Paravalanche Gallery – Natural light at the service of road safety for mountain bikers

Avalanche road tunnels are dark passages that are potentially dangerous for cyclists. At the initiative of the CETU and Nature et Confort, Espaciel has implemented an original solution for the department of Haute Savoie, in partnership with Alpes Ecologie.

Tour de France cycling peloton on a mountain road – Photo Rob Wingate



  • Contracting authority: Department of Haute Savoie
  • Type of building: Avalanche road gallery
  • District : Glières – Val de Bornes (74)
  • Openings : Reinforced concrete arches
  • Space to be illuminated: Road and bike path
  • Model Espaciel installed : Special installation

Configuration and solution search

When I was creating Espaciel, if I had been told that I would have to work on the lighting of a work of art, I wouldn’t have believed it. Here is an original application of the Espaciel reflectors that was imagined by the CETU (Centre d’Etude des Tunnels) and Nature & Confort for the Haute Savoie department.
The idea is to illuminate the dark interior of a paravalanche gallery using Light Reflectors. The aim of this equipment is to make traffic in the gallery safer, especially for sporty cyclists who ride along mountain roads.

Example of a very dark paravalanche road gallery on the mountain side of the road while the valley side is illuminated

Espaciel intervened to design a complete solution integrating the supporting structure, the Reflectors and the means of adjustment and fixing. Each Reflector module is composed of 4 Reflectors of 50 x 100 cm which constitute giant Reflectors of 100 x 200 cm.

Cyclists may be confronted with risk situations related to lack of visibility – Photo Victor Xok


Solution implemented

The solution consists of two rows of Reflectors: a row of Primary Reflectors, under the sky, outside the avalanche gallery and a row of Secondary Reflectors inside, under the gallery ceiling. The optical design office Ingelux was commissioned to optimize the effects of this lighting concept by redirecting natural light. A numerical modeling was carried out to adjust the placement of the Reflectors and their optimal angular adjustment. Ingelux is also planning a follow-up over a whole year using cameras installed by the company Degeneve.

Schematic diagram of the Reflectors: primary in front of the openings and secondary in the road gallery – Infographie Espaciel

Espaciel brought an innovative solution of fixing and implementation allowing an installation with traditional means of building site, without resorting to cordists of the building. This is a guarantee of ease for the later maintenance of the structure as well as for the repetition of this device on a larger scale on other avalanche barriers of the same type.

The company Call Help completed the system of Light Reflectors by painting a part of the Paravalanche (mountain side) white to diffuse the luminosity even more.

The project’s contributors : project management, project management and companies – Photo Nature & Confort

Results Achieved

The brightness on the road in the avalanche gallery is significantly improved. Following the installation of the Espaciel Reflectors by Alpes Ecologie, the bicycle path seems to be materialized by natural light. It is very impressive to see the result when only sky light is used. Indeed, the potentially dazzling sun rays have been suppressed as much as possible by the position of the Reflectors themselves.

This project is a world first that shows the unsuspected potential of daylighting technologies using light redirection. Espaciel is proud to have taken part in this adventure and hopes to teach it to other sites.

Sous leUnder the avalanche, the bicycle path is drawn on the ground by the natural light reflected by the Espaciel Reflectors – Photo Nature & Confort 

Before / After effect

The brightness gain with and without light reflector is impressive in the avalanche – Photo Nature & Confort

Passage of the Tour de France Cycling 2020

This amazing and efficient project will be inaugurated by the Tour de France 2020 on September 17. The paravalanche is on the route of the Méribel / Roche-sur-Foron stage.

A solar event, the Tour de France catalyzes energies throughout the country – Photo L’indépendant


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