Groundforce have provided a temporary propping solution to main contractor Eiffage for the construction of a new underpass to allow easier access for traffic to the town of Molsheim in the Bas-Rhin region of France.
At present, the only access to Molsheim is over the PN20 level crossing, despite the construction of a bypass in 2008. Road traffic remains extremely heavy - a total of 16,000 vehicles, including 500 heavy goods vehicles, use the crossing each day and approximately 128 trains per day travel over the lines.
This means the barriers are closed for a total of almost three hours a day, which is why level crossing PN20 was one of the 50 top-priority level crossings in France for redevelopment to help reduce road congestion. The nearby presence of numerous schools, Molsheim station and cycle paths also generate significant volumes of pedestrian and cycle traffic.
The cumulative effect of all this traffic led SNCF Réseau, who manage French rail operations, to decide to close the level crossing and replace it with a road tunnel. The decision was supported by the French state authorities, the Bas-Rhin departmental council, Grand Est regional council and Molsheim town council.
Eiffage approached Groundforce to supply a support solution for the tunnel entrance and a total of 43 hydraulic props have now been delivered. These include MP50, MP150 and MP250s, plus Mega and Super Mega waling beams, along a total length of 141m.
Work on the closure of the level crossing started in June 2017 and is due to complete this spring .
The project consists of installing a 200m tunnel approach made up of 400m of diaphragm walling descending to a depth of 14m. With 200m of floor slabs measuring up to 1m in thickness the total area covers approximately 4,500m3.
Three temporary decks with rail tracks were laid by Eiffage August 2017 to allow rail traffic to continue to operate while works continued underneath in preparation for the new permanent concrete decks to be installed to support the new rail tracks. These were prefabricated off-site and installed in March 2018.
The excavation to build the new rail decks between the walls and under the Groundforce props covered an area of approximately 2,200m3. This part of the project was completed in September 2018.
“Using Groundforce’s hydraulic props offered numerous advantages, such as increased safety when installing and removing the props, plus time-savings,” said Nicolas Farges.
“Eiffage pays very close attention to safety, it’s one of our top priorities. The safety criterion was decisive in the choice of this process due to the reduced number of handling operations and installations which is far less complicated than the so-called “traditional” solution.”
Groundforce also provided onsite support for Eiffage GC by sending one of their technicians to train the teams in the installation of the hydraulic props and the waling beams.
“Groundforce is an equipment supplier but we are also a service company. We often work with clients at early design stages, and the challenges presented by this project further demonstrate Groundforce’s expertise when it comes to working on large infrastructure projects." said Albert Marini, engineer for Groundforce.