The Oudayas Tunnel is part of the Bouregreg Valley development project in Rabat, Morocco's capital, being the solution of the heavily trafficked road dividing the two historic town sectors: the "Kasbah des Oudayas", the ancient fortress on the rock facing the Ocean and closing the river outlet, and the Medina, the tight and pulsing town's heart. The twin tunnel connects the river shore and the ocean coast passing underneath the Kasbah. The design considers the low overburden as well as the sea level, minimizing the effects of the hydrostatic pressure. The densely constructed surface and the narrow available corridors at the portals require two extremely close tunnels. Major project aspect are the ancient walls overhanging the riverside portal. These walls are temporarily stabilized through a steel scaffolding; they are then cut at the base, inserting a confining concrete beam resting on micro piles. The ancient structures are subsequently disconnected from their foundation for the excavation and the realization of the culvert upper slab. Finally the culvert is completed. At the end, the ancient walls will rest on the culvert, dismantling the temporary stabilizing structures.
The traffic conditions in Rabat, the capital city of Morocco are heavy. An urban development plan of the city was set up by the King of Morocco in order to improve the exploitation conditions of many interesting areas along the river next to the town centre, to ease the congestion of many crucial avenues, bridges and crossings as well as to make attractive the investment in real estates in this area. The agency "Agence pour l'Aménagement de laVallée du Bouregreg" (AAVB or the Agency) was created, by the name of the project, with the task to follow up the concept formulation, the design, the realization and the management during exploitation.