Line E of the Toulouse tramway has been operating since 2010. Works for extending this line to the southern part of the city and the airport started in early 2012. This new line, called the G as for “Garonne”, is expected to transport 30,000 passengers per day and is planned to be inaugurated in spring 2014.

The project of the new G tramline has been appointed to Bouyges TP. This project includes the installation of 3.4 km of rails and the construction of 6 new tram stations, initiating in the “Arènes” station up to the “Gran Rond” station. In one part of the path, the tram will pass over the Saint Michel Bridge. To allow the safe installation of the rails on the bridge, the bridge piers needed to be reinforced.

The contractor, DFC Battage, has been chosen by Bouyges TP to do the reinforcement works needed on the bridge. For this work, DFC Battage has decided to use the PTC Vibrodriver 4PHF. Its driving power combined with its compact and light body offered the best solution to undertake the job.

Vibrodriver 4PHF reinforcingthe « Saint Michel » bridge piers, France.

Phase 1 : Sheet pile Wall

Due to the reduced space available underneath the bridge, The 4PHF Vibrodriver equipped with Agriplex clamp (40t) had to be mounted in a small 8 ton excavator. As this excavator does not have enough power to operate the Vibrodriver, a PTC power pack was required.

The equipment was mounted on a barge to drive GU 6N Arcelor Mittal hot rolled sheet piles to a depth of 6.5m. This sheet pile wall was built with the help of a floating guide frame and its total length was 58 linear meters. When the sheet pile wall was finished, concrete was poured between the wall and the bridge pier. Sheet piles were left in the ground.

Phase 2 : Cofferdam

Due to local scour around the bridge pier No. 3, the upstream side of the pier had to be reinforced. To do this, DFC Battage again used the 4PHF Vibrodriver installed on the barge to build a cofferdam around the bridge pier. This cofferdam was constructed with PU12 sheet piles and its total length was 39.6 linear meters.

When the cofferdam was ready, a team of divers poured concrete inside the cofferdam. This was done to make a water-resistant area and to pump the water out, allowing for Pier reinforcement works. When this work was finished, the sheet piles were cut at the concrete level and left in place.

KEY FACTS

• Client: Bouyges TP.

• Contractor: DFC Battage.

• Sheet pile wall:

- 6.5 m deep.

- 58 m linear meters.

• Cofferdam:

- 5.5 m deep.

- 39.6 linear meters.

PTC - Job report - Excavator mounted piling

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