Over the last decade, local jurisdictions and transportation agencies have increasingly used transportation demand management (TDM) programs to manage the traffic impacts of new commercial and retail developments. More recently, however, King County and the cities of Kirkland, Redmond, and Seattle, Washington, have introduced TDM programs for residential developments or origin sites. The objectives of the evaluation were (1) to document the implementation of home-end TDM strategies, and (2) to evaluate their effectiveness in mitigating the number of vehicle trips generated by residential development.
Since few projects had been built and occupied by the time the evaluation concluded, quantitative evaluation was limited, and the success or failure of residential TDM programs could not be determined. However, it was possible to gain an understanding of the nature and reasons for the implementation problems encountered through qualitative means. These means included interviews with jurisdictional staff, developers, and managers and a focus group among residents. The analysis pointed out problems related to (1) the decision process leading to the imposition of mitigation requirements, (2) the institutional memory of requirements, (3) monitoring, (4) enforcement of compliance, and (5) the adequacy of mitigation measures. The paper concludes with recommendations to mitigate these implementation problems.