ANKARA RAPID TRANSIT

This article describes the design and construction of Phase 1 of the metro system at Ankara, Turkey, and includes a route map. This line will cover 14.6km from Kizilay Square in the centre to Batikent in the north west suburbs, and is due to open in March 1997. It is a twin- track line with twelve stations, of which five are underground, five in open cut, and two elevated. There are 3.15km of bored tunnel, 3.95km of cut-and-cover, 1.56km of open cut, 2.57km of at-grade route, and 3.44km of elevated route. Due to the dry ground, four of the five cut-and-cover stations have been excavated without diaphragm walls by tangent piling to below invert level; rock anchors and temporary struts will maintain stability until the roof slabs are cast. Due to its huge size, Kizilay station is being constructed top-down, using four parallel 38m deep diaphragm walls along its length and across its ends. All the bored tunnels will be driven using a purpose-built Lovat M232SE 5.92m diameter earth-pressure-balance (EPB) machine. A reinforced concrete segmental lining, consisting of six tapered segments, is being erected within the machine's tailskin.