James Street Swing Bridge, Cardiff
NO LONGER EXTANT.
Carried a road across the Glamorganshire Canal.
Constructed by Andrew Handyside and Co in 1890.
It crossed the canal at an angle of 73 deg., and had a long arm of 71ft. and a short arm of 33ft. The width of roadway between centres of girders bridge was 25ft. 2in., and the width of the bridge between parapets was 38ft. 4in. The assumed moving load was a vehicle weighing 32 tons on four wheels, with a wheel base of 14ft. On the short arm was the additional weight of the machinery and the balance weight of 133 tons, made up of blocks of kentledge. The whole of the dead load of 360 tons rested on a 12" dia. ball pivot when equally distributed over the whole bridge or over the long arm only, was divided between the pivot and two wheels at the long end of the bridge, whereas when it was distributed over the short arm it is divided between the pivot and two wheels at the end of the short end. Those four wheels were, however, in contact without pressure with their wheel paths when there was no load on the bridge. There were six other wheels associated with a turntable whose outside diameter correspnded to the width of the bridge. Both the pivot and cup were made of hardened steel.
The bridge was rotated manually through a two-speed gear train. When it was initially built it was found that in slow gear two men could swing the bridge through the angle of 78 deg. in 4 min. 40 sec., and when in fast gear four men could swing it in 2 min. 10 sec.
The above information and illustration are drawn from an article in The Engineer by the bridge's designer, Max Am Ende [1].
Converted to electrical operation in 1921. Removed in 1957. Canal filled in.[2]