Wayss & Freytag using Herrenknecht 6.5 m shield completed first 550 m in very unstable soil consisting of sand, silt, clay and gravel using bentonite and foam. Another 550 m tunnel and two at 800 m to be driven. Best advance 25 m/day. June 1998.

Second section in two parts: 3.2 km line through stations at University and Bornova involves 836 m tunnel, 1,480 m cut-and-cover and 715 m at surface; alignment through stations at Bahceliever, Haimevieri, the Islamic Institute, Poligone and F Altay involves 2.19 km of double-track tunnel with internal diameter of 11.8 m to be driven through andesite using NATM techniques. March 1999.

Prequalification for phase two cancelled and sent back to the drawing board. Plans now involve constructing just the section from Bahceliever to F Altay which now will comprise a 1.35 km bored tunnel and 2.85 km cut and cover, subject to detailed design. New prequalification planned for May, 2000. October 1999.

General contractor Yapi Merkezi reports completion of 11.5 km first stage with ten stations from Ucyol to Halkapynar including the workshop and depot area in less than four years. $600 million contract was handled on a turnkey basis by Adtranz-Yapi Merkezi for Municipality of Greater City of Izmir. Five of the stations and 5.8 km of the line are underground. The stations at Konak, Cankaya and Basmane were constructed by cut-and-cover 10-13 m below sea level using 25-33 m-deep diaphragm walls. The Ummuhan Ana twin tunnels of driven length 2.75 km were in waterlogged ground comprising sands, silts and clays. They were constructed by the Herrenknecht 6.54 m EPB using a VMT guidance system and lined with 1.2 m-wide, 5.7 m elastomeric-gasketted precast concrete 7 + 1 rings. Average advance was 19.2 m/day on the fourth drive with a maximum of 28.8 m or 24 rings in 2 x 12 h shifts. Measured settlements were less than the 10 mm allowable. Foam and bentonite injection was available on the machine. More from www.yapi-merkezi.com November 1999.