EGIP begins eletrification work

EGIP is shorthand for the Edinburgh-Glasgow Improvements Programme. It is being funded to the tune of around £1 billion by Transport Scotland on behalf of the Scottish Government and is a significant investment in the rail infrastructure linking Scotland’s two main cities and their surrounding towns, enabling increased service levels and reduced journey times.

With the new infrastructure financed through Network Rail’s Regulatory Asset Base, EGIP is expected to deliver a range of benefits by 2016 including a fastest journey time of 37 minutes on the main Edinburgh Waverley-Glasgow Queen Street route and increased service levels on all routes between the two cities from the current five or six trains per hour to 13.

EGIP will also see the electrification of 350km of the existing network through the central belt, including Waverley-Queen Street, as well as bringing more service opportunities and shorter journeys to the line connecting Alloa with Dunblane.

Clearance solution

Work has started on site recently with the electrification of the north lines between Princes Street Gardens and Haymarket, via the Haymarket north tunnel. Martin Murray, Network Rail project manager for the Glasgow-Edinburgh enhancements, outlined the scope of works – costed at £6 million – and some of the background involved.

The North line tunnel has remained non-electrified until now because there have been relatively few electric trains approaching Edinburgh from the west – just two per hour and these have not caused any operational difficulties. However, with the advent of the Airdrie-Bathgate service and the further electrification between Scotland’s two principal cities, there could be as many as 13 trains an hour. Restricting them to just the South lines would be too high an operational risk.

That the north tunnel was not wired in the past was down to prevailing economics when the Edinburgh-Carstairs Junction electrification was performed in the late Eighties and the need to overcome its restricted clearances and profiles. Whilst nowadays there are several solutions available to resolve such issues without the need for extensive engineering, these were not necessarily an option 20+ years ago when the southern lines were wired.

The solution adopted by main contractor Carillion with its designer Jacobs has been to use the Furrer+Frey rigid overhead conductor rail which consists of a rectangular extruded aluminium beam with the contact wire clamped between the webs. With linespeeds no more than 40mph in the tunnel, this is well within the present system limit of 50mph.

Making good the profile

Other work is needed too as Martin explains. “We’re quite proud of the overall scheme – it’s a total balanced solution, not just changing the track, the overhead line equipment or the tunnel. It’s a mixture of all three. We have succeeded in optimising all the parameters.” The track is being lowered and realigned in places, and a new drainage system installed. The rail is only a couple of years old and is therefore being reused.

The 550m long tunnel was originally driven through rock with a lining mainly in brick. Most of it is in reasonable condition but a short section has always been known to be distorted. Detailed investigations over the years suggest that this was probably the result of covering up problems when the tunnel was built. No recent or historic movement has been detected so the clearance issues have been addressed using conventional stabilising techniques.

Preliminary work in weeknight possessions has been carried out to grout-up voids and stitch the brickwork together with 12mm GRP rods. Rock anchors 4m long tie the whole assembly back to the surrounding rock. All this allows the portions of lining that encroach on the structure gauge to be cut away and the profile made good with Shotcrete.

Beyond the tunnel

The trackwork has been carried out in staged possessions – five on the Down line and four on the Up. The design of the scheme ensured that the end of each stage was located at a point where an absolute minimum of re-work was needed to start a new stage.

There is new wiring outside of the tunnel of course, with the wires extending to Haymarket Central Junction, over the crossover along with the provision of overrun protection on the non-electrified routes. Power supplies have not needed to be reinforced and signalling modifications have been unnecessary as any bonding work was carried out many years ago when the adjacent lines were electrified.

So, with this project well on the way to completion, the EGIP team are looking towards the works needed to prepare for the further extension of the electrification. Putting the wires up is the last stage – there are plenty of bridge, track and power alterations needed first!