İstanbul İkitelli-Olimpiyat Köyü cut & cover tunnels about 2000 meter lenght 20-30 meter buried have been designed. Tunnels are box type and width and height varies according to track line and soil profile. As soil profile changes from top to down, the excavation and bracing type varies. Fill layer design and excavated with slopped open trench. Limestone or stiff layer braced with soil nailing and anchored piles. There are eight structurally different types of tunnels including double floored type. Tunnels divided into 36 meter lenght blocks with expansion joints to avoid thermal expansion forces.