A popular A-road will have speed limits cut for well over a year, with experts warning of "tailbacks" and "congestion". Sections of the A34 will be dropped from 70mph to 50mph for 15 months.

The new speed restrictions will apply 24 hours a day on both the northbound and southbound carriageways. National Highways restrictions will apply on the southbound carriageway between Bagley Wood Road overbridge and the Faringdon Road overbridge. Meanwhile, the northbound carriageway will also have a speed restriction between the Wooton Road underbridge and Lodge Hill Interchange overbridge.

Despite 15 months being allocated for the works, the National Highways Road Traffic Act Notice suggests it could take a year and a half.

The notice reads: "It is expected that the works would last for approximately 15 months starting on or after Monday 7th July 2025, but provision has been made in the event of works overrunning beyond 18 months under Section 15(2) of the Road Traffic Regulation Act. The overnight carriageway closures would take place between 20:00 hours and 06:00."

National Highways is also expected to begin further work on the A34 through Oxford in July.

However, David Henwood, Oxfordshire County Council's shadow cabinet member for transport management, suggested the work could cause serious delays.

David predicted the work to "undoubtedly cause more tailbacks and yet more congestion" around the area.

He even suggested that a 20mph drop was "excessive" with a 10mph reduction to 60mph a "far more sensible" solution.

David explained: "70mph to 50mph is excessive and may in some cases in poor weather conditions create hidden dangers when braking in poor weather.

"The way to introduce speed limits to to be consistent; consistency delivers safer road practice. Inconsistency delivers uncertainty and poor management."

Road closures will also be introduced from Monday, July 7 overnight between 9pm and 6am. The route will be closed between Hinksey to Marcham carriageway on Monday for barrier work.

Meanwhile, the A34 southbound Chieveley carriageway will be closed between the exit and entry slip roads.

County council deputy Neil Fawcett stressed safety was the most important factor when organising roadworks.

Neil explained: "The A34 has a high rate of deaths and serious injuries even when there isn't work going on.

"It is imperative that we put the safety of road users and workers first when a major project like the Lodge Hill slip roads is being delivered.

"It would be completely irresponsible to suggest that shaving a few seconds off a journey is worth risking people's safety for."