NEW images show how the Farnworth tunnel project – part of a £1 billion investment to create electrified railways across the North West – is progressing.

Engineers have strengthened the smaller of the two Farnworth tunnels under the A666 so trains can still pass through it.

The larger tunnel will be filled with concrete before specialist equipment bores 300m into it to create an even bigger space which will accommodate both tracks and overhead wires.

When this is complete, the smaller tunnel will be filled in.

These new pictures, released by Northern Rail, show the concrete strengthening measures in place inside the smaller tunnel.

Another image shows work to lower the track on the side of the new tunnel.

The complex engineering challenge is part of a £1 billion project to electrify the network in the north of England – dubbed the biggest railway investment in the last 100 years.

But it means Farnworth, Moses Gate and Kearsley stations closed earlier this month – along with Bolton station at weekends – and will remain shut until October 4.

Rob Warnes, planning and programme director for Northern Rail, said bringing electric trains to the North West was the only way to cope with the growing demand.

It is hoped the improved trains will operate between Manchester and Preston, providing more capacity on the line, from 2016.

There are currently eight fewer trains running through Bolton every hour on weekdays, none at weekends and no trains running through Farnworth Tunnel after 10pm.

Northern Rail is providing replacement buses at the weekends between Manchester, Preston, Blackburn and Wigan via Bolton but from Moses Gate, Farnworth, Kearsley and Clifton there is a Saturday service only.

Bethan Dale, Network Rail’s scheme project manager, said: “Farnworth station and its platforms will have to be shifted to the side slightly to meet the new track.

“We are also increasing line speed to 100mph, lowering the track and four bridges, and closing a pedestrian level crossing to replace it with a footbridge.”

Although there are fewer trains running, rail bosses say they are providing additional carriages and temporarily lengthening some platforms.

For more information on new train times: go to northernrail.org/news/7644