HNTB performed independent design review and verification for the Istanbul Strait Road Tunnel Crossing through the Bosphorus Strait.

Linking the Asian and European sides of Istanbul, the project was challenged by the area’s varied geology and propensity for earthquakes, high pressure below sea level, and the tunnel’s large-diameter/double-deck lane configuration.

HNTB’s experience with large-bore tunnels helped delivered significant value through:

  • Detailed seismic analysis, which helps ensure minimal ground movement and maximum stability/safety during construction and after the tunnel is open
  • Time management and efficiency, allowing the tunnel to go into operation 55 months after the contract was executed
  • Funding models, providing a blueprint for future infrastructure projects in Turkey

The completed tunnel will ease traffic congestion by carrying 100,000 vehicles daily, reduce travel time across the strait from 90 minutes to fewer than 15 minutes, and deliver economic benefits by better connecting the region.

  • Detailed seismic analysis promotes safety
  • Experience keeps project on schedule
  • Traffic congestion and travel time decrease, economic benefit increases

Location: Bosphorus Strait, Turkey