To be called ‘the world’s most powerful vacuum excavator’ is a big claim, but that is exactly what the new RailVac RA7 is. Built and designed by the Swedish companies Railcare AB and the DISAB Group, the RA7 really does do what these companies say it will, and they have seen it in action for many years on Sweden’s railways.

That said, when can vacuum excavation be used and how does it work? For those familiar with track maintenance and renewal work, it’s easier to start by describing what the RailVac RA7 does not do. Vacuum excavation means there is:

– no need to cut rails or remove sleepers – perhaps keyhole surgery could describe the way vacuum excavation works, because the RA7 excavates between the sleepers to the required depth and width;
– no need to waste time disconnecting switches, tie-rods or crossing components;
– no risk of impacting on any highly valuable infrastructure such as existing pipework, drainage, cabling and electrics, any damage to which only exacerbates the time and cost issues involved.

Damage prevention

In seven years of using the RailVac, the Swedish company that operates it, Railcare AB, has never once had a possession over-run or even broken a cable. Any rail engineer will realise how that can benefit normal railway operations by the lack of disturbance to schedules. So how does vacuum excavation compare with traditional techniques?

Digging by hand, or excavating with mechanical tools, cannot avoid having an impact on track and the trackbed, so a CAT scan is often used in conjunction with these traditional techniques, adding to the time and cost required. By comparison, the impact made by vacuum excavation means is much less so CAT scans aren’t needed. Furthermore, with vacuum excavation, no track has to be taken up – and that’s largely why there are no over-runs with the RailVac.

Possession time is the common factor in any rail maintenance or renewal project, and the RailVac maximises valuable track possession time. With the RailVac wagon in place, excavation can start immediately. Shutdown is just as fast, so all the time is focused on repair and maintenance. Once the RailVac has done its job, and the repair is completed, new ballasting is done immediately while the RailVac takes away all the old ballast it has vacuumed for disposal.

Undercutting is another form of traditional excavation technique. However, while faster than doing things manually, it takes far longer than vacuum excavation and doesn’t cope with compacted material like clay.

Anything goes

On the other hand, the massive suction power of the RailVac will handle any material, as seven years of successful operation has proven. Basically, anything that fits up the RailVac’s hose – goes. The RailVac’s 225mms diameter flexible suction hose has a metallic end pipe which is manoeuvred by a hydraulically-operated excavator arm. Just one operator controls this (think of a PlayStation console!) while standing close enough to see what’s going on at the sharp end.

Typical repairs that demonstrate the benefits of using a RailVac are:
switch and crossing units, which normally need the track to be cut back, taken out and lifted, while 300-400mm of ballast is removed and a new unit is installed and ballasted. Typically, this requires 16 hours and a 12-man gang, with a 24 hour possession and all the subsequent impact and disturbance to normal running schedules. The RailVac doesn’t need to work this way; 300-400mm of spent ballast can be removed with everything else in place and a C, D or E crossing fitted over four 3-4 hour shifts of track possession time during the week, so there is no disruption to normal schedules nor any need to disturb weekend running either.

Other typical repair examples include plain line re-ballasting, drainage installations, level crossing refurbishments, and under track crossing (UTXs). A RailVac can vacuum excavate a double track UTX in 20-30 minutes, up to 1.5 metres below the sleepers and with no disturbance to the sleepers or normal operational schedules.

The number of operatives required on site also underlines the RailVac’s advantages over traditional techniques. A typical track repair usually needs upwards of a dozen men. The RailVac needs fewer – just a controller, two other RailVac operatives and a small gang for jacking and packing. Using a RailVac can be safer for as well.

On a recent trial at Beeston in Nottinghamshire, a Gv crossover was replaced with the RailVac excavating 300mms below the track. The operation took 8 hours in total – just two four hour possessions for each unit, with no interruption to normal daily operational schedules.

UK specific

The RA7 RailVac unit is Railcare AB’s first bespoke air/vacuum excavator, or to give its full name, a Ballast Vacuum Extraction System (BVES), for the UK market. Designed and built in partnership with the most powerful vacuum equipment available from the DISAB Group of Sweden, it conforms with W6A loading gauge standards. In wagon mode the RA7 can be dead hauled in train formation, and when in a track possession situation and working in the self-propelled mode, it is classed as on track machine (OTM).

The RA7’s suction power comes from two Caterpillar C9 diesel engines, two vacuum pumps and two air compressors, creating an impressive 19,000 cubic metres of air flow per hour at around 95% vacuum efficiency. The machine’s flexibility comes from a manipulator arm for excavation and a unique hydrostatic transmission system that is powerful, reliable and precise in its operation. There are about 40 identified RailVac applications suitable for the UK, some of which are already creating benefits for Network Rail.

The braking system on the RA7 is controlled from all driving/operating positions. To reduce the risks of injury to personnel and damage to the infrastructure, a number of emergency safety systems have also been built into the machine.

A Network Rail Engineering Acceptance Certificate (EAC) was issued early in 2012 and the unit can now provide ballast excavation services for infrastructure owners and maintainers all over the UK. Network Rail has already granted Railcare AB a certificate of Full Product Acceptance for the RailVac method of work.

RailVac excavation services in the UK are supplied by Bridgeway Railcare LLP, a collaboration between Bridgeway Consulting Ltd in the UK and Railcare AB of Sweden. As a specialised contractor, Railcare AB is now investing heavily in the UK railway market. Coming from Sweden, where the 7 day railway philosophy is already a reality, Railcare AB’s methods are not only innovative but very well placed to help the UK’s railway operators and owners make a dramatic difference to the traditional techniques, time and costs of track maintenance and renewals.

