A joint venture led by Dywidag International has been awarded a contract to extend partly underground Line 1 of the metro in the Algerian capital, Algiers.
The contract calls for 4km of new route, more than half of which will be underground. Work has already commenced on site for the project though clearance for the approximately 32-month project is anticipated by September.
Construction of the 2.7km long single bore tunnel for the metro line is to be executed by the New Austrian Tunnelling Method (NATM), said Dywidag’s parent group, Strabag. Four box stations are to be built by cut and cover for the project.
Geology along the route comprises three main strata: young glacial sediments with cohesive characteristics; below is molasses with sandy, clayey deposits, and groundwater level at 15m depth; and, the deepest layer is homogeneous, impervious clayey marl.
The NATM drives will proceed from two shafts, which are expected to take about four months to sink. Tunnelling is to commence in February 2009 and it is expected that three, possibly four, faces will be excavated at peak. Cover to the excavations, which have a 63m2 cross-section, will range from 7m to 26m.
The excavation with primary lining is to be finished by March 2010, then another year is planned for the final lining. The primary and secondary linings will have a combined thickness of 400mm. The tunnel will be sealed by a grout umbrella, membranes and a concrete invert.
The €252M (US$390M) contract involves construction of the underground and surface sections, the four stations, and bridges over a road and a river. The entire project with its tight schedule is one of the largest and most complex in the country, said Strabag.
Dywidag is the majority (51%) partner in the German-Algerian-Italian JV, which includes partners Cosider and Trevi. The firm has an office in Algiers. The local economy is becoming more active, with consequent increased traffic and movement of people, as the country benefits from development of oil and gas reserves.
The capital plans to build three metro lines with a total length of 56km and 54 stations. To date, approximately 8km of route has been constructed with eight stations.
