The world is changing and economics now dictates that every opportunity must be taken in order to maximise the benefits of long engineering possessions. It started with the Christmas break, which has enabled infrastructure contractors to efficiently carry out major renewal work for Network Rail. Over recent years, this opportunity has extended into London Underground (LU) which is now homing in on other suitable periods during the year including the summer holiday period, when the schools are closed and holidays beckon.
This summer was no exception with LU closing the Uxbridge branch of the Metropolitan and Piccadilly lines for 23 days from 19 July until 10 August. The work being carried out under this block closure marked the culmination of a major programme of improvements that have been carried out in recent years to replace life expired track and drainage and modernise other infrastructure on this part of the network. This work is part of London Underground’s £10 billion programme of continuous improvement, which has already delivered huge improvements to the London Underground network.
This part of the LU system is maintained by Track Partnership which is a strategic alliance between LU and Balfour Beatty Rail. It works as an integrated team delivering track and drainage upgrades to the LU network to ensure its life expired track infrastructure is replaced to keep London moving.
Zak Zvakaramba, project manager and Lukasz Wlodarz, construction manager, were in charge of the work. They started to plan for the block closure about 18 months ago and as part of the plan, they decided to use a portion of Hillingdon Station car park as the depot for this work. Alongside the usual welfare facilities, they installed a command centre where they coordinated a phone conference twice daily as well as progress meetings every four hours. This ensured that they knew what was happening at all times and that they could make any necessary adjustments required.
At any one time there were two to three hundred people working shifts around the clock to get the job done. They accumulated a total of more than 120,000 hours worked. A much-appreciated subsidised canteen was brought to site providing a variety of meals and an unending supply of cold bottled water, which was an essential requirement during this very hot summer period.
New track drainage tested
Having said that, during the first week of the work there was a torrential storm that flooded the A40 which is next to the railway. Within an hour more than one metre of standing water made it impossible for cars to pass. However, the construction team were delighted to see that the recently renewed track drainage, installed in preparation for this work, dealt perfectly with the storm and the track formation remained undisturbed.
In total, 5.9km of track was renewed during the closure between Uxbridge station and Rayners Lane. Road/rail excavators were used to tandem lift the old track, excavate the old ballast, place new ballast to line and level before placing new Fastclip concrete FE sleepers using a seven-sleeper bale. LU’s Rail Sleeper Delivery Train (RSDT) was used to place the 216m lengths of new rail into the sleeper housings ready for clipping up, destressing and welding.
Steve Naybour is Track Partnership’s business performance and improvement manager. He is responsible for introducing new, innovative, cost-saving initiatives such as the new sleepers which are designed with lighter housings and therefore cheaper.
In addition, a new flash butt welder has been adapted to comply with specific safety requirements due to the fire risks that apply to the often-confined environment associated with the underground network. More than 170 welds were completed by this machine and, in one shift, they managed to produce an impressive 36 high-quality welds, adding an additional element of longevity to the infrastructure.
Steve explained the value of the road/rail Unimog they were using: “The machine is agile and has the capacity to haul up to six trailers, each with a capacity to carry a 20 tonne load. It became an invaluable asset, reducing the need to use engines and ballast trains and therefore reducing cost and increasing flexibility on site.”
Another new machine introduced to this work was the tracked McCulloch Trac Rail Transposer (TRT) – a series of low-slung, tracked machines which are ideal for moving long lengths of rail.
High rail temperatures
One concern that arose during the closure was that, because of the hot weather, the rail temperature when installed was high, often more than 35 degrees and peaking at around 50ºC. Although this should not present an immediate problem, it has the potential to become problematic as the winter months come round. One of the main aims of the closure was to renew infrastructure that then could be left alone. To ensure this, additional night shifts were introduced to destress the rail to the correct temperature.
