Analysis of Commuter Modal Choice Decisions in Boston, Massachusetts
As a result of an increasing shift towards solo car commuting in the United States and other industrialized countries over the last decades, congestion on major highways has become an increasing problem leading to considerable private, social and environmental costs. Objective The objective of this research is to (1) identify the key variables influencing commuter modal choices in peak periods and (2) determine their relative importance based on an analysis of a case study of commuters in Boston, Massachusetts. This study provides a step in the direction of developing an understanding of behaviour ultimately leading to traffic congestion and solo car commuting. Methodology Standard practice in travel demand analysis is to use discrete choice models in the analysis of transport mode selection. The study follows these generally accepted principles by using a multinomial logit model for the quantitative analysis of the case study data. Case Study Findings and Conclusions The city of Boston was used as the case study for the analysis. Boston was primarily chosen for its increasing congestion problem, the relatively large choice set available to commuters, and limited roadway space in the greater metropolitan area. Data on commuters in the greater Boston area was collected and analysed. Specifically, a distinction was made between radial and orbital commuters. Overall, the analysis showed that orbital commuters tend to choose their cars because of the lack of feasible alternatives as well as the heavily subsidized nature of parking. This group was also found to be very resistant to altering modal choices. Radial commuters appear to be more responsive to changes in policy variables. For example, the analysis found that an elimination of free or subsidized parking would shift solo car commuters towards public transport. In particular, such a change was found to reduce the number of solo car commuters overall by 16 percent, and 20 percent for radial commuters specifically. As a result, the solo car modal share was found to be reduced by approximately 9 percent. The changes are almost exclusively caused by radial commuters adjusting their behaviour. Recommendations Based on the findings and conclusions of the case study, recommendations for policy and further research were made. Again, the recommendations were split so that orbital and radial commuters could be targeted separately. Modifications to pricing, especially pricing of parking supply, improvements to public transport and the encouragement of more sustainable travel patterns were discussed as part of the overall policy suggestions.
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