National Highways closed one lane of the southbound carriageway for emergency works by the Botley Interchange for “safety reasons” after finding the collapsed manhole.
The road will be closed tonight so the emergency repairs can take place.
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The A34 underneath the Botley Interchange was already due to be closed tonight for the ongoing bridge repair works but these will now not take place.
One driver, who asked to remain anonymous, said it took him more than two hours to get from Bicester to the Botley Interchange.
He said: “They could quite easily just put signs with advanced warnings.
“It just gives everyone time to prepare. I wouldn’t mind if people were working, but no one is ever there.
“There are no vans. They just shut the road off.”
National Highways has apologised for any inconvenience caused.
A spokesman said: “One lane of the A34 southbound carriageway near Botley Interchange is closed for safety reasons due to a collapsed manhole. There will be a full southbound closure tonight to allow us to carry out these emergency repairs”.
“The works at A34 Botley interchange planned tonight will be standing down to accommodate these emergency repairs.
“We apologise to local drivers for the inconvenience caused.”
Over the next two months, work for the bridge repairs at the interchange will see several overnight weekday closures.
A National Highways spokesperson said: “We’re carrying out essential bridge repairs on the A34 Botley interchange to keep the structure safe and secure.
“During the course of our work, there will be periods of overnight closures affecting journeys between the A34 and A420.
The one-way section of Seacourt Lane will also remain closed.
“We’ve successfully installed our traffic management around the A34 Botley Interchange with a single narrow lane on the roundabout and reduced speed limits in place 24/7 to protect our workforce and travelling public.”
The A34 underneath the Botley Interchange will be closed on weeknights only between 9pm and 6am from Tuesday, January 8 to Thursday, January 11, Monday, January 15 to Friday, January 19 and Wednesday, February 7 to Friday February 23. This is excluding weekends.
Botley Interchange, including the A420 between Cumnor and West Way will be fully closed on weeknights only between 9pm and 6am from Monday, February 26 to Thursday, February 29.
When the Botley Interchange is closed, drivers will be diverted either via the A415 or A338 towards the Marcham Road interchange for the A34.
Alternatively they will leave at Hinksey Hill for Oxford using the A4144, B4044 and A40 towards Peartree or the A34 and Peartree interchange.
When the A420 over the Botley Interchange is closed, drivers will be diverted via Peartree or Hinksey Hill interchanges and return. Through traffic will be diverted off and on again via Botley interchange.
When the A34 underneath the Botley interchange is closed, drivers will be diverted up and over the junction to continue their journey.
Journeys between the A34 and A420 will not be directly affected by a closure although there may be delays in the area at peak times.