Riva Tunnel, Turkey

Project type:

  • Road tunnels


  • Final lining


  • Owner: Ministry of Transport and Infrastructure
  • Contractor: IC İçtaş & Astaldi JV

The Riva tunnel is a 562 m (1844 ft) long 4-lane carriageway tunnel located in northeast of Istanbul, Turkey. Measuring 22 m (72ft) in diameter, it has one of the biggest cross sections of all tunnels in Europe. The tunnel is part of the North Marmara Motorway project (NMH / KMO) that consists of two twin tube tunnels.

The challenge

The biggest challenges in creating the final lining for the tunnels was the large size of the cross sections and the limited construction time required. Installing traditional reinforcement in a tunnel this wide would have been not only time-consuming, but also very risky.

The solution

To ensure optimal reinforcement, contractor IC İçtaş & Astaldi JV used C30/37 concrete reinforced with 20 kg/m³ of Dramix® steel fibers 5D 65/60 BG. By replacing the traditional steel cages with steel fiber reinforced concrete, the contractor was able to finish the project a lot faster and easier. Over the course of two and half months, 15750 m³ of concrete was cast over 540 m (1772 ft) of tunnel sections. Dramix® 5D 65/60 BG steel fibers resisted calculated load, increased fire resistance and durability.