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Open Access Publications from the University of California

Commute Mode Choice, Parking Policies, and Social Influence

  • Author(s): Khrodagui, Nagwa
  • Advisor(s): Brueckner, Jan
  • et al.

This dissertation examines the impact of parking policies and social influence on commute mode choice using discrete choice analysis. A key feature of the dissertation is overcoming the problem of insufficient data by using unique datasets, building unique datasets, or exploring appropriate estimation strategies and assumptions.

Chapter 1 studies the impact of parking prices on the decision to drive to work using the California Household Travel Survey. The chapter tackles estimation challenges posed by insufficient parking information. The first challenge is the estimation of parking prices for those who do not drive, which is addressed by using a sample selection model. The second challenge is to understand the effect of the extent of the prevalence of Employer-Paid parking coupled with incentive programs offered in-lieu of parking. To address this challenge, two extreme scenarios are examined, and a range for the marginal effects of parking prices is estimated; one scenario assumes everyone receives Employer-Paid parking coupled with in-lieu of parking incentives, and the second assumes that no one is offered such incentives. The results suggest that higher parking prices reduce driving, regardless of the followed approach. It is estimated that a 10% increase in parking prices leads to a 1 - 2 percentage point decline in the probability of driving to work. Moreover, there seems to be no evidence of sample selection bias. The evidence suggests that parking pricing can indeed be an effective transportation demand management tool.

Chapter 2 extends the analysis of Chapter 1 to simultaneously estimate the impact of parking pricing, parking availability, and urban form on commute mode choice. The joint role of these three factors is examined using a dataset that is constructed by merging three major different data sources. The California Household Travel Survey data are matched to two unique datasets on parking for Los Angeles County; one for prices and the other availability. Chapter 2 first examines how these three factors affect the binary decision of whether to drive, while controlling for a rich set of covariates. The analysis then becomes more specific and examines how these factors affect particular commute modes in a multinomial context. The results indicate that parking prices have a significant negative impact on the decision to drive to work, where a 10% increase in parking prices is associated with a 1.1% drop in the probability of driving to work. Both on-street and off-street parking availability at home, as well as urban form measures of the workplace tract, are found to significantly affect commute mode choices. These findings have important policy implications in terms of minimum parking requirements, maximum parking standards, employer-paid parking, and parking pricing policies.

Chapter 3, on the other hand, examines the impact of a number of fundamental determinants of commute mode choice on transit use, and introduces the role of social influence. The determinants explored cover socioeconomic characteristics, built environment and neighborhood characteristics, transit accessibility, and trip characteristics. Social interactions have been found to affect many of the decisions of economic agents, and are likely to play a role in the decision to use transit. A unique dataset is built to conduct this analysis across a number of major US cities and examine the effects in both the residence and workplace neighborhoods, where a neighborhood is defined as a census tract. Social influence is explored along three different dimensions: space (neighborhood), income, and race. A novel instrumental variable is constructed in order to identify spatial social influence, and an alternative identification strategy is devised to identify income-group and racial social influence. The evidence suggests that spatial social influence exists among both coworkers and residential neighbors, and that peer effects among coworkers are larger than those among residential neighbors. Moreover, income-group social influence, among both coworkers and residential neighbors, plays a significant role in the rich commuter's decision to use transit. However, racial social influence does not affect a commuter's decision to use transit, regardless of race.

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