Major repairs to a viaduct on the A1 in West Yorkshire have been delayed with the completion date pushed back to April 2024.
National Highways said the delay is due to further issues that have been uncovered on Wentbridge Viaduct since the refurbishment work on the Grade II listed bridge started in February.
The closure of one of two lanes through the roadworks area frequently causes slow traffic and congestion.
The waterproofing and resurfacing of the bridge had been initially due to finish in winter 2023.
John Stebbing, a project manager for National Highways, said: “We understand that this revised completion date is disappointing, and are doing all we can to reduce the impact on drivers and residents."
Mr Stebbing said "good progress" has been made so far but problems need to be addressed now so that the condition of the bridge doesn't worsen in the long-term.
He added: "A number of issues were uncovered after we removed the road surface and waterproofing layer. While these issues will not have presented a safety risk to the public, we must address them now to ensure they do not worsen and cause future closures for emergency repairs."
“We are working as hard as possible to rectify these issues and have the structure open to traffic as normal."
Over the last few weeks National Highways has concentrated on testing the concrete structure to understand the scale of work to maintain the lifespan of the bridge.
The bridge joints have now started to be replaced which will involve overnight closures on the Northbound side on 14, 15 and 16 August.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know.