FRANZETTI CI is a stakeholder in this project!
The Abidjan underground system is set to transport 180 million passengers per year as of 2028 and will revolutionise and streamline urban transport in this city.
The project, which crosses the city along its existing railway, is of course generating numerous works orders, in particular those linked to the transfer and protection of utility networks located in its future passageway.
The Line 1 project
This line adds to existing services which do not adequately meet the strong demand for transport between the various municipalities of the Abidjan Autonomous District. In addition to improving traffic flow and quality of life thanks to the extension of public transport, it should reduce air pollution and noise, as well as the vehicle accident rate.
37.4km of network – 18 stations – 540,000 passengers per day
A first order for FRANZETTI CI
As part of this project, the sewer mains in the Marcory area must be rerouted along some 3km. This order was entrusted to the Bessac – Spac – Egis – Franzetti consortium by the Société Ivoirienne de Construction du Métro d’Abidjan [Ivory Coast Abijdan Metro Construction Company] (SICMA) and the Ivory Coast Water Distribution Company (SODECI) as project manager.
The order consists in:
- The temporary rerouting of wastewater networks (400mm-diameter), to be executed in 5 months;
- The definitive rerouting of the existing mains (1,800mm-diameter) by microtunnelling under the railway, to be executed in 18 months;
- The filling of the existing mains.
Discharge rerouting works
The aim is to intercept discharges upstream to ensure the continuity of network services for the duration of the works. Interception chambers with temporary pumping (4 pumps operating in series) will be connected to a 400mm-diameter steel pipeline, laid overground along the entire network.
Two upstream and downstream fronts will be opened, each manned by 5 joint SPAC/FRANZETTI CI teams to ensure the scheduled advance of 30m per day per team.
Railway crossings will consist in either aerial feedthroughs (gantries), the use of stormwater pipelines or trenches. Traffic diversions will be implemented and night works scheduled to avoid colossal traffic jams.
These works are located in squat areas which are regularly reoccupied. The teams will ensure support for local residents on a daily basis. Furthermore, certain areas in the vicinity of the railways are open landfills which require additional precautions prior to operations.
Mains rerouting works
As the underground plan runs along the existing railway, which is to be raised, deep foundations must be dug. Given the high risk of damage to the existing mains by these foundations, the decision was made to replace this facility by new mains, built by microtunnelling and located outside of the works zone.
Works will consist in 6 diaphragm wall shafts (3 leading and 3 exiting) located every 500m, including one at a depth of 8m and the subsequent at 15m. Phasing as follows:
- Building of shaft n°5 (the furthest downstream), followed by exit shaft n°6 which will later be transformed into a lifting station
- Connection of shaft 5 to shaft 6 during the digging of shaft 4
- Connection of shaft 5 to shaft 4 during the digging of shaft 3
- Connection of shaft 3 to shaft 4 during the digging of shaft 2
- Connection of shaft 3 to shaft 2 during the digging of shaft 1
- Connection of shaft 1 to shaft 2
During this phase, FRANZETTI CI will build the platforms, leading and exit shafts, in addition to the reception facilities. Digging of the shafts will begin in July 2023.
Points for attention
The presence of the water table at 1m requires water management in terms of structures and the waterproofing of the facility, with geotechnical and waterproofing tests.
The railway is to remain in operation, requiring the implementation of all security measures related to operations in the vicinity of railways in use.
FRANZETTI CI is proud to play a role in this major infrastructure project for the benefit of the population. This structuring project for Abidjan will lead to other orders for FRANZETTI CI. Two initial orders are already under way in Adjamé and Port Boué. And there will be more to come!