The UK department of transport has scrapped plans to electrify railway lines in Wales, the Midlands and the North.
The cost of the proposed plans had spiralled upward, leading the government to rethink the initiative.
Transport secretary Chris Grayling said the government would instead introduce faster trains with more seats and better on-board facilities.
In response Labour shadow transport secretary, Andy McDonald, said the government was “taking people for a ride”.
Under the new plans, routes between Cardiff and Swansea, and between Kettering, Nottingham and Sheffield, and between Windermere and Oxenholme will be affected.
Modern bi-mode trains will be used on Great Western and Midland Main Line, with passengers in Wales benefiting from new Intercity Express trains which will each deliver over 130 more seats and faster services, the government argued.
Long distance journey times from Nottingham and Sheffield will also be reduced by up to 20 minutes in the peak, with the train operator in the
Lake District beginning work to trial an alternative-fuelled train in this World Heritage Site.
Thanks to this new technology disruptive electrification works between Cardiff and Swansea, Kettering, Nottingham and Sheffield, and between Windermere and Oxenholme, will no longer be needed.
Grayling said: “We are making the biggest investment in the railways since the Victorian era and upgrading services across the country, including in Wales, the midlands and the north.
“Passengers expect and deserve high quality rail services and we are committed to using the best available technology for each part of the network, delivering significant benefits for those who use our railways.”
From autumn 2017, passengers in Wales will benefit from new Intercity Express trains which will each deliver over 130 extra seats, faster journey times and improved connectivity for South Wales to London with 40 per cent more seats in the morning peak once the full fleet is in service.
The first new Intercity Express trains will enter service from this autumn and once the whole fleet is introduced and electrification to Cardiff is complete journey times between Swansea, London and other stations along the route will be approximately 15 minutes shorter.