The Bouchemaine suspension bridge, beautiful French heritage bridge built in 1950, is the only one in the area to give direct access to Angers (49). Made up of three spans, for a total length of 205 m, it carries over the Maine river an average of 10,000 vehicles per day.

In 2018, Freyssinet was awarded to restore the suspension bridge that was suffering from corrosion.

  • Name of the owner and client
    Departmental Council of Maine-et-Loire
  • Delivery date of the project
    2018
  • Partners of the project
    Asbestos removal subcontractor: MTS
    Scaffolding subcontractor: ECTS

Maintenance of a suspension bridge

Being warned by a regular inspection about the presence of asbestos paint and corrosion on the structural elements of the suspension bridge, the Maine-et-Loire Department commissioned Freyssinet in 2018 for:

  • Restoring the anti-corrosion protection for the carrier tendons, hanger collars, hangers and saddles
  • Replacing the anti-slip system of the hangers
  • Removing asbestos from hanger collars and replacing fixing bolts
  • Adjusting the loads in the hangers
  • Replacing the expansion joints
  • 2,460
    Length of carrier tendon treated for corrosion protection (ml)
  • 62
    Number of hangers removed for treating the collars
  • 31
    Number of jacks used simultaneously for adjusting the structure
  • 220
    Total weight of the scaffolding installed on the structure (tons)
Scaffolding structure of the bouchemaine bridge
Scaffolding structure of the bouchemaine bridge

Scaffolding covering the entire suspension bridge

The works required the installation of a complete scaffolding on the entire structure in order to access all the suspension elements. Its installation was very complex given the need to work on and under the structure at the same time. For this, fixed scaffolding as well as suspended platforms were used throughout the work. This configuration forced the site team to organise themselves methodically as the bridge was to remain open to traffic during the works, keeping a centred lane on the structure.

Freyssinet has the ability to deliver remarkable performance on structures that are as complex as they are historical. Let’s be proud of the resources and opportunities that our company offers us to conserve this beautiful French heritage.

Christophe Houix -  
Freyssinet France, Sales team leader

Custom-made solutions

Drawing on our extensive knowledge and experience in this field, our teams imagined new solutions to face the different challenges of this project.

Temporary hangers on the Bouchemaine bridge

1. Anti-slip system

The anti-slip system of certain hangers was in an advanced state of corrosion and no longer fulfilled its intended role. Freyssinet designed and manufactured a new system based on specific fittings that prevent the hangers from slipping on the cables. 

2. Temporary hangers

The restoration of the hanger collars required the hangers to be completely dismantled with a custom-designed load bearing system. This system consisted of temporary hangers, attached to the carrier tendons and under the deck of the structure. To release an existing hanger, it is necessary to install two temporary hangers positioned on either side of the existing one, halfway between two hangers.

3. Suspension bridge structural adjustment

The loads in each hanger were checked and adjusted to ensure the correct functioning of the structure. This operation, carried out at night to benefit from the interruption of traffic, was the critical point of the site. To achieve that, we designed and manufactured especially for the site a system for attaching the jacks to the deck, optimised as much as possible to limit the impact on the existing structure.

4. Collar cloning

While reassembling one of the hanger collars, it broke into two due to a manufacturing defect. The site team was able to respond quickly by proposing to manufacture a new collar identical to the existing one, by mobilising many internal sizing and design resources.

Thanks to its prompt responsiveness, Freyssinet was able to deliver the site according to the initial schedule.

Bouchemaine bridge overview at sunset

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