A train-mounted imaging system is set to replace manual track inspections on parts of the UK network.
Its developers claim the technology will improve on the existing regime of checks that can be unreliable in bad weather or be affected by a lack of resources.
Most checks are carried out by sub-contracted labour, some of who may not be properly trained for the job.
Recent accidents such as Potters Bar and last week’s derailment of a Great Western train carrying nearly 500 passengers near Ealing have increased fears over the quality of manual inspections. The high-speed derailment was believed to be caused by a fault at a rail joint, on a section of track checked by a maintenance patrol two days before.
Fear of lower skills
With the fragmentation in the rail industry, maintenance firms may be forced to use less highly skilled staff, said Rod Smith, professor of mechanical engineering at Imperial College. ‘I have a fear that the chain of command is so long, it is quite difficult for contractors to retain their own trained personnel, so there must be a temptation to use whatever they can get. There is also a concern that because they cannot get continuity of employees, companies are not prepared to invest as much in staff training.’
Automation can allow huge amounts of track to be checked very quickly, he said.The new system will allow rail inspectors to carry out virtual track examinations using digital images and information gained from measurement trains being introduced on to the UK’s network.
Eurailscout, a joint venture between UK maintenance firms Carillion Rail and Europool, is introducing two inspection vehicles, a medium speed Class 121 and a more advanced, high-speed version, which will obtain images and information on the condition of the track as they run over a route.
Existing track inspections, undertaken on foot by section managers and patrolmen, can be subject to varying local instructions by contractors, said Edward Gardiner, managing director of Eurailscout.
Some patrolmen also report only what they know they have the resources to tackle, while defects can be missed because of bad weather, the large number of different faults to look out for, or because a patrolman was not concentrating, he said. With more and faster trains travelling along the track, inspections are also becoming more dangerous.
The Class 121 is a single diesel former passenger unit which has been refurbished and fitted with AEA Technology’s Trackmon, a track geometry monitoring system, and Omni Inspector, which consists of five digital frame-grabbing cameras at each end of the unit.
The Trackmon system contains sensors that detect bumps and dips in the track, as well as twist faults caused by one rail being higher than the other, all of which could potentially lead to a derailment, said Gardiner.
Poor track areas
The Omni Inspector contains a GPS system, which makes it aware of the exact time and location of each picture, and can automatically retrieve the corresponding four images taken by the other cameras. ‘It is designed to be an indicator rather than a detailed track geometry system. it will point to areas of poor track, which can then be checked out,’ he said.
Once the train has inspected a route, any serious defects are immediately reported to the local supervisor, while the rest of the information is downloaded and processed on to a DVD.
Specially trained inspectors would then review the digital images and the data obtained by the Trackmon sensors to identify any faults.
The system is undergoing trials on the West Coast Main Line between Euston and Carlisle, as Eurailscout builds up a safety case to introduce the vehicle into full use by 2004.
Meanwhile Eurailscout also plans to introduce a more advanced vehicle, the UFM 160, which can provide a far more detailed inspection of the track while travelling at speeds of up to 100mph.
The vehicle contains a track geometry system for measuring bumps, dips and twists, a rail profiling system for detecting wear, a ‘Railcheck’ system to identify surface defects such as missing clips, an overhead line height detector, a GPS positioning system and a video recorder at the front and back. The vehicle will also contain an Unattended Track Geometry Measurement System, developed by EH Reeves & Associates in the US, that carries out inspections using a combination of laser and camera technologies.
The UFM system is going through the UK approval system, and is to be used on Network Rail’s Southern Region.