After rapidly increasing for 3 decades, Thailand’s growth had slowed in the years prior to project appraisal in 2009. Reinvigorating growth by strengthening competitiveness thus became the centerpiece of the government’s economic policy. To address the transport sector’s deficient infrastructure and high logistics costs, which significantly constrained growth, Thailand’s Department of Highways (DOH) implemented the Four-Lane Highway Widening Project (Phase II) to which it invited the Asian Development Bank (ADB) as a cofinancier.
In response, ADB approved in December 2009 a $77.1 million loan for the Greater Mekong Subregion (GMS) Highway Expansion Project, which would expand 178 kilometers (km) of the national highways along the GMS East–West Economic Corridor (EWEC) and the Southern Economic Corridor (SEC). The project marked ADB’s reentry in Thailand’s transport sector, after 13 years. Its anticipated impact was increased competitiveness of the local economies along EWEC and SEC. Its planned outcome was a more efficient and safer EWEC and SEC in Thailand.
At completion, the project upgraded 105 km of the GMS highway along EWEC and 73 km along SEC from a two-lane to four-lane highway standard. It also constructed new bridges and widened existing ones; reinforced and extended concrete box and pipe culverts; put in place new asphalt pavement and strengthened existing surfaces; set up pedestrian overpasses; and improved signage and pavement markings.
As the additional two lanes were constructed within the right-of-way, no land acquisition was required. Nevertheless, a total of 353 households, mostly living in temporary shops selling food and goods within the right-of-way, were affected. Several of these households were provided in-kind relocation assistance.
Upgrading of the highways led to increases in annual average daily traffic: by 77% along EWEC and 19% along SEC in 2015, compared to 2010. Over the same period, travel time decreased by 12%–15% along EWEC and 12%–16% along SEC. There was no significant change in passenger and freight operating costs.
However, the number and fatalities from traffic accidents increased, with the traffic accident rate in some sections rising by 1.5–3 times after project completion. Speeding and turning right onto the highway from access roads comprised the main reasons. The DOH subsequently carried out additional safety measures, including installing more warning signs and concrete barriers on highway medians. As a result, the number of fatalities began to decrease in 2017.
By 2017, shops along EWEC enjoyed increased sales due to the increased traffic volume. New hotels, resorts, gas stations, restaurants, and shops had opened, and the number of tourists had increased. On the other hand, shops along SEC reported reduced sales due to the greater number of similar shops and the decreased traffic from the opposite lane because of the barriers on the highway medians. With the ongoing dramatic traffic increases, however, sales of the shops along SEC were expected to increase to pre-project levels soon.
ADB’s Southeast Asia Department rated the project successful. DOH was the executing agency. The Bureau of International Highways Cooperation served as the implementing agency.
