Little Bridge across Botany Stream is one of those affected, along with Mill Cottage, a footbridge linking the High Street to Cannon Lane and the new Aldi.
The former was built towards the end of the 19th century, at the same time as the Big Bridge, and was opened in 1888.
They were forged at a local foundry which was more well known for cutlery, and the two cast iron bridges were mischievously nicknamed ‘knife and fork’.
The faults are caused by ‘increased design and loading requirements since construction’ with Mill Cottage having also suffered from ‘deterioration’.
Both structures, which are classified ‘main bridge greater than three metres’. require monitoring every six months.
A KCC spokesman said: “Little Bridge was the subject of a principal inspection in 2012 and is currently programmed for a further principal inspection in 2019.
A principal inspection is a ‘close examination within touching distance of all inspectable parts’.
He added: “The bridge was completely re-waterproofed and resurfaced in spring 2014 and was subsequently repainted in autumn 2014 to address problems with water ingress and limit corrosion to the structural elements.”
Mill Cottage was also the subject of a principal inspection in 2015. KCC added: “This confirmed ongoing deterioration which, due to the age and construction of the bridge, was unrepairable without major reconstruction works which are programmed for 2019/20.
“However, following review of all the latest available information it is necessary to restrict use to cars accessing the adjacent property to ensure continued safety until such time as the bridge is replaced.”
A total of 39 structures across the county have been classified as sub-standard – five of them in Tonbridge & Malling – with 36 of them exceeding 1.5 metres out of a total of 945.
The term ‘sub-standard’ refers to any structure that ‘does not meet current design standards for loading’ – or coping with modern transport demands.
The RAC Foundation submits a Freedom of Information request every year seeking data on sub-standard structures over 1.5 metres in span.
If a structure is found to be ‘sub-standard’, interim measures must be used pending strengthening or replacement. Last year the cost of works carried out in Kent was £21.6million.
Andrew Loosemore, KCC’s Head of Highways Asset Management, told its Environment & Transport Cabinet Committee that the measures ensured safety for road users.
He said there was a need for further funding but that the ‘approach to managing structures was based on risk’. Those identified as an immediate risk would be completed as a priority.
He confirmed that bridges submerged in water received specialist underwater inspections.
The bridge that links the swimming pool to the Racecourse sportsground is currently closed having been deemed to have ‘reached the end of its usable life’, according to the borough council’s Engineering Manager Andrew Young, who is ‘looking at the options available’.
In addition, there is still a 50mph speed restriction on a flyover on the the A21 bypass between Tonbridge and North Farm.
Highways England said “This section has a weak structure [subway] beneath not posing an immediate and unacceptable safety risk.”
Sub-standard bridges
Little Bridge, Tonbridge High Street – main bridge, greater than 3 metres
Stair, Old Hadlow Road, Tonbridge – minor bridge, 1.5 to 3m
Mill Cottage, Tonbridge – main bridge, greater than 3m
Hampton, Hampton Park Road, West Peckham – main bridge, greater than 3m
Arnolds Lodge, Seven Mile Lane, East Peckham – minor bridge, 1.5m to 3m
