The Washington State Department of Transportation (WSDOT) regional planning programs address current and forecasted deficiencies of State highways through the conduct of corridor studies. This Guidance for the conduct of corridor planning studies is the product of a comprehensive evaluation of how to incorporate the consideration of Transportation Demand Management strategies into several business areas of the Washington State Department of Transportation (WSDOT). Corridor studies are an integral part of the transportation planning process, which support the State Highway System goals and objectives at the state and regional levels, as well as the vision for the corridor by the communities that the corridor serves. The Moving Washington approach recognizes the importance of using all the tools in the toolbox to cost effectively achieve the state transportation policy goals. This includes the mobility goal of maintaining the predictable movement of goods and people throughout the state of Washington. This Guidance describes a recommended approach to TDM strategies as part of least-cost planning for improving mobility. The Guidance asserts that all three methods: (1) managing travel demand, (2) optimizing traffic flow, and (3) accommodating travel demand by increasing capacity, should be used concurrently. This approach will advance the integration of TDM into the selected solutions aimed at reducing traffic congestion, providing mobility choices, enhancing transportation affordability, and meeting the State of Washington’s goals for reducing air pollution and greenhouse gas (GHG) emissions and improving community livability. This Guidance recommends use of a systematic process for identifying mobility needs, assessing existing TDM programs and resources, and evaluating potential TDM solutions against chosen performance metrics.