The one-way tunnel will start from Blvd Jardin Exotique (near the gardens), after incoming traffic has turned off the Moyenne Corniche to enter Monaco, and snake down in a wide circle to Blvd Charles III where traffic enters the Principality via the coastal route, the Basse Corniche.

Referred to as the tunnel descendant (descending), as opposed to its ascendant twin which opened in 1993, its progress has been complicated by the fact that while it starts and finishes in Monaco, a large section goes through French territory. Because of the steepness of the gradient, the tunnel takes a wide arc to achieve its goal 1.7 km later near the entrance to the cemetery. This involves excavating under around 40 different properties in the neighbouring Cap d’Ail and La Turbie municipalities in France.

The depth of the tunnel will vary between 20m and 200m. The project is scheduled to start in September 2010 and take about four to five years to complete. CL