Police say the accident happened between Siston and Dramway at around 3pm.
Police this morning confirmed that the motorcyclist, who was in her 20s, died from her injuries at Southmead Hospital.
The collision involved a Mercedes 180 car, a Vauxhall Astra van and a Vespa moped. The busy road was closed for more than three hours which caused chaos, particularly as Webbs Heath is currently closed for Wessex Water works.
Police are appealing for anyone who witnessed the incident to call 101 and speak with the Collision Investigation Unit.