The Christmas shutdown gives Network Rail, and London Underground for that matter, a chance to undertake those jobs that would be difficult at other times of the year. Some are major pieces of work, others are routine but take a long time (such as the wholesale replacement of track drainage at Weedon, Northamptonshire).
The justification for these works is usually fairly obvious. Failing infrastructure, operational bottlenecks, capacity improvements, and even new railway construction.
Sometimes, however, the need for a project to take place can be a little obscure. Take, for example, the Crossrail preparatory works carried out by Network Rail at Christmas to install a new emergency escape footbridge at Ealing Broadway station. The project had an interesting ‘raison d’être’ since there is already adequate access to the platforms for the existing trains. However, the new bridge is required because of the enormous capacity of the intended new Crossrail trains. It was decided that the current station infrastructure would unacceptably restrict emergency evacuation of passengers, and that this should be resolved by an additional footbridge at the other end of the platforms.
This sounds simple enough until one considers the surrounding environment at the site. Residential properties are very close to the line, making it difficult to find adequate site access and ensuring that noise and vibration would be significant issues. Ground conditions meant that piled foundations would be necessary, and the only feasible way to place the footbridge structure would be by employing a large crane.
Preparation is key
Taylor Woodrow, part of the Vinci organisation, was employed by the project to carry out the works. The project team held detailed meetings with local residents about the impact of the works, agreeing, for example, to restrict piling activity to daytime hours over the Christmas period. The possibility of obtaining access to the new bridge site via an adjacent NHS facility was identified, and negotiations were entered into with a view to gaining agreement both to temporary access for the crane and construction works and to permanent access to the completed footbridge. Thanks are due to the NHS for their cooperation in this regard.
Christmas 2015 was planned as the date to erect the footbridge span serving Platforms 2 and 3 with a second span to Platform 1 to follow at a later date. Sarens was engaged to carry out the contract lifting operations over the Christmas period.
The piled foundations for the first span were installed beforehand so that, at Christmas, effort could be focussed on the lifting operations. A four-day hire of a 400 tonne mobile crane commenced at 05:00 on Christmas morning and nine main lifts were completed by 11:30 the same day. These lifts involved the placement of support columns, stair units and the bridge span itself. Extremely high winds had been forecast for the day, and the team were relieved that all these main lifts were successfully completed before the winds arrived.
Just down the line at Stockley, the works there were less fortunate. Only 10 miles or so further west, that site was hit earlier by the winds and some of the lifts there had to be postponed. At Ealing Broadway the only crane lifts delayed by the winds were secondary lifts of materials and plant, and these delays had no significant effect upon the programme.
Additional works at the site included some piling to the rail embankment adjacent to the new footbridge. This provided embankment support where it was necessary to trim the bank to construct the access route from the new bridge onto the NHS site and thence to the public road. The large crane was used to assist this work during the remainder of its contracted four-day stay on site.
The plan now is to install the piled foundations and pile caps on Platform 1 ready for the stairs to be installed there and for the installation of the second bridge span over to that platform. The aspiration is to undertake all of these works before Easter, using normal weeknight possessions rather than blocking the line over the Easter holiday.