After a brief mention of the principles of design applied to the construction of the Lamosangu-Jiri Road in the central region of Nepal. the authors describe the effort undertaken to rehabilitate a road section heavily affected by a flood in the early monsoon season of 1987. Innovative techniques for the construction and maintenance of roads in the Himalayan region. such as anchoring, drilled subsurface drains, and flexible river protection. were introduced. In view of design options for low-volume roads in hilly terrain, practical suggestions such as low initial investment and event-related rehabilitation are discussed.

Extreme difficulty of access is one of the dominant characteristics of mountain communities and is a formidable constraint to the effective implementation of essential programs of rural development. This is the case throughout the hills and high mountain districts of Nepal. For this country, situated between India and China and dominated by the Himalayan range, road transportation is vital for the development of industries and commercial agriculture because other types of transportation (railway, ropeway, or air) are only complementary to road travel and do not contribute substantially to the transport of goods or passengers. The present road network in Nepal consists of approximately 7000 km. resulting in a density of 1 km per 21 km2 (J). Most of these are gravel or dirt roads, and a large number of them can only be used in fair weather. Construction of all-weather roads through the mountains to improve access to remote areas is extremely costly and technologically challenging, particularly on steep and unstable slopes or across mountain rivers. Most road failures occur during the monsoon season (July to September) because of floods or slides, which sometimes are triggered by earthquakes.