As part of the Paisley Corridor Improvement (PCI) project, Balfour Beatty Rail won the £27 million multidisciplinary contract to construct additional running lines and install the associated overhead line equipment.
At first sight, the basics of track work look almost straightforward – upgrading 4.5 miles of widely spaced two-track railway to three tracks, with a 1.5-mile section of four tracks added in for good measure. But when was a major rail project ever straightforward, particularly when it involves one of the busiest rail corridors in Scotland?
Balfour Beatty Rail’s Project Director Doug Lee and Construction Manager Austin Black recognise that access is difficult enough when 300 trains a day ply the route, but the scheme also demands the installation of 39 point ends within tight schedules and some pretty hefty civil engineering. As the project progresses, the OLE will also need to be modified. Doug points out that “Because of access problems on this busy route, the project does not comprise a simple linear progression of works. Instead, staged works will feature heavily – 26 stages in fact over a 12-month period. For this reason we have needed to undertake very careful and precise planning.”
Complications arise particularly in the 1.5 miles between Arkleston East and Paisley Gilmour Street. “The existing Up and Down loops here will be replaced by a bi-directional four-track section” describes Austin, “but in order to accommodate some complex crossovers at the eastern end, a rock cutting will need to be widened. This will involve the removal of some 1,400m3 of material using on-track machinery. Following this, netting will be applied to the cutting faces.”
The formation for the four new tracks at Arkleston will be moved 12m north of the existing alignment, requiring ground levels to be made up. In addition, new retaining walls are to be built at various locations along the route. All existing drainage will be renewed – of which more than two miles is shallow drainage – for which four new pumping chambers are being provided. The outfall will be into an existing motorway main drain and involves the sinking of an 8.5-metre shaft to link with it. Balfour Beatty Civil Engineering Ltd will undertake all of these works.
Balfour Beatty Rail is responsible for installing overhead line equipment along the route. In the three-track section, new OLE portals were erected under the PCI enabling works but the new catenary equipment still has to be fitted. A further 284 OLE foundations will be installed, involving a mixture of tubular piling and concrete depending on ground conditions.
Although not widely used in the UK, the Siemens SICAT catenary system was installed previously in the Paisley corridor. This will be used for the new additions and the repeated OLE modifications that will be needed as the project progresses. The existing Eglinton OLE feeder station will provide power for the expanded system but about a mile of additional lineside feeder cable will be laid – this will involve the creation of a troughing route through some quite difficult areas.
Gaining access to the various worksites is one of the biggest challenges. Austin Black explains that “A lot of disciplines need to work together and a variety of access regimes will be employed, including weekend possessions, night work and single line working. The Down line is a particular problem because of the number of freight trains that need to use the route over a 24-hour period. This means we only have access to it once every six weeks!”
Space constraints too have caused some headaches. “We will make use of both modular and conventional S&Cs”, continues Austin. “These are assembled at the Balfour Beatty Track Systems facility in Sandiacre under a separate contract. Network Rail then supplies them to us on a free-issue basis. We will make use of PEM/LEMs, Kirow cranes and loose lay, depending on the location.”
Despite these logistical challenges involved, the project team is confident that careful planning and consultation with the various stakeholders will bring the works to a successful conclusion.