Distress of poorly drained pavements typically takes the form oflongitudinal settlements and cracks along shoulders (both shouldersof straight aligned stretches and the lower shoulder of superelevated curves) and results from water penetrating the structural layers of the pavement system, flowing along the transverse and longitudinal grades, and saturating materials of lower areas. Water flowing in the pavement along the longitudinal gradient may feed perched water tables in pavement layers of low embankment sections. Seepage from the perched water tables into the shoulders and subgrade may originate edge slides. Pavement cross-section design should take into account the permeability of available natural materials as well as processed base materials. Adequate provision for prompt outflow of pavementwater should be given except for impervious pavements that do not require to be drained and for pavements over pervious subgrades whereefficient subdrainage is achieved by percolation to deep-water tables. A catalog containing eight standard pavement cross sections has been proposed for the malagasy low-volume, bitumen-paved roads and the unit prices of 10 road construction and rehabilitation projects were used to derive comparative construction costs of the different standard cross sections. This paper appears in transportation research record no. 1291, Fifth international conference on low-volume roads, may 19-23, 1991, raleigh, north carolina, volume 2.
Abstract