There are many reasons why it becomes necessary to re-profile rails from time to time. It may be to restore the profile of worn track. This often happens on curves, or in areas where axle loads are high, or both. The whole top surface of the rail may have to be removed, along with incipient cracks caused by rolling contact fatigue before they get any worse. Corrugation causes a noisy ride, so removing it will be kind to both passengers and neighbours.
Whatever the reason, the most common solution is to run a rail grinder over the track. This is a vehicle fitted with several grinding wheels that passes along the affected track, removing the top surface of the steel rails as it goes. Using several wheels allows the grinder to put a particular profile onto the rail. However, each pass doesn’t remove much metal (unlike a rail miller – but that’s another story), so the grinding machine will have to make several passes to have the desired effect.
Small is beautiful
Rail grinding is not new – it has been around since the early days. Today, modern computer- controlled machines can yield impressive results. However, they are big, heavy machines looking rather like diesel locomotives. They do good work, but are expensive to deploy and are best suited to a long run of damaged track.
Then what is the best solution for short stretches of track, and light railways with tight curves such as tramways? Often not connected to the heavy rail network, tram systems have a particular problem. What is needed is a small machine which can negotiate the tight curves and restricted clearances.
The answer may be sitting in a car park next to some tram tracks. It is a big articulated lorry, smartly turned out and emblazoned with the name ‘Sersa’, a company synonymous with rail grinding and track maintenance. But this vehicle is huge, a large Mercedes tractor-unit with a triple-axle trailer. Surely it is too big? It looks more like a formula one transporter than a track treatment vehicle.
But the rear ramp descends, and a small truck backs out, preceded by its even smaller trailer. THIS is the vehicle in question.
Off and running
Driving straight onto the embedded tram tracks, the operator lowers the flanged rail wheels. These are adjustable and, although currently set for standard gauge (1435mm), the one machine can work on anything from 980mm to 1660mm.
Three minutes later, it is off – running at almost 20mph to its work site for the evening. The embedded tram tracks make it easy, but any level crossing or access point will do.
On reaching the correct location, the grinding wheels are lowered to the track and adjusted, and then grinding commences. There is a shower of sparks, which can be directed either outwards or inboard, but the noise is surprisingly low at around 70dBA. This is a good feature on urban tram tracks where houses can be close by.
This time the GRail1 sets off at a reduced speed, only about 5mph. A few hundred metres later it stops, reverses, and comes back the other way. More sparks – it is truly bi-directional. On reaching its start point, the vehicle reverses again. And it goes on until, one hour later, 200 metres of shiny track glints in the moonlight and Sersa’s new mini- grinder lifts up its grinding wheels and sets off to the next piece of damaged track.
At the end of the night, the GRail1 returns to its truck and drives up inside again. It is clear of the tracks, and passenger services can resume.
In the front half of the massive trailer is a full workshop where repairs can be carried out and all the tools and spares needed to keep the small grinder running are stored. The team of two operators are also the mechanics and everything is designed to be simple. Grinding wheel changes take less than one minute and compressed air is used to keep the wheels on the track rather than more-complicated hydraulics.
The grinding wheels are adjustable. The three cup stones, used for head and gauge corner treatment, can be set between 20° field side to 45° inside with variable rotating speeds. The disc units on the trailer, for gauge corners, lipping, rail grooves and guide rails, are adjustable from 45° inside to 90° inside.
The new grinder has been based in the UK for the last year, and it has already worked on the tram systems in Nottingham, West Midlands and Croydon and the Nexus metro in Newcastle upon Tyne. However, as part of the company’s international operations, it has done sterling work at Nice on the metre-gauge Chemins de fer de Provence and on a number of other light rail systems in Germany and Switzerland.
But this versatile piece of kit isn’t only at home on light railways. It has also proved its worth on heavy gauge. As a trial, it was brought in to smooth out a very noisy piece of corrugated track that was annoying local residents. Working between two level crossings, 500 metres apart, the GRail1 team measured the track, removed the corrugations by grinding, and then remeasured the track and its profile, all in a single shift, arriving and departing by road. It was much more economical than bringing in a dedicated rail-only grinder for such a short section.
Switches and crossings are another area where the small machine excels. Passing backwards and forwards over a couple of turnouts in a station throat, it can again get on track, do the work, and get off track again in a normal night- time work period.
As well as the low noise, the diesel engine which drives the machine meets European emission standard Euro Cat V. There is also a recovery system built into the grinding mechanism so the majority of the waste materials are recovered.
Currently certified to RIS1530, which was overseen by Interfleet, the Sersa GRail1 is now undertaking approvals to operate on Network Rail infrastructure all over the country.
All in all, it’s a great little machine. Can we keep it?