As traffic congestion grows but existing roadway capacity remains fixed or limited, downtown congestion pricing offers potential as a tool to manage the transportation system. Though the idea is not new, congestion pricing has received a resurgence of attention in the United States in recent years because it could offer both congestion relief and transportation revenue. However, in order for a modern congestion pricing proposal to be politically feasible and publicly acceptable today it must be designed to offer more, such as equitable or progressive distribution of impacts, greenhouse gas emissions, and encouragement or support for alternate modes, including new mobility services.
In Seattle, serious consideration of the implementation of congestion pricing by 2021 is underway, and numerous policy questions remain open. One which many anticipate, particularly the public, is the question of where congestion pricing revenue would be spent. It is likely that at least some of the revenue will be allocated for transit, but where should service improvements be targeted, both geographically and demographically, so that mobility and access are not impaired, particularly for the already transportation-disadvantaged, and so that multimodal travel is not just possible but preferable to driving? Could a regional partnership between transit agencies like Sound Transit and King County Metro and the City of Seattle secure transportation outcomes that align with both transit agencies’ ambitious service expansion goals and Seattle’s core equity, multimodal mobility, and climate goals?
This thesis seeks to answer these questions by using a mix of statistical models of transportation system level of service and individual-level mode choice. These models are used to predict how travelers across the region would change their travel behavior in response to cordon pricing in Center City Seattle under two investment scenarios. It is projected that investing in transit broadly across the region by decreasing transit service times produces transportation system outcomes that advance both local and regional strategic goals more than concentrated investment on downtown Seattle roadways and transit could advance Seattle’s goals alone. Regional transit investment would decrease congestion more in Center City Seattle by improving transit access from outside Seattle into Center City, especially among neighborhoods with the lowest housing and transportation affordability, highest automobility, and highest transportation-related greenhouse gas emissions. Therefore, the findings strongly motivate that congestion pricing revenue in Seattle be spent on regional transit service improvement and expansion. Furthermore, the findings suggest that even regional transit investments that may not be directly linked to Center City will help to produce a mix of better transportation outcomes in Center City than concentrated investment would.Civil, Architectural, and Environmental Engineerin
