The Welsh Government has announced £44m funding to redouble and improve the railway line between Wrexham and Chester.
Proposals were first put forward in 2008, but delayed after a review.
The Welsh Government says the scheme has been agreed with Network Rail to be delivered by spring 2015.
The seven-mile stretch of railway will run between Wrexham General and Saltney Junction, enabling trains to travel at 90mph in some sections, and potentially increasing the frequency of services along the line.
It will improve North Wales-South Wales journey times by 16 minutes.
Transport Minister Edwina Hart said: “This new scheme will meet our objectives and provide value for money. It will ensure more people in north east Wales will be able to benefit from the improved rail links to the rest of Wales delivered by the Welsh Government.”
Transport Minister Carl Sargeant says the Welsh Government will develop a business case for the electrification of the north Wales main railway line. He says it will be a robust case, emphasising the social, economic and environmental benefits.
I want to see rail operations across Wales developed to achieve enhanced services with efficiency savings leading to a fairer deal for passengers and taxpayers. Modernising the north Wales rail line is a key element of this ambition and has the potential of greatly improving the rail services and unlocking economic growth for the region, which will in turn help tackle poverty.
– Carl Sargeant AM, Transport Minister
As well as the main line from Holyhead to Crewe, the Welsh Government will also see if a convincing case can be made for electrifying the line from Wrexham to Chester. Electrification from Wrexham to Bidston will also be considered. This would allow trains to run through to Liverpool.
Faster trains between Swansea and London could be running by 2018. The line's electrification is part of an almost one billion pound plan by Network Rail to upgrade the country's railways. Improvements are also planned for the route along the north Wales coast. Here's Carl Edwards.
The Welsh Secretary, David Jones, has expressed his pleasure at today's Network Rail announcement.
Mr Jones described a modern rail network in Wales as "crucial" for the growth of the country's economy.
As a regular rail user, I know that the re-signalling of many rail lines across Wales can only be good news for all passengers and I am particularly pleased that the important north-south line links will be some of the first to be upgraded. The Newport to Shrewsbury re-signalling also marks the start of the build programme for electrification of South Wales mainline which we announced last year.
– David Jones MP, Welsh Secretary
He also welcomed news that the mainline between London and Cardiff will be electrified by 2018.
Mark Langman, Network Rail route managing director for Wales, said there was 'potential for quicker and more frequent journeys on a network that is more resilient and reliable' in future.
He was speaking as the organisation set out plans for investing £1billion in the rail system.
This is an exciting time for the railway. We are now carrying a record number of people on record numbers of trains at record levels of reliability. This is an ambitious plan that will help move the railway in Wales to the next level.
Improved signalling, station improvements and faster trains are among the measures planned by Network Rail. Work to electrify the line between the Severn Tunnel and Swansea should be complete by December 2018, paving the way for bigger, faster and more environmentally-friendly electric trains.
Network Rail has set out how it plans to spend £1billion in the Welsh rail system. It's been described as the biggest investment in Welsh rail infrastructure since the Victorian era.' The business plan covers the period from 2014 - 2019.