Shani Wallis, TunnelTalk

Cairo Metro - Line 3 will link to the airport

A new EPBM capable of converting to a slurry system is on order for a new section of the Cairo Metro in Egypt. To be supplied by NFM Technologies, the 9.46m diameter machine will work on the Line 3 Phase 2 contract awarded by Egypt's National Authority for Tunnels (NAT) to a JV lead by Vinci of France and comprising Bouygues, also of France, and Egyptian partners ARABCO and ORASCOM. The new €323 million (US$463 million) civil engineering contract that includes detailed design, covers the next 7.2km section of Line 3, extending the Line's first phase which is currently under construction by the same consortium. The French-lead JV has worked consistently on the city's metro construction since building the first line in the early 1980s.

The new NFM machine will be the first EPB machine used on the metro. To this point, bored tunnelling on the system has been completed using a slurry TBM system. Cut-and-cover carries the service under the central city district on Line 1 and for the underground works on Line 2, the JV consortium introduced a Herrenknecht Mixshield to excavate the large diameter single-tube, double-track running tunnel of the underground sections, including a crossing under the Nile. The same Herrenknecht slurry machine is currently completing the 4.3km for Line 3 Phase 1, with about 1.2km left to excavate before final breakthrough. To date the Herrenknecht Mixshield has excavate about 20km on Lines 2 and 3.

For Line 3 Phase 2, the alignment runs through material that is better suited to EPB excavation. The 5,138m of 9.46m o.d. tunnelling to link top-down station excavations at Cairo Fair, Stadium and Kolleyet El Banat passes through mainly clay, sand and sandstone. An EPB machine was needed, even had the JV's slurry system been available for the contract.

There is however, a risk of running into material unsuitable for EPB excavation. Additional soil investigations for the contract is ongoing and will last several months, but the machine order requests that the new TBM be capable of converting from EPB to slurry mode. "It may not be necessary on this Phase 3 contract," explained Rémy Roussel, Project Manager for the JV in Cairo. "If needed the conversion would take about two months to achieve and would be managed with the TBM in an excavated station box or shaft. The possibility of converting to a slurry system will also be available for a future project."

With the order for the EPBM, NFM will supply all the equipment needed for the conversion and the NFM technicians needed to oversee the work. The new machine will be manufactured at the NFM Le Creusot plant in France and be ready for shipping to Cairo in June next year. The order includes the conception and design of the machine, as well as the manufacture, assembly, tests in the factory and on-site, plus part of the transport. The order does not include a separation plant.

Cairo's Metro currently comprises two main lines. Line 1 was built by VINCI in the early 1980s and now carries more than 2 million passengers a day. The second line, at 22km long and with 20 stations, 12 underground, was opened in the 1990s and carries 1.8 million passengers a day. When complete Line 3 will have 29 stations on its 33km length across the city from east to west and will provide a link with Cairo airport. Phase 1 of Line 3 by the JV is more than 60% complete and is scheduled to open in October 2011.

The Phase 2 section with its four underground stations is scheduled for opening in October 2013 after 51 months of works. As part of a separate consortium, Vinci's subsidiary Eurovia Travaux Ferroviaires, has won the €20 million contract for the Phase 3 track and power installations, supplying and laying 14km of track and power rail in the tunnel. Station finishes and M&E installations are also under separate contract but awarded to another group in which the civil partners are joined in consortium.

A further Phase 3 of Line 3 will extend the line by 7.5km west with another crossing under the Nile and with a 3km long underground side branch with another four underground station. Phase 4 will carry Line 3 the final 11km, mostly underground, to the international airport. If the French-led JV was to prove successful in bidding Phases 3 and 4, the Mixshield would continue into Phase 3 and Roussel confirmed the NFM TBM would continue into excavation of the underground sections of Phase 4 towards the airport.