more efficient and effective use of the road network. The New Zealand Government has recently announced policy changes to expand public transport services and encourage public transport use, developing a walking and cycling strategy (aiming to increase both activities), allow more tolling of roads and to introduce electronic road user charging (Ministry of Transport, 2002). The Government announced it would investigate further the option of congestion charging based on time and location of travel. To impose tolls or congestion pricing, regional councils in Auckland, Wellington and Christchurch have previously identified where a cordon could be placed around the central city areas in their respective regions. But how well will proposed policy changes meet their objective of alleviating congestion by reducing car use? Changes in transport policy or the conditions of a public transport service may not have their expected impact because policy makers do not understand the constraints affecting an individual’s travel choices. The need for research to understand the impact of policies has been recognised by organisations such as the European Commis- sion (1994), the US General Accounting Office (1996) and researchers (see for example, Rosenbloom, 1998). As part of a larger research programme entitled ‘Identifying Factors to Change People’s Transport Use’, carried out by Pinnacle Research and its collaborators and funded by the Foundation for Research Science and Technology in New Zealand (described at www.pinnacler- esearch.co.nz/main_survey.htm), we have undertaken stated preference (SP) experiments in Auckland, Wellington and Christchurch to explore the potential effect of several different policy measures on the respondent’s decision to choose to drive a car to work or their own place of study in the morning peak period (before 10 a.m.). At the same time, we collected information on various factors that we 0967-070X/$ - see front matter q 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0967-070X(03)00015-5 Transport Policy 11 (2004) 17–29 www.elsevier.com/locate/tranpol 1 www.pinnacleresearch.co.nz * Corresponding author. Tel.: 64-4-25-2404-196. E-mail address: pinnacle.research@clear.net.nz (C. O’Fallon).