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Shaping up in Belgium

Tracklaying for Belgium's latest 300km/h railway is speeding along from Liege to Brussels at a kilometre every working day. Report and pictures by Mike Winney.

Tight beside the E40 motorway leading east from Brussels, the bare formation of Belgium's second high-speed railway defines a neat geometric corridor across the countryside.

With its steep gradients and lazy curves, the new earthwork could easily be mistaken for the foundation of yet another highway to relieve the overcrowded carriageways. But once down to the formation, it becomes apparent that a railway is taking shape.

Precisely spaced either side of the 13m wide graded stone formation, covers conceal the tops of piles ready to take the catenary poles. There is 200mm of hard sub-base on 700mm of carefully compacted granular material. Bundles of multicoloured power and signal cables sprout at regular intervals from the neat concrete troughs marking the shoulders of the formation.

Installing these cables is one of the first jobs to be done in the highly disciplined task of assembling railway infrastructure fit for 300km/h operation. Another is the precise traverse survey required to establish setting out points for rail geometry that must be maintained to less than millimetre accuracy.

But when you meet the first obvious section of the railway track laying operation, hustling along towards Brussels, it looks anything but precise. A large rubber tyred mobile gantry runs back and forth collecting great sections of rough, woodensleepered rusty rail. It plonks them down on the bare formation. Close behind, a platelayer bolts on fishplates to clamp the rails to the previous 18m long section of the crude track.

He dodges out of the way as the gantry operator guides his charge back down the line, driving it right over the top of a loco waiting with a train of flatbed trucks loaded with more sections of track. This is the temporary as opposed to the permanent way. There is a 6km run of it. The job of these two men is to get the rails in place as fast as they can following a stringline set up from the survey points.

Further back the rough track has a first scattering of ballast around it. Ballast trains have come along overnight to scatter their 1200t loads while the track assembly crew sleep. The crushed Belgian Porphry is visible evidence of a huge logistics operation that is putting a strain on SNCB Belgian Railways' motive power department. Half a dozen ballast trains make deliveries to the site every 24 hours. Each one has to be hauled by two locos in tandem. But because severe speed limits are imposed if freight wagons are pushed, the ballast trains need two locos on the back as well.

Night work also sees the first passage of the specialised machines that fettle and lift the temporary rails so that ballast can be built up and compacted below sleeper level. It is a continuing operation which will eventually see 350mm depth of ballast under the permanent way sleepers.

Some 9t of ballast will be needed for every metre run of twin track. All these materials are imported to the site on rail via a large temporary depot at Voroux, 5km from the eastern end of the new railway route.

Working around the ballasting operations, the new UIC 60 section rails for the permanent way are also brought in at night.

Rolled in Austria in 100m lengths by Voest Alpine, they are carried to SNCB's workshops north of Brussels where they are electrically welded to form continuous 300m lengths.

After delivery to site by special trains they are carefully unloaded on to the levelled ballast either side of the temporary track. Positioning has to be precise as their first job is to act as support rails for special multipurpose gantry cranes.

These are at work near the back end of the temporary track where the real business of tracklaying is most apparent. They are driven by operators who sit in open cabs above the drive wheels on the outside of the track-spanning portals at each end of a machine. Linking these two portals, the main chassis of the machine is a powerful transverse clamp that can rapidly be raised or lowered.

The first of the gantry machines grips hold of the last, disconnected, section of temporary track and lifts it high in the air while being driven forward ready to stack this load on to a train of flatbed trucks. It shunts backwards and forwards, pulling up the track and setting each piece down on the train which steadily moves forward.

Fully loaded with a day's lengths of track, the train later has to make a detour back to the depot to clear the line for the overnight ballasting operation.

First thing in the morning it has to be in place up at the front end of the temporary track ready to be unloaded by the rubber tyred gantry.

Meanwhile, the second gantry machine is kept busy in the main tracklaying area, lifting the new pre-tensioned concrete sleepers off the back end of the flatbed train, shunting these back and setting them down on the now bare ballast bed.

A neat arrangement of the gripping mechanism enables the operator to pick up 30 tightly packed sleepers by their ends, set down alternate ones in their final positions and then regrip the remainder so they can be lifted and placed in their correct location. Ancillary jobs for the gantries include towing a specially made plough along the ballast bed to form a trough at the centre so sleepers do not bear at their mid points and fail in bending.

Next along this highly mechanised track production line comes an intensely manual operation. Resilient pads have to be set down ready to support the rails and steel bars and are used to jiggle the sleepers sideways to their final alignment matching the curves.

On the day of NCE 's visit, breakdown of the mechanised arm used to swing the heavy sections of rail up into place on their seating failed to slow the operation. It is surprising what you can do with a wheeled excavator and a lifting chain hung from the bucket when the whole job depends on it.

More special kit follows on.

This time it is a mechanical elephant running on the new rails.

Its cantilevered trunk-like booms pick the rails up just enough to allow a pair of multi-lobed wheels to shuffle the sleepers so that they lie precisely at right angles to the track centreline and exactly at 600mm centres.

Behind this machine two men work as a pair with a mechanical trolley driving the Pandrol clips home to secure the rails to the sleepers.

Ends of the 300m long continuous rails are trimmed off ahead of this operation to remove any impact damage from the works traffic. A powerful hydraulic clamp jack then grips the web section at the rear end of the leading rail and simply pulls all 300m of rail back up against the already fixed line.

Site jointing is completed by Thermit insitu welds, after very careful preparation of the rail faces and level adjustment. Either side of the joint position the rail has to be pre-set to a rise 1mm in 1m. During cooling after the molten steel has been run in to form the weld, the square headed flat bottom rail section straightens out to lay flat and true.

The Thermit process is spectacular and effective. A ceramic mould is fixed and sealed around the gap between the rail ends and the assembly preheated with a propane torch. Then a pot filled with factory batched Thermit powder - a patent mixture of aluminium powder, iron oxide and appropriate alloying materials - is set in place above the mould.

One touch of the ignition match and there is a rapid exothermic reaction. Smoke and flames are generated, then in seconds a rivulet of steel pours into the mould.

At the end of the day's work a temporary, lapped taper connection is made between the last section of new rail and the back of the rough timber sleepered track so that the works trains can move back and forth in the night. Ballasting and lifting the permanent track continues behind the main work front along with the separate operation of building the second permanent track.

This is done using modified road pavers placing ballast conveyored across from a works train on the adjacent track.

Crawler excavators with special attachments are used to swing the sleepers over from flatbed wagons and purpose made booms lift the new rails up on to them. When the rails are within about 60mm of their final level, client TUC Rail will carry out a very precise survey. If the 'quality coefficient' is high the JV contractors earn a bonus. If not, they suffer a financial penalty.

One of the last tracklaying jobs will be installation of the permanent high speed crossings.

These are very special sections of track in timber sleepers involving a 150m merge with each line and are regarded as too valuable to suffer traffic from heavy works trains.

Catenary erection, power supply and final installation of the signalling system follows on from the tracklaying.

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