The Olympics and Paralympics are over, and life on the railways can now get back to normal. That, of course, means night- time and weekend possessions as the never-ending job of maintaining and renewing the railway continues apace.
However, not everything stopped during the Olympic period. Certainly, there was a hold put on disruptive work on the main feeder routes into London, and the south- eastern area in general. But, further north, that simply meant that more work was done on non-critical routes. High output machines were diverted to freight lines, where more work was actually done than normal.
To see what was happening in the middle of the Olympic shutdown, the rail engineer went off to a mixed traffic line near Selby in Yorkshire. South Milford is on the Leeds to Hull line, near where it crosses the East Coast Main Line at Milford Junction. It is a passenger route used by both First Transpennine and Northern, and also carries 8.5 EMGTPA (equivalent million gross tonnes per annum) of freight, mainly coal.
Over time, the ballast has deteriorated due to the tonnage of freight that is carried on that route, and also from the coal dust that drifts down from passing wagons. Without intervention, a temporary speed restriction would have been required.
The job of replacing the ballast falls to Network Rail’s track delivery team. This is part of the new Network Rail Infrastructure Projects organisation and is headed up by Steve Featherstone, with a budget of £600 million per annum. Its primary role is delivering condition-driven renewals of plain line rail, sleepers and ballast, using both conventional and high output means, and switches and crossings.
Track delivery is divided into four regions, with Ben Brooks managing the LNE and East Midlands (EM) routes. Meeting Ben at the Network Rail offices in Doncaster, he explained some of the challenges that track renewals teams have in general.
“Introducing the seven day railway concept has been exactly the right thing to do – moving passengers when they need to travel is our primary purpose as a railway after all. We’ve reduced our typical weekend renewal durations from 30 hours to 16 for conventional renewals on primary routes, with a maximum of eight hours available on weekday evenings. This is why the high output track renewals fleet is so important to us – this machinery can deliver effectively in eight hours with adjacent lines open safely, achieve high hand-back speeds and minimise the likelihood of network disruption.”
Ben currently has three high-output machines in his area, one ballast cleaner and two track renewal systems. Like all the high output machines, they belong to Network Rail but are operated by Amey-Colas under a contract that runs from January 2010 to March 2014.
Conventional renewals on Ben’s LNE and EM routes are contracted out to Babcock, which had won the contract which also runs to March 2014 after Jarvis folded in April 2010. In total, Babcock delivers 50% of the national track renewals programme. Its Doncaster Shaw Lane depot delivers more S&C and more conventional plain line than any other depot in the country, and set a record by installing 1002 yards of plain track in 9.5 hours on the Boston to Skegness route last summer.
There must be something about being based in Doncaster. Amey-Colas has also set records from its Doncaster depot, at Gresley House. In one midweek, eight-hour possession earlier this year, 800 yards of ballast was cleaned using the same Plasser & Theurer RM900 high output ballast cleaner that was now working at South Milford.
But, just to show that not only Doncaster- based teams can break records, this September the high output team located in Newcastle delivered 968 yards of rail and sleeper replacement using a track relaying system on the Newcastle – Carlisle line. There seems to be some healthy inter-team rivalry going on.
To call high output systems “trains” is no misnomer. At 845 metres long, and weighing 3,200 tonnes, the ballast cleaner is over three times as long as one of the new Thameslink trains (243m) that are soon to be ordered from Siemens. Each system costs over £50 million, and has an operating crew of 15 plus one fitter.
In a normal midweek shift, a ballast cleaner can deliver 300-500 metres, and 600-800 metres in a 16 hour weekend shift. That is over 20 kilometres in an 11 week campaign.
However, don’t think that 800 metres in 16 hours means that the train runs at 50 metres per hour – it is not that simple.
Ballast cleaning explained
A ballast cleaner works by scooping out all the ballast under a section of track, using a cutting chain. The old ballast is recovered into the train where it is shaken through screens so all the dust and small stones are removed. The ballast which is still the correct size is returned to the trackbed, and new ballast is mixed with it to restore the correct volume.
