First Bosphorus Bridge 1973

Bridging Two Continents

Prior to cable spinning, a temporary footwalk (catwalk) system was erected to enable work across the entire span. To achieve this, a track rope and a hauling line were laid across the Bosphorus and lifted to the tower tops.

This was the only time that the very busy Bosphorus international waterway was closed during the whole bridge construction.

The main span cable contains 10,412 parallel wires, each 5mm in diameter. They are formed into 19 strands (shown right), each containing 548 wires.

The total length of wire was 40,000km – enough to wrap around the world. The cable is wrapped and then squeezed with a compactor before hanger ropes are fitted.