High-Speed Railways in Spain

Signaling

Signaling presents one of the greatest challenges both to the speeds trains can reach and to the interoperability of high-speed rail across the entire European network. Trains traveling at such high speeds demand at least 8 kilometers to brake, and 12 kilometers to brake comfortably and not alarm passengers—something impossible with, for example, road signals such as traffic lights. “These signaling installations have to be designed in such a way that if you have a problem in one site, the system has to know at each moment where the rest of the trains are and get the information to all the trains, allowing them time to slow down and prevent a collision,” says David Sanz García, account manager for sales and marketing at Dimetronic, a Spanish signaling company.

Each country, though, has developed its own technology, its own signaling systems. This has presented a challenge to the interoperability of the European high-speed rail network. Trains crossing borders needed to be equipped with a variety of technologies to read the different types of signals. To deal with this, in the early 1990s the European Union demanded a standardized system called ERTMS. It works by standardizing both the information and the means of transmission that trains automatically send and receive to and from signaling control systems, so as to obviate the need to change systems upon changing countries.

This new signaling system was developed to be open and available for the use and integration of any number of companies around Europe; any company could develop a system that would meet the specific European standards.
“It’s as if in 1990 there were no cars,” says Sanz. “So the government comes and says that we have to have a transportation system for everyone that works in all countries, and then goes and tells the industry to make cars. So let’s say each company, Volvo or Fiat or any of the others, each has its own car, but each one is capable of traveling on all the roads.”

From the beginning, the Spanish government, working in conjunction with top Spanish companies, decided to be a pioneer in the establishment of this system, utilizing it for the construction of all the high-speed rail lines in the country.

So far, there are three levels of ERTMS; two are available and one is under development. In the first, a system of devices collects all the track information, such as location of trains, and centralizes it in a computer. The information is relayed back to trains by pieces of equipment along the track, which are called balises.

Every element of this system has been specified and standardized. The accuracy of this system allows trains to reach speeds of 250 to 300 kilometers per hour. Level 1 of ERTMS was installed in Spain for first use in a pilot program in 2002 and is being used for all new high-speed lines built since. ERTMS Level 2 uses less rail-side equipment and provides a higher level of accuracy, thus both allowing trains to run at increased speeds and allowing an increased density of trains running on a given track. Instead of using balises—discrete information delivery—Level 2 sends information continuously through a standardized radio system called GSM-R, using electronic safety equipment called radio block centers (RBCs). ERTMS 2 is in the final testing phase and will be commissioned by Dimetronic by the end of 2006 for the high-speed line between Madrid and Málaga in the south. Level 3 is under development and will allow even higher speeds and train densities on the tracks.

Dimetronic has taken the lead in Spain in developing a system to meet these needs. The system contains two main parts. One consists of the hardware: the balises and the electronic units that process the information that the balises relate to the trains, and the RBCs. The other is the system of software, programming each element and all the messages that will be transmitted. This, however, is similar to what all other signaling companies are designing around Europe. “As ERTMS is standardized, there are more subtle ways for companies to distinguish themselves from one another,” says Sanz, “such as the reliability of the system and its general performance.” Dimetronic has designed peripheral equipment and subsystems of the signaling system that make it competitive on the international market.

The design of a testing system has made the biggest difference in the Dimetronic technology. This complex computer system allows engineers to input all the relevant data and ensure that all testing can take place in a laboratory, avoiding long real-time trials and resulting delays in the system’s use. Says Sanz, “This system is something that no other company has. It’s not the core of ERTMS, but it’s a related product that adds value and allows the client to put the product into service that much more quickly.”