Asia and Europe are now united below sea level, thanks to the Eurasia Tunnel. This new road tunnel connects Kazlicesme to Göztepe, thereby reducing the heavy traffic that has always been a feature of this route. The tunnel is 14.6 kilometres long, 5.4 kilometres of which run right beneath the sea bed, and has two separate levels, one for each direction of traffic. It is a highly complex feat of engineering that has taken 55 months to build and an overall investment of 1 billion 300 million dollars. The excavations began on the Asian side of the Bosphorus Strait and finished on the European side. The project has also included reorganising traffic circulation. This has meant improving the access roads to the tunnel and creating two toll plazas. These changes have cut the level of traffic in Istanbul enormously and improved the quality of the local environment by reducing both atmospheric and acoustic pollution. In addition to the immense achievement of its engineering, the project also stands out for the extremely high quality of its design. The inside of the tunnel, for example, has both a functional and a decorative lighting system. The competition held for the latter was won by by Skira Architectural Lighting Design. The customer's specifications for this second architectural lighting system was that it should create a pleasant sense of rhythm inside the tunnel.
The lighting project proposed by Dean Skira
is based on lines of light and the colour blue. Blue was chosen after Skira made a careful study of traditional Turkish iconography. The interweaving lines, on the other hand, evoke the geometric patterns used as decorations on local carpets, tiles, windows and buildings. These looping lines of light inside the tunnel also influence driving rhythms as they are spaced at different intervals and therefore have different effects. The ones that are closer together transmit a sense of acceleration whereas those further apart seem to slow speed down. For the tunnel interiors, Dean Skira has created a blue background using RGB Ledtubes
and then projected lines of light onto it using a combination of RGB Trick
luminaires specifically designed for this project. One of the lines of light is created with a luminaire using 5000 K colour temperature LEDs, whereas the other 2 Trick devices produce a light blue line and a dark blue one. The tunnel, in fact, has two types of ceiling: a vaulted one for the upper deck and a flat one for the lower deck, but the pattern created by the light lines is the same for both. The tunnel also features curves and alternating dips and rises. The rhythm created by the light also varies between the start and the centre of the tunnel as the distance between the luminaires changes. At the start, for 750 metres, the luminaires are spaced at a distance of 3m (pattern 1), then for 500m they are spaced at 6m (pattern 2), then for another 750m the distance between them becomes 10m (pattern 3). This design, combined with the progressive spacing out of the loops, accentuates the idea of travelling in space and time, and makes driving through the viewless tunnel less monotonous. In the centre, the longest 1000m section of the tunnel returns to pattern 2 and then the loops move together again as the exit nears. The luminaires are fitted to the metal structure that runs along the whole length of the tunnel and contains the various system cables, which cannot be attached to the walls. A team consisting of Dean Skira, architects Dino Krizmanić, Leonid Zuban and the structural engineer Berislav Medić also designed the architectural structures for the toll plazas that feature steel arches that criss-cross at different angles and are projection-lit by RGB Linealuce
luminaires which create a light effect that anticipates what awaits travellers inside the tunnel.