Gabion walls were installed to prevent risk of Rockfall on the new coastal road. The existing coastal road is constantly under threat of hazards, such as rocks falling off the cliff.
The Regional Council started working on the project of construction of the New Coastal Road (NCR) at the end of 2013. The main challenge of the new road was primarily to put an end to a constantly unsafe situation for the thousands of users, professional or otherwise, who drive along this major road on Reunion Island every day.
The existing coastal road is constantly under threat of hazards, such as rocks falling off the cliff. For the last few years, the Regional Council, supported by the French State, has put up 450,000 m² of nets, with the aim of reducing the risks, but these are inefficient against major rock falls, such as the dramatic one that cost the lives of two Reunion Island road users on 24th March 2006.
The choice of a new coastal road partially out at sea was made in 1999, and then confirmed in 2006. 20 years of studies, expertise, enquiries and public debates confirmed the need for a new infrastructure. All the experts concluded that this solution responds to the different challenges of the road, not only technically, but also financially and environmentally.
It has a length of 12.5 km, including 6.7 km in dikes and 5.6 km in viaduct, and a width of 29m. Total cost of the project: 1.6 billion euros.
The solution defined by the designer on the four land sides dikes was an Rockfall embankment reinforced by geosynthetics with double twist gabions in facing. The dikes have a variable height between 1 and 17 m. In addition to the support function, the structure had to be able to resume an impact related to a block drop of 1300kJ intensity, corresponding to a block of 6.5T launched at 70km/h.
Having already participated in a research project called REMPARE, which aimed to study the impact of blocks on gabion structures, and having recognized experience in this type of work, Maccaferri was chosen to carry out the implementation plans and supplied approximately 60,000 m3 of double twist gabions !
On the walls of greater height it had contain a facing with double gabions that could be replaced in case of impact (massive freestanding back).
The gabions are in double twisted wire mesh with polymer coating for a best durability and required in coastal environment.
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