A Scottish Parliament inquiry has concluded that the structural defects that led to the closure of the Forth Road Bridge last December could not have been foreseen.

The infrastructure and capital investment committee also concluded that the Fort Estuary Transport Authority (FETA) decision to reprioritise projects within its capital plan following the Spending Review in 2011 – including work on the truss end link mechanism which failed – was an appropriate course of action.

The report follows an inquiry called by the committee which heard from a range of witnesses in January and February.

Committee convener, Jim Eadie MSP, said: “The closure of the Forth Road Bridge led to significant disruption and many legitimate questions have been raised about the nature of the structural problem and whether it could have been avoided.

“The committee heard from a number of structural engineers and representatives from FETA and Transport Scotland. All of our witnesses were of the view that the defect which caused the closure of the bridge could not have been foreseen.

“As a result we have concluded that the decision by FETA to reprioritise the proposed work on the truss end links was an appropriate course of action on the basis of both the prevailing financial circumstances and the engineering advice available at the time.

“The committee concluded that the development of the Forth Replacement Crossing would have had an influence on decisions to reprioritise certain capital projects. The committee is of the view that FETA dealt with the challenge of reprioritising its capital proposals in a professional and responsible manner.

“We commend all those who worked so hard to repair the bridge and have it reopened ahead of initial estimates. However we are also conscious that the impact on the travelling public and businesses – particularly the haulage industry – was significant.

“The committee therefore intends to recommend that its successor committee in the new Parliamentary session give consideration to exploring such issues further.”

Transport minister Derek Mackay said he welcomes many aspects of the committee’s report and will now carefully consider the conclusions and report back to Parliament later this year.

He added: “We particularly agree with the finding that the defect, which led to the bridge being closed, has been recognised as ‘unforeseen’. It is clear the decision to close the Bridge was the right thing to do and the efforts in getting the bridge fully quickly reopened were a ‘remarkable engineering achievement’ given the challenging conditions. The closure of the bridge was an incident of national significance and we remain grateful for the support of the business sector and local communities who were affected. During the closure, we took every opportunity to accelerate work on the Queensferry Crossing and Forth Road Bridge, minimising future disruption for the travelling public.

“The majority of the committee considered that the decision by FETA to defer work on the Truss End Links and to develop an alternative approach was an appropriate course of action. Had FETA believed there was a need accelerate this work to address a matter of public safety Transport Scotland would have provided financial support. As stated repeatedly during the inquiry hearings, FETA’s key priority works were always fully funded within the ‎available maintenance budget and no further works were identified as safety critical by FETA.

“We believe there is a clear procedure in place for the closure of the Bridge and we have the same powers as FETA to immediately close it if there is an immediate safety risk. Now that the main priority of fully reopening the bridge has been achieved we are already making preparations for a full incident debrief to record what worked well and identify any opportunities to further improve performance.”

The Institution of Civil Engineers Scotland (ICE) has welcomed the report’s undertaking that the committee’s successors will “give consideration to exploring such issues further”.

ICE Scotland raised the issue of existing infrastructure maintenance, such as bridges and transport links, during the launch of their Manifesto for Infrastructure last month following their State of the Nation Report launched in November. The Manifesto laid out a vision of what needs to be done to ensure Scotland has transport, energy, waste, water and flooding networks for the future, and urged parties to include measures in their forthcoming election manifestos.

Mac West, chair of ICE Scotland, said: “As the report suggests, such events are often unforeseen and unforeseeable, even at times when tough financial priorities are having to be managed.

“However, we are pleased that the committee have picked up on a point we raised in our recently launched Manifesto for Infrastructure. While we very much welcome on-going capital investment in new infrastructure, it is vitally important that adequate financial provision is made for the maintenance of existing key infrastructure to ensure its future well-being.

“The Forth Road Bridge was a modern marvel when built but it was never designed to cope with the volume and weight of traffic to which it is now subjected. It is a tribute to the civil engineers involved that they returned the bridge to working order ahead of schedule and in such appalling weather conditions.”