Lines of communication

A rail traffic management system tested in Sweden could cut a train's energy consumption by up to half while boosting its operational efficiency, its developers claimed.

The system, called CATO (Computer Aided Train Operation), combines a custom-designed driver interface and software with GSM-R digital radio technology to continuously calculate and display the optimum running speed of a train.

Information from the line is transmitted to a Traffic Control Centre (TCC), processed using the algorithms developed for the system and returned to the driver interface as a speed value.

This allows the locomotive to proceed at the ideal rate relative to the traffic situation ahead of it, eliminating the 'stop-start' progress along tracks that wastes both time and energy.

According to rail technology specialist Transrail, which developed CATO in a project funded by Sweden's railway authority, trials on freight trains running on industrial tracks in the north of the country yielded highly promising results.

Transrail's chief executive Per Leander told the Intelligent Transport Systems World Congress in London that on the test lines 'we could easily reduce energy consumption by as much as 40-50 per cent even if we try to operate the trains at higher average speeds'.

Leander said the key to CATO's seven-year development is advances in communications technology, which allow a train's onboard system to be in continuous dialogue with a TCC.

Most driver-assistance systems are self-contained, he said, but communication with a TCC allows the real situation on a line to be assessed, rather than just the ideal rate of progress demanded for the timetable.

This allows drivers to run their trains according to the 'slots' available to them on a line, even when the service is not running as expected.

'Knowing the situation in front of the train, the system can give information to the driver that it should run into its slot at the right time and at the right speed,' said Leander.

The system also unlocks the potential for highly efficient automatic train operation, where the driver allows the train to run itself in accordance with the optimal speed profile.

The levels of energy saving seen on the freight trains were achieved in conjunction with the highly power-efficient regenerative braking systems used on that line, said Leander.

Regenerative systems feed the excess energy usually lost during braking back into the locomotive as power. Leander said that as these are increasingly adopted as standard on new rolling stock, their potential can be maximised by using them with systems such as CATO.

However, Transrail claimed that energy and environmental benefits are matched by increased operational efficiency.

'During tests with the freight trains, on journeys of between 50km and 100km we could make a driver arrive to within a few seconds of where he should be,' said Leander. He said this could translate into a five to 10 per cent increase of capacity on a line without needing to upgrade the infrastructure of the track.

CATO is designed to operate as an adjunct to major European train safety systems such as ERTMS. Leander said Transrail hopes to develop CATO as a standard, allowing manufacturers to develop various components for use on the train or in the control centre.

Swedish railways are to adopt technology that could make it cost-effective to keep open previously loss-making regional lines, ITS was told.

The system, called Regional ERTMS, gives trains on low-traffic local lines equipment that can provide basic train control, removing the need for upgrades to track infrastructure that could render the routes uneconomical. Sweden will install Regional ERTMS on 13 lines by 2010.