On February 7 local time, the “CREC 1294” TBM, the largest-diameter tunnel boring machine exported from China to Europe, successfully broke through the Sariyer–Kilyos Highway Tunnel in Istanbul, Türkiye.
The Sariyer–Kilyos Highway Tunnel has a total length of approximately 7 kilometers, constructed using a combination of conventional drill-and-blast and TBM methods. The TBM excavation section extends 4.8 kilometers, with a maximum overburden depth of 172 meters and a minimum horizontal curve radius of 190 meters, under complex geological conditions.
To address construction challenges such as great burial depth, high water pressure, and extensive in-tunnel equipment installation, China Railway Equipment Group, a subsidiary of CREC, custom-developed the “CREC 1294” earth pressure balance TBM. The machine features a cutterhead diameter of 13.65 meters, a total length of approximately 95 meters, and a total weight of about 2,850 tonnes. Equipped with advanced technologies such as continuous tunneling, it achieved a maximum daily advance of 33 meters and a maximum monthly advance of 550 meters during excavation.
The Sariyer–Kilyos Highway Tunnel is Türkiye’s first highway project constructed using a tunnel boring machine. Once completed, it will significantly reduce travel time within Istanbul, enhance connectivity and integration across urban areas, and effectively alleviate local traffic congestion.
