This is a suspension bridge with a central portion, between two lofty and massive stone towers, consisting of bascules which can be raised by hydraulic machinery to admit the passage of vessels.
The bascules rotate through an angle of 82°, and their rear ends in the bascule chambers of the piers carry 365 tons of counterweight, the total weight of each being 1070 tons.
Long, and the bascules can be lifted or lowered in one minute, ?®?+? ? ::=::IAr':..
The opening bridge between the river towers consists of two leaves or bascules, pivoted near the faces of the piers and rotating in a vertical plane.
There are two high-level footways for use when the bascules are raised, the main girders of which are of the cantilever and suspended girder type.
The two bascules are each constructed with four main girders.
A more common type is a bridge with two leaves or bascules, one hinged at each abutment.
The bascules are locked at the centre (see fig.
The weight of ballast in the short arms of the bascules is 365 tons.
Clear, with balanced bascules over the centre span.