Hitachi, the company behind the new Great Western Railway trains says it will launch an investigation into the cause of the disruption of rail services that left plenty of commuters stranded today, 17 October.
The cancellation of all trains between Reading and London is caused by overhead power cables being "severely" damaged by a Hitachi train on a test run on Tuesday night.
The train was on its way to a Bristol depot.
A spokesperson said they are working to find out the cause.
The company confirmed the train that caused the damage to the lines is not yet used for passenger services and is still in its test phase.