Bridge security
The task assigned by the Departmental Council of Loire-Atlantique was precise, namely to intervene as a matter of urgency and within a very short period to secure the bridge of Varades.
This was completed 2 months ahead of schedule!
This suspension bridge is 310 metres long and dates from 1952. Built to replace the bridge destroyed during the bombardments of 1944, it has been closely monitored for several years after the appearance of signs of fatigue in its suspension.
In early 2020, the Departmental Council of Loire-Atlantique issued an invitation to bid under an emergency procedure to make the structure safe.
The Baudin Châteauneuf (agent)/ Charier consortium was selected. Our solution: supporting the bridge by temporary pile clusters, a design/construction that consists in placing 12 temporary supports on the underside of the bridge.
The suspension is then released to lower the bridge onto these pile clusters.
One of the main difficulties was the time allotted to complete the works.
The bridge imperatively had to re-open for lorries of over 19 tons before end 2020, whatever the contingencies encountered (type of ground, level of the Loire river, etc.).
We managed it: the bridge re-opened 2 months ahead of schedule.
As such they bear the load of 300 t in overhead support.
The upstream and downstream piles are capped with a metal channel and balancing parts.
Baudin Châteauneuf then carried out the jacking operation designed to lay the bridge on this channel so as to restore its original capacities.
Another works phase to replace the cable stays will be done in due course.
This was completed 2 months ahead of schedule!
Project
- Client: Departmental Council of Loire-Atlantique
- Duration: 5 months
- Amount: €5.7 million
Distinctive features and constraints
- Urgent works to be completed within a very tight deadline
- Working on a high-risk structure
Making the bridge safe as a matter of urgency
This suspension bridge is 310 metres long and dates from 1952. Built to replace the bridge destroyed during the bombardments of 1944, it has been closely monitored for several years after the appearance of signs of fatigue in its suspension.
In early 2020, the Departmental Council of Loire-Atlantique issued an invitation to bid under an emergency procedure to make the structure safe.
The Baudin Châteauneuf (agent)/ Charier consortium was selected. Our solution: supporting the bridge by temporary pile clusters, a design/construction that consists in placing 12 temporary supports on the underside of the bridge.
The suspension is then released to lower the bridge onto these pile clusters.
One of the main difficulties was the time allotted to complete the works.
The bridge imperatively had to re-open for lorries of over 19 tons before end 2020, whatever the contingencies encountered (type of ground, level of the Loire river, etc.).
We managed it: the bridge re-opened 2 months ahead of schedule.
In technical terms
The foundation piles of the pile clusters (28m long and placed in pairs on either side of the bridge) were driven into the ground down to the rock at a depth of 15 m.As such they bear the load of 300 t in overhead support.
The upstream and downstream piles are capped with a metal channel and balancing parts.
Baudin Châteauneuf then carried out the jacking operation designed to lay the bridge on this channel so as to restore its original capacities.
Another works phase to replace the cable stays will be done in due course.
