Police are renewing their appeal for witnesses following the accident on Saturday
The collision happened on the A5 southbound on-slip prior to the Redmoor Roundabout at about 7.30pm on Saturday.
A white Suzuki Swift left the carriageway before coming to rest in a ditch.
Sergeant Matt Cadmore of the Joint Operations Unit for Roads Policing based at Taplow said: “First and foremost, our thoughts are with the family of the woman who has very sadly passed away of her injuries.
“They are being supported by officers at this extremely difficult time.
“I am re-appealing for anybody who may have witnessed this collision to please get in touch with police.
“I am also again urging a Good Samaritan who stopped at the scene to please come forward.
“If you are this man, or know who he is, please contact us.
“The easiest way to do this is by leaving us your information online, using reference number 1831 (11/4). Alternatively you can call 101, but please be aware that call times are longer than usual.”
