Ankara Metro
Ankara's infrastructure planners go about upgrading the city's metro system with several new lines in adition to the two existing lines "Metro" and "Ankaray". The route for the Line M4 runs with overburdens of between three and 22 meters under roads, bridges, and buildings mainly in clay and tuff. It will connect downtown Ankara with the northern suburbs. The underground section was excavated by a Herrenknecht EPB Shield with a diameter of 5,950mm between March 2006 and June 2014.