RAIL users will now have to wait until December for the first electric trains through Bolton, after rail bosses admitted that they will miss their latest target.

Upgrade works to electrify the railway line between Manchester and Preston via Bolton had been due to finish by the end of 2017, before the completion date was put back to May 2018.

However, further delays to the project mean that the engineering work cannot be completed until later this summer — meaning passengers will have to wait until the next timetable change in December until they finally see electric trains coming through Bolton.

Once the electrification is complete, TransPennine Express is planning to reroute its Scottish services through Bolton, while passengers will also be able to enjoy faster, more reliable, and higher capacity services.

The delay will also mean more cancellations of weekend services.

Network Rail has agreed with train companies to carry out its additional work at weekends, meaning replacement buses will be brought in.

Weekend closures are planned from now until end of April, while Network Rail is currently working with train and freight companies to agree weekend dates from April to the end of August.

Martin Frobisher, route managing director of the London North Western Route at Network Rail, said: “While we are disappointed to miss our May 2018 target on the Manchester-Preston upgrade, it is important we view this within the full context of the Great North Rail Project. The ultimate prize for customers is 2020 when Network Rail’s current GNRP upgrades are fully complete.

“Customers in the North are already benefiting including from faster, electric services between Liverpool and Manchester and from Manchester Airport to Glasgow. There is far more to come in future, including better Manchester-Preston services.”

Cllr David Chadwick, Bolton Council's cabinet member for transport, said: "To say that I am disappointed is an understatement. I was really looking forward to having electric trains running through Bolton by the middle of this year.

"But the conditions that Network Rail have found around Bolton and Salford are obviously causing major problems."

Jeff Davies, chairman of the Bolton Rail Users Group, added: "I have been watching the progress — or, rather, lack of it — for a month or two now and have been expecting another deferment.

"I don't know what is going on with Network Rail, but I hope that things will be better in the future."

Unexpected running sand and hard rock in the vicinity of old uncharted shallow mine workings have slowed progress to electrify the line.

Rob Warnes, performance and planning director at Northern, said: “This is disappointing news for our customers who will have a longer wait, with more disruption, before they can experience the service enhancements Manchester to Bolton electrification will make possible.

“We are committed to working with our industry partners to complete the project to its revised schedule, while doing everything we can to minimise disruption to customer journeys. We will share more detail on any changes the delayed electrification work will have on planned improvements for the May 2018 timetable change as soon as we can.”

Jerry Farquharson, service planning director for TransPennine Express, added: “It is disappointing that this complex project will now take longer to complete. We are working closely with Network Rail and other train operating companies to minimise disruption for our customers while the upgrade is concluded and to deliver our planned service improvements as soon as possible.”

The work Network Rail still needs to do on the Manchester-Preston scheme is the installation of foundations for steel columns to carry overhead power lines at Chorley, Bolton and Salford.

Due to poor ground conditions at these locations, three out of every 10 foundations have been unsuccessful at the first attempt.

Some 1,700 foundations are already in place at Preston, Chorley, Horwich and Bolton. But there are 200 still to put in.

Another challenge, which slowed the scheme’s progress, was the need to carry out emergency repairs to Moses Gate railway bridge in Bolton last year after it was damaged by a burst water main.