Detailed investigation work is getting underway ahead of proposed improvements to a world famous bridge spanning the River Tweed between England and Scotland.

Northumberland County Council, Scottish Borders Council and the ‘Friends of Union Chain Bridge’ are working together on an £8 million project to safeguard the future of the Union Chain Bridge near Berwick - the world’s oldest single span suspension bridge still open to traffic.

Constructed in 1820 and spanning the River Tweed on the Anglo-Scottish border, the bridge requires urgent conservation and engineering repairs to secure its future. It has been on Historic England’s ‘Heritage at Risk’ Register since 2013.

A funding bid for the restoration is now being prepared for the Heritage Lottery Fund, with a maximum of £5m available towards the bulk of the work.

The county council’s cabinet will next month consider recommendations to contribute funding over three years towards the scheme, with both Northumberland and Scottish Borders Council ultimately contributing towards the project. Other stakeholders will also be making significant contributions.

Ahead of this, site investigation work is getting underway on the bridge from June 26 for up to four weeks, which will mean the road will be closed to vehicles from July 3 on weekdays for a fortnight.

The investigation work is important in providing a greater understanding of the status and condition of the bridge - and allowing a more robust bid to be submitted to the Heritage Lottery Fund.

Councillor Glen Sanderson, cabinet member for environment and local services, said: “The Union Chain Bridge is of international significance but its condition has been of growing concern for a number of years.

“Along with our colleagues in Scotland we are committed to safeguarding its future and status, both as a key transport link and as a contributor to the local tourism economy.

“The site investigation work is vital ahead of any major project starting and engineers will be working to keep disruption to a minimum throughout.”

The bridge itself is a single suspension span of 137m of timber construction supported from wrought iron chains by wrought iron hanger bars. If these vital repairs are not undertaken, the bridge would ultimately close to vehicles, losing its World status as the oldest surviving suspension bridge carrying traffic, causing serious loss to the local community.

Councillor Gordon Edgar, Scottish Borders Council’s executive member for roads and infrastructure, said: “I am pleased we are seeing progress in the bid to retain the Union Chain Bridge as the world’s oldest single span suspension bridge still used by traffic.

“The iconic crossing has provided a vital link between Scotland and England for almost 200 years, and we want that to remain the case.

“The short-term closure of the bridge to vehicles will cause some inconvenience but will provide important information for its long-term future.”

Northumberland County Council’s Cabinet will discuss the report on the bridge on July 11.