Network Rail is the proud owner of a multitude of infrastructure databases – and, no doubt, many more in other disciplines too. They range from the whimsically named TiCled to the positively antediluvian GEOGIS. The former is the Tight Clearance database, the latter the complete record of track and its components which started life in the days of huge dot matrix printers and mountains of folding paper. To be fair, GEOGIS has now been consigned to history, replaced with the INM (Integrated Network Model).

Then there’s CARRS (Civils Asset Register And Reporting System) and TRUST (Train Running Under System TOPS -that’s the Total Operations Processing System) and RDMS (Rail Defect Management System) amongst a host of others.

They’re all really worthy in their own rights and have proved invaluable to those whose specialty relates directly to the database in question. In the joined up railway – the digital railway – there’s a problem for frontline engineers. To put it mildly, it’s not practical for those dealing with day-to-day decisions to start aligning all the databases to see where the critical influences occur. Because of history, because of technology, because of the original intent and use of the information, few of the databases are readily compatible.

Cyclic top isn't always visible.

Cyclic top isn’t always visible.

The Track DST

This is where the team building the Track Decision Support Tool – the Track DST – comes in. It is working within the ORBIS programme, which has the objective to “serve Network Rail and the GB rail industry as the trusted source of asset-related information and insight, from which informed decisions can be made to balance risk, performance and funding to best deliver Network Rail’s Promise”.

ORBIS – Offering Rail Better Information Systems. For a more comprehensive account of ORBIS, have a look at the May 2015 edition of the Rail Engineer or browse through our ‘In print’ archive on www.railengineer.uk, it’s in issue 127.

As Jonathan Schofield, communications manager for the ORBIS programme, explains, the overarching vision for the Track DST project is to develop decision-making capabilities that enable Network Rail to make evidence-based decisions for renewals and refurbishment, for predictive and preventative maintenance, and to improve effectiveness.

All of this means painstakingly boiling-down all the data sources and making them readable and intelligible. Victor Adeoye has that task and, thanks to his efforts and those of his colleagues, a comprehensive database containing a wealth of information is being built and refined.

Drilling down

At the moment, what is being constructed is a proof of concept. It is assembled on a weekly basis and so is not real time – although, ultimately, this could be the aim. The Track DST splits the railway into 220-yard lengths. To some this may look like one-eighth of a mile – which indeed it is. To others – those long in the tooth – it looks like 10 chains, suggesting that some of the databases are pretty old, predating full metrication by several decades. In fact, within these 220-yard lengths, it is possible to access much finer detail.

Drilling down, data mining, or whatever is the current term, is an accepted technique in the construction of any modern decision tool. But it is this feature that has taken a great deal of effort by the team bearing in mind where all the information has come from. Drilling down is now possible, and possible to an impressive extent.

The focus of the task is not only to see the history of a stretch of track in terms of work done and money spent, but also to use all that history to build a predictive tool so that future problems can be treated before they cause problems with speed restrictions or line availability.

The Track DST was originally built as a tool to assist in the management of switch and crossing assemblies, but it has now been expanded to include all issues relating to plain line. In the future, it may be further expanded to include features in what is traditionally known as ‘the permanent way’ – fencing, drainage, earthworks, structures and even signalling and electrification.

Presenting the most recent version of the tool, Martin Mason, information development manager, was able to show how it is possible to make reliable predictions of the development of serious track faults based on objective observations by the track recording coach. Future spends can be predicted, and thus decisions on whether to renew or maintain a stretch of track can be made.

Using the tool appears disarmingly simple which, in itself, is an indicator of the effort taken to integrate all the information sources.

The issue of Cyclic Top

In a recent development, some fascinating analysis has been carried out on the perplexing problem of cyclic top.

Perhaps it’s worth explaining cyclic top and why it is so important in the modern railway.

First of all, it’s important because it causes derailments – and major derailments at that. What is it? Basically, it’s a series of faults in ‘top’ – the quality of the longitudinal profile of the rail. Cyclic top faults are those that occur at regular and evenly spaced intervals. Of particular concern are those faults that typically occur every 4.5, 6, 9, 13.5 and 18 metres, but the precise interval can vary according to the prevailing rolling stock and speed.

Why are these faults a problem? Here it is worth looking at a bit of history. Fifty years or so ago, most freight wagons had short wheelbases – typically about ten feet. They were particularly prone to derail at track twist faults, where one rail changes its relative elevation to the other rail at a gradient of 1 in 240 or worse. The wagons could not tolerate this severity of twist and would easily flange climb and fall off. Speed was – by and large – not relevant. Twist faults can be seen on inspection and, most importantly, they can be measured with a simple crosslevel gauge. In this way, ground level staff were able to identify and control problem sites.

The derailments of short wheelbase wagons died out when the use of these wagons ceased. But other strange types of derailment started to occur. These involved longer wheelbase wagons at sites that appeared to have track with no twist fault exceedances.

When the derailment sites were surveyed, it was found that top faults occurred at regular intervals and it was soon established that the problem involved not only the track, but also the suspension characteristics of the vehicles along with speed. Cyclic top had been discovered, but this was little comfort to those at ground level who had no means of measuring the sites and no access to the early computer programmes that simulated the behaviour of particular types of wagon.

Although today there are test trains that can identify cyclic top and give a measure of risk associated with each one, it is still a difficult issue to manage between train runs.

A breakthrough

The recent development in the Track DST can be termed a breakthrough in infrastructure management. Team member and network data manager Andrew Nwichi-Holdsworth, who started on the railway as a trackman in the Shipley Kango gang in 1979, has been analysing a number of sites. He has applied a selection of filters to get rid of the ‘noise’ and to reveal cycles at different wavelengths of top fault.

This analysis shows that, far from occurring at only a few locations, critical wavelengths are almost everywhere. It is as if the whole of the railway has been affected by the resonance of vehicle suspension. The top faults are largely benign, but they can grow to serious proportions when vehicles encounter a trigger point. This can be something like a wet bay, a dipped joint, a bridge-end or a level crossing. Derailments happen when wagons start to bounce and roll and yaw – all triggered by these regular top faults which Andrew’s analysis clearly shows are developing to critical levels.

He can also show how these faults grow from one recording to the next and so this is the start of a predictive tool that can prompt the remedial action needed to prevent a disruptive fault. There are, of course, further issues in that the longitudinal stiffness of track has to be understood so that preventative action has a beneficial effect rather than making things worse in the long term.

One mile worth data at the 13m wavelength. As can be seen, there are several cycles where the amplitude to the wave crosses the threshold of 4.5mm at around 35m0825yds, indicating a cyclic top event (three or more peaks). The middle chart shows potential precursors (wet beds) to this cyclic top event.

Exports

The team is busy, not only refining the Track DST, but also presenting its findings to those charged with the responsibility of maintaining assets on the ground.

These audiences now include railways from outside of the UK. Problems with asset management exist all over the world and cyclic top, for one, is no exception. Heavy-haul freight railways are realising that they need to get a grip on this problem, especially when there are limited time windows available to intervene.

The ride characteristics of wagons on other railways will differ from those in the UK, but this can be overcome by applying different filters to the data so as to isolate different wavelengths. The tool can be applied worldwide if needed, a sign of the UK railway industry asserting itself again as a world leader.

At the start of the digital railway programme, the founding minds were at pains to stress that the real benefits from coordinating all the asset data would really kick in some five or so years down the line. It is now five years on… and the predictions are coming true.


Read more: Read the May issue of Rail Engineer here