A small fleet of "rescue trains" operating on the East Coast Mainline will now be able to react more quickly after speed rules were changed.
The four rescue trains have been nicknamed 'Thunderbirds'
Rail operator GNER campaigned to have the maximum speed for the single-engine Class 67s raised from 75mph, a limit which was set 40 years ago.
The vehicles can now travel at up to 100mph, allowing them to respond to breakdowns more quickly.
A GNER spokesman said rescue times will be reduced by up to 15 minutes.
The company leases four rescue locomotives, nicknamed '"Thunderbirds", from freight operator EWS.
To ensure that they can arrive on the scene quickly, the locomotives are stationed at strategic locations along the East Coast Main Line - King's Cross, Doncaster, Newcastle and Edinburgh.
GNER's rolling stock engineer Dick Page said: "Getting the approvals to run the Class 67s at a higher speed for rescue operations has been a long and complex process.
"We are delighted to have been able to alter an outdated 40-year-old rule. The change means that there will be reduced delays in the rare event that a train fails or passengers are stuck behind a stationary train."
Class 67s already had permission to travel at 100mph on high-speed parcels services.