Forth Road Bridge | |
---|---|
Coordinates | 56°00′06″N 3°24′15″W / 56.0017°N 3.40406°W |
Carries | Motor vehicles, cyclists and pedestrians |
Crosses | Firth of Forth |
Locale | Edinburgh, Scotland |
Official name | Forth Road Bridge |
Maintained by | Forth Estuary Transport Authority |
Characteristics | |
Design | Suspension bridge |
Total length | 2512 m (8242 ft) |
Width | Dual two-lane carriageway, two cycle/footpaths (total width 33 m) |
Longest span | 1006 m (3298 ft) |
Clearance below | 44.3 m |
History | |
Opened | September 4, 1964 |
Statistics | |
Daily traffic | ~32,000 vehicles (2004 estimate) |
Toll | Motorcycles - free Cars - £1 Goods vehicles - £2 |
Location | |
The Forth Road Bridge is a suspension bridge across the Firth of Forth in east central Scotland. The bridge connects South Queensferry and the wider locality of Edinburgh to North Queensferry in Fife.
History
The modern-day site of the bridge had been an important ferry crossing since as early as the 11th century, including as a vehicular ferry in the 20th century. When the Great Britain road numbering scheme was drawn up in the 1920s, the importance of the crossing was to be underpinned by the A9 road being routed here; only the unwillingness to have a ferry crossing as part of a major route led to this being shelved (the A90 number was assigned instead).[1]
The government of the United Kingdom passed an Act of Parliament in 1947 establishing the Forth Road Bridge Joint Board (FRBJB) to consider the construction of a road bridge across the Forth to replace the car ferry service and complement the existing rail Forth Bridge. Final approval for construction came in 1958. Mott, Hay and Anderson and Freeman Fox & Partners designed and constructed the bridge, which was completed at a cost of £19.5 million. The bridge was opened by Queen Elizabeth II and the Duke of Edinburgh on 4 September 1964.[2]
Statistics
The bridge's central main span is 3298 ft (1006 m) long, its two side spans are each 1338 ft (408 m) long, and the approach viaducts are 827 ft (252 m) on the north side and 1437 ft (438 m) on the south side. It was hence the longest suspension bridge outwith the United States and the fourth-largest in the world at the time of its construction. The main strung cables are 590 mm in diameter and each carries 13,800 tonnes of the bridge's load. They carry over 10,000 5 mm diameter high tensile wires.[3]
The bridge forms a crucial part of the corridor between south-east and north-east Scotland, linking Edinburgh to Perth, Dundee and Aberdeen by the A90 road and its sister M90 motorway which begins at the bridge's northern terminus. It achieved Category A listed status in 2001. The bridge carried around 2.5 million vehicles per year after opening but this has risen steadily over time. The bridge carried its 250 millionth vehicle in 2002 and 2004 figures put usage of the bridge at 11.8 million vehicles per year.[4]
Tolling issues
The bridge has been tolled since construction to pay off the construction cost. The current toll is £1 for most vehicular traffic, which (since 1997) is paid only by northbound traffic, the belief being that traffic will invariably use the bridge in both directions for one given return journey, so collecting just one £1 toll instead of two 50p tolls will have no adverse financial effect and will improve the flow of southbound traffic.[5]
The legislation enabling the levying of tolls has been renewed by Parliament (originally that of the UK but now the responsibility of the Scottish Executive) repeatedly, most recently on March 1, 2006, where the toll remained unchanged.[6] This is despite the fact that the original cost of construction plus interest accrued was paid off in 1993.
The Forth Estuary Transport Authority (FETA), who manage the bridge, have justified the continued use of tolls by suggestion they are necessary for a raft of maintenance and improvement works. These include the construction of defences around the submerged piers forming the bases of the main towers in the event of collision in the Firth. The main towers have also been strengthened with internal steel columns (the original tower structre having been hollow) and hydraulic rams used to jack up these steel sections and transfer a portion of the load to the new steelwork. Also, the vertical cables suspending the deck have had their bolts replaced after a single detected failture. A new paint system required development for the bridge (the original having been phased out due to environmental concerns) and the toll plaza and booths have been replaced allowing more comfort for toll-collection staff and the introduction of electronic tolling.
