Look at any railway, and the most obvious thing to see is the track. One or two sets of steel rails, supported on concrete, wooden or metal sleepers that are partly buried in ballast.
Just occasionally, the whole track bed is concrete – ‘slab track’ – but outside the world of very-high-speed railways that’s comparatively rare, most often used in busy stations and problematic tunnels.
What is less obvious is the fact that, alongside the railway lines, there is another network – an electrical one. Cables for signalling, power, telecommunications, computer networks and CCTV camera feeds all have to run alongside the railway, going on to the next station or back to the control centre.
These cables are often hidden in ducts, which keep them safe, dry and out of sight. These ducts, which can be concrete or plastic, are usually roughly square in section, and can be partially buried or supported on small columns.
Danish desire
The railways in Denmark are no different. In fact, the first-ever national rollout of the European Rail Traffic Management System (ERTMS) will entail even more wires and cables being needed. They need to be kept safe yet quickly maintained, with the possibility of whole new cable runs being easily installed.
So, in 2013, infrastructure owner Banedanmark felt that a new design was called for to run alongside its high-speed railways. It contacted PcP A/S in Vildbjerg, Central Jutland, which was known as a manufacturer of simple gratings and stair treads as well as highly specialised heat shield decks on oil rigs.
The remit was for PcP to come up with a design of cable ducting that would be maintenance-free, durable, vandal resistant, easy to install, fire proof and would enable water to drain away freely.
After two years of design and testing, the new system was accepted by Banedanmark for use on the Danish network having met all of the design criteria, and even surpassed them in some areas.
Design concept
The basis of the design is a three-metre-long 100mm-deep aluminium tray, with holes for drainage, which sits on dedicated supports that are driven into the ground. Available in two widths, 320mm and 420mm, the trays are closed using galvanised steel lids, which can then be secured using special tamper-resistant screws.
Using two different materials, aluminium for the trough and HSS420 high-strength steel for the lid, ensures that no magnetic field is set up. Where necessary, a 2.5-metre-long glass-reinforced polymer neutral section is inserted every 300 metres or so along the trough.
The height of the lid above the ground – usually around 200mm – makes it easy for passengers to step over them if they have to be evacuated from a stranded train. Indeed, the lid has a non-slip surface so it can even be used as an emergency walkway.
The 100mm gap between the bottom of the trough and the ballast prevents the build-up of water and blown debris such as leaves, reducing the need for routine maintenance.
Speedy installation
After trial installations of five, 10 and 12 kilometres, the new system was specified for the main rail link from Copenhagen and Ringsted, a distance of 50km. This is when its installation speed was revealed for the first time.
The 70mm-diameter tube, up to four metres long, which will support the carrier (saddle), is driven into the ballast/ground, with care being taken that it is upright. A template is used to identify the location of the next tube three metres away, so setting the correct separations is easy.
Next, the saddles are fixed to the top of the tubes and adjusted for height. The trough is fastened in place between two adjacent saddles and the lid affixed.
Using two teams, one setting tubes and one fastening the troughs to them, two kilometres of ducting was installed in a single, one-shift day. With the largest aluminium trough weighing 14.4kg, and its corresponding steel lid 25.5kg, just two people can install and fix all of the components.
Now for Norway
Recently, a six-kilometre installation has been supplied for the Nordlandsbanen railway line between Trondheim and Bodø in Norway. This line is noted for including Hell station, in the village of the same name, which has understandably become a tourist attraction. Perhaps to combat the underworldly tone of the station name, one of the buildings is labelled ‘Gods-expedition’, although that is actually old Norwegian for Goods Handling.
The PcP cable ducting system is now coming to the UK. Its patented design and elevated installation, which ensures good drainage, is complemented by its light weight and ease of installation.
And no, it’s not the cable ducting from Hell, it’s from Vildbjerg!
Read more: Keeping wheel and rail together
