RN57 - Securing of cliffs at La Cluse-et-Mijoux (25)

Work on securing the cliffs along the RN57 in the Combe de Joux area (25) will take place from Monday, 13 April to Friday, 24 July 2026.

Objectives of the works:

• Protection against rockfalls upstream of the road.
• Replacement of a drinking water pipeline dating from 1900, located beneath the RN57.
• Road surface reconstruction and maintenance of road equipment.

Funding:

• Total amount: 1.6 million euros.
• 1.1 million euros for cliff security, funded by the State.
• 0.5 million euros for road surface and maintenance works.

Work schedule:

Phase 1 (16 March – 10 April 2026):

• Renewal works on the drinking water pipeline at the sawmill parking and the Fourgs crossroads.
• Two-way traffic maintained, with reduced lanes and speed restrictions.

Phase 2 (13 April – 24 July 2026):

• Closure of the RN57 in the Switzerland → France direction, between the Hospital diversion and the Château de Joux inn.
• Traffic maintained in the France → Switzerland direction.
• Implementation of categorical diversions:
• Light vehicles: via Oye-et-Pallet.
• Heavy vehicles < 3.9 m in height: via Oye-et-Pallet.
• Heavy vehicles > 3.9 m in height: via Frasne.
• Works for cliff stabilization (620 m of rockfall protection nets) and renewal of the drinking water pipeline.

Phase 3 (31 August – 11 September 2026):

• Closure of the RN57 only at night (19:00 to 05:00), in both directions.
• Categorical diversions implemented in both directions.
• Road surface reconstruction and equipment maintenance.

Specific measures:

• Fixed signage from the Hospital diversion.
• Height restrictions on the RD437 to limit access for heavy vehicles > 3.9 m.
• Dynamic signage with height detection on the RD437 upstream of the Rosiers intersection.

Access to Château de Joux:

• No impact on the schedule.
• Access possible via usual routes, following diversions if necessary.