No time for error

Author: Vincent Bertheau, May 2016 

Four days, 96 hours - this was all one French contractor was given to complete the monitoring and guiding operations during a major railway bridge shift project. Authorities could only allow for a major train route to be out of service for four days before causing significant strain on the country’s transportation system.

SCP Bertheau Saint Criq, a chartered surveying firm with extensive experience in rail operations, was hired by the project surveying company on record, civil engineering company GTM Sud-Ouest, to ensure the Toulicou Bridge in southwest France safely underwent several repositioning procedures to move 47 metres to its final location. The undertaking wouldn’t be easy as the bridge measured in at 75m long, 12m wide and 9m high.

The Toulicou Bridge was built between February and October 2014 to provide a safer crossing for the RN21 train between Tarbes and Lourdes. The bridge was constructed at 47m away from its final location, resting on a concrete slab. The existing track portion of the Toulouse-Bayonne railway needed to move for better maintenance of the line.

A long working weekend

From 7 to 10 November 2014, several tasks had to be completed to ensure the Toulicou Bridge was shifted to its new location in the short time the Toulouse-Bayonne train would be out of service. First, the railway tracks of the bridge had to be removed along with the overhead lines. Next, the existing embankment slope had to be levelled to accommodate the bridge plus another slope had to be created. After the shifting was completed, the tracks needed to be replaced. Finally, a concrete wall had to be poured.

To accomplish all this on such a tight deadline, 200 people were mobilised on a scheduled that covered 96 hours:

• 15 hours for the removal of the track and overhead lines
• 26 hours of earthworks
• 13 hours of skidding
• 9 hours of filling
• 31 hours of replacing the catenary

Between the interruption and restart of the circulation for the construction accounted for two more hours.

If everything went to schedule, the bridge would be ready for turn over to the customer one hour before deadline.

Explore next chapter: Ensuring a smooth shift

Story: No time for error
Chapter 1: A long working weekend
Chapter 2: Ensuring a smooth shift
Chapter 3: Automating for accuracy