The major purpose of this research is to test the effects of street-level urban design attributes on travel behavior. There are two goals: (1) operationalizing path walkability, which includes developing a walkability measurement instrument and quantifying path walkability, and (2) testing the effect of path walkability on transit users' access mode choice and walking distance to the station.
A case study was conducted in the station area of Mountain View, California. In 2005, three different surveys were done. A station user survey was conducted by distributing self-administered, mail-back questionnaires to the entering transit users at the gates of the station. The user survey collected access mode choices, trip origins, and socio-economic data from 249 transit users who provided their routes. A walker perception survey was conducted with 68 transit users who walked to the station. This on-board survey asked them to score their walking routes. Based on the routes identified by both surveys, this research selected 270 street segments. For each segment, 30 street elements were measured by using a two-page survey instrument. The surveyed street data produced more than 40 path walkability indicators.
The first part of this dissertation conducted a factor analysis with the path walkability indicators derived from the 249 surveyed routes, and found four path walkability factors: "sidewalk amenities," "traffic impacts," "street scale and enclosure," and "landscaping elements" With the four factor scores as new variables, a pair of logit analyses was conducted. All four path walkability variables significantly influence transit users' mode choice decision--good walkability increases the transit users' chance of walking over driving to the station. The second part created a composite walkability index based on the walker perception survey result. The walkability index was also tested in mode choice models, which confirmed that good path walkability increases the chance of walking. The third part conducted a regression analysis of transit users' walking distance, and found that a traveler's walking distance increased by more than 300 feet for every 0.5 increase in the composite walkability score. This research also found a donut-shaped critical walking zone, where walkability mattered more.
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