Oxygen tank, fins, wetsuit and bright red overlay "to scare the catfish": Frédéric is ready to enter the water.
With his 35 kg on his back, this diver specializing in the inspection of engineering structures dived under the Invalides bridge in Paris on Wednesday, September 8.
With his colleague Christophe, they inspected the condition of the five meters of submerged buildings on behalf of the City of Paris.
Both work for the Center for Studies and Expertise on Risks, the Environment, Mobility and Planning (Cerema). This public administration, which depends on the Ministry of Ecological Transition, has been inspecting the thirty-seven bridges of the capital since 2015. It then makes recommendations to the mayor of Paris by defining the degrees of urgency of any work to be carried out.
"Ok masonry in good condition, can you go and see if everything is good at the front?
".
Remained on the surface, Ludovic communicates with the two divers thanks to a radio.
“If something is broken, missing, twisted… they give me position and depth information and I transcribe them on paper,” explains the diver, noting a diagram of the Invalides bridge.
Then we write a report for the client.
The divers shoot videos underwater to accompany their observations.
They also place sensors on major cracks to be able to follow their progress.
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Most often, bridges are damaged by flooding.
They carry heaps of materials which pile up along the piles.
Structures also suffer from the oxidation of their wooden foundations, attacked by the air when the water level drops.
Heavy renovations to come in the coming years
“The lifespan of a bridge in good condition is 30 to 70 years,” explains Pascal Berteaud, CEO of Cerema. After this period, heavy work is required. To ensure that this work is started on time, the city of Paris has its bridges inspected every six years by the Cerema. More regular interventions can be organized on structures where many disorders have been observed. Many of them should require renovations "in the next 20 to 30 years," says Pascal Berteaud. And for good reason: “a good half of the bridges in France were built after 1945,” he explains. Their lifespan before renovation will therefore come to an end in the coming years. "
