Much has been written, in Rail Engineer and elsewhere, about the Great Western Electrification Programme. Articles have covered the design of the overhead equipment, the purchase and deployment of specialist plant to install it, preparatory work needed in Box, Patchway and Severn tunnels, and the complete reconstruction of Reading station.
More recently, readers have been kept informed about rigid conductor beam installations through the Severn tunnel, and the announcement that electrification will be ‘paused’ short of Bristol.
But very little has been written about work at the other end of the line, completion of the electrification at Paddington Station. Most of the station had been electrified for the Heathrow Express service in the early 1990s, but the more difficult platforms were not wired up. Introduction of electrified stock on the GW Franchise would make these platforms redundant.
Changing standards
While this had been proceeding as planned, complications occurred when it came to Platform 14. One of the last three platforms to be electrified, Network Rail appointed Carillion Rail to design, install and commission an upgrade which would allow the platform to accommodate 164-metre electric trains. Platform extensions, grading and level changes, track layout alterations, canopy modifications and 354 metres of new overhead wiring would all be required. TSP was brought in as primary designer.
The track for Network Rail’s Platform 14 at Paddington sits alongside that for Transport for London’s Platform 15. So a collaboration between Network Rail, TfL, Amey and Carillion worked out a scheme whereby the track renewals for Platform 14 would be supported by a work train parked on the TfL track at Platform 15. In return, a Network Rail train in Platform 14 would be used for work TfL was planning to Platform 15. Inter-company cooperation – it’s a wonderful thing! The major complication came as a result of a change to Group Standard GL/RT1210 – AC Energy Subsystem and Interfaces to Rolling Stock Subsystem – which was updated in December 2014. The job changed from being a simple electrification to a pilot for the new Group Standard.
Whereas it had been acceptable to just follow the standard in terms of electrical clearances, and to demonstrate that those stipulated clearances had been achieved, it was now necessary to show an appropriate level of knowledge and expertise for the evaluation of the design. All reasonably practicable measures and controls had to be in place to ensure that the risks associated with the OLE on Platform 14 were reduced as much as was reasonably practicable.
In addition, the project had to continue to run to schedule as the next available access to accommodate any postponement would not be until after the new Great Western IEP service was meant to be in operation. Delay was not an option.
Complete rethink
So what did this all mean for the project?
As lead design organisation (LDO), the Carillion and Network Rail project team had to rethink its plans. All the current approvals in principle had to be shelved and the designers had to go back to the drawing board. A systematic approach was needed.
One option was the raising or removal of bridges within the station, along with further track lowers and associated platform civils work to accommodate those changes. On paper, it seemed simple and straight forward, but Paddington is one of the oldest stations in the country.
Options were limited. To extend the platform’s operational length to 164 metres, it had to be extended at both ends. On the London end, the buffer stop had already been moved by 11 metres, and that was all the room available. The country end had also been extended as much as possible.
The existing soffit height of 4,470mm restricted clearance at two specific locations, with no room for alternatives.
Project delivery had to be staged across Christmas 2015 and Christmas 2016 due to the difference in cross fall limitations between Platforms 12 and 14.
The most significant challenge, however, was the need to lower the track still further. Platform 14’s historic footing of concrete below the sleepers and the Thames sewer beneath the tracks already meant that existing ballast depths were non-compliant.
To overcome these challenges, the project team considered various options, some of them quite innovative, before submitting plans to the Office for Rail and Road (ORR).
Where possible, the platform was lowered to achieve normal clearances. The extent of the live section was reduced, especially towards the London side, which was limited by the undercroft.
Some options were discarded due to time and budget constraints. These included raising the undercroft, demolishing the London Underground footbridge and installing platform screen doors.
Others were adopted – additional training for station staff emphasising the dangers of 25kV electrification, additional markings, more signage around the station and a further design change in the form of a contact wire grading under the undercroft.
It was time to work together. Teamwork between Network Rail, Carillion, Amey and TSP ensured that the first scheduled train from the rebuilt platform, the 07:18 departure for Hayes and Harlington on Monday 5 September, left on time. It was a true collaborative effort, with team members giving up weekends to make sure that everything was completed to schedule.
And, so far as the passengers were concerned, it was almost unnoticed. Which is as it should be.
