Mistakes in controversial Edinburgh active travel plans put to the public for feedback were discovered more than three months before city councillors were alerted, it has emerged.
In April the council revealed that "errors" had been made in a consultation on making Spaces for People schemes permanent. The errors means the consultation had to be re-started, at a cost of nearly £20,000.
A freedom of information request has now revealed that transport chiefs had known about the blunder since the start of the year.
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They have pinned the blame for the problems on external contractors - and said withholding the information for 15-weeks was necessary to undertake a "detailed review" of all plans.
But a senior councillor said there were "very serious questions" to be answered in light of the "deeply concerning" revelations.
Transport convener Councillor Scott Arthur - who was also kept in the dark until April - said time was needed to consider "how best to proceed to address the errors".
The consultation was launched in November seeking residents' opinions on Spaces for People measures rolled-out during the pandemic, to help the council determine which ones should remain in place for good.
The scheme - since re-branded Travelling Safely - involved installing segregated cycle lanes across the city and closing roads to traffic. The council said the aim was to "improve safety for pedestrians and cyclists".
Although positively received in some areas, the changes have not been popular everywhere and have proved controversial in the capital over the last three years, with the local authority accused of taking a gung-ho approach and not listening to residents' views.
On April 26, just a few weeks before the consultation was due to be wrapped up, the council's active travel team emailed councillors to notify them "some minor errors" had been identified in the traffic orders advertised to the public, including inaccurate information on bus lanes and yellow lines.
This meant the entire process had to be re-started, dragging it out by another six months and costing £19,425. The council said this sum will be claimed back from the consultants responsible for the errors.
However a freedom of information request by the Local Democracy Reporting Service found senior transport officers were aware of the inaccuracies as early as January 10th - more than three months before elected members were briefed about the fiasco.
Liberal Democrat group leader on Edinburgh Council, Kevin Lang, said: "I think there are very serious questions as to why it was that errors in the traffic orders were not highlighted to councillors until months after officers first became aware."
Councillor Lang said the process had been "a troubled one from the very start".
He added: "Given all the concern and all the frustration from residents who felt that the council was not listening on these projects, it is deeply concerning that such important information was not brought to the attention of councillors at an earlier stage.
"I expect officers to always be open and transparent with elected members but on what has been such a troubled project for three years now, I think it's all the more concerning that errors in process were not brought to elected members' attention at an earlier stage."
Councillor Scott Arthur, transport and environment convener, said: “After some errors and discrepancies were initially discovered within the Travelling Safely scheme ETRO documentation produced by external consultants, officers carried out a detailed review of all of the documentation for each of the five ETROs to identify any further errors.
"Consideration then had to be given as to how best to proceed to address the errors, prior to briefing elected members.
“I was formally notified of the problem on the 21st of April, but was made aware there was an issue during the preceding week.”
Transport spokesperson for the SNP group Danny Aston questioned why it took almost three months for Cllr Arthur to find out about the mistakes.
He said: "It's dreadful that he didn't know about this and then rolled over to his Tory and Lib Dem allies when it came to light. Who's really running this council?"
