Today’s railway system might be a singular entity but it was formed from many discrete parts, pushed through the Victorian landscape by competing companies to secure commercial advantage. Writes Graeme Bickerdike

Coal proved a powerful inducement across the north of England, prompting a convoluted network to develop on which passengers often played second fiddle. It was only later in the nineteenth century that corporate collaboration brought a more joined-up approach with the widespread development of connecting spurs to meet emerging needs, rather than costly new lines being laid.

A typical case study can be found in the flatlands four miles north of Doncaster. The railway arrived here in June 1848 when the Lancashire & Yorkshire and Great Northern companies met end-on at Askern Junction, providing the latter with its first route into Leeds. The West Riding & Grimsby overflew this line just south of the junction in 1866, fired by the prospect of minerals being dispatched to export markets. Five years later, the North Eastern Railway pushed today’s East Coast main line northwards from Shaftholme Junction, then constructing an east-facing chord to the WR&G in 1877. Last to trouble the cartographers in 1916 was a now- closed joint effort by the Hull & Barnsley/Great Central, again with an eye on local colliery output. All these routes were threaded under and over each other in less than one square mile of countryside.

Inconceivable back then was any notion that Britain might become dependent on coal imports. But we are, bizarrely. So the railway now finds itself trying to work in reverse, accommodating significant flows – around 30 trains daily – from Immingham to the Aire Valley power stations. Much of this travels via the WR&G, now known as the Skellow line, before transferring to the East Coast Main Line via the 1877 (Applehurst) chord.

Trundling slowly northwards for 14 miles as far as Hambleton South Junction, this freight acts to constrain the capacity for additional long-distance passenger services to York and beyond, needed to meet forecast growth.

Photo: Four by Three.

Photo: Four by Three.

Get up and go

The solution – part of a £600 million package of CP4 interventions on the ECML – is to connect the Skellow with the L&Y’s lesser-used Askern line via a new 3.2km railway known as the North Doncaster Chord. A 12-month consultation period and the submission of proposals to the Infrastructure Planning Commission culminated in the Secretary of State formally granting a Development Consent Order in October 2012. By this stage, an alliance had been formed between Network Rail and Morgan Sindall – the appointed contractor – which based itself in York while URS finalised the design.

Mobilisation swiftly followed, with the land take getting underway in December and the project team moving into offices alongside the Skellow line on 2nd January 2013, overlooking the wasteland occupied by Thorpe Marsh Power Station until its demolition over the previous summer.

In overview, the chord extends southwards from Owston Grange Farm No.1 crossing on the Askern line, climbing on embankment at 1:120 to a 246 metre six-span viaduct over Joan Croft Lane, the East Coast main line and Applehurst chord, then curving eastwards as it descends – again on embankment – to cross an underbridge at Bell Croft Lane before meeting the Skellow line 520 metres beyond Applehurst Lane crossing. You will gather from those words that muck shifting formed a very significant part of the project in its early stages, averaging 2,500 tonnes per day and peaking at almost 5,000 tonnes.

On the move

The search for sources of general 1A fill was focussed locally to minimise the impact and cost of transportation. For the eastern embankment, washed colliery spoil from three pits – Hatfield, Kellingley and Maltby – was assessed for two qualities: a 35° or greater internal angle of friction – determined by shear box testing – and sufficient durability to deliver a 120- year design life. Maltby’s stood out as meeting these criteria, with the added advantage that delivery by rail was possible. The power station’s former sidings were fettled back into shape to receive it. Also achieving the required structural properties was a limestone material from Wentbridge Quarry, north-west of the site, which arrived by road to form the slightly smaller embankment at the north end.

That at least was the plan. The landslip at Hatfield Colliery in February 2013 (issue 105 – July 2013) effectively cut the Skellow line off until July, putting paid to the train-hauled importation of spoil. And prior to that, the ubiquitous Great Crested Newt disrupted work on the eastern embankment until the arrival of spring allowed their relocation to a purpose- made habitat on the other side of the railway. This frustration drove a greater use of road transport, approaching from the west side, to serve the section between the viaduct and Bell Croft Lane bridge. The team worked wonders to make up for lost time.

Access routes for the 20-tonne wagon fleet were the subject of lengthy discussions with the local council. The communities hereabouts are served by narrow lanes which are not in great order, certainly unsuitable for the loadings and volumes demanded by the North Doncaster Chord. This prompted a swift programme of resurfacing, kerbing and junction improvements on the highways linking the site to the A19, together with the laying of temporary haul roads across fields to straighten a couple of tight corners. Allied to this has been the establishment of a 30mph speed limit and one-way system for construction traffic. Two farm crossings over the railway have also been upgraded; these remain open to construction traffic unless a train is approaching, requiring regular dialogue between the relevant signaller and crossing keeper.

Handling the vast task of constructing the earthworks – all 500,000 tonnes of them – has been Jakto. Due to the underlying soft laminated clay, Tensar Basetex – a reinforced geotextile starter layer – surrounded with 400mm of drainage stone was introduced upon which to build-up the 7.2 metre high embankments. Negating the need for ground improvements, this approach helps to even the loading, control settlement and increase the embankments’ resistance to deep-seated failure planes.

