THE COASTAL ROAD IN THE ISLAND OF LA REUNION

The author describes the preliminary studies, planning and construction of the road. The road is built at an elevation of 8,50 M and the structure consists of (1) a rip-rap spoil bank protected by a concrete block shell used as a base for the vertical retaining structure; (2) a vertical retaining structure consisting of a reinforced earth wall with concrete scale facing and aluminium reinforcement; (3) a ballast-pit crusher run embankment separated from the rip-rap foundation with a rounded gravel filter, between two layers of non-woven materials. The whole width of the road comprises 27 m-wide carriageways separated by a central reserve, with 2 emergency stop lanes. A wide ditch on the side of the road near the rock slope is used for drainage and for catching falling stones. Small-scale model tests have shown the need for modifying the concrete rock shell, and the first stage of construction showed the rapid corrosion of stainless steel cables making it imperative to revise the protection system designed with concrete blocks. (TRRL)