The earth road construction standard that is required for a given traffic volume appears to be a function of the terrain morphology and type of soil. Instead of a formal application of a priori concepts, site investigation of natural conditions and road performance should be a sound basis for design of good-quality and cost-effective rehabilitation and upgrading of earth and gravel roads. An appropriate design methodology based on comprehensive field investigations was developed for road rehabilitation schemes in madagascar and testedin contract works in that country, and also in zaire. The methodology proved to save money and time, and rather than resulting in poor design, capturing conditions and resolving design problems in the field may improve the design quality. The methodology comprises three phases. The first phase is the comprehensive inventory and detailed condition survey, the second phase is field design, and the third phase is complementary office design and estimation of quantities. Theaccuracy of quantity estimates derived from this simplified design methodology appears to be satisfactory for contract rehabilitation works. This paper appears in transportation research record no. 1291, Fifth international conference on low-volume roads, may 19-23, 1991, raleigh, north carolina, volume 1.
Abstract