TRAVEL BEHAVIOR, EMISSIONS, & LAND USE CORRELATION ANALYSIS IN THE CENTRAL PUGET SOUND

A growing body of research documents that land use relates with travel mode choice, distances and time spent traveling, and household level vehicle emissions. However, to date little work has been done at a sufficiently disaggregate scale to gain an understanding of how local governments should alter their land use policies and plans to reduce vehicle use and encourage transit and non-motorized forms of travel. This study of the four county Central Puget Sound region links parcel level land use data with travel data collected from the Puget Sound Household Travel Survey (PSHTS). The primary aim of the study is to describe how measures of land use mix, density, and street connectivity where people live and work influences their trip making patterns including trip chaining and mode choice for home based work trips, home based non-work trips, and mid day trips from work. Land use measures are developed within one km of the household and employment trip ends in the survey. Tour based models are developed to estimate the relative utility of travel across available modes when controlling for level of service, regional accessibility to employment, and socio-demographic factors. A secondary aim of the project is to estimate the linkages between land use and household generations of Oxides of Nitrogen and Volatile Organic Compounds that are precursors to the formation of harmful ozone. Emissions are estimated based on modeled speeds for AM, PM, and off peak travel at the trip link level and then aggregated to the household level. Household emissions are then correlated with land use patterns where people live when controlling for socio-demographic factors. An exploratory analysis was also conducted as part of this work to estimate how land use patterns where people work influences their modal choice and engagement in travel demand management (TDM) programs offered by employers. The project relied on the Commute Trip Reduction Database from Washington State Department of Transportation (WSDOT). However, it was found that additional development of these data is necessary before this type of analysis can be done. Results are presented that document how much of an increase in the utilization of specific modes of travel for work and non-work travel would likely accrue from specific types of land use changes, and from changes to travel cost and travel time.