A TRAIN operator has said it could take several hours to return to normal services after a major signalling failure caused trains to be stranded on the line this morning.
A power failure caused signals to black out and five trains became trapped on the line, leading the firm to halt all services through Swindon.
Dan Paines, of First Great Western, said: "We had a power issue this morning and all the equipment alongside the track, which makes sure everything can run safely, was simply not working.
"It has now been up and working for the last 20 mintues but it while take a little while to get back to normal.
"Five services earlier became trapped and could not move as a result but I understand these are now on the move and we are working hard to get customers to where they need to go.
"When this happens the problem we get is the network and the track gets much more congested and we are running a great big traffic jam between London and Bristol and Swansea.
"We cut down the number of services running and make sure what trains we do have are ready to go. We also arrange rail replacement services.
"At peak times that's not always easy as we would like as we have to pull them from locations across the network and coach companies are often busy with school runs.
"We are doing pretty well - we are just getting our trains moving again. It is quite difficult but it won't be before noon that we are back to normal."
Services between South Wales and London Paddington in both directions have had to be either diverted via an alternative route, such as Westbury, with increased journey times, or cancelled.
Services between Bristol Temple Meads and London Paddington in both directions are also be either diverted via an alternative route with increased journey times, or cancelled.
Services between Cheltenham Spa and Swindon will also be cancelled. Replacement road transport has been ordered.