British Transport Police are now hunting the gang following the raid in the Kittybrewster area of the city on Tuesday.
Officers believe an articulated heavy goods vehicle was used to steal the track.
Constable Ashley Forbes, the BTP officer in charge of the enquiry, said: “A lorry, which may have been involved, was seen driving off on Bedford Road and Powis Place, which, even at this time of the morning, is a busy route in and out of the city centre.
“I am appealing for anyone who was in the area at the time, particularly pedestrians or taxi drivers, and who may have noticed someone acting suspiciously to contact BTP.”
Officers have been trawling CCTV footage and carrying out door-to-door enquiries in the area in an attempt to identify those responsible for the theft.