New Galata Bridge
The New Galata Bridge replaced the previous steel pontoon bridge
which had been constructed in 1912. Mott MacDonald was appointed to
carry out construction supervision of the 470m bridge, which is one
of the largest of its types in the world.
The bridge features deep piled foundations comprising of 1,122m
diameter steel tube piles. The piles up to 80m long were driven in
water depths of up to 40m. The working load for the piles is 1,200
tonnes and load tests up to 2,000 tonnes were performed. Corrosion
protection of the piles is provided by a cathodic protection
system.
The superstructure is 42m wide and provides for dual
3-lane carriageway with a central busway capable of later
conversion to accommodate the city’s light rail system. The
approach spans leading to the central bascule span are double
decked and of insitu post-tensioned concrete construction. The
lower deck offers space for 6,000m
2 of shops and
restaurants, allowing social amenities provided by previous bridges
at the site to be preserved.
The bascule bridge has four hydraulically powered leaves providing
a navigation opening of 80m. Fabrication of the steel bascule deck
was undertaken in Turkey. The
Bascule Bridge piers were
designed to withstand impact from ships of up to 8000 dwt. The
massive, buoyant box piers, each 44m x 15.6m x 43m high, were
constructed above water and lowered in stages to 33m below water by
means of a 3,000 tonne capacity heavy lowering system.
