Volume Nine - Pre-Victorian to the present day - even more aspects - Swing Bridge Connections : Penarth Dock, River Taff and Glamorganshire Canal . . .

	The smaller swing bridge over the Glamorganshire Canal is shown in elevation by Fig. 6, in plan by Fig. 7, and in cross-section by Fig. 8.
Fig. 6 - side elevation of canal bridge
Fig. 7 - plan view of canal bridge	Fig. 8 - cross sectional view of canal bridge

Like the larger bridge, it is composed of a pair of wrought-iron plate girders ; but in this case the girders have a uniform depth of 4 ft. 6 in. throughout. The opening span over the canal is 28 ft., whilst the total length of the bridge is about 60 ft., and it is supported on one of the abutments, the centre of the supporting arrangement being situated 18 ft. from one end of the bridge. As the bridge thus projects un-equally on each side of the turntable on which it rests, the longer arm is counterbalanced by cast iron weights fixed to the extremity of the shorter arm. The main girders are placed 18 ft. apart transversely in the clear, and they are connected by cross girders 10 in. deep resting on their lower flanges, as shown in Fig. 8. The cross girders are covered with 4 in. fir and 2 in. oak planking, as in the case of the larger bridge.

The general arrangement of the turntable on which this bridge rests is similar to that adopted in the case of the larger bridge, but the rollers are smaller, their width on the face being 7 in. In the case of the smaller bridge also, the diameter of the central pin is 5½ in., and the lower roller path, instead of being connected to the central boss by radial arms, is distinct from it, both the boss and roller paths being secured to ashlar blocks imbedded in rubble masonry.