I was lucky enough to have Canal and River Trust lay on an open day at Sutton Weaver Swing Bridge on my birthday - here is a bit of background information.
Sutton Weaver Swing Bridge carries the A56 over the River Weaver Navigation, built in 1926 to replace the original bridge built in 1872 which was 75' long by 14'wide, weighed 20 tons and was manually operated by one man.
By 1923 it could no longer cope with 'modern' traffic.
The present bridge is 150' long by 44' wide giving a clear roadway of 26'8" plus two footpaths of 5' and is operated by electric motors. The swinging section and the pontoon it sits weigh about 520 tons including 420 tons of iron and steel. The pontoon weighs about 33 tons and is 35' in diameter and sits in a water filled caisson.
The pontoon is hollow and functions by displacing water equal to the volume of air in the pontoon reducing the weight borne by the rollers it turns on by about 200 tons.
When being swung road traffic was stopped by heavy iron gates hung on ball bearings and connected by underground gearing. These gates are still in situ but are not used. Road lighting on the bridge was electric but the red and green signal lamps were paraffin.
Canal and Rivers Trust are refurbishing and upgrading the bridge in a 12 month £4.5 million project, £3/4 million of which is for a temporary bridge to avoid major disruption of traffic and to enable the contractors to work on the bridge as a whole rather than have traffic on one side at a time and working on the other side thereby offsetting more than the cost of the temporary bridge.
Sutton Weaver Bridge (photo from a wikicommons)
The winding gear under the control room -
- driven by this 30bhp drive motor
The cable runs in this channel to the pontoon
The PA system in the control room is outside the scope of the refurbishment.
The original 1926 controls for operating bridge which work more reliably than many modern controls so the decision was made not to upgrade them. If it ain't broke don't fix it.
My glamourous assistant (in full PPE) demonstrating the controls.
The control room.
The horizontal rail through the centre of the picture has completely rusted through at the left of the photo.
Sand blasted and painted vs not sand blasted and painted.
Original decking. If you jump on this, water squirts out of the holes.
The pontoon does not sit exactly in the centre of the bridge so this cavity under the road deck contained about 80 ton of counterweights (or counterlage as the engineer called it) consisting of -
- these ingots. The new decking is lighter than the old but they are not sure by how much. They weighed each end of the bridge at the beginning of the project and will replace enough weight to match the original proportions.
Refurbished lattice work
More photos to follow ...