Thames Valley Police confirmed on Friday afternoon that a man in his 20s was pronounced dead at the scene of the incident on the southbound carriageway near Abingdon.
The incident had taken place just hours before on the dual carriageway – leading to a long closure in both directions.
At the time of writing, emergency services continue to keep the dual carriageway closed heading south while accident investigation work is carried out.
Police officers have since reopened the northbound entry slip road at the Marcham Interchange.
A police spokeswoman said: “The A34 remains closed southbound, in Abingdon following a fatal road traffic collision.
“Police are leaving the scene and have reopened the northbound entry slip road at Marcham Interchange.
“The southbound carriageway, between Abingdon and Marcham Interchange, remains closed for Highways England to continue their work.
“Sadly a man, in his twenties, died at the scene. His next of kin have been made aware and are being supported by specially trained officers.
“Our thoughts remain with them at this distressing time.
“We would like to thank all motorists for their patience whilst we responded to this collision.”
National Highways has confirmed that the crash involved a motorcycle and a HGV.
The southbound carriageway was closed at about 7.40am and Thames Valley police confirmed that the road was closed northbound at 8.52am, as well.
A spokesman for National Highways said: “The road was closed to allow Thames Valley Police and South Central Ambulance Service to work safely at scene.
“National Highways Traffic Officers were dispatched immediately to assist the emergency services, with our area team crews installing full traffic management on approach.”
A spokesman for Oxfordshire Fire and Rescue Service said: “Our thoughts remain with the loved ones of the man who very sadly died on the A34 earlier today.”
Abingdon North county councillor Nathan Ley, a Lib Dem, described the A34 as “borked”, a slang term meaning it is not working properly, broken, damaged or ruined.
He said: “Tell me the A34 is borked without telling me.
“A34 both directions between A4183 Abingdon and A415 Witney. Road remains closed following a serious collision.
“Long delays of 20 miles of congestion on the approach. Traffic is being diverted through town.”
The particular stretch of the A34 southbound is just after the 50mph restriction ends for the Lodge Hill slip roads, where motorists can travel back up to 70mph.
Motorists reported poor visibility on Friday morning due to fog.
Community answers
Book of Condolence
“We have opened a book of condolence for a man in his 20s who sadly died in a crash on the A34 near Abingdon on Friday. This is for anyone who wants to leave a tribute to him or condolences for his loved ones. Please know we will moderate content to ensure it remains a respectful space. There may be a delay in messages being made public as they require approval.””
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From Maria de Lima
Leave your tributes hereMy sincere condolences to the entire family; only God can provide comfort at a time like this
From Jenny Palmer
Leave your tributes hereSuch tragic news.., thinking of the poor man’s family