Train operator GNER is adding more carriages to some of its East Coast Main Line trains over the Christmas period in a bid to prevent overcrowding.
Passengers travelling on HST diesel trains which serve Bradford, Skipton, Harrogate and Hull will benefit from an extra 1,700 seats.
The additional leased coaches will add 60 seats to each train, including two wheelchair spaces and disabled toilet facilities.
In capacity terms, the investment is the equivalent of adding an extra train to the GNER fleet.
Company chief executive Christopher Garnett said: "The deal demonstrates how the rail industry works together to ensure that any available rolling stock can be put to good use on other parts of the network.
"The additional seats provided on this busy route will go some way to easing
overcrowding, especially during the morning and evening peaks."
GNER is currently carrying out a £8.7m refit of carriages on its HST diesel trains as part of its £100m investment agreement with the Strategic Rail Authority.