The digital infrastructure requires a fast deployment of optic fiber network. This demand is positive to the development of innovations in civil engineering, in particular cutting and making trenches. Within this framework, the CLEANFAST was finalized for a fast deployment of networks in urban environments. The deployment of network in micro-trench takes part particularly in a mechanized installation, which leads to a strong work pace and progress, and a big geometrical uniformity. What are then the various stages of the CLEANFAST process?

Maintaining a high deployment work pace (from 500 to 1000 linear meter a day) requires an important preparation, location and detection work in order to minimize the accident risk at the construction site. Thus, after securing the work area, a detection system called GEORADAR is used to examine the underground before any trenching activity.
The GEORADAR is a device that allows underground analysis in search for heterogeneous zones. Thanks to an antenna system able to emit towards the ground some radar waves to be reflected on the possible obstacles and then return back to the device, we obtain an image of the elements that constitute the ground until 2m depth.
All types of piping are detectable: Duct or wire cables, plastic duct (PEHD, PVC), concrete buzzards, clay buzzards, technical gutters, deep cuts, underground cavity, paved zones, woven wires…
With this technique, the GEORADAR operator can paint on the ground all the listed detected buried networks in order to avoid them at the trenching stage.

This technique is based on the use of an integrated machine, engineered to make a micro-trench with a  regular dimension and free of any debris. The trenching-suction unit is made of a truck which assembles all the  trenching and suction equipments. Opening the trench is made by a cogwheel that provides a dry trenching regardless of the underground category. This cogwheel is installed in a tight crankcase for soundproof and protection purposes. The wheel protection crankcase is connected to a power unit installed on the truck in order to suck up all the materials produced by the wheel trenching action. The truck carries a tight container storing all the trenching debris. This waste is either dumped or recycled.

This operation is very simple and is made in a short time, behind the trenching unit. The laying unit consists of a front wheel drive vehicle and its driver, a trailer and an operator to guide and assist in the ducts laying operation. A detection wire, attached to the ducts, is simultaneously laid down. It allows, afterward, locating the network in transverse, in longitudinal and especially in depth, assuring, thus, a better safety during later underground works on the same site.

The  CLEANFAST process includes a quick backfilling technique increasing the safety on the work site. Once, the ducts are laid down in the micro trench, the backfilling unit goes into action. It consists of a driving unit with hydraulic progress pulling on a well controlled speed the backfilling tool, and a cement mixer containing compacted cement materials.
The choice of the backfilling material was the object of an attentive conception in order to reach the following objectives:

• Quick backfilling and restoration of the road
• Preservation of the road foundations
• Reduction in building costs
• Manual future backfillings

The backfilling of the micro trench with specific cement materials helps for a quick restoration of the road. A later final repair operation with a cold milling machine is required in order to have a sufficient sealing condition of the micro trench and to preserve the road foundations.
In conclusion, the urban public road network  constitutes a favorable context to apply for new civil engineering techniques, such as the CLEANFAST process. The reasons are: quick network deployment process, limited disturbance to residents, a minimal  network depth of 30 cm allowing sufficient potential for everyday network maintenance, cleanliness  and preservation of the environment.