Monday 7 December 2015

The Bridge / Bron / Broen ......Time Line.


1958 - The original design was expected to be good for 120 years from date of completion at the 1950's predicted rate of traffic growth.

1964 - The bridge opens to much fanfare as the longest single span suspension bridge in Europe and fourth largest in the world outside the US.

1990 -  The first concerns about the impact of traffic patterns already exceeding the bridge's design capacity are made to the Secretary of State for Scotland resulting in a 1992 report 'Setting Forth' which looked at all the possibilities for a replacement, rejecting a tunnel because of the unstable nature of the local geography and proposing the route the new crossing is now being built over. Alistair Darling accuses the Tory Government of wasting money on the report and was joined by Menzies Campbell in urging the Scottish Office to drop this 'ludicrous project'. Lang's successor at the Scottish Office, one Micheal Forsyth, agrees with Darling and Campbell and the project is dropped.

2001 - FETA warned about damage to expansion joints by heavy traffic streams on the bridge

2004 - Engineering reports confirm the earlier warnings that the Forth Road Bridge was now under severe engineering stress as a combination of corrosion and over loading had caused a 10% loss of strength in the main span cabling. The engineers predicted the bridge would have to be closed to heavy goods vehicles in 2013 and shut completely by 2020 if no solution was found. 

2006 - The only solution to closure and main cable replacement was to apply leading edge, untested Japanese dehumidifying technology and hope.

2007 - Transport Scotland reported on the state of the Forth Road Bridge: " In the past fatigue has not been a major factor for the Forth Road Bridge, except for the hangers. The most critical fatigue details are likely to be located on the deck of the main span. The deck plate and trough thickness would be considered thin when compared to current practice. ...... All routine maintenance is planned and carried out by FETA staff.

Opponents are already making claims a new bridge will cause total grid lock in the West of Edinburgh and be a nightmare for the local economy.

2008 - In the SNP quango cull FETA is scheduled to be shut down and after competitive tendering Amey get the Forth Bridge maintenance contract to commence 1st of May 2015.
In the past fatigue has not been a major concern for the Forth Road Bridge, with the exception of the hangers. However, it may become more important in the future. The most critical fatigue details on the bridge are likely to be located on the steel deck on the main span. The deck plate and trough thickness would be regarded as thin when compared with current practice, and so to prolong its life it has to rely on composite action with the surfacing. - See more at: http://www.transportscotland.gov.uk/report/j8512a-03.htm#sthash.2pf9xwOQ.dpuf
In the past fatigue has not been a major concern for the Forth Road Bridge, with the exception of the hangers. However, it may become more important in the future. The most critical fatigue details on the bridge are likely to be located on the steel deck on the main span. The deck plate and trough thickness would be regarded as thin when compared with current practice, and so to prolong its life it has to rely on composite action with the surfacing. - See more at: http://www.transportscotland.gov.uk/report/j8512a-03.htm#sthash.2pf9xwOQ.dpuf
In the past fatigue has not been a major concern for the Forth Road Bridge, with the exception of the hangers. However, it may become more important in the future. The most critical fatigue details on the bridge are likely to be located on the steel deck on the main span. The deck plate and trough thickness would be regarded as thin when compared with current practice, and so to prolong its life it has to rely on composite action with the surfacing. - See more at: http://www.transportscotland.gov.uk/report/j8512a-03.htm#sthash.2pf9xwOQ.dpuf
In the past fatigue has not been a major concern for the Forth Road Bridge, with the exception of the hangers. However, it may become more important in the future. The most critical fatigue details on the bridge are likely to be located on the steel deck on the main span. The deck plate and trough thickness would be regarded as thin when compared with current practice, and so to prolong its life it has to rely on composite action with the surfacing. - See more at: http://www.transportscotland.gov.uk/report/j8512a-03.htm#sthash.2pf9xwOQ.dpuf

2009 - Initial design work completed on second crossing, coming to the same conclusion as the 1992 report 'Setting Forth' that local geological instability made tunneling impracticable and a stayed crossing on the proposed 1992 route was the best solution given the known engineering problems with the current bridge

2010 - Bill passed at Holyrood to commence building the new crossing with only three votes against. 

Forth Estuary Transport Authority warned about impending catastrophic failure of truss end plates but decides to delay repairs on the basis of a cost / benefit analysis. This decision was made by the FETA board with no reference to Transport Scotland.

2011 - Construction of the new bridge commences, 57% of Sub Contractors are Scottish based companies.

2013 - The Japanese technology has slowed the rate of degradation of the Forth Road Bridge main span cables to normal operational parameters

2015 - May: the new bridge contractor, Amey, takes over from FETA and immediately begins to undertake the end truss strengthening program which FETA had decided to delay prior to the quango being wound up.


December - catastrophic failure of an end plate weld previously not thought to be at high risk, forces reduction to two lanes on the bridge and eventual closure as a combination of severe weather and traffic loading is considered too dangerous to leave the bridge in even part operation.



Unionist media ignores Transport Scotland's December press release and starts on a 'SNP bad' witch hunt totally ignoring the trail of actual events, FETA and the Unionist Parties' clear role in the current failure and delay in building a replacement bridge (and also the reason why the SNP were correct to ditch the quango of Labour council worthies):


The Scottish Government has fully funded all FETA programmes since taking over the funding of the annual grant in 2008. Prior to its dissolution, FETA made decisions on its programme and priorities of repairs completely independently of Transport Scotland. Amey has informed us the ongoing truss end strengthening works are to a different part of the truss end linkage system to that which failed this week. The truss end link member was not previously identified as requiring strengthening or to be at risk of failure. The unexpected nature of weld cracking leading to failure is highly unpredictable and this issue is unrelated to the other strengthening works. It’s deeply regrettable that when Amey has made every effort to explain the background to a complex situation, others are seeking to create mischief and apportion blame.

This is a deliberately simplistic time line of key events to help us understand what has actually been going on and what the mainstream media are happily ignoring. The evidence points the finger at FETA for the failure to repair the truss end plates having been warned of the need to strengthen the main span steel work in a 2007 Transport Scotland report - part of which is quoted above.

If there is a 'political slant' in all of this it is more probably the role of the local Labour council's 'put off until tomorrow' decision making within FETA and a strong hint of 'taking the huff' when the SNP decided to do away with the councilors' nice wee earner on the FETA board.

6 comments:

  1. Very nice Peer...

    Straightforward summation of the facts.

    ReplyDelete
  2. Very nice Peer...

    Straightforward summation of the facts.

    ReplyDelete
  3. Further to the above;

    It was common knowledge, that the cables on the bridge were deteriorating at an accelerated rate, due to an invasive inspection technique.

    Holes were drilled in the outer sheathings, of the main cables, to inspect the inner cable bundles. The bundles were fine but, by drilling through the protective sheathing. They inadvertently exposed the inner bundles to salty moist air, thus the cables rapidly began to rust and lose their integrity; hence the need for a new bridge.

    ReplyDelete
    Replies
    1. Also explains the need for the untested dehumidifier technology.

      Delete
  4. Jim, care to provide sources for your statements about the rust being due to coring through the outer sheaths ?

    ReplyDelete
  5. Jim, care to provide sources for your statements about the rust being due to coring through the outer sheaths ?

    ReplyDelete