ABSTRACT
The geographical setting of the northeastern part, the largest region of Thailand, consists of flat terrain on the east side and mountainous areas on the west side (see Figure 25.1b). Most of the areas are quite dry, thus medium to large rivers are rarely found. Only short-to medium-span bridges are therefore usually required. In this area, the soil is covered by stiff sand. Hence, spread foundations were
generally preferred. The eastern and southern parts are characterized by high terrain areas. However, there are some parts, especially in the lower regions, which are covered by long mountains. These regions consist of small and medium rivers, and therefore both small to medium bridges are recommended. The foundation type may be pile foundation and spread footing, depending on the location of bridge site construction and soil conditions.
