SAFETY works on the Forth Road Bridge were put off for at least seven years, amid mounting concerns behind the scenes over funding and transport disruption, a special Sunday Herald investigation has uncovered.

Works to replace the 51-year-old bridge expansion joints - which were described as a "safety and maintenance liability" eight years ago in a report to the now defunct Forth Estuary Transport Authority - were eventually put off till 2016, after costs soared and the Scottish Government announced that a new Forth crossing would be in place the same year.

The expansion joints project was one of a series of bridge repair plans that were put off as the Forth Replacement Crossing was being planned.

As the new crossing would reduce use of the original bridge, one of Scotland’s most important and heavily used road routes, leading to a reduction in the weight of traffic on it, Transport Scotland felt it would therefore extend the operational life of the bridge.

Details of cuts to bridge repairs emerged after it was announced that it was to remain closed to all traffic until early January for emergency repairs, which will cause disruption for commuters, hauliers and holidaymakers. It has led to calls for a parliamentary inquiry.

Scottish businesses have called for a clear signal over precisely how long the stricken Forth Road Bridge will be closed as some small firms struggle to survive.

Steelwork problems involve a fractured link between a main span truss and the bridge’s north east main tower.

Audit Scotland warned last year, two years after highlighting cuts of 65 per cent to FETA's three year capital grant that there was a risk that constraints on expenditure could lead "to some essential but not committed schemes not being carried out and that the long term integrity of the bridge and its approaches could be compromised".

And after plans for a new round of project deferrals, a FETA report from February, 2014 said: "There is always a residual risk when maintenance works are deferred and it was noted that deferral of part or all of these projects does increase the risk to the long term structural integrity of the bridge and is likely to increase the actual cost of the works when they are eventually carried out."

The main expansion joints are essential for allowing the deck of the Forth Road Bridge to expand and contract as required by weather or weight of traffic.

They are the oldest and largest of their kind in Europe, and had been scheduled for replacement in 2010.

Experts say that without those joints, the bridge butt joints would crush and buckle in hot weather.

According to a 2007 Forth Estuary Transport Authority report members were advised by consulting engineers Atkins that existing joints and bearings were considered to have "reached the end of their service life".

The document said Atkins "concluded that all three types of bridge expansion joints have generally performed well but have reached the end of their service life and are now becoming a safety and maintenance liability."

They had concluded that the replacement of all the expansion joints "should be considered a priority as the rate of wear will increase rapidly".

The cost of the contract works to replace the joints was first estimated as £3.5 million and was included in a capital plan.

It was estimated it would require eight weeks of carriageway closures and FETA acknowledged that necessary bridge closures will cause "widespread and significant disruption to the whole of the road network in the east of Scotland".

It was estimated that the costs of closing one carriageway on the bridge was around £650,000 per weekday. But those costs did not take into account the costs to the wider business community which it was acknowledged would be of a "higher order".

Temporary bridging to try and reduce traffic delays were later added to the project but the costs rose to £13.8 million, £5 million above an original estimate.

In October, 2008, FETA accepted a tender from Balfour Beatty to carry out the work but it meant it would exceed a three-year government capital spending grant by around £5 million.

But as discussions were underway, the Scottish Government committed to the construction of the Forth Replacement Crossing, sparking a review of this and other bridge projects.

It was then decided that no contract could then be awarded for the expansion joints works until the issue of funding was resolved with the Scottish Government.

FETA documents show that after the new crossing announcement, a review of the authority’s maintenance programme was carried out "to determine whether schemes that cause major traffic disruption could be deferred".

By February, 2009, a review team had decided to put any replacement off for seven years as long as inspections were increased and that "temporary failsafe devices", key components such as pins and springs would have to be replaced. The move would save the public purse £6 million, FETA were told.

"In extending the service life of the joints the risk that a component fails obviously increases," said then chief engineer and bridgemaster Barry Colford in a report six years ago. "The mitigation measures will minimise the safety risk to users to an acceptable level. However, following any failure event there will be a risk that current operating service levels are reduced as remedial works would necessitate closures of a carriageway."

It is understood the replacement of the problem truss end links on the Forth Road Bridge was recommended by consultants WA Fairhurst five years ago. But that work too was not approved because of the issue with lengthy closures before the £1 billion Queensferry Crossing was open.

Transport Scotland said FETA altered the scope of those works to deliver "a more proportionte solution" with less disruption and a lower cost. It said the Scottish Government "was not alerted to any critical consequences arising from this change of scope". Instead work began earlier this year to strengthen the brackets that support the top end of the links.

It is understood an analysis by consultant Aecom around six years ago indicated that the end of the deck would drop by 150mm under dead weight alone if a pair of the links should fail. That would lead to massive buckling of the adjacent expansion joint. A major repair operation would then be needed, involving long term closure of the bridge.

Papers also reveal that an option to repair or replace the main cables of the bridge was put off despite "fairly significant corrosion", and a strength loss on the cables of eight per cent being discovered 11 years ago.

Consulting engineers WA Fairhurst were appointed in September 2006 to examine possible options for "replacement or augmentation".

The findings showed that it was technically feasible but warned it would result in significant delays to the strategic road network over years if it had to be carried out without an alternative crossing in place.

Colford had said that dehumidification on the cables was the best way forward "in theory" to stop the galvanised steel corroding and was installed in 2009.

But he told MSPs the following year: "I cannot give an absolute guarantee about whether the cracks within the steel wires that have already corroded will form breakages in the future."

In April it was discovered that since the end of January, engineers noted 24 wire breaks on just one cable alone.

Since installation nine years ago, an acoustic monitoring system on the two main cables detected 93 wire breaks in total.

Concerns over the suspension cables were a factor in the decision to build a new £1bn Forth crossing, which is due to open next year.

Alex Rowley, deputy leader of the Scottish Labour Party said: "We need a full parliamentary inquiry to get to the bottom of what went wrong here. The thousands of people and businesses affected by the closure of the Forth Road Bridge deserve full transparency."

A Transport Scotland spokesman insisted that the "bottom line" is that FETA took the decision over the repairs programme and not ministers.

"The Scottish Government fully funded all FETA programmes since taking over the funding of the annual grant in 2008," he said.

"Since 2008 Audit Scotland has recognised that the unpredictability of maintenance requirements remains a key risk for the operation of the structure. They make no reference to critical maintenance being neglected as a consequence of underfunding," he said.