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Saturday, June 15, 2024

Highly organised high output

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On a dark night, with rain in the air, a car turns left onto a narrow lane on the outskirts of Belper in Derbyshire. As it makes the turn, a stream of vehicles approaches from the other direction to turn right and follow it down the lane. A few cars are mixed in with an assortment of white vans bearing logos such as AmeyColas, McGinley, Sky Blue and Network Rail. The high-output tracklaying team is in town.

Network Rail has two of these high-output teams, as well as five for ballast cleaning, one of which the rail engineer visited recently (issue 96, October 2012). Based around the country, this particular team has been working in the East Midlands for the last six months. However, before that they were in the West Country, and many of the team originated from Scotland as they originally worked for First Swietelsky before they transferred over to AmeyColas.

Now, wherever they came from, and whichever company they are actually paid by, they are an integrated team, replacing and rebuilding Britain’s railways on a nightly basis.

And they have some great toys to play with! The high output tracklaying train, built by Matisa in Switzerland, is about 800 metres long and weighs up to 2500 tonnes. It can tear up old track, smooth off the ballast, place fresh concrete sleepers on it and then lay continuously welded rail into position, fastening the clips up neatly – all faster than you can walk.

Plain line track replacement is now thoroughly mechanised. Like any high-volume system, it has its limitations. However, when conditions are right, the amount of work it can carry out is truly impressive.

Tonight’s job forms part of the complete renewal of an eighteen mile stretch of the midland main line between Derby and Chesterfield being undertaken during night-time possessions on Mondays to Thursdays. Eight miles out of Derby on the Down line, the worksite has just reached Belper. In another few weeks, at Christmas, it will be time to turn around at Chesterfield and come back again on the Up line.

Diggers and brute force

It’s time for a safety briefing, ably conducted by Flint from McGinley. It looks as though most of the trackside team come from McGinley. The machine operators are all AmeyColas, while Sky Blue employees are there to do the welding.

Flint stresses that tonight’s work will be conducted on the Down main line, and that the adjacent Up line will remain open, albeit with a 20mph speed restriction. There will be lookouts posted, and the COSS, Controller Of Site Safety, will be in contact with the signallers throughout the night, so he will know of any approaching train well in advance.

Out on track, with Flint acting as guide and shepherd, at first it is all a bit of an anticlimax. A Quattro road-rail excavator trundles along and, without fuss, digs a hole both sides of the track, depositing the spoil on the grass embankment to one side. It then moves off to go and do some work on an overbridge a little further along the line.

Next, a man stands on the track between the two holes and attacks the trackbed with a shovel. To start with, he doesn’t seem to be achieving much, but it becomes apparent that he’s knocking the ballast directly under the track sideways into the two holes, creating a void that will leave three or four sleepers hanging in the air. This will be the starting point for the machine.

Up ahead, a gang of men with keying hammers are knocking all the clips out of the sleepers. In fact, they are leaving one in twenty in place, as they will retain the track just enough for the machine to run on it.

The train arrives

Once that is all finished, there is a blare of sirens from the lookout-operated warning system, a row of orange flashing lights, and headlights in the distance. Pulled by a class 66 locomotive, which interestingly is in Bardon Aggregates colours, the high-output machine is arriving.

This is TRS2 (track renewal system 2). The other one is TRS4. Don’t ask! No numbering system is perfect and there is sure to be a logical, if lengthy, explanation.

Once the loco has passed, it is followed by a flatbed wagon loaded with 120 concrete sleepers on five pallets. And a second wagon. And a third. And another. And another.

Twelve wagons later (the train can actually handle a maximum of 31 – enough for 2000 metres of track), the clever part of the machine arrives. Three vehicles make up this section, the first of which looks a bit like a conservatory. In fact it is the Pancut (Pandrol and rail Cutting) area where members of the team can work on the track safely protected not just from the weather but also the hazards of the work site and from passing trains on the adjacent line. As the train moves, they walk along protected in their little glass house with opening sides. There are also tripwires to stop the train in case anyone falls.

An abrasive cut-off wheel is used to cut the track directly under the train. In addition, the new rail, which is lying alongside the existing one, is cut to the same length.

Sleeper cars

Meantime, the rest of the train is getting ready. The countless wagons with the concrete sleepers have a flat steel rail on the outer edges of their flat beds.

These are joined up by spacer beams between the wagons to form a railway along the whole length of the train. Three gantries run along these tracks, with long spindly legs and a cabin on top, they can straddle the wagons and pick up pallets to move them up and down the train. Due to gauge limitations, the operator in the cabin on top of each gantry is almost lying down.

One gantry picks up pallets from the far end of the train and brings them most of the way back to the operating end. It then deposits it on a wagon and goes off to fetch a second. Another gantry collects that pallet and brings it to the middle work vehicle which also has a flat bed at the front end. This operation could be performed by a single gantry, but the distances along the train are so large that it is more efficient to have two sharing the work, even with the gantries running at about 16 km/h.

A third and more specialised gantry then picks up one layer of sleepers off their pallet. At this stage they are pointed fore-and-aft, as this allows the wagons and pallets to be narrower and keeps the gantries clear of the open adjacent line, but the cranes on this gantry are on turntables, so in lifting them they are rotated through 90° ready to go on track. They are placed on a conveyor to be fed down into the bowels of the machine.

