The target completion date for the entire project was 'spring 2017'
Former first minister Alex Salmond turned the first sod on the massive M8/M73/M74 upgrade in April 2014, with more than 17 miles of roadworks expected to be finished within three years.
From the outset, the Scottish Government and Transport Scotland said the target completion date for the entire project was "spring 2017".
And the contract awarding the job to the Scottish Roads Partnership (SRP), a company led by Spanish construction giant Ferrovial, declared the "Planned Full Services Commencement Date" to be March 16, 2017.
However, there are still miles of cones on all three motorways and several major junctions remain closed, while motorists still face fines from the 50mph average speed cameras.
It was meant to be complete by the spring, but everyone can see it’s not even close
Margaret Mitchell – MSP
Scottish Conservative Central Scotland MSP Margaret Mitchell said: “The Scottish Government needs to answer for this and I will be trying to put them on the spot again this week.
“It was meant to be complete by the spring, but everyone can see it’s not even close.
“Commuters are fed up with unannounced changes, poor signage and suddenly being taken on diversions to who knows where.
As of March 24, the transport quango was still insisting the project would be complete by end of May
“Businesses too are beginning to complain about the impact this is having on them.
“Everyone locally accepts this has to be done, and that it’ll be good when it’s finished.
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“But the Scottish Government promised it would be open by a certain point when everyone could see that was never going to be the case.”
Last month, infrastructure secretary Keith Brown staged a triumphant photocall to open the "missing link" of the M8 a week ahead of schedule.
In fact, the original pledge was to have the entire project completed in the spring of this year, not just the new section of motorway between Glasgow and Edinburgh.
Transport Scotland announced in August 2013: "The project is currently on track to be completed by spring 2017."
This target date was repeated when the average speed cameras went live in July 2015 and again at Holyrood in January last year.
Finance Secretary Derek Mackay told MSPs: "Officials will continue to work closely with the construction contractor to deliver the project on time in spring 2017."
Last August, this newspaper was told the project was running several months behind schedule but the claim was categorically denied by Transport Scotland.
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A spokesman said: "Transport Scotland and Scottish Roads Partnership [are] fully committed to delivering the M8/M73/M74 Motorway Improvements Project in spring 2017."
As recently as March 24, the transport quango was still insisting the project would be complete by the end of May.
Now Transport Scotland is saying the M8/M73/M74 is on schedule only to "open to traffic soon".
A spokesman said: "Our contractor is working around the clock to connect the new infrastructure with the existing road network, which requires extensive traffic management.
"Roads are being opened to the public as they become available and the scheme remains on schedule to open to traffic soon."
Hugh Bladon, treasurer of the Association of British Drivers, said: "I just don't understand why we are so slow in doing things. Very often you drive through the roadworks and you hardly see any workmen and if you do they are leaning on their shovels drinking a cup of tea. It is extraordinary how long these big projects take.
"They should have an absolute time limit to do the job and if they don't they should be penalised by something like a million pounds a week. This project is costing a huge amount of money and there's no reason why it shouldn't be finished on time.
Scottish taxpayers will repay £1,391million in charges over the 30 year contract
"We as motorists suffer it in silence. We can moan about it in the pub but generally what can you do as a motorist? We are not like the French where they would be blockading the road and burning tyres and we don't want to import that sort of behaviour, but how else can you complain and get something done?"
The capital value of the roadworks is £310million, although Scottish taxpayers will repay £1,391million in charges over the 30 year contract.
Ferrovial owns 40 per cent of the shares in SRP through its subsidiaries Amey and Cintra, with investment funds Meridiam and Aberdeen owning the remainder.
Loans have been provided by the European Investment Bank, the EU's own in-house bank, and the German finance house Allianz.
The construction contract went to Cintra and Belfast-based Lagan Construction, while the maintenance contract has gone to Amey.