A crumbling concrete bridge over a Tube line is to remain closed to all vehicles until it can be propped up.

A section of Broadmead Road – a major road in Woodford – has been closed since July this year due to “significant structural defects” that threaten the Central Line tracks running underneath it.

The bridge’s owner, Redbridge Council, hopes to install a temporary “propping tower” structure to prevent the road from collapsing.

However, at a full council meeting last month, cabinet member for environment and sustainability Jo Blackman said she was “unable to provide details or timelines” for when work will start.

Conservative group leader Paul Canal said the bridge – a key east-west route for cars, buses and emergency vehicles – is a “lifeline” for Woodford residents.

Redbridge Council and Transport for London (TfL) initially refused to explain what structural defects the reinforced concrete bridge is suffering from.

However, documents obtained by the Local Democracy Reporting Service through Freedom of Information requests say that concrete is falling off the structure in a process known as spalling and metal reinforcements have become corroded.

As early as 2014, TfL – which inspects structures travelling over its network – raised concerns about the bridge and warned Redbridge Council that failure to take action would result in “injury or service loss with the ensuing legal actions”.

In recent years Redbridge appears to have carried out repair work and has already installed a propping up structure under the bridge on the eastern side of the Central Line tracks.

But in July this year, following another TfL warning about defects and repairs that are “beginning to fail”, the bridge was closed.

A surveyor for Redbridge Council said they had “concerns of magnitude” about the defects and called for a propping up tower as an “urgent interim measure”, as well as a hammer tapping survey, more frequent inspections and a review by a specialist in concrete deterioration.

Long-term solutions could include “full or partial reconstruction” or a cathodic protection system, which is often used to protect ships and undersea equipment from corrosion”.