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Chiltern Evergreen: Jolly green giant

The Chiltern Evergreen project is being upgraded with a unique funding deal between Network Rail and its contractor.

An anonymous industrial estate on the outskirts of Banbury in Oxfordshire isn’t the first location that springs to mind as playing an integral part of what could become the future for major rail project funding.

And yet tucked away in one of the industrial units alongside the railway station car park is the nerve centre for the delivery of the Evergreen3 Mainline project, a £125M investment by train operator Chiltern Railways.

The project will slash service times between London Marylebone and stations through to Birmingham by as much as 30 minutes.

Increased line speed

“Our objective is to increase the line speed so that the fastest trains will be able to get between London Marylebone and Birmingham in 90 minutes,” says Chiltern Railways operations director (projects) Tom Birch.
We want to grow our market by offering a better alternative to the M40 which is already very busy,” Indeed the move to improve the service is key to Chiltern Railways’ success in winning the extended 20 year franchise along the line.

“Our objective is to increase line speed so trains will be able to get from London to Birmingham in 90 minutes”

Tom Birch, Chiltern Railways


Network Rail has lent Chiltern the money to fund the upgrade and will recoup this from track access charges paid by Chiltern’s train operating arm. The train operating business will in turn earn revenue from fares (see box overleaf).
The overall Evergreen3 programme, as the project has become known, features the upgrade of the main line between Banbury and London Marylebone, the upgrade of the existing line between Bicester and Oxford and construction of a completely new link between the Chiltern line and the Bicester to Oxford line.

The programme is divided into two phases with the Evergreen3 Mainline work as the first phase and the rest of the improvements including the reconstruction of stations at Bicester Town and Islip, new platforms at Oxford and a new station at Water Eaton Parkway due to be delivered under the second phase of the project.


It has not been plain sailing, however. Network Rail took over the management of the upgrade project in March amid concern that it was running late as a result of delays caused by the collapse of Jarvis, one of the original contractors (NCE 10 March). The project also suffered badly from delays getting the design approved.

For the first phase, design and construct contractor Bam Nuttall alongside engineer Atkins is carrying out a host of line improvements and station and junction remodels that will help increase the overall line speed between Aynho Junction and Marylebone.

In all there are more than 50km of permanent way line speed improvements involving realignment and recanting works with 45km of line speed increases. There are also three major junction remodelling areas at Neasden, Northolt and Aynho.

“We have focused as closely as possible on minimising the amount of structural work we have had to carry out to help keep a ceiling on costs. In terms of structures there have been bridge deck replacements and strengthening but it is only at Northolt where we have had to replace a single track bridge with a twin track one,” says Atkins project director Fraser Greenwood.

Embankment exrtension

There has been significant remodelling work on the scheme to extend the existing embankment at Northolt (see box) and also near Gerrards Cross station in Buckinghamshire but it is the Neasden junction remodelling work that has recently been the focus of the project team’s furrowed brows.

This work was carried out under a 17 day blockade at the end of August. The team put the finishing touches to work at Neasden as well as completing work on a section of track from Wembley in north London to Princes Risborough in Buckinghamshire, including Northolt junction.

Neasden is a complex junction with the local up and down lines to Harrow-on-the-Hill and beyond squeezed next to London Underground’s Jubilee and Metropolitan lines as well as the up and down Chiltern mainline itself.

“There really was only one feasible solution at Neasden and that is the one we had to go with”

Ashley Glover, Bam Nuttall

The object across all junctions on the scheme was to stretch them out to increase line speed, a difficult proposition at Neasden because of its tight confines.

Nailing Northolt

As part of the work to extend the embankment along the main line route Bam Nuttall’s sister company Bam Ritchies installed more than 3,500 soil nails along the track near Northolt.

More than 2,900 of those are the 32mm self drilling Dywidag nails with a further 900 or so of 38mm diameter nails being used to stabilise the slopes of the extended existing embankment and also boost its load bearing capacity.
The Northolt site is split into four quadrants - North East, North West, South East, South West - and throughout the Northern sector work has predominantly involved strengthening the existing embankment.
Across the southern sector, nails have been installed through existing gabions and extra fill placed to widen the embankment.


“There really was only one feasible solution at Neasden and that is the one we had to go with,” says Bam Nuttall project director Ashley Glover, “the confines of the site didn’t allow any other options.”

Thankfully for the project team there was a spare, unused arch beneath the bridge that carries the North Circular road across the line. This afforded some much needed space for the track realignment.

Realigning curve

To achieve the line speed increases across the junction - typically 85mph from 60mph at the up line’s main entry to the junction - the Bam Nuttall team is realigning the curve through it. This involves building up the cant or embankment around the curve so that Chilterns trains can power around it at the increased speeds. Much of the work for the Neasden remodelling was carried out outside the blockade under standard weekend and evening engineering possessions. Over the two months preceding the blockade the existing track routes were excavated down to the new formation profile and then reinstated using temporarily placed ballast. The track itself was then replaced on the original line allowing traffic to continue to use it. The final realignment work was carried out under the blockade.

“It meant that some of the unknowns that could bite us during the blockade, like poor ground conditions, had already been cleared prior to us starting work,” says Glover, “That’s why we had such confidence in the blockade programme,” he adds.

The first week of the blockade saw the completion of the permanent way programme and the installation of nine new switches and crossing units. The team used a Kirow mobile track mounted crane with a 125t capacity to help lift in preassembled S&C units as well as 105 complete sections of track.

“The unknowns that could bite us, like poor ground conditions, had been cleared prior to us starting work”

Ashley Glover, Bam Nuttall

The second week of the blockade focused on the area from Wembley to Princes Risborough. This again involved a Kirow crane which helped complete the remodelling work around Northolt, High Wycombe and Princes Risborough.

The complex new signalling system was also completed.

“In terms of signalling the second week of the blockade was far more complex than the first,” says Greenwood.

“Every single point had to be tested, even things we hadn’t touched.”

Recabling needed

Where the design had called for the re-use of existing equipment recabling work was often needed and during the blockade there were are 100 signal works testers on hand to ensure that everything had been installed and tested correctly.

“Signal works testers are a very scarce resource and all of them are registered by Network Rail so it knows who is available and when. They take on a huge amount of responsibility when they verify the work,” says Greenwood.
It is a responsibility that is already being put to the test now that Chiltern Railways has opened up the line to its 100mph service, ready to begin clawing back its investment.


Funding : the future?

All eyes are on the Evergreen3 project and particularly the mainline element of the scheme thanks to its unusual finding stream.

Normally network operator Network Rail would directly fund any improvements to the rail network but here on the Evergreen3 scheme the overall £250M package is being financed by a mortgage deal taken out by Chiltern Railways with Network Rail in return for a longer franchise period. The move will allow the train operator to reap the benefits of an improved service through the projected increase in passenger revenue. It has also improved the speed and efficiency of delivering a major rail project according to Bam Nuttall project manager Ashley Glover, something that will be advantageous in the wake of the government’s plea to improve efficiency and drive down the costs of major construction projects.
“I think because we have been able to get greater access to the client we have been able to make decisions more quickly. I think this sort of funding could be the future for major rail projects,” he says.

Readers' comments (1)

  • David Williams

    Lodon to Birmingham in 90 minutes for just £125M: seems like rather good value compared to HS2. Add electrification and another 10 minutes could be saved. This sort of significant improvement for modest expenditure seems right for our present time of austerity.

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