Rail Industry Focus

Full steam ahead for Fillie at Farnworth

RTM’s David Stevenson reports from a recent site visit to Farnworth Tunnel where Nick Spall, LNW route delivery director for Network Rail, discussed how a major block of work is helping to deliver further electrification in the north west.

As RTM went to press, the biggest tunnel boring machine (TBM) in Britain was edging closer to completing the re-boring of Farnworth Tunnel – an important enabler of electrification between Manchester and Preston.

We attended a site visit on 11 August, shortly after the giant TBM started its journey to re-bore a 270m railway tunnel at Farnworth.

At 9m in diameter at its cutter head, Fillie the Farnworth TBM is bigger than the machines used to build London’s Crossrail (7.1m), the Thames Tideway ‘super sewer’ (8m) and even the Channel Tunnel (8.8m). The machine was built by Oldham-based Tunnel Engineering Services (UK).

Closure

The project has required the closure of one of the two tunnels at Farnworth, which has caused disruption to services between Bolton and Manchester for several months. This was because the twin tunnel bores, built in the 1800s and which carry the railway under the main A666 Manchester to Bolton road, aren’t big enough to accommodate the overhead line equipment (OLE) required for the forthcoming electrification.

Network Rail and its programme delivery partner Buckingham Group opted to take the Up tunnel out of commission, fill it with 7,000 cubic metres of foam concrete and re-bore a significantly bigger tunnel. The Down tunnel, however, has remained open, allowing Northern Rail and TransPennine Express (TPE) to maintain a weekday service. The team has also made this track bi-directional. Once the work is complete, the Down tunnel will be used for maintenance.

This significant part of the north west electrification work is timetabled to finish on 4 October, and Network Rail is confident this will be achieved. When RTM visited the site alongside the transport secretary, the TBM was ahead of schedule with 10m of tunnel bored, instead of the planned 9m.

‘On programme’

Nick Spall, LNW route delivery director at Network Rail, told us: “We are on programme. There were a few teething problems, there always are with these things, especially as this is a really complex piece of kit. It is [worth] nearly £2.5m, and was manufactured locally. We didn’t get a chance to test it very much until we started digging. So, we had a few small commissioning issues and we took time making sure it was aligned properly – making sure the temporary works were in the right place.”

The old stone around the tunnel’s entrance and the actual tunnel lining, which was made of very strong engineering bricks, meant it took a lot of work to get the TBM boring through it. “The first couple of metres are the hardest, but once you get into the rhythm of it they do get quicker,” said Spall.

Under a framework contract, Buckingham Group is the principal contractor on the Farnworth Tunnel work, but J Murphy & Sons is carrying out the actual tunnelling operation to a design by OTB Engineering.

About 120 people are working round-the-clock – in two 12-hour shifts – on the project, and around a dozen people are constantly working on Fillie – named by a local schoolgirl following a competition – as she bores the tunnel.

Overlooking the work, which has so far gone to plan, is a small shrine to St Barbara, the patron saint of miners and engineers, located above the entrance to the tunnel face.

Good progress

One engineer involved with the Farnworth Tunnel project since the beginning is Beth Dale, scheme project manager, who told us that getting the machine buried and into the tunnel was a “massive achievement”.

She told us: “We have set the first two permanent rings now, so we should make good progress. There are about 190 permanent rings in total we’ll put in place, and it is just moving ahead from here.”

Work to build the original tunnel began in the 1830s, and surveys of the Up bore revealed an assortment of defects. “It is an incredibly old tunnel,” said Dale. “We have taken extensive measures to make this tunnel (and the one next door) stable, to make sure they remain fit for operating an operational railway during the blockade. And everything is going according to plan.

“The smaller Down tunnel has had an additional 200mm layer of sprayed concrete set on the inside, to strengthen weak sections.

