Rail services into and out of Cheltenham have been severely disrupted after a freight wagon left the tracks.
It happened early on Tuesday as the train was hauling a consignment of mixed industrial materials along a line at Barnwood, north of Gloucester.
Central Trains, First Great Western, Wessex Trains and Virgin Trains are all operating replacement road transport.
Network Rail was hoping to reopen one line by noon, but warned the service would still be very restricted.
Spokeswoman Kirsty Anderson said: "The train, which was pulling 19 wagons, had travelled some miles along the track with the derailed wagon and caused some damage."
She added engineers were assessing the damage and rail accident investigators were at the scene.
Services are likely to be disrupted until the weekend, First added.
A spokesman for the freight company, EWS, said the driver was not injured and the consignment was not harmful to the environment.