Starting up

By now the rails have been cut, and the train inches forward. Men in the Pancut area have knocked out the remaining track clips and left them between the rails, from where a rotating magnetic drum further back on the train will pick them up and recover them. The old rail is splayed out from where it has lain on the old sleepers and the new rail, having been located by a pair of flanged rollers, is now curved up and over the old rail, and into place.

Working in the pre-dug hole with a steel bar, one of the train team has bunched up three sleepers to create a space. Pick-up forks are lined up, and the first sleeper is lifted off the trackbed and placed onto a conveyor. A small ballast plough running ahead of this location has cut a groove in the ballast shoulder to expose the ends of the old sleepers and, as the train moves forward, a snowplough-looking blade under the wagon pushes the old ballast aside to create a flat bed for the new track.

New concrete sleepers, looking very white in the dim light, and pre-fitted with green Pandrol Fastclips, come down another conveyor and are laid on that newly-ploughed trackbed in a measured line.

One small snag is that there is a bogie just ahead of the sleeper conveyors, at the back of the middle work wagon. And at this stage, there is no rail under that wagon as the old rail has been curved away and the new one won’t be lined up until the sleepers have been placed. So what is the bogie running on?

The answer is – fresh air. As it reached the cut ends of the rail at the end of the previous section, the bogie simply ran off the end. However, there was no big bang and expensive derailment. Instead, the weight of the train is being taken on a small set of caterpillar tracks running on the old sleepers which, at that location, are still in place. But it is enough to worry even a seasoned railwayman the first time they see the bogie being deliberately run off the end of the track!

So the caterpillar track runs on the top of the old sleepers. Then the unsupported bogie goes past. The old sleepers are picked up, the ballast is ploughed away and the new sleepers are placed on the smooth bed, and finally the new rail curves in and into place. It sits down on top of the sleepers, is held in place by rollers while the clips are fastened, and the new track is in place.

At the start, the new rail is fastened to the end of the previous section by Robel clamps. The welders will follow on and, when the train is clear, weld up the joint.

On the move!

Once the new rail is clamped in place, and all the conveyors are primed, the train can start to move at operational speed. It has taken about two and a half hours to get this far, and a cynic would say he could have laid quite a bit of track by traditional methods in that time. However, once the train gets moving, it was easy to see how, even on restricted access times, the train can lay so much more track. In one eight-hour shift, during which the train only works for about 2.5 hours, it can easily lay 648 metres of new track and the record is 864 metres in seven hours. The 432 metres it was being asked to do tonight was well within its capabilities and was the end of a section of work.

Track sections tend to be in multiples of 216 metres. This rather strange measurement system came about from the old 60 foot track panel. New rails are now manufactured by Tata Steel in Scunthorpe in 108 metre lengths, the equivalent of six 60 foot panels. Two of these are welded together to make a single 216 metre length, which is what is actually delivered to site. This then becomes the base unit. Tonight they are laying two new sections. Often, they manage three.

Moving at speed, the whole train is an impressive sight. The main section is 140 metres long and has sixteen powered axles. The two class 66s, one each end, are just used for ferrying the train to and from site – at this stage the train is running under its own power and is controlled from the rear vehicle. Twenty people work on the TRS itself, removing clips, running the gantries, positioning the new rail and controlling the operations. The gantries bring in pallets of new sleepers, feed them into the conveyors, lift recovered sleepers into pallets and place them back down the train. They even recover the wooden spacers between the layers of sleepers on the pallets and tidy them into a bin so they can be reused.

While the machine is running, the sirens blare again and an East Midlands Train class 222 comes past on the adjacent line. It is empty stock being relocated overnight, but it just shows that the high output track layer can work without blocking the railway completely.

Before and behind

Up ahead, a signalling team is removing under-track cables and signalling connections before the train arrives and tears them up. They will all have to be replaced later.

The excavator has dug some relieving pits over the bridge, so that when the ballast is pushed out of the old trackbed it falls into the pits rather than stressing, and perhaps collapsing, the walls of the bridge. Once it has done that, the RRV will carry on to the end of tonight’s section and dig another couple of holes so that the high output machine can extract itself from the railway in a reversal of the way it arrived.

Behind the train is a gang of welders and a hand trolley, with a ballast regulator behind them, and a Plasser & Theurer 09-3X dynamic tamper bringing up the rear. The tamper is fitted with DTS (Dynamic Track Stabilisation) which shakes the track, compacting the ballast by simulating the passing of heavy freight trains.

When everything is finished, the section will be handed back to the operators with an 80mph temporary speed restriction. Tomorrow night, when the tamper has been over it again, it will be back to full line speed. Yesterday’s work has already been retamped and is now fit for 125mph running, even though the current linespeed is only 110. The line is therefore already prepared for a future linespeed enhancement on this section of the route.

The train may be expensive, but it lays track at a rate of knots and does so without completely closing the railway and with a small, highly competent and integrated team of people. In addition, apart from a few missing clips, the only gap in the track at any one time is about 40 metres long under the train. If something goes badly wrong, such as a complete power failure, the train can be extracted and that short gap rebuilt by hand. In a conventional track replacement, the old track has to be lifted out and new panels lifted in – something that can result in half a mile or more of missing railway.

Friday is a day off, and then over the weekend the machine, which is parked up and maintained at Toton near Nottingham during the day, will be working between Derby and Birmingham. Night-time working is impossible here as the access is too restricted, so it works the longer weekend possessions on this stretch of line.

But on Monday night, whatever the weather, TRS2 will be appearing again on a track near Belper. Replacing and upgrading the railway network is a never-ending job.


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