Due to increasing concerns as to the suitability of unsealed gravel as the default rural road surfacing in the high rainfall climates of South East Asia, DFID and World Bank have co-funded research into appropriate Low Volume Rural Road (LVRR) pavement and surfacing options in cooperation with the government of Vietnam. The research has been managed through the South East Asia Community Access Programme (SEACAP). The previous widespread provision of unsealed gravel roads was influenced by relatively cheap construction costs in a constrained resource environment. However project SEACAP 4 research on previously constructed gravel roads has shown that in many circumstances these surfaces demonstrate unsustainable levels of material loss and deterioration due to a range of factors such as: high rainfall, flooding incidence, steep gradients, incompatible traffic loading, inadequate quality assurance, and insufficient maintenance capacity.
The complementary SEACAP 1 project involved the construction of low volume trial roads using a range of locally available materials in a representative selection of road environments throughout Vietnam. A wide range of sub-base, base and surfacing options have been trialled including bitumen emulsion stone chip and sand seals, un-reinforced, steel reinforced and bamboo reinforced concrete slabs, concrete bricks, fired clay bricks, cobble stone, dressed stone paving, and lime, cement and emulsion stabilisation. Standard local practice; hot bitumen seals and unsealed options, have been constructed as comparative control sections. Construction of the trials was completed between June 2005 and July 2007 and representative lengths have been selected for long term condition monitoring which is now proceeding. Initial trial road performance information is now becoming available and this, together with the construction cost and construction quality assessment data, is allowing the development of practical Whole Life Cost and Option Selection models.
This paper summarises the outcomes of the SEACAP 1 and 4 projects with particular focus on the guidelines developed for improved rural road pavement/surface selection, design, construction and maintenance in challenging tropical environments.