Transportation demand management (TDM), or simply demand management, is defined a set of strategies aimed at maximizing traveler choices. Traditionally, TDM has been narrowly defined as commuter ridesharing and its planning application restricted to air quality mitigation (conformity analysis), development mitigation (reducing trip generation rates and parking needs), or efforts to increase multi-modalism in transportation plans. A more contemporary definition of TDM consists of maximizing travel choices, as stated in the definition provided in an FHWA report on TDM:
Managing demand is about providing travelers, regardless of whether they drive alone, with travel choices, such as work location, route, time of travel and mode. In the broadest sense, demand management is defined as providing travelers with effective choices to improve travel reliability.
While transportation systems management and operations is an umbrella term for a set of strategies that includes transportation demand management, it is helpful to focus on specific needs for integrating TDM into existing activities that are carried out under the transportation planning process by States, metropolitan planning organizations, and local agencies. TDM can be effectively integrated into the planning processes at all levels using an objectives-driven, performance-based approach that includes a process for setting specific, measurable objectives for TDM.