Sarens was entrusted with the complex task of transporting a tunnel boring machine (TBM) for the Grand Paris Express, one of Europe’s most ambitious infrastructure projects. The operation involved moving a 1.500-tonne, 100-metre-long TBM across a 700-metre distance, from its assembly platform to the starting point of tunnel excavation for Line 17 of the Grand Paris Express - led by the “Société des grands projets”.

This was no ordinary transport. The TBM of this incredible magnitude—comprising both the 1.000-tonne tunnel shield (boring head) and the 500-tonne trailer assembly—was moved as a single unit. Sarens, in collaboration with its client Razel-Bec, responded to the challenge with an ambitious and highly innovative engineering solution.

The operation began with the tunnel shield being lifted over 2,5 metres using the Sarens Climbing System CS250. Once elevated, 34 axles of Self-Propelled Modular Trailers (SPMTs) were positioned underneath: two sets of 17 axle lines at the front, and two sets of 10 axle lines at the rear, which were critical for braking control. Since the rear trailers were equipped with non-braking rollers, an additional SPMT was placed at the back to provide the necessary braking capacity, especially vital over a 300-metre stretch that included a 6% incline.

With this configuration in place, Sarens transported the entire TBM assembly, weighing 1.500 tonnes, over the full 700-metre route, including the steep incline. Once the destination was reached, the TBM was lowered back into position using the same CS250 Climbing System. The final 20 metres of the operation were executed using the Sarskid 400 system, a precision skidding solution developed specifically for controlled, exact placement.

The client, Razel-Bec, required that the shield and trailers be transported together in one operation. This approach was crucial due to tight project deadlines and the site’s challenging location at the end of a runway, which made traditional lifting methods impractical. According to Razel-Bec’s representative, moving the TBM as a single unit after completing all functionality tests was the most efficient solution to meet project timing constraints.

Key equipment used in the operation included two sets of 17-line SPMTs under the tunnel shield, each line capable of supporting 48 tonnes per axle, and two sets of 10-line SPMTs for braking at the rear. The Climbing System CS250 was employed for both lifting and lowering the TBM, while the Sarskid 400 system was used to finalise the placement.

This operation presented several unique challenges. It marked the first time a TBM of this size was transported in a fully combined configuration, demanding highly detailed planning and flawless execution. The need to move the full assembly in a single operation added pressure to deliver under a stringent timeline, while the 6% incline required additional safety measures to maintain complete control throughout the move.

Ultimately, the successful delivery of this transport brought immense value to Razel-Bec. It ensured the TBM could begin excavating a 6-kilometre tunnel leading to the future Charles de Gaulle Airport metro line, keeping the Grand Paris Express project on schedule.

Sarens’ role in this project exemplifies its ability to solve complex engineering challenges with bold thinking, technical excellence, and a commitment to pushing the boundaries of what is possible.