Prof. Joan Walker

Department of Civil and Environmental Engineering, UC Berkeley

May 02, 2013, 12:15, Room GC C3 30 (click here for the map)

You Can Lead Travellers to the Bus Stop, But You Can't Make Them Ride

<p>Latent modal preferences, or modality styles, are defined as lifestyles built around the use of a particular travel mode or set of travel modes. Traditional models of travel mode choice assume that (1) that all individuals are aware of the full range of travel modes at their disposal and make a rational mode choice based on level-of-service and (2) individual modal preferences are characteristics of the individuals that are exogenous to the choice situation and stable over time. Though these assumptions simplify the model, they risk overlooking the impact of more deeply entrenched individual variations in modal preferences. </p><p> This talk presents a latent class choice model (LCCM) that allows modal preferences to be endogenous to the choice situation and variable across individuals. The model is applied to analyze modality styles and travel mode choice behavior of 25,000 people in the San Francisco Bay Area. The study identifies six distinct modality styles in the sample population that differ in terms of their taste parameters and choice sets. Most notably, nearly a third of the sample is found not to consider any mode other than auto. Results show that an individual's value of time is sensitive to the level-of-service, and an increase in congestion can induce decision-makers to lower their value of time. Findings further reveal that incremental improvements in the transportation system result in far smaller changes in travel behavior than predicted by traditional models; what is needed is a dramatic change to the transportation system that forces individuals to reconsider their modality styles. </p><p> This is joint work with UC Berkeley doctoral candidate Akshay Vij.</p>


Joan Walker's research focus is behavioral modeling, with an expertise in discrete choice analysis and travel behavior. She works to improve the models that are used for transportation planning, policy, and operations. Professor Walker joined UC Berkeley in 2008 in the Department of Civil and Environmental Engineering and as a member of the interdisciplinary Global Metropolitan Studies initiative. She received her Bachelor's degree from UC Berkeley and her Master's and PhD degrees from MIT. Prior to joining UC Berkeley, she was Director of Demand Modeling at Caliper Corporation and an Assistant Professor at Boston University. She is Chair of the Transportation Research Board's Committee on Transportation Demand Forecasting, an Associate Editor of Transportation Science, and a recipient of the Presidential Early Career Award for Scientists and Engineers (PECASE).