---
title: Tunnelling milestone on the Lyon metro
url: "https://www.systra.com/en/news/tunnelling-milestone-on-the-lyon-metro/"
type: post
date_published: 2021-06-10
date_modified: 2021-07-16
schema:
  @type: Article
language: en-US
word_count: 400
reading_time: 2 min
canonical: "https://www.systra.com/en/news/tunnelling-milestone-on-the-lyon-metro/"
featured_image: "https://www.systra.com/wp-content/uploads/2021/06/photo-tunnelier-coline-equipe.jpg"
---

# Tunnelling milestone on the Lyon metro

![Tunnelling milestone on the Lyon metro](https://www.systra.com/wp-content/uploads/2021/06/photo-tunnelier-coline-equipe.jpg)

This extension is a project that SYSTRA has been working on since 2015 on behalf
of SYTRAL, the authority responsible for organising urban and inter-urban
transport in the Lyon conurbation. When the line enters service in 2023, the new
automatic trains will carry more than 25,000 passengers a day on this extension
to the regional hospital complex.

Coline began digging in November 2019 at Saint-Genis-Laval, from where it
drilled the entire tunnel to the Orsel shaft, located not far from the current
terminus under the municipality of Oullins.

During the entire journey, the SYSTRA team monitored the construction phase of
the work as part of the Melyes project management team, led by Egis. The
dismantling of the TBM in the Orsel shaft is now underway, in a cramped space:
this shaft is also used for the ventilation of the existing line B, which cannot
be interrupted.

> In 19 months, Coline passed through highly permeable alluvial deposits, hard
> rock, and even limestone, which required constant attention to the control of
> the machine and the monitoring of the work. Digging went ahead without any
> major incident because Coline is a latest-generation variable-density TBM and
> uses innovative slurry specially designed for the project.
>
> Federico VALDEMARIN, SYSTRA’s Project Manager for the MBHLS Project (Métro B
> To Hôpitaux Lyon-Sud)

### Minimal impact on old buildings

The slurries, developed by the Implenia-Demathieu-Bard consortium, made it
possible to dig at a shallow depth under a very sensitive urban fabric, where
there are stone and rammed earth buildings.

The subsidence measured along the entire length of the urban area did not exceed
5mm, which is quite an achievement! In addition, the vibrations caused by the
presence of granite were kept well below the expected thresholds and
disturbances for local residents were reduced.

### Reuse of excavated materials

The tunnel boring project is a shining example of SYSTRA’s sustainable
development vision, thanks to the recycling of excavated materials which was
implemented by SYSTRA: 150,000 tonnes of the 400,000 tonnes excavated by the TBM
were reused on site, thanks especially to the recycling of sand in the tamping
mortar and the recharging of the tunnel with untreated gravel, saving the
traffic of more than 7,000 lorries and the use of surplus materials.

### Key features: TBM Coline and line B extension

- Variable-density TBM
- 120 metres long
- 9.75-metre diameter
- 2,200 tonnes
- 2.4km of tunnel dug
- More than 400,000 tonnes of excavated material