An innovative process for urban works

An innovative process for urban works



Constant adaptation. To meet the special requirements of diaphragm wall construction in urban areas, Soletanche Bachy revisited the conventional method used to build such structures.  In devising these solutions, its focus was on working in confined spaces, optimising tool performance and minimising disruption due to the works.


Soletanche Bachy developed the Cit’Easy®.

A special Hydrofraise® machine, the Hydrofraise® XS, was developed for urban diaphragm walls, which as a rule have moderate thicknesses and depths.

Requiring less space and consuming less energy than the conventional Hydrofraise®, the XS nevertheless offers equivalent or superior drilling efficiency. A new-generation mud plant is used in conjunction with this machine. It has three shipping container-sized modules that can be stacked and highly simplified connections between the elements.

The plant has a small footprint and takes very little time to set up. The Cit’Easy® process is not limited to a single high-performance machine set. New methods and a new production organisation have been designed to accommodate further tool development.



Construction of a diaphragm wall using the Cit’Easy® process as part of the RER A light rail line cover project in Nanterre, France


  • The Hydrofraise® XS was started up three days after it arrived at the site (compared to one week’s set-up time for a conventional Hydrofraise®)
  • The machine can operate from an 8 metre wide platform, reducing the volume of the platform to be provided
  • Optimised production compared to design, with 3.60 metre wide unit passes
  • 30% increase in instantaneous excavating efficiency