Indeed, to continue these efforts FETA made a proposal for variable tolling planned for 2007, with charges dependent on the time of day and number of passengers in a vehicle, with a view to reducing congestion during peak times. The debate over their introduction became a major political issue in January 2006, with Scottish First Minister Jack McConnell and his transport minister Tavish Scott refusing to rule out toll increases while opposition political parties claimed that Chancellor of the Exchequer and Labour Party colleague Gordon Brown had done exactly so.[7] The proposals were however shelved in February and the toll frozen at £1.[8]
Structural issues
Structural wear-and-tear has become a major concern for FETA. The planned theoretical capacity for the bridge (30,000 vehicles per day) is routinely exceeded as traffic levels have outstripped predictions. FETA predicts the demand will rise to an average of 40,000 vehicles per day by 2010 and the Scottish Executive admit that 60,000 vehicles is not uncommon for weekday travel. This has raised concerns about the lifespan of the bridge, originally planned at 120 years.[9][10]
2003 saw a inspection programme launched (at a cost of £1.2 million) to assess the condition of the bridge cables after excessive corrosion was discovered in a number of bridges in the United States of a similar design, size, and era. 32 of the high-tensile steel wires are known to have snapped. There have been allegations of poor workmanship on the bridge which, combined with the adverse weather under which it was constructed, has led to speculation that these steel wires have becomes crossed instead of being parallel as planned. Further investigation of the implications of this are underway with a study using listening devices to monitor any further strands snapping and pinpoint their location within the main cables.
The traffic loads and worries over corrosion have halved the bridge's predicted lifespan to just 50-60 years; there are fears a ban on heavy goods traffic will be necessary by 2013 due to the severe stress the traffic loading has on the bridge and internal corrosion of the steel cables.[11]
A number of options are being considered to increase the bridge's lifespan:
- Dehumidifying the cables to slow corrosion rate
- Splicing individual strands. This is believed to be very difficult to achieve without damaging adjacent strands, especially those in a central position.
- Complete replacement of the main cables. Such a drastic project has never been undertaken before but is also under consideration for similar bridges including the Benjamin Franklin Bridge and the Bronx-Whitestone Bridge in the United States.
Proposals for a new Forth Road Bridge
With a complete closure of the existing Forth Road Bridge predicted by approximately 2020 without drastic action, there is a threat of serious economic consequences due to the strategic importance of the bridge in the Scottish transport network and the estimated 10+ year timescale for construction of a replacement.[12]
Proposals for an additional road crossing had initially been drawn up in the early 1990s but met stiff opposition from environmentalists and from Edinburgh City Council on the grounds of the increased traffic it would generate. Following the Labour victory in the 1997 General Election the proposals were shelved; however they have resurfaced as of 2005 given the concerns over the existing bridge's lifespan. A new bridge, either as a complement to the existing bridge or as a complete replacement, is now under consideration by FETA with its cost estimated at £700 million. There remains considerable opposition to the project on the same grounds as before, particularly from the Scottish Green Party.[13][14]
A decision on the proposal is expected by Easter 2006.[15]
References
- ^ List of road numbers assigned by the Ministry of Transport in 1922
- ^ Forth Estuary Transport Authority: About the bridge
- ^ Forth Estuary Transport Authority: About the bridge (facts and figures)
- ^ Forth Estuary Transport Authority: About the bridge (traffic statistics)
- ^ Forth Estuary Transport Authority: About the bridge (bridge tolls)
- ^ "Bridge tolls shake-up announced" BBC News, March 1 2006
- ^ "Not even an election can bridge the gap between Gordan and Jack" Scotland on Sunday, January 29 2006
- ^ "Variable bridge toll charge rejected" The Scotsman, February 28 2006
- ^ Forth Estuary Transport Authorty: About the bridge (transport statistics)
- ^ Scottish Executive's Tolled Bridges review
- ^ "Traffic wrecking Forth Road Bridge" The Scotsman, May 5 2005
- ^ "Time running out for new bridge" The Scotsman, January 26 2006
- ^ "Another illogical, expensive, Lib Dem white elephant?" Scottish Green Party, April 29 2005
- ^ ForthRight Alliance campaign against a second Forth Road Bridge
- ^ "Activists to oppose plans for new Forth road bridge" The Scotsman, January 28 2006