Riviere des Galets Bridge
A few years after its last operations on the La Reunion island, Matière® is back for the construction of the Riviere des Galets bridge.
The birth of the project
Several factors have prompted decision-makers in the region to launch a new metallic bridge project, especially the congestion caused by the current infrastructure on RN1:
– A concrete bridge crosses the Riviere des Galets River in the direction of Saint-Paul
– A second structure in the opposite traffic direction, towards Saint-Denis
Nearly 70,000 vehicles use this road on a daily basis and many clogs form.
The second problem stems from the age of one of these bridges. Built in the 1950s, the metallic bridge has suffered the effects of time and is now in danger of resisting a violent weather event such as a cyclone that is common in this part of the world.
The new bridge on the Riviere des Galets River
The final solution of the project was validated several months ago. This will be a 430 meter long metallic bridge, including 7 lanes of traffic: 2 fast lanes and one reserved lane in each direction of traffic, as well as a secured lane specially adapted for pedestrians and bicycles.
The final cost of the bridge will finally amount to 80 million euros.
Schedule of works
From the beginning of 2017 studies and preparatory work were launched. The foundations were thus made possible from May.
The installation of the deck is scheduled for next summer.
Work on pavements and road connections will be the final stages of the construction site. They are scheduled for early 2020.
The project schedule provides the opening of the bridge to users by the end of 2020.
A priori the duration of the works may seem extended, even for a project of this size, this is explained in particular by the prohibition of works in the river bed between January and March of each year.
Details of the construction site
Matière® performs relatively complex work for this project because of the area chosen for the installation of the structure.
To resist water flow and weather conditions, the foundations of the bridge must be deep. They will thus go up to 35 to 40m of depth with condition for the respect of the water table. The supports will be made by bars in reinforced concrete. There will also be 4 lines of support and 2 abutments.
The two decks will be assembled on the right bank so as not to cause additional traffic problems. The metal superstructure will then be installed via a launching operation.
This site will require the intervention of 3 cranes of 80m to 100m and nearly 30 000m3 of concrete.
Finally, the connecting roads at the ends of the bridge will be installed about 500m on either side of the structure.
Once the new bridge is in service, the deconstruction of the old metallic bridge can begin.
The experienced constraints
As we have seen, the construction site of the Rivière des Galets bridge requires considerable know-how in order to manage difficult situations.
Several stages of the work will require traffic cuts at RN1 level. To limit the disturbance caused by these cuts and to minimize the impact on users, certain operations will take place at night.
In order to protect the environment, and more precisely the fauna present on the island, the site made a truce of its night activity between 19 and 29 April 2017, dates between which took place the massive take-off of Barau’s petrels. This event will take place every year and the work will have to take this into account by inquiring at the Ornithological Study Society of Reunion to know the precise periods of these flights.