Two freight trains went through red lights because drivers were too tired, an investigation has found.
An investigation was launched after two trains running from Acton to Westbury drove through a signal near Reading.
Both drivers said they momentarily fell asleep on approaching the signals. The Rail Accident Investigation Branch (RAIB) said inadequate rest facilities at Acton were partly to blame.
The drivers' employer, DB Cargo UK, said new facilities had been installed.
Both incidents involved a "signal passed at danger" - when a train passes a stop signal without authority to do so.
The first happened on 28 March 2015 when a driver went through a red light to the west of Reading station.
The second was on 3 November at the Ruscombe Junction in Berkshire.
'Robust processes'
Neither incident resulted in injury or damage.
http://www.bbc.co.uk/news/uk-england-berkshire-37507191
The RAIB investigation concluded the drivers had suffered from fatigue because they had not obtained sufficient sleep, which was in part due to rest facilities not being fit for purpose.
It added they were nearing the end of a long night shift.
The final report called for changes in covering shift planning at Westbury depot, fatigue management and identification of fatigue risk.
Lee Bayliss, from the company, said roster issues had been addressed in addition to changing facilities at Acton.
He added: "Fatigue is an issue we take very seriously and we have implemented robust processes and policies to manage it."