Sunday, July 04, 2010
The governments report on the comparison with other bridges worldwide is available here from page 14 . They compare the prices not with the £2,000 m it will cost us but the lower £748 price quoted which is not what it will actually cost. Nonetheless other countries prices are far lower. I have taken from the report what are described as "particular challenges" to other bridges (marked -) & reason for the Forth crossing being more expensive (bulletpointed).
Severn Bridge £575 million:
- Long crossing – the longest river crossing in the UK.
- Notorious currents, a 14.5 metre tidal range (2nd highest in world) and strong winds (hostile weather put the project three months behind schedule by 1995).
- The deck had to be installed from a floating barge.
- A rail tunnel was already below the bridge crossing.
- Monorail fitted to the bottom of the bridge for servicing.
• Only two towers, thus no central tower with stability issues.
• Single, shorter span than FRC.
• Depth of water in which the towers were installed is lesser than that faced by the FRC’s South tower and the foundations were simpler.
Mersey Gateway £380 million:
- Three towers like the FRC. In particular a unique design where the central tower is shorter is being employed.
- A curved approach at each end of the bridge.
- A lower deck with space for future light rail system.• Depth of water in which the towers are being installed is substantially less than that faced by FRC’s towers.
• Shorter crossing & FRC’s spans are more than double the length.
• Geology is more benign and environment is non-marine and sheltered.
Millau Viaduct £353m:
- Construction timetable of 3 years.
- Height of towers.
• FRC has longer spans.
• VdM towers built on land, thus simpler push-launching deck construction techniques used.
• Upper towers and cables could be added after deck in place.
• Easier geology and foundations.
Rion Antarion Bridge, Greece £539m:
- Length of crossing longer than FRC.
- Deeper water than FRC and weak seabed.
- This brought the need for rigid pyramid towers – the largest ever built for a bridge.
- Strong seismic activity, possible tectonic movements and high winds.• FRC requires piled foundations rather than pad footings like RA.
• FRC has longer spans.
• RA had more favorable weather conditions for construction.
Stonecutters bridge, Hong Kong £206m:
- Straddles narrow shipping channel near busy container port.
- High deck and towers to allow passage of super container vessels.
- Environmental constraints including fault line under bridge foundations, typhoons, current, visibility and daylight hours.
- Need for prevention of ground settlement to protect existing structures near bridge.
- Scope for structural modifications limited as appearance of the winning project from a design competition had to be maintained.
• Towers located on land and so easier foundations and less ship impact risk.
• Cheaper labour and material costs in Asia• Towers located on land and so easier foundations and less ship impact risk.
• Cheaper labour and material costs in Asia
• Environmental regulations less onerous
Oresund, Denmark/Sweden £804m:
* The bridge also comprises a double track railway on the lower deck.
* An artificial island was constructed to connect the bridge with the tunnel.
* Stringent environmental standards.
* The bridge crosses the Flintrannan shipping channel.
& Rough sea conditions and fitting of piers and spans from floating platforms.
• Two towers compared to FRC’s three.
• Single shorter main span.
• Shallower water for tower installation.
• Simpler spread foundations on well defined geology
To me these excuses or "Reasons why the costs may be lower than that for the FRC" look rather like ideas you might come up with after a few beers & seem contradictory - the reason given for the Greek bridge being cheaper is because the weather is better there (excluding the minor matter of earthquakes) but the weather is much worse in Hong Kong & Oresund; Oresund is described as "well defined geology" when it is built on an entirely artificial island; Severn & Oresund are cheaper because they only have 2 towers but Millau is not said to be artificially more expensive because it has many towers; the Hong Kong bridge is said to be cheaper because of cheap local labour but Hong Kong is actually 17% richer per capita, than we are now; the lack of regulation given as a reason in Hong Kong may be true but if so Oresund, where over regulation is specifically mentioned, should be more expensive unless we are suffering from even more state regulatory parasitism.
However the bottom line is that all the others come in at between £19m & £48m per lanes/km & the Forth one, taking the total cost as £748 million is £72m. However the other bridges are priced in terms of total actual. Taking the full cost of £2,300m which I very strongly expect is the absolute minimum we would end up paying that would be £221 million per mile. Of course if it went over budget like the trams & the parliament building etc it would be far more but I'm sure we will be promised it won't go over budget (just as we were specifically promised the trams & Parliament building wouldn't).
The comparison with tunnel costs is even more blatant.