The teenager, from the Stirling area, is understood to have been the daughter of former Central Scotland Police Constable Paul Johnson and his wife, a doctor.
She was a fourth year pupil at private school Morrison's Academy, in Crieff. Pupils were told of her death at assembly today.
Anna's body was discovered by a passing motorist at about 7am on Tuesday under a bridge close to Bannockburn interchange, Stirling.
Police are still looking to hear from anyone who was travelling in this area between 6.15am and 7am, or who witnessed the incident to call them on 01786 456000.