Safety fencing. It’s something that’s always around, yet no-one sees. It needs to be put up at the start of almost every lineside job, and taken down afterwards, but other than that it’s just there – like sleepers and ballast.

However, it needs to be put up quickly, as everyone else is waiting to get on with the job, and taken down even more quickly if the work is running a little late and the hand-back time is approaching.

So what is needed is a simple, even foolproof system. It also has to be light, easily transportable, and to do the job of separating people from trains.

Lightweight safety fencing, which fastens to a track while protecting people working in the cess or on an adjacent track, is not new. There are several systems on the market which clip to the rail in one way or another, but now there is one which is even simpler, and doesn’t use clips at all. Instead, it capitalises on two of the great facts of life. Rails are made out of steel, and steel is magnetic.

The new Magnetic Safety Barrier from Rail Safety Systems (RSS) has been brought to the UK by Innovative Railway Safety. Based in Swansea, they are specialists in such equipment and know a good safety system when they see one.

What is it?

A square-section steel tube, zinc-plated to protect it from the elements, is fitted with a broad black plastic head containing two powerful magnetic strips. When this head is attached to the web of the rail, the tube extends horizontally out from the side of the track. As the head is hinged, some vertical movement of the tube is possible and the tube itself is shaped with a double kink which rests on the top of a sleeper and keeps the tube approximately horizontal.

At the other end, a sleeve fits over the tube. This then curves upwards to form a vertical stanchion, again in lightweight square-section steel tube. The actual position of the stanchion is adjustable – the sleeve can slide along the horizontal tube and is bolted in place using a series of pre-drilled holes. As standard, there is a total of 600mm of possible adjustment, allowing the fence to be positioned the correct distance from the running track.

On the outer face of the vertical stanchion are two, pre-positioned plastic clips. Once a row of stanchions is in place, horizontal poles can be clipped into these, forming the fence itself. Both fibreglass and aluminium poles can be used – if aluminium then there are plastic isolators along its length to prevent any problems with the metal poles bridging signalling circuits.

Installation

Poles and stanchions are transported to site in specially designed bins. Normally, the horizontal tubes and vertical stanchions are already bolted together with the correct clearance. These are then simply clamped, about three metres apart, to the side of the rail web over a sleeper on which the kink in the horizontal tube rests. The installer never has to go close to the running rail, but can stand in a position of safety holding the vertical stanchion while attaching the magnets to the rail.

Once a run of stanchions is in place, the first fence poles are clipped in place. Subsequent poles are attached using a patented bayonet connection and clipped up. A team of people, working together, can install a run of fencing remarkably quickly. Once they get into the swing of things, and assuming the stock of components is close by, several hundred metres can be erected in just a few minutes. No ballast needs to be disturbed – provided that the rail web is accessible, the fence can go up.

In operation, the strong magnetic clamps hold the fence securely in place. It is practically impossible to just pull the magnet off the rail, so work can take place behind the fence in complete safety.

Removal

Taking the fence down is almost a reversal of putting it up. The poles are removed first, the bayonet couplings making splitting it into short lengths easy.

Despite the magnetic clamps being almost impossible to pull off in service, removal is actually quite easy. The stanchion, and it’s attached horizontal pole, is just pivoted up vertically. This assembly hinges on the magnetic head until that hinge hits a stop. Continued upward movement rolls the magnet off the rail – the head has a radiused upper edge to allow this. So the whole bracket comes free without undue effort.

Then it is only a case of putting everything away and removing it from site. As no ballast was disturbed in erecting the fence, there is nothing to be replaced.

Critical acclaim

The Magnetic Safety Barrier was first introduced onto the Dutch railway system in 2010. In March 2011, it won the Europe Innovation Award at the Rail-Tech Europe trade fair in Amersfoort. “All together, the crucial significance of safety for employees performing maintenance work on the track was reason enough for the jury to send Rail Safety Systems home with the 2011 European Innovation Award”, said jury chairman Professor Riessberger.

The new fencing has been tested by TÜV and is approved for use in Germany and is now also approved by Network Rail for use in the UK. Initial use has found that is can be up to twenty times quicker to erect and dismantle than conventional barriers, reduces the physical effort of the operatives and the ballast is not disturbed. Installed correctly, it does not affect axle counters or DC track circuit signals.

Innovative Railway Safety arranged the first major use of the new fencing in the UK last month and, with the advantages that Magnetic Safety Fencing offers, no doubt it will shortly be appearing on a work site near you. Once erected, it still won’t be noticed, but it will certainly appear and disappear a lot quicker!

City authorities in York have agreed Network Rail’s plan to build a new rail operating centre and workforce development school close to York station.

Says Phil Verster, Route Managing Director, ‘This decision is great news for York and the railway. These operating and training facilities will allow us to deliver a modern, efficient railway while at the same time maintaining York’s position as a proud rail city.

‘The centres will retain jobs in the city and, over time, see all of our rail operations for the LNE route consolidated on this site.

The operating centre is the largest of just 14 proposed centres across Britain and will bring the expertise and technology we need to operate the route into a single location.

Meanwhile the investment in modern training facilities will make sure our rail employees remain among the best in the world.’

The land identified for development is known as the engineer’s triangle and lies between York station and Holgate bridge.