Crash investigators say slippery rails were a cause of the collision involving two trains at the entrance to Fisherton Tunnel in Salisbury.
Fourteen passengers suffered minor injuries and a South Western Railway driver was more seriously hurt in the crash, which happened at 1845 on Sunday October 31.
A South Western Railway service passed a red signal and collided with a Great Western Railway service at Salisbury Tunnel Junction, as both trains moved onto the same track in the same direction.
It was quickly established that the SWR driver had applied the brakes, but the wheels slid along the rails and the train was unable to stop.
The line was expected to remain closed for two weeks. One of the main routes into and out of Salisbury, the A30 London Road, was also shut.
The 1720 SWR service heading west from Waterloo to Honiton passed signal SY21, which was at danger, 220 metres before the junction. It struck the third coach of the 1708 GWR service from Portsmouth Harbour to Bristol Temple Meads, which was entering Fisherton Tunnel from the south.
To read the full story, see RAIL 944