A 27-year-old woman, who was a pillion passenger on a motorbike, died in the incident on the A465 Heads of the Valleys road between Brynmawr and Ebbw Vale on Thursday evening.
She was named on Friday as Sarah Jayne Jones from the Tredegar area of Blaenau Gwent.
The rider, a 56-year-old man, has suffered serious injuries.
The road remained closed on Friday morning while investigation work continued.
A main route across the top of the south Wales valleys which closed after a fatal accident has reopened.