RAIL passengers travelling through Newport will see their travel times extended by up to 45 minutes next month, when the Severn Tunnel closes for six weeks.

The four-mile long 130-year-old tunnel is undergoing renovation work, as the main South Wales line prepares to become electrified.

From Monday, September 12 to Friday, October 21, trains to London Paddington will be heading towards Gloucester in order to bypass the work and at a reduced capacity, although replacement bus services will be running.

“The programme of works we have scheduled during the six week closure has been carefully planned to ensure we can deliver these essential upgrade works on time,” said Anthea Dolman-Gair, senior programme manager for Network Rail.

“We are on target to see electric trains running to South Wales by 2019.”

The electrification of the line will cost £2.8billion, and the six week closure accounts for a significant part of the project, the programme manager added.

Work on the tunnels, which started in February, has so far included the removal of 40 tonnes of soot.

“There is never an ideal time to close the railway to complete essential upgrade works, and we thank passengers for bearing with us during this time,” added Ms Dolman-Gair.

“We have worked closely with all our train and freight companies when considering the timing and it has been collectively agreed that autumn is the best time to carry out this critical milestone in the electrification of the South Wales Mainline, also when considering the other major upgrade work planned elsewhere on the network.”

At present, specially-made drills are creating holes in the brickwork and more than 7,000 brackets will be fixed in place, allowing the electric cables to hang above the trains and railway line.

Network Rail have said that the six-week closure of the tunnel is essential, otherwise the electrification would take up to five years to complete through overnight work alone.

“Without a solid six-week closure it would take engineers up to five years to complete the upgrade, causing long term disruption for passengers and delaying electrification until 2021,” Ms Dolman-Gair added.

It will take three years before the line will be completely electrified, but it is hoped that once complete, the service will provide the region with significant long term benefits.

Ms Dolman-Gair added: “These include faster, more frequent trains as well as a boost to economic growth in South Wales thanks to better connectivity to and from London, a critical factor for attracting inward investment.”

Replacement buses will run between Severn Tunnel Junction and Bristol Parkway, and between Bristol Parkway and Newport, with journey times involving a replacement bus are likely to be extended by approximately 45 minutes

There will be one service an hour between Paddington and Newport but this will not call at Bristol Parkway.