When in Bristol recently went to check out the Plimsoll Swingbridge and it's central reservation control tower. The swingbridge marks the start of Bristol's Cumberland Basin, originally a re-routing of the River Avon by William Jessop, which began in 1802.
[ via Sabre ]
The swingbridge opened in 1965, the bridge forms part of the first 'multi level interchange' in Bristol, being just a small part of the much larger Cumberland Basin Junction that surrounds it. It carries the A3029 across the Avon from the A370 which diverges at Ashton Gate to the south, and theA4 which is met a little to the north.
The bridge itself is a steel structure, with a central pivot which lies between two channels. It is likely that both were once locks, regulating the level of the harbour upstream, but one has now been blocked to boats, and so the harbour remains tidal beyond. The steel structure carries two cantilevers which in turn carry the full D2 dual carriageway over the harbour. Additionally, standard concrete spans on either side of the swing section carry the A3029 over sliproads connecting to the A4
It's worth checking out as you can still walk up to the control tower and view the traffic below, as well as admire the original 1965 swinging bridge technology...
& the view of the A3029 from the control tower [ click the pano for expanded view ]
Lots more Bristol concrete to upload very soon...
**UPDATE!**
via Adam J Smith, here's some images of how the Plimsoll Swing Bridge looked back in the day:
