Teams from Eiffage Génie Civil, in a consortium with those from Perez & Morelli and Capocci, have successfully completed the demolition of a viaduct on the former A186 freeway overhanging the A3 at Romainville. This operation was carried out in 5 days and 6 nights for the Seine-Saint-Denis Departmental Council, the contracting authority, and Artelia, the project manager!
This work, necessary for the extension of the T1 tramway between Bobigny and Noisy-le-Sec, was carried out under exceptional closure of the A3 freeway between Bagnolet and Rosny-sous-Bois, from August 12 to 18.
The structure, a pre-stressed reinforced concrete viaduct, was the last of the A186, demolished to make way for the T1 route. It overhung the A3 but also the Branly bridge, and was the subject of a multi-phase demolition methodology ensuring the integrity of the latter.
The deck under the Branly bridge, supported by a metal frame, was first sawed into 13 sections of about 50 t, extracted with a mobile crane with a capacity of 700 t. Temporary bents on self-propelled trailers then supported the structure on either side of the Branly Bridge in order to guarantee the safety of the sawyers and the slingers. Once the sections at the ends of the steel structure had been extracted, the temporary bents were removed to allow the demolition machines to nibble away at the banks of the structure above a gravel protection mat, previously installed on the freeway.
Approximately 3,000 m³ of rubble were sorted and evacuated, along with the protective mat, to an area adjacent to the construction site, in order to reopen the A3 freeway, as planned, on 18 August at 5 a.m. They will be crushed there in the coming weeks, in order to be used as a roadway sub-base for the future development of T1.
Congratulations to the teams for the success of this exceptional operation!