Lyon: Croix Rousse Tunnel, a first worldwide

6 December 2013 - Events - France

Created as a second tube of the existing road tunnel under Croix Rousse, a hill in Lyon, the tunnel reserved for soft modes of transport (bicycles and pedestrians) and buses has been officially opened.

Led by Dodin Campenon Bernard, a VINCI Construction subsidiary, the works were carried out by consortiums comprising Spie Batignolles TPCI, VINCI Construction France subsidiary Chantiers Modernes Rhône-Alpes, VINCI Construction Grands Projets, Cegelec and GTIE Transport. The design sub-consortium was made up of Setec et Architecture, Strates and Clément Vergély Architecte.

Opened in 1952, the Croix Rousse road tunnel is one of the main arteries through the city of Lyon. Used by 47,000 vehicles a day, it is 1.8 km long. Just as significant works were to be executed to upgrade the tunnel to the new standards imposed following the fire in the Mont Blanc Tunnel in 1999, the city authorities decided to seize the opportunity to innovate.

Its decision, a first worldwide, was to restrict access to the tunnel to cars and trucks and create a second tube for pedestrians and cyclists.

The new tube is 10 metres wide and consists of a cycle lane in each direction, a bus lane and a pavement for pedestrians. Particular care has been taken with the lighting, with the installation of a unique system that projects images onto the tunnel walls.

As soon as notification of the design-build contract award was received in the middle of 2009, the project communication strategy was organised. VINCI introduced the tools that have been used throughout the duration of the works. Nothing was left to chance: quarterly magazine, newsletters for neighbouring residents and businesses, SMS alerts to warn of explosions, meetings and coordination with the Greater Lyon municipality’s departments, educational actions and participation in consultation meetings with neighbourhood non-profit organisations. In addition, very sophisticated complementary geological studies were carried out before excavation work started to avoid any risks of cave-in. Around 100 sensors were installed which, together with the constant presence of geologists and land surveyors, allayed all fears.

The methods, too, were selected only after detailed discussions with neighbouring residents and businesses on the control of noise, dust, air quality and water discharges, without forgetting the change made people’s habitual routes. Sensors were installed in the area around the site to ensure that any noise caused remained below the required thresholds. In addition, to avoid excessive noise, screens and protective walls were erected. Similarly, air quality was checked regularly. To reduce gas emissions, a speed limit was imposed on trucks within the confines of the site. Extractor fans were installed to evacuate post-explosion fumes and the dust caused by drilling. Moreover, dust removal units filtered the air before it was released back outside. Prior to evacuation, water was treated to remove fine particles and polluting products were stored in retention tanks. All waste was systematically sorted.

Another special feature of this project is that it was carried out under a design-build arrangement, managed by VINCI from the design phase through to the execution of civil engineering and installation of equipment.

The project also enabled equipment suppliers to give full vent to their strengths by installing new-generation systems in the road tunnel. These included a lighting system that adjusts automatically to variations in the light outside, video surveillance comprising 200 CCTV cameras and an automatic incident detection system, fire protection system and the Greater Lyon tunnel information system (SITG). VINCI Energies subsidiary Axians installed a 2 km beam to which were fixed the projectors and sound system for the digital images displayed all year long for people using through this unique structure.