This is a fantastic opportunity to showcase a high tech and aesthetically pleasing example of British engineering, appropriate to the proximity of the architecture at Canary Wharf.
The bridge would have a span of approximately 320m (depending on location and engineering requirments) and it is reasonable to assume it would need to offer the same clearances as Tower Bridge – 8.6m (closed) 42.5m (open)
Opening Bridge Options
The original Sustrans proposal was for a vertical lift bridge whereby the central span of the bridge rises vertically. This usually requires towers containing counterweights at each end of the span. There is increased visual impact but it is a good engineering solution. Visually, it could be designed as a “high tech” complement to the 21st century image of Canary Wharf.
The best example of a tilt bridge is the Gateshead Millenium Bridge
It accomodates vessels with a maximum height of 24m and has a span of 126m. The Brunel Bridge would be approximately twice this size.
Like the vertical lift bridge, the central span rises vertically; in this case however it is operated by hydraulic rams buried in the river bed. This option might be impacted by the proximity of the Jubilee line which passes under the river at this point.
This is rather like a drawbridge. There are a number of examples in the vicinity, the best known being Tower Bridge. The “Red Bridge” on Rotherhithe Street is another example.
The movable span rotates about a central point. It seems unlikely that this would provide a sufficiently wide passage in this location.
Similar to the vertical lift and table bridges, but the span is submerged instead. Not widely used but could be a potential option subject to proximity of the Jubilee line.
Fixed bridge options
That would require a central span high enough to allow all river traffic – in reality no higher than the upper walkway at Tower Bridge.
Pedestrians and cyclists would reach the higher level via a ramp (possibly a spiral) – or maybe a lift.
London Mayor Boris Johnson has suggested that pedestrians be flung across the river “using some form of catapult”.
Even allowing for the fact that Boris has a classical education, we assume he is not offering this as a serious option!