The concept has become confused as each discipline has tried to mold the concept to their set of tools. This “silo” thinking inhibits the kind of policy integration that is needed to develop a sustainable urban transport solution strategy. There remains much confusion as to what a sustainable transport system would comprise. It is helpful therefore to consider different approaches to sustainable transport along a spectrum of viewpoints, ranging from weak to strong sustainability. Generally efforts to address the impact of transport on climate change to date have been largely focused on technology. The impact of this technological-led approach has been very limited in the transport sector. TDM has the potential to move the transport sector from a position of weak to strong sustainability by combining behavior-change with technology improvements. In this context transport demand management is understood as a much broader concept. Implicit in the use of the term is the assumption that it is accompanied by the implementation of sustainable mobility, introduction of full cost pricing and organizational or structural measures to ensure a broad range of complementary interventions work effectively together to realize the benefits of sustainable transport. It is the unifying philosophy of TDM, not specific measures associated with it, that underpin the policy objective of a more sustainable system of transport. This philosophy of managing demand accepts that meeting unfettered demand for travel is impractical and that therefore the system needs to be managed. That demand for travel needs to be managed by: Expanding the supply and availability of (more sustainable) alternatives; Controlling demand for the use unsustainable modes; Providing incentives and rewards for undertaking sustainable travel habits; and Imposing full-cost pricing on the use of the automobile. Arguments in favor The need to manage travel demand has now become urgent for a number of converging reasons. Oil prices have now passed the previous peak in 1980, and 95% of all energy used in transport is oil. Vehicle travel in the United States, which has been rising steadily since records began, started to level out before the fuel price increases and is now in decline. Part of this decline is likely to be people making fewer trips, with potentially far-reaching economic and social consequences. Countries and cities where the car is one of many travel choices are more likely to prosper, as people can choose to drive less but are still able to travel by