The “Route en Corniche”, or “Route du Littoral”, is a 13 km four-lane roadway linking Saint-Denis to La Possession. Its location, although extremely strategic, makes traffic very dangerous on this road: the cliff on one side with the risk of falling rocks, the sea on the other, threatening with a possible swell. The many works to secure and try to restore this stretch of road have made it one of the most expensive roads of France.
The road construction, the first problems
The idea of the current Route en Corniche emerged in the 1940s. This project, selected from three projects, aimed to easily connect the north and south of the island, which the road of La Montagne, the road used at the time, did not allow. The construction began in 1956, and the two-lane road was delivered in 1963.
But from the beginning of the works, difficulties arise: cracks and collapses of tunnels, rockfalls ... Consolidations, safety systems, reconstructions are also undertaken, which already incurs extra costs. Upon delivery of the road, traffic is important, but endangered by falling rocks most of all, a risk that is always running when the road widens to a four-lane roadway in 1976.
A permanent danger
To address these risks, work is undertaken regularly , including purges of the cliff after each episode of heavy rain. Safety nets , gallows , gabions , surveillance patrols are settled... The reduction of the four lanes on the two lanes seaward , or on the mountain side, depending on the origin of hazards, rockfall or swell, is also set up quite frequently , and the decision to completely close the road to traffic , although it occurs less frequently , has yet been required repeatedly .
Despite ongoing work on the Route du Littoral , the danger persists , since it has killed 31 people in 30 years. Including , among others, the case of three young people killed by the fall of about 20000 m3 of stone in 1980 , or that of two people, dead buried after the collapse of a whole section of the cliff in 2006.
Currently security work are taking place, costing € 90 million, including the installation of new nets, breakwaters ... But this does not solve the problem. That is why the construction of a new road is considered, fully secured , including passing a dyke over the sea.