Against the backdrop of growing momentum for regional cooperation and integration (RCI) in Asia, this paper examines the link between regional roads and Asian Development Bank (ADB) support between 1966 and 2008.

The novel methodology used in this paper includes an Asia-wide definition of regional roads that fall on the Asian Highway (AH) network. The AH network is a system of about 140,000 kilometers (km) of standardized roads crisscrossing many Asian countries and with linkages to Europe.

The United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP) conducts research on Asian roads and works with member countries to identify financing sources for AH network development. In relation to assessing ADB's contribution to regional roads, three tasks are attempted in this paper: (i) an identification of ADB-financed regional roads and other kinds of roads in ADB's portfolio, (ii) an estimation of ADB's contribution to the AH network, and (iii) the development of a map where ADB's contribution to regional road construction and infrastructure can be easily juxtaposed with the AH network.

The paper finds that regional highways have been a notable and growing part of ADB's road portfolio since the 1990s, particularly in ADB's subregional programs such as the Greater Mekong Subregion (GMS) and Central Asia Regional Economic Cooperation (CAREC) programs. It also finds that ADB road investment has made a significant contribution to the AH network, representing about two thirds of the network's core roads. While parts of the AH network have been completed, substantial gaps still exist, including an estimated $43.8 billion required for priority projects. As part of its mandate to promote better integration of Asian infrastructure, ADB may have a role to play in addressing the financing, planning, and institutional development of the AH network. Furthermore, strengthened coordination among ADB, UNESCAP, and other actors can enhance both the AH network and the process of regional road development in Asia.