In total, 18,000 tonnes of ballast was replaced, 10,000 concrete sleepers installed, 6km of rail and 5,000 conductor rail ceramic pots were replaced. However, the porcelain third-rail insulator pots, which consist of nine parts, were not replaced like for like. Instead, another piece of innovative kit was introduced – the polyurethane pot which only consists of three parts. It was designed to make it easier to adjust the height of the pot to ensure that the right level was achieved.
All three tracks in the station at Uxbridge were renewed. Each track is in a single corridor between platforms so working space was very limited. To make life a bit more difficult, the existing drains running down the centre of each track were in poor shape and also had to be renewed. They were up to two metres below sleeper bottom. Very careful digging and an effective use of plant using 3D excavators and the Unimog were essential to ensure that this part of the work was completed successfully.
Platform copings were then renewed and adjusted to the new track levels which improved the step clearances. This was particularly appreciated by wheelchair users in the area, many of whom were following the works’ progress on Twitter. Track Partnership used the Metropolitan Line’s Twitter account to post photographs and updates that were followed by 26,000 locals. The feedback comments were fascinating. It was a good example of effective communications with local communities; one that will surely be followed by others and it was a great way of showing railway engineering at its best, especially to young people who are thinking about their future careers.
The track renewals extended east of Hillingdon beyond Ickenham station toward Ruislip. During the renewal of the platform copings following the track renewal, a section of concrete forming the platform wall and supporting the platform copings, which had deteriorated badly, collapsed. A quick solution was designed and the section of platform wall reconstructed. In total, about 170 metres of copings were modified at Uxbridge and Ickenham stations.
Within the track renewal sites, three under-bridges were stripped of ballast and formation in order to expose the bridge structure and renew the waterproofing. This work was carried out by specialist contractors Waterseal Ltd which is experienced in working in a railway environment having used a combined spray and Wolfin sheet system for possession works.
In addition, the opportunity was taken to renew a crumbling 70 metres-long masonry retaining wall that separated sidings from the main line. The debris from the wall was becoming a safety hazard and something needed to be done. A series of 152mm square RSJs, each 2.5 metres long, were installed and precast concrete sections slotted into them to provide a simple but effective solution.
For two weekends, the track closure was extended to enable S&C units at Harrow-on-the-Hill to be renewed. This, and much of the above work, required effective and reliable back up from LU Power & Signalling, which was always provided. In addition, many labour suppliers – McGinley, Westview, VGC and CRS – provided the additional support required at different stages of the work. Also, alongside all the work, every opportunity was taken by the LU maintenance teams to renew S&C units in sidings and along the route to maximise the benefits of the closure.
Significant attention was put into the detail, not only to ensure that the welfare of the people involved was kept to a high standard but also to seek out cost savings and innovative ways of getting the job done. The new flash butt welding machine, Unimog, TRT and the polyurethane insulation pots, were just a few of the many initiatives which will help LU to fulfil its commitment to creating an urban railway network fit for the twenty-first century.
There was absolutely no doubting that Track Partnership would ensure that this challenging package of work would be completed on time and to a high standard of quality. Thanks to the hard work and determination of the delivery team, the works were actually completed ahead of schedule. This meant that the Metropolitan line was able to run a special service on Friday 8 August to allow passengers to use the line on the busy Friday commute.
Stuart Burnett, London Underground’s Head of Strategy & Planning, commented: “Carrying out a block closure of this section of the network enabled us to complete the work in just over three weeks as opposed to fourteen weekend closures, which meant that we didn’t lose time to set-up and hand-back of works.
“As we were ahead of schedule we even managed to run a preview service on the Metropolitan line on Friday afternoon before the final weekend of this block closure. The hard work and dedication of our team has allowed for a reliable, on time and within budget project to be delivered for our customers.”
No doubt there will be many more LU block closures in the future. The Twitter community will surely be waiting enthusiastically for the many photos that will be posted. Everyone on site was keen to capture every stage of the work with their cameras – the incentive was a prize for the best photograph of the work.