“On the Up tunnel we’ve done a process called grouting. So, we drilled behind the lining of the tunnel, as the original timbers they used to build it will have rotted away by now, leaving a void. We then filled all of that with grout, which is keeping it stable. The tunnel itself has been filled with foam concrete as well, to help keep it stable.
“This is probably the most complex project anyone in the north west has ever worked on. There are so many different companies coming together with one aim: getting this tunnel built and getting the railway back in order by October.”

Track lowering and platform work

As well as getting the tunnel bored, the team have lowered over 1.6km of track and rebuilt a retaining wall and road bridge at the west end of the tunnel, as well as moving Farnworth station’s platforms northwards to meet the new track alignment. Similar work has been undertaken at Moses Gate station.

“[At] the two stations where we’ve had to take out the platforms, we are all on programme at the moment,” Spall told us. “Farnworth is coming on well and the new platform is just about finished on the new alignment.

“It is a construction project, so we are in the business of managing risk. We are still not without risk. There may be issues that slow us down a bit, but so far, so good. We know the importance of the October deadline, and I’m confident we will do it.

“With regards to the overall portfolio of projects at the moment, live and on-site, this is one of the top two or three challenging projects.” Spall is also confident that Fillie will have completed the boring work by early- to mid-September.

Electrification

Discussing the recent deferral of electrification work on TransPennine and Midland Main Line, Spall said: “It is bad news, but there are two established OLE delivery teams there. And the fact that this work has been deferred has actually meant that, locally, it has worked to our advantage, because all of a sudden we’ve got a lot more options in our supply chain – where we didn’t before.”

However, he did admit that the transport secretary’s ‘pause’ of TransPennine and Midland Main Line electrification also means all north west electrification programmes are being re-examined at the moment.

RTM was told that Network Rail, Northern Rail and TPE have worked extremely closely to deliver the programme around this blockade – and have received only six complaints.

Talking about this collaborative way of working, Spall said: “This, for me, is a landmark way of how we should be planning our projects and, increasingly, we will be doing so. We were so joined up with Northern and TPE to figure out how we could do it while minimising disruption.”

Alex Hynes, managing director at Northern Rail, added that he was “really impressed” by the ambition of the work at Farnworth. “I’m not an engineer, but I think to re-bore a new tunnel through an existing hill and alignment is very impressive,” he said.

After the Down tunnel was strengthened, in order to operate a single line service, it was also alarmed to detect any movement caused by the re-boring of the Up tunnel. But, so far, no movement has been detected, said Hynes.

Nick Donovan, managing director at TPE, said that while everything is on plan, “contingency plans have been developed in case anything goes wrong”.

He added that all the partners are “very confident” that Farnworth Tunnel will be complete on time. “And with regards to the electrification between Manchester and Preston – we’re confident that this will be delivered on time,” he said. “The important thing for this route – once this is electrified – is that it enables our Anglo-Scottish trains to run via Bolton, which is a slightly faster route than the Wigan one they take at the moment. It also puts back in connectivity between Bolton and the West Coast Main Line.”

‘There will always be disappointments,’ says McLoughlin

After visiting the site, and getting on board Fillie, transport secretary Patrick McLoughlin told us: “You can’t upgrade any rail infrastructure without causing disruption. It is the same [with] road infrastructure as well.”

McLoughlin added that once the tunnelling work is complete in September, commuters will get “a better, more resilient service and a brand new tunnel that takes two trains through it rather than the one as is currently in position”.

“These projects are big. Anybody who has been down on-site and seen what is happening will understand why it takes place. But at the end of the day people will get a better rail service,” he said.

“This work has not been ‘paused’: it is actually happening. It is not that far away from completion. That is the important point: the Northern Hub is £1bn of investment in lifting and upgrading the rail network. It is a commitment to transport and better connections between the major towns and into the cities in the north west, it is very important and is part of the ‘Northern Powerhouse’.

“Yes, there will always be disappointments along the route. The fact that I had to put the Leeds to Manchester electrification on pause was not something I desired, but it is a pause and it is to make sure we get the right decisions and we do the job in the most efficient way possible.”