Satellite keeps railway safety and efficiency on track

European researchers have developed an innovative satellite-based control and command system for low-density railway lines that could herald a minor revolution in train transportation management.

“There is a real need for this technology,” says LOCOPROL project coordinator Michel Rousseau. “Existing command-control systems adapted for medium traffic density lines or the future ERTMS/ETCS [European Rail Traffic Management System/ European Train Control System] system dedicated to high speed and/or high-density traffic railway lines are too expensive to be used on railway lines with low and very low traffic density.”

He notes that as a consequence, many low-density traffic lines (LTDL) in the EU, Eastern Europe, the US and in developing countries are still equipped with ageing and dangerous human-based safety equipment with high maintenance costs, keeping the capacity of these lines to a very low threshold.

“We saw the need to develop an innovative and cost-effective system for low-density traffic lines based on new available technologies such as satellite location. The concept is to offer the same level of safety as high-density lines and enhancing the efficiency of these lines in order for rail transport to become more attractive,” he says.

A new sensor configuration developed by LOCOPROL was successfully tested in two test tracks in Belgium and in France during the project, says Rousseau.

Satellite-based positioning is the heart of the LOCOPROL system, emphasises Rousseau. An innovative positioning algorithm has been developed to provide train-borne signalling equipment with a failsafe interval of the train position, by making use of satellite range signals coming from a GNSS receiver. This ‘1D algorithm’ is so-called as it uses one degree of freedom movement.

The most recent tests carried out on the Gembloux-Jemeppe link in Belgium, a typical low-density line in a hilly environment with varying satellite visibility, were devoted to the 1D satellite positioning sub-system, intended to be used as the means to locate the trains in the failsafe LOCOPROL signalling system.

“The tests demonstrated that the combination of wheel sensors and GNSS sensors associated with the 1D algorithm developed in the frame of the project allows a level of performance at least compatible with LDTL requirements at a significantly reduced life cycle cost,” says Rousseau.

The beauty of the system is that the level of safety will be the same as on high-density lines, while the efficiency of these LDTL will be enhanced through reductions in operating and maintenance costs, helping to make railway transport more attractive, he says.

Another bonus is the fact that the system can be readily upgraded to cope with increased traffic or other signalling changes on a line.

In its basic configuration as implemented in the Nice-Digne line in France, the equipment is limited to the control centre and to the train-borne equipment.

To increase the performance of the line, the points can be upgraded with control or command sub-systems that can be controlled by the LOCOPROL system through an object controller installed in the station. In the same way, level crossing control can be handled by the LOCOPROL system, points out Rousseau.

The feedback from railway operators involved in the trials was overwhelmingly positive about the possibilities for providing enhanced line safety and efficiency at lower costs with the LOCOPROL solution.

“The trials demonstrated that it is really possible to operate a low traffic density line with LOCOPROL,” says Rousseau. “The availability of the system depends on the visibility of satellites. With GPS this availability is a little bit low in some areas but it is clear that the problem will be solved by the new GALILEO constellation working together with GNSS,” he says.

“The market for LOCOPROL is characterised by single track lines with simple stations and a low density of traffic typically in the range of 1-2 trains per hour. Large opportunities for the system have been identified for freight, passenger and mixed lines,” he says.

Among freight networks, he cites the mining lines in South Africa and Brazil as potentially ripe for commercial exploitation, while passenger lines such as the secondary network in Nordic countries, Germany and the United Kingdom also hold exciting possibilities.

“The lines in eastern European countries represent substantial potential as the infrastructures of these countries undergo modernisation. The strong growth in China and the consequent demand for a more efficient railway will also offer rich opportunities to exploit the LOCOPROL system,” he ends.