Site-Specific Transportation Demand Management: Case of Seattle’s Transportation Management Program, 1988–2015

A central theme of U.S. transportation planning policies is to reduce single-occupancy vehicle (SOV) trips and promote transit and non-motorized transportation by coordinating land-use planning and transportation demand management (TDM) programs. Cities often implement TDM programs by intervening with new development during the municipal permit review process. Seattle’s Transportation Management Program (TMP) under a joint Director’s Rule (DR) requires a commitment from developers to adopt select strategies from six TDM element categories: program management, physical improvements, bicycle/walking programs, employer-based incentives, transit and car/vanpooling, and parking management. TMP targets new developments and requires some TDM elements, recommends others, and leaves the rest to negotiation. The result is an individualized TMP agreement that is site-specific, reflecting both city policy and developer needs. This case study presents a qualitative analysis of the guiding eight DRs and 41 site-specific TMP agreements in Seattle’s Downtown and South Lake Union (SLU) area since 1988. Overall, a content analysis of TMP documents reveals that the average number of elements adopted in an agreement falls short of requirements set by DRs (34%–61%). Major findings include developer preference toward non-traditional TDM measures such as physical improvement of frontage and urban design features, as well as parking management. High-occupancy vehicle (HOV) elements showed higher adoption rates (59%–63%) over biking/walking programs (1%). It is concluded that future TDM policies could benefit if future research includes examining the effectiveness of the range of management options stemming from the real estate trends toward green buildings, tenants’ values in sustainability, and city policy to reduce automobile trips.