Network Rail completes the ‘big push’ at Werrington “This is one of the corner pieces of the East Coast Upgrade and we won’t be able to complete the jigsaw without it.” Ed Akers, Principal Programme Sponsor, Network Rail
Between January 16-24, Network Rail and its contractors completed a first in UK engineering, by jacking an 11,000-tonne curved concrete box into place beneath the East Coast Main Line near Peterborough. PAUL STEPHEN reports
NETWORK Rail’s £200 million project to provide grade separation at Werrington Junction has entered the final straight, after the successful installation of the main tunnel structure.
Following a nine-day possession of the short section of the East Coast Main Line that now sits above the tunnel, and some
24,000 working hours, NR achieved handback at 0403 (52 minutes early) on January 25.
NR and its main contractor Morgan Sindall have been on site since August 2018, when a Transport & Works Act Order (TWAO) was granted to replace a flat crossing three miles to the north of Peterborough.
The TWAO followed a public consultation in which the far more visually imposing option of building a large flyover on the flat Fenland landscape was firmly rejected.
Due to enter service in
November, the double-track dive-under will enable slowmoving freight trains to travel on a dedicated route beneath the ECML, as they make their way between Stamford line on the western side of Peterborough station and the Great Northern-Great Eastern (GNGE) Line to Doncaster via Spalding (see trackplan).
Removing this conflict with express services on the ECML forms part of the wider £1.2 billion East Coast Upgrade, and NR’s commitment to increase the number of long-distance highspeed train paths between London King’s Cross and Doncaster from six trains per hour to 8tph from May 2022.
Since August 2018, the formation at Werrington has been widened and the Up and
Down Stamford lines slewed approximately 30 metres to the west, providing room for a ramp to be constructed to provide access to the site of the southern portal of the dive-under.
Meanwhile, on the northern side of Werrington Junction, more than 120,000m3 of material has been excavated, to carve out an approach cutting to the opposite portal.
It is here where the 11,000tonne dive-under structure has been cast in 16-metre sections, and from where it was recently guided into position.
At 155 metres long, 9.5 metres wide and 5.1 metres high, the concrete structure is known in engineering circles as a ‘box jack’. This is understood to be the first ‘curved box jack’ to be built in the UK.
Before it could be pushed (jacked) into place, two drive guide tunnels were bored and guide rails were installed along the course of the dive-under.
A nine-day possession was then required in order to complete the jacking and the removal and reinstatement of track and overhead line, power and signalling equipment from a 200-metre stretch of the ECML above.
This had been planned to take place between September 5-13 2020, before the outbreak of COVID-19 earlier in the year resulted in a three- to four-week delay in the boring of the guide tunnels.
This was only a minor delay, until safe methods of working could be established. But when combined with other delays incurred by flooding and high winds over the previous winter, it was enough to cast doubt on the project teams’ readiness to conduct the ‘big push’ when originally planned ( RAIL 914).
NR subsequently looked at rescheduling the work to Christmas. However, completing the jacking at the same time as a major nine-day possession was also under way at King’s Cross as part of the station remodelling (see pages 38-43) was thought to place too great a strain on resources.
It was eventually agreed with industry that the Werrington possession could be taken in January. Work finally commenced at 0100 on January 16, to begin disconnecting the signalling, to remove track and ballast, and to raise the height of the overhead line equipment on the ECML.
By 1345 that same day, bulk excavation had begun in order to dig a path for the ‘box jack’ to be pushed into place over the next five days.
From January 17-21, excavators worked around the clock to remove soil to the base level of the dive-under and to uncover the guide tunnels, which were broken into to reveal the guide rails.
Four hydraulic jacks then pushed
the ‘box jack’ (which is heavier than the Eiffel Tower) at a rate of 150cm per hour, before being released at 2200 on January 21.
Once in position, the ‘box jack’ was backfilled, while work then began from January 22-24 to rebuild the track bed above, reinstate ballast and track, and to reconnect signalling, OLE and other systems.
Passenger disruption was minimised by the Stamford and the GN-GE lines both being made available as diversionary routes for the reduced timetable that remains in place in response to the Coronavirus pandemic.
Speaking three days after the completion of the ‘big push’ on January 27, NR Principal Programme Sponsor Ed Akers told
RAIL: “This is one of the corner pieces of the East Coast Upgrade and we won’t be able to complete the jigsaw without it.
“The King’s Cross remodelling is another huge piece of work that needs to be completed - and the Power Supply Upgrade to the north of Doncaster. But in ingenuity and engineering terms, Werrington is number one without a doubt.”
John Agar, engineering manager at Morgan Sindall, added: “It’s been a massive undertaking and does prove the concept (of curved box jacks) for future grade separation projects on the railway.
“The conditions at Werrington were ideal, which is why we were able to do this in just nine days, keep trains running and avoid far more disruption.”
Despite reaching this major milestone, the project team still has a busy six to eight months’ worth of work ahead of them before the dive-under can be brought into service.
This includes construction of a base slab in the tunnel and the installation of 8,000 metres of permanent way in the tunnel and on its northern and southern ramps, before tying in the new stretch of railway to the existing network.
Much of this work can be completed ‘offline’, although one final 72-hour disruptive possession will be taken at Werrington from June 4-6, to coincide with the final weekend of commissioning at King’s Cross.
The physical works at Werrington are then scheduled for completion in August, before paperwork is completed and authorisation sought from the Office of Rail and Road for entry into service in November.
“I’ve already heard from freight operators asking when the diveunder will be available,” Akers told
RAIL.
“The answer is that it will be available for use immediately after we get authorisation, and then we’ve committed to the industry that [the extra capacity delivered by] Werrington and King’s Cross will be available in a longer-term plan from May 2022.”
NR had originally committed to making the additional train paths released by the East Coast Upgrade (ECU) available from December 2021. However, Akers conceded that the relatively short gap between the target service entry date at Werrington of November 30 and the December timetable change “is a little bit racy” and perhaps too ambitious, bearing in mind the mistakes made by various parties in preparation for the ill-executed timetable change of May 2018.
As consultations on the May 2022 timetable change are not due to commence until March, it remains to be seen whether the additional train paths are utilised immediately or not.
Given the collapse in passenger numbers due to the Coronavirus pandemic, as well as widespread uncertainty over when (or if) volumes will return to the levels of 12 months ago, is Akers concerned that the full benefits of ECU will now never be realised?
He replied: “The whole industry is concerned about patronage and what the return will be, and I don’t have a crystal ball. But if I was a guessing person, I would suggest that we will see a reasonable return of discretionary and leisure travel.
“What people should remember is that the ECU programme is built around long-distance travel, not necessarily just the commutertype railway that we have at the south end of the ECML - although that will also benefit from things such as increased resilience and reliability.
“I don’t think we will regret the investment and I think this is still absolutely the right sort of investment to make, even if it takes a bit longer to build back up to the level of demand that we had and hope to see in the future.
“I still think that we will need the interventions that we’ve made, and we won’t regret the money we’ve spent, which will pay dividends for us even if it is a couple of years later than it otherwise would have been.”