Paris (AFP)

The bridge that collapsed Monday in Mirepoix-sur-Tarn (Haute-Garonne), costing the lives of at least one person, was a priori "not in bad shape," according to several sources. An investigation was opened to determine the causes of the disaster, some evoking a "rupture under surcharge".

Was the bridge degraded?

"It was not a classified work with reinforced surveillance or in critical condition," assures Georges Tempez, Center for Studies and Expertise on Risks, Environment, Mobility and Development (Cerema). This public body carried out in 2017 a detailed inspection of the book.

This inspection "does not conclude to a work in bad condition, either in its entirety or on parts of the work," says the director of the technical direction transport infrastructure and materials Cerema. "There were some recommendations for routine maintenance, classic things, but nothing urgent."

Was it regularly monitored?

Regarding the national road network, inspections must be conducted every six years, explains Georges Tempez. If the law does not impose it for the infrastructures departmental, intercommunal or communal, "many communities adopt this mode of operation" by requesting an inspection every six years.

In this case, the Cerema had conducted a previous inspection of the bridge Mirepoix-sur-Tarn in 2011. "A traditional monitoring", says Georges Tempez, for this suspension bridge of steel structure built in 1931, replacing a previous work destroyed by the flood of the Tarn a year earlier, and renovated in 2003.

What about risk bridges?

"If a bridge that was not listed as dangerous has collapsed, what about bridges that are clearly identified as being at risk?" Worried PS Senator Michel Dagbert at AFP .

In June 2019, he was one of the senators calling for a "Marshall Plan" for renovation, concluding a mission launched after the collapse of the motorway viaduct of Genoa (Italy), which killed 43 people in August 2018.

According to the conclusions of this mission, "at least 25,000 French bridges" are in a bad structural state, of the 200,000 to 250,000 structures in the country - the exact number of road bridges in France is not known.

How to explain the collapse?

"At this time, we still do not know the precise causes of the accident," the government said on Monday, announcing the opening of an investigation by the Office of Investigation of Land Transport Accidents (BEA-TT).

If "no recent climatic phenomenon" can be implicated in the collapse of the structure, according to the mayor of Mirepoix-sur-Tarn Eric Oget, the eyes are on one of the damaged vehicles, "a priori a heavy vehicle ".

Because the bridge is prohibited to vehicles over 19 tons, as stipulated a sign at the entrance. But "it is common" that "trucks of larger tonnage" use it, regretted the president of the community of communes, Jean-Marc Dumoulin.

In view of the first images of the disaster, Georges Tempez has considered a "mechanism of rupture under surcharge", but insists on the need to wait for the conclusions of the investigation.

How to establish responsibilities?

"In this type of situation, the question of responsibility follows almost always the same process, which involves two types of investigations" to determine the causes of the accident, explains to AFP Alexandra Cohen-Jonathan, associate at Cabinet August & Debouzy. A criminal investigation, the accident having caused at least one death, and the administrative investigation of BEA-TT.

In addition, the accident involving vehicles, "this leads in principle insurers known as law 1985, that is to say the car insurers, to intervene in a phase of compensation" victims. In a second time, they "will most likely look for other causes and other responsibilities," says Cohen-Jonathan, "thinking that no matter the weight of the vehicle of their insured, the bridge would not had to collapse. "

They could target the maintenance, asking the question "if it is normal that the passage of a vehicle, even heavier than 19 tons, can justify the collapse of the bridge", or the signage, because "a sign, in a case of dangerous situation, is not reasonably enough to avoid this situation," anticipates the specialist in litigation insurance and industrial risks.

© 2019 AFP