The intercontinental underwater tunnel that connects Kazlicesme on the Europe-an side of Istanbul with Göztepe on the Asian side, is 14.6 kilometers long of which 5.4 km is located below the seabed. Every day the road traffic takes over 2 million people over the Bosphorus Strait, causing significant congestion and noise. This challenging engineering venture, which lasted 55 months skillfully solved the infrastructure problems of the city, starting the operation on the Asian side five years ago and shortening the whole journey over the Bosphorus strait from former 100 to 15 minutes drive.

Given the importance of the project, investors wanted to mark the entrances and exits of the tunnel, and solve the architectural decorative lighting inside and on the approaches to the tunnel. Popular talismans the "Blue Eye" and Fatima's hand, which bring turkish people happiness and well-being, are the inspiration for the concept of the architectural decorative lighting. The lighting solution linear effects with shades of blue and white vary by floor level, but also the density of the light pattern through the tunnel is changing in three variations on the theme of interwoven lines.

Following the design of the decorative lighting the architectural concept was de-veloped in which the main theme is the arch, a historic building element which extends through the world and in particular the turkish history of architecture.

A complex steel structure was proposed as the tunnel approach, not just an en-trance portal as with most other proposals. The architectonic of this approach, in a symbolic and functional sense consists of 80 interlocking arches, with different radii and inclination placed in series, whose each developed length reaches 30m and passes over four car lanes with the supports span of 20 m. The steel structure extends from the position of the toll plaza to the entrance of the tunnel, with a length of 250m on the european side and 150m on the asian side. The entire pro-cess from the concept design to the shop drawings was controlled and developed through parametric design to enable greater freedom of searching and selecting the interweaving structure in the conceptual design stage, and greater precision and control in the final phase of the project.

Architectural Design: Dean Skira, Dino Krizmanić, Leonid Zuban
Architects in charge: Leonid Zuban, Dino Krizmanić (Urbis)
Project director: Dean Skira

Architectural lighting design: Dean Skira
Lighting design team: Dean Skira, Božidar Pustijanac

Project location: Istanbul, Turkey
Completion Year: 2016.
Gross Built Area (square meters or square foot): 250m’ Europe side+ 5400m’ Tunnel + 150m’ Asia side

Structural Engineer: UPI 2M, Berislav Medić
Lighting Design and Procurement Contractor: Kitoko Lighting and Engineering
Client and Main Contractor: YMSK JV (Joint Venture of Yapı Merkezi Insaat Sanayi A.S. and SK Engineering & Construction Co. Ltd)