The 'EST project' was undertaken in the late 1990s and early 2000s and was led by the OECD, in cooperation with UNEP and national governments. It was born out of the need for a new policy approach to the aim of mitigating the adverse environmental and health impacts of transport. Conventional approaches tended to use observed and projected transport trends to assess the impact on the environment ex post. Although they helped to reduce the environmental and health risks and to improve efficiency, they fell short of advancing steadily towards environmentally sustainable transport. This required a new, target-oriented approach that put environment and health at the top of the policy agenda for transport-related sectors. Recognising that need and the gravity of the transport-induced environmental problems, the OECD's Environmental Policy Committee's Task Force on Transport initiated the project on environmentally sustainable transport (EST) in 1994.

The 'EST Project' contributed long-term visions of EST consistent with EST criteria and strategies for reaching those goals. As part of the project, future EST scenarios were developed, criteria for sustainable transport were identified, EST guidelines were developed and policy instruments that could help to deliver EST were identified. Additionally, various case studies of EST in practice were developed, including for Sweden, Norway, Germany, the Netherlands, Canada and Japan. Another report looked at the economic and social implications of EST and the role of mobility services and logistics in delivering EST.