Security work on the Sentier des Falaises and the Sentier de Sous-Terre will begin on 16 February 2023. Scheduled to be carried out in two phases, the work will be completed by the end of the year. The aim is to protect these footpaths from landslides and rock falls, which are becoming increasingly frequent. The Sentier de Sous-Terre was closed earlier than planned on 27 January 2023.
The Saint-Jean cliffs site is a key concern : very busy footpaths, a forest environment to be preserved and the need for the City of Geneva to protect the paths against landslides.
The Sentier des Falaises is located along the right bank of the Rhone, between the Pont de Sous-Terre and the Viaduc de la Jonction.
This site has long been known to suffer from unstable land. Since 2007, the City has been forced to intervene on several occasions in order to keep the footpaths open and secure for the population. In recent years, events such as rock falls and landslides have become more frequent.
Work to make the footpaths secure
Major work will be carried out throughout 2023 to add new protective nets, repair and strengthen damaged nets, add protective barriers and consolidate the retaining walls. The covered gallery close to the pumping station will be demolished and replaced by an open-air walkway.
This work follows a geotechnical study of the entire area. It is intended to ensure that the population continues to enjoy access to the Rhone and the surrounding nature while protecting the Sentier des Falaises and the Sentier de Sous-Terre from landslides.
A two-phase process
The work schedule takes account of the popularity of these busy footpaths among the local population. The phasing of the project includes a summer opening period allowing local residents and the general public to take advantage of the site.
The first phase of work, which will involve clearing the areas necessary for the work to be carried out, will being on Thursday 16 February 2023 and will, in theory, continue until 24 February 2023.
The second phase will involve the structural work to make the paths secure. It will take place between April and December 2023, and will include a summer break
Le calendrier des étapes est consultable dans le communiqué de presse:
Phase one: land clearing
The first phase of work will take place from 16 February to 24 February (subject to change). It will involve performing the land clearing work strictly necessary to the completion of the work.
These operations can only be done in winter. During this work phase, the Sentier des Falaises will be closed to the public during the day on week days. The Sentier de Sous-Terre will remain entirely closed as is currently the case.
A precise census has been carried out of the largest tree trunks, for the most located at the top of the cliffs, and they will have to be evacuated by helicopter due to the difficult access to certain sectors of the cliffs and to ensure the preservation of the forest environment.
This is the only way to guarantee the security of the workers and the protection of the surrounding trees.
The trunks will be taken to Bois de la Bâtie on the other side of the Rhone and recycled by the Parks and Gardens Service (SEVE). It should be noted some of the remnants (trunks and branches) will be left on site by the lumberjacks so that they can decompose and serve as a refuge for the local wildlife. It is planned to reopen the Sentier des Falaises to the public on 25 February until the end of March, if all the land clearing work has been completed as expected. The Sentier de Sous-Terre will remain closed until the summer.
Phase two: structural work
The second work phase will involve structural work and the installation of nets between early April and December 2023. During this period, the two footpaths will be closed to the public, except during the summer.
Sentier des Falaises
The protective steel nets already in place will be repaired, modified or extended, depending on the sectors. Certain protective barriers already present will be replaced and others will be added. This work will also provide an opportunity to repair a section of the footpath.
Downstream end of the Sentier des Falaises
The covered gallery linking the pumping station and the path will be partially demolished and a walkway will be created to maintain the route. About 30 metres long, this gallery has suffered serious damage. The concrete in the structure has been turned to carbonate and the steel has been highly oxidised. A new open-air path will replace this structure.
Upstream end of the Sentier des Falaises
The retaining wall located upstream of the play area is shown signs of fissuring and has had to be protected by a temporary fence. The retaining wall is beginning to open and will gradually reach breaking point. The repairs to the wall will include the installation of a protective mesh.
Sentier de Sous-Terre
The installation of metal nets will make it possible to remove the temporary wooden cover. The retaining wall will also be consolidated.
Sentier du Ravin
The measures necessary to ensure the security of the Sentier de Sous-Terre will extend to the cliff and the retaining wall bordering the Sentier du Ravin.
A credit application was granted in 2016 in order to conduct the studies and large-scale work necessary to secure the cliffs, totalling CHF 3,086,300, incl. tax. The building approval was obtained in September 2022.
The City of Geneva would like to thank the residents and walkers for their patience while this work is being carried out. The public is asked to respect the ban on entering the work zone due to the risk of accidents present at all times.
Contact
Département de l'aménagement, des constructions et de la mobilité - Direction
Anaïs Balabazan
Déléguée à l'information et à la communication
Article modifié le 20.02.2024 à 11:34