Train operator GNER has welcomed the news that engineering firm Jarvis is pulling out of day-to-day rail maintenance.
Nobody was hurt in the Kings Cross derailment
Network Rail is set to take over the work after Jarvis handed back its maintenance contracts because of worries about its profits and reputation.
The firm is being investigated for its role in the Potters Bar crash last year and a derailment at Kings Cross station in London last month.
Jarvis maintains a quarter of the rail network, including the East Coast main line from London to Edinburgh, but has been heavily criticised for the standard of its work.
The RMT union said Network Rail should now take control of maintenance for the whole UK rail network.
The head of GNER - the rail company that runs express services on the East Coast main line - said improvements should follow Jarvis' exit.
"Certainly the aftermath of the Kings Cross derailment was, as far as we were concerned, just one thing too many," GNER chief executive Chris Garnett told the BBC.
"I think the fact that they're going is very good news for all our passengers and for all our staff."
But Rail Passengers Council chairman Stewart Francis noted that Network Rail still had to prove it could improve on Jarvis.
"I think passenger confidence in Jarvis had been shaken due to a number of incidents on the railways," he said.
"Passengers don't care who maintains the railways as long as they are delivered safely and their trains run on time."
Jarvis is pulling out of routine maintenance of three sections of the UK rail network, partly because it is worried about its reputation being damaged by accidents caused by poor workmanship.
But the company will continue to be involved in major track replacement projects - including the modernisation of the West Coast main line.
THE AREAS AFFECTED
East Coast Mainline: The route from London to Scotland passing through Peterborough, Doncaster, York and Newcastle
Central: Covers north Lincolnshire, Yorkshire and the North West, including cities such as Lincoln, Hull, Leeds, Bradford and Middlesbrough
Liverpool, North Wales and Merseyrail: Includes cities such as Liverpool, Chester and Bangor
Network Rail will take over the maintenance contracts itself and the 3,500 engineers working on them.
Seven people died at Potters Bar when a train derailed because of faulty points.
Jarvis was responsible for their upkeep and has suggested the accident might have been caused by sabotage.
Police are still investigating why a set of bolts was missing.
Last month there was a close shave at Kings Cross station, when an intercity train derailed because it was diverted onto a section of track that was missing.
Jarvis admitted it had been doing maintenance work in the area, and something had gone wrong. No one was injured.
Announcing its decision Jarvis chairman, Paris Moayedi said: "The Board of Jarvis has decided to focus the business on delivering its core services to even higher standards of excellence."
It said maintenance accounted for less than 15% of turnover and Jarvis now intended to concentrate on its other core activities.
Investors welcomed the news and Jarvis shares ended the day more than 5% higher at 323.5p.
"The publicity has been so awful that getting out of it is probably something the market feels quite happy about," said Geoff Allum, an analyst at Investec Securities.
Network Rail has already brought three other contracts back in house.
The three Jarvis contracts are expected to have been handed over by April next year.
Network Rail chief executive John Armitt said that just because Jarvis had run into controversy doing the work did not mean his firm would face difficulties.
"Perhaps they (Jarvis) felt that was impacting on the rest of their business but that doesn't mean that the process of carrying out maintenance in itself on the railways should necessarily be a complex and controversial one for other companies," he told the BBC.
"We are going to take over the work and carry it out safely and effectively."
Government 'should act'
The general secretary of the RMT union, Bob Crow, said Network Rail should now take control of all maintenance work across the rail network.
"The fragmentation of the railways has been an unmitigated disaster since privatisation, and we have called for maintenance to be brought back into the public sector from day one," he said.
"The Government should now stop standing by doing nothing and act to speed the process that has already begun by default.
"Network Rail should take a deep breath and signal their intention to bring all maintenance work back in-house. It is the only way forward."