The working section of the train is roughly in the middle. In front of it is a row of empty wagons which will take the discarded small stones and dust, known as spoil. All the wagons are fed by conveyor belts that run the length of that section of train – when one wagon is full the spoil is automatically taken to the next empty one.
Behind the centre section is a row of identical wagons, but these are already filled with fresh ballast. As it is required, the conveyors bring new ballast forward to be mixed with that which was recovered in the cleaning section.
How much work a train can do depends on the percentage of recoverable ballast there is in the existing formation and the time available for the renewal. If it is to be completely renewed, so that all the old ballast goes off to the spoil wagons and is completely replaced by fresh ballast from the back of the train, then after about 250 metres the on-board supplies are exhausted. Separate work trains have to be brought up so that spoil can be loaded onto it and stock of new ballast replaced. At South Milford, better than 50% of the ballast was being recovered, so that was not an issue.
To get back to running speeds, the simple fact is that the ballast cleaner cannot run throughout the possession. A look at the time chart shows why.
At South Milford, on the weekend of 18/19 August, the possession was due to be taken at 22:25. At 23:15, S&T engineers started the two- hour process of disconnecting any signalling cables that ran under the track. If they were left in place, the cutter bar of the ballast cleaner would just rip them out along with the ballast. Any that were to remain in situ had to be buried much deeper than normal.
At the same time, an RRV excavator dug a hole in the ballast in which the cleaner’s cutter bar and excavator belt could be rigged and started. When that was completed, the whole train could be slowly brought forward until the central cleaning stage was over that hole.
The entire Amey-Colas team now got to work. The site management team and track gang were joined by the 15-man system crew on the train. The cutter bar was rigged in the previously dug hole, running under the track. The chutes down which both recovered spoil and dispensed fresh ballast were deployed and the machine was ready to go. It was 00:45 and, although the S&T wasn’t completely finished, it was clear far enough ahead so that the train could start rolling.
The chain began to move, digging ballast out from under the track and carrying it up the left hand side of the machine. As the whole train inched forward, fresh ballast was poured back into the hole created and blades under the train pushed it into place. The whole thing moved along at a slow walking place.
The plan was to work for 285 minutes, until 05:30 – four and three quarter hours. In that time it would do about 800 metres. After that, the cutter bar and other equipment would be removed, the train could move off, and the S&T team could start reconnecting again. That in itself would take over three hours.
A tamper would go through the worksite once the ballast cleaner was clear. Each high-output machine has a Plasser and Theurer 09-3X tamper, complete with an on- board dynamic track stabiliser, working with it. Once that had completed two passes, taking another three and a half hours, the site could be handed back at a linespeed of up to 80mph.
So in a sixteen hour possession, the expensive high-output train only worked for less than five hours. It seems inefficient, but it isn’t. The rate of work is so high that renewals are now 15% cheaper than they were back in 2009 and high output delivery methods are cheaper than conventional renewals.
Conventional is not old-fashioned While the big train was working at South Milford, more conventional techniques were being deployed not far away, at Immingham. This is the busiest freight port in the country in terms of tonnage, and consequently the railway line takes 48 MGTPA, making it the UK’s most heavily trafficked freight railway. As it is so busy, the only access possible is on a Saturday night, typically from 23:10 Saturday to 15:10 on Sunday.
Working only in those tight time restricted windows for five months, Babcock have replaced five miles of life-expired track formation, ballast, rail and sleepers, at a rate of a quarter mile of new railway per week. Supported by suppliers SES and Network Rail NDS (Hydrex), Babcock introduced innovative parallel working methods to maximise output. The bar chart shows 32 different work activities happening across the 16 hours, many at the same time and all coordinated to make sure that the work was delivered in full, to budget and with no unplanned performance impact on railway freight operations.
Access issues were overcome through use of specialist road rail vehicles from Hydrex and Trac, whilst Network Rail maintenance signalling personnel supported with the disconnection and reconnection of equipment.
So while the rest of the country was busy watching the Olympics, the LNE/EM track renewals team was busy working on the nation’s railways. Embargo? What embargo?