The river crossing from Jarrow to North Tyneside had been expected to be back in action late this year, but it now looks likely to be more like 2019 before work is finally finished.
The project has been dogged by problems since a decision to renovate it was made a decade ago – with costs now stretching to more than £15m.
A spokeswoman for Newcastle City Council, which is running the scheme on behalf of the North East Combined Authority, said: “The refurbishment of this Grade II listed structure is an extremely complicated and challenging project and we are committed to bringing it into public use as soon as possible.
“The work on the refurbishment of the Tyne Pedestrian and Cyclist Tunnel has unfortunately been beset by a number of complex issues which has resulted in a series of delays as the work required was far greater than we anticipated.
“This includes dealing with asbestos which shut down the construction work for eight months to allow a deep clean to be carried out, the loss of contractors through administration as well as the issues with water entering the tunnels.
“However, we are now in the final stretch of the work and we look forward to opening the tunnels back for public use in early 2019.”
South Tyneside councillors are due to be updated on the scheme at Thursday’s Jarrow Community Area Forum (CAF).
According to a report prepared ahead of the meeting, work is expected to be ‘substantially complete’ by the end of this year, but won’t actually be ready to open until early in 2019.
Bosses behind the scheme have previously promised it would be finished this year.
The tunnel closed in May 2013 for restoration work, which was supposed to be finished by 2015.
However, delays due to the original contractor entering administration and the discovery of asbestos have seen this pushed back several times.
Costs have also ballooned, from an original budget of about £6.9million, to an expected final cost of £15.65m.
The crossing opened in 1951 after taking four years to build at a cost of £833,000.
James Harrison , Local Democracy Reporting Service