Crossing the bridges in Istanbul, Turkey

Istanbul is lovely city, very multicultural which embraces two continents. Probably, my first thought on Istanbul will be: incredible big diversity of almost everything on the one hand, and on the other great unity which I found out in this city. From my point of view those two incredible suspension bridges in Istanbul are more then just a way to cross the Bosphorus. There are also symbols of connection between cultures, religion, trade etc. with one arm reaching out to Asia and the other to Europe. So let me now focus on them.

One is called Bosphorus Bridge I, built in: 1970-1974.

What was special? ... Well it was the 4th longest suspension bridge in the world when was completed, and the longest outside the United States of America.

The Bosphorus Bridge was finished on 30th October 1973, one day after the 50th anniversary of the founding of the Republic of Turkey.

The core function is highway (no pedestrians are allowed to use the bridge today – maybe due to many suicides in previous years).

The designer:

- William Brown (also a designer of suspension: Messina Straits Bridge in Italy, which should be finished in 2012, he worked for Freeman Fox & Partners, renamed as Acer Consultants and currently renamed: Hyder Consulting Ltd.UK, he died in March 2005);

- Gilbert Roberts (born in London in 1899, deceased in 1978. He worked for Freeman Fox & Partners as well. He was a designer of: cantilever truss bridge Auckland Harbour Bridge – built in 1959 in New Zealand; suspension Forth Road Bridge – built in 1964 near Edinburgh in UK, suspension Humber Bridge – built in 1981 in UK. He was also an Engineer of arch bridge: Sydney Harbour Bridge – built in 1932 in Australia).

Firms involved with this structure:

- Structural Engineering: Freeman Fox & Partners (UK)

- Construction: Enka Construction & Industry Co. Inc. (TUR)

- Co-constructor: Cleveland Bridge & Engineering Co. Ltd. (UK, this company was one for instance involved in the construction of Millennium Bridge in London) and Hochtief AG (GER)

Some of the technical information:

It is suspension bridge with a gravity-anchored, inclined hangers and steel pylons. The aerodynamic deck is hanging on zigzag steel cables as distinct from the Fatih Sultan Mehmet Bridge (second suspension bridge in Istanbul) where steel cables are parallel to each other. Construction material used to build cables and pylons: steel.

Dimensions: It is 1,560 m long with a deck width of 39 m. (Main span: 1074m; Span lengths: 40 m - 3 x 45 m - 56 m - 1 074 m - 4 x 63.75 m what makes 1560m long) The distance between the towers (main span) is 1,074 m (World rank: 13th) and the clearance of the bridge from sea level is 64 m.

The cost of the bridge amounted to 200 million USD.

This picture of Bosphorus Bridge has been taken by Barbara Ropa from the ferry.

The second one suspension bridge over Bosphorus is Fatih Sultan Mehamt Bridge.

The bridge is named after Ottoman Sultan Mehamet the Conqueror, who captured Istanbul in 1453 and ended Byzantine Empire. This bridge was built in1986 – 1988 and it was the 6th longest suspension bridge in the world when completed in 1988. The core function is highway. (No pedestrians are allowed to use the bridge).

Some technical information:

It is a gravity-anchored suspension bridge with steel portal frames. The aerodynamic deck is hanging on double vertical steel cables. It is 1,510 m long with a deck width of 39 m. The main span is 1,090 m long. The clearance of the bridge from sea level is 64 m.

Firms involved with this structure:

- Designer: Acer Consultants (UK – formerly named Freeman Fox & Partners); Bosphorus Technical Consulting Corporation (TUR)

- Co-contractor: An international consortium of three Japanese companies (a. Ishikawajima-Harima Heavy Industries – mainly activities are bridges, at this moment engaged in construction of railroad & road bridge Messina Stairs Bridge between Sicily and Italy ; b. Mitsubishi Heavy Industries Ltd. ; Nippon Kokan), one Italian (Impregilo S.p.A. - for instance involved in Mont Blanc Tunnel rehabilitation) and one Turkish company carried out the construction(STFA Group)

The cost of the bridge amounted to USD 130 million.

This picture of Fatih Sultan Mehamt Bridge has been taken by Barbara Ropa from ITU Maslak Campus.

Plans for the future investments in Istanbul: Project Marmaray.

The purpose of this project is to link the European and Anatolian halves of Istanbul by an undersea rail tunnel across the Bosphorus strait. The name Marmaray comes from combining the name of the Sea of Marmara, with ray, the Turkish word for rail. Construction of the Marmaray project started in May 2004 and completion is expected to occur in 2009. Without doubts, a biggest challenge for this project from my point of view can be difficulties with design and construction in the earthquake zone.