Goodbye Joan

Located 100 metres north of the new viaduct, Joan Croft is one of several manually- controlled gate crossings over this section of the East Coast main line. Whilst acutely unremarkable, its significance to the project should not be understated. By replacing it with a bridge, the overhead line equipment could be lowered, in two stages, by 1594mm in total. This allowed the elevation of both the viaduct and embankments to be reduced, cutting the quantity of import materials needed and bringing consequential benefits in terms of transportation and cost. In turn, this has lessened the chord’s visual impact. And all that comes before any consideration of the safety and operational improvements brought by another level crossing closure.

Photo: Four by Three.

Photo: Four by Three.

An initial concern was that the foundation piling for the viaduct’s abutments would have to be rotary bored, rather than the more efficient CFA piling, which would have resulted in another rig being mobilised. But this was soon discounted following further local ground investigations undertaken with the piling contractor Bachy Soletanche. Once piling for the bridge could start in earnest, 52 piles were augured in just two weeks.

Efforts were then concentrated on the concrete works, delivered by Brenbuild, with protection screens erected during possessions to remove any ongoing railway interface. These doubled as formwork for the abutments.

Eight weeks after starting, a 500-tonne crane lifted the nine precast concrete bridge beams into place during a single overnight possession; others were taken to install the permanent formwork for the deck and the parapet barriers. No time was lost before Jakto came in to build up the approach embankments, the programme being that tight. “The rate of fill placement has been phenomenally good because the weather has been on our side,” reflected Morgan Sindall’s engineering manager Tony Naylor. “If we had lost days through weather, we would have been stuck.”

The road bridge played a key logistical role, offering the only means of access to the east side of the railway for the 1,200-tonne Gottwald AK680-3, supplied by Sarens Construction, and its convoy of assorted components which would be assembled over five days to lift in the viaduct’s longest span.

The limited availability of this crane defined a critical path for the project – if the piers weren’t ready for an open window over the August Bank Holiday of 2013, there wouldn’t be another for the best part of two months. This served to concentrate minds, instilling a can-do must-do approach to any problems that arose.

Digging deep

Piling for the viaduct started at the end of April last year, two weeks after the road bridge piling. Working north-to-south with an 85-tonne Soilmec SF-120 CFA rig, between 12 and 32 piles were sunk per pier to the Sherwood Sandstone bedrock, 19 to 22 metres below ground level. These vary in diameter from 600 to 900mm, dependant on the loadings, and support a concrete raft on which stands a pair of seven metre high concrete columns. Progress with this work had to be carefully driven to coincide with weekend possession and isolation opportunities, allowing the rig to be taken over Joan Croft level crossing without it having sat idle for several days. Much time and application was invested to evade the potential embarrassment of it running aground or striking the overheads. It did neither of course.

The build for Pier 2, closest to the East Coast main line, again exploited a protection screen to minimise its effects, this time attached to the sheet piling that safeguarded the excavation for the pile cap and then propped off the foundation base. Cleveland Bridge, the project’s steelwork partner, helped to ease the time pressures associated with this pier by revising its programme such that span 4 was in place before Joan Croft Lane – which passes under the northernmost span 6 – was closed on 29 July 2013. Thereafter work progressed southwards from the abutment as planned.

Weighing 462 tonnes, the longest steelwork section of 65 metres – crossing the ECML and Applehurst chord – went in overnight on the 24/25 August. Unlike the spans to the north, its main girders, cross beams and formwork panels had all been built-up beforehand at ground level using a 250-tonne crawler crane. After being lifted in, this occupied span 2 and part of span 1, and was then spliced to a second prefabricated section – weighing in at 227 tonnes – which was positioned two days later. It’s worth making the point that all this activity over the East Coast main line was fulfilled in standard Rules of the Route possession periods.

Photo: Four by Three.

Photo: Four by Three.

Whilst closure of the Skellow line unhelpfully held up the embankment works, it did allow VolkerRail’s track team to install the S&C at the eastern end considerably earlier than anticipated, working four weeks of days. However, five disruptive weekend possessions were needed on the Askern line for the new junction. The track formation thereabouts was poor – resulting in a long-standing 20mph PSR – so stabilisation work has been instigated involving the installation of steel sheet piles along both sides of the railway and formation renewal work. This will allow the speed restriction to be lifted.

The chord itself has been receiving track since November, a process that was substantially complete before Christmas, with just the top ballast and tamping yet to be completed. Signalling is rarely simple, a reality that emerged here as the design work, led by TICS, came to its conclusion. Commissioning is likely in April 2014, having cost £44 million from start to finish.

Making it happen

All this magazine’s writers will find an echo of familiarity in the words spoken by project leaders when describing their team’s efforts. “We’ve all worked together” is an obvious favourite, perhaps reflecting times past when this wasn’t always the case. What’s clear about the North Doncaster Chord is that every contributor – from subbies to the principal contractor – has had a voice and this has engendered a spirit without which the project would probably have been in trouble as a result of the difficulties thrown at it.

Network Rail’s alliance manager Adrian Elliott recognises with generosity that “Everyone who’s walked onto site has engaged with the ethos of getting it over the line. It’s been a challenge but we’re getting there.”