More than 1,000 areas for improvement have been identified on a major rail line plagued by faults.
Network Rail said it will carry out work to improve a 53-mile stretch of the Great Western Main Line between Didcot Parkway in Oxfordshire and Paddington, west London.
Reliability has deteriorated on the route since the middle of last year, affecting Great Western Railway, Elizabeth line and Heathrow Express passengers.
In December, broken wires left thousands of passengers stranded on trains for four hours at night, near Ladbroke Grove, making national headlines.
Network Rail route director for the Western route, Marcus Jones, admitted that the Government-owned company has been “letting people down”.
“We haven’t been performing well enough and we are sorry for that,” he said.
“We’re letting people down and it’s awful to be in a position where we’re doing that.”
The 1,000+ actions for improvement identified include inspecting certain pieces of infrastructure more frequently, fitting data logging devices to some assets to get quicker information about problems, and renewing some sections of overhead wires.
Network Rail has spent four months developing its project, but warned it will take 18 months for the route to have good performance as standard.
“We’ve got a plan and we’re confident”, Jones told the PA news agency.
For the next four weeks, there will be fewer trains late at night as engineers carry out work to the tracks, signalling and overhead wires.
Six months of work will aim stabilise performance, followed by a year-long programme to put long-term solutions in place.
Jones said the improvements aim to “stabilise” services and “stop things going wrong” over the next six months, and have maintenance and infrastructure renewals be “back on track” after 18 months, at which point good performance will be “business as usual”.
