GSM-R is the new expanding railway digital radio system in Europe – a main component of ERTMS – enforced by European law. 154,000 km of track are planned to be covered with GSM-R, of which more than 68,000 km are already in operation.
As for the GSM-R mobile stations statistics in Europe, 40,223 cab radios, 1,880 EDORs (ETCS Data Radio) and more than 115,000 handhelds are reported to be activated.
As network implementation advances, and as more and more cab radios and EDORS are activated, GSM-R is increasingly used in border crossing and roaming situations.
The UIC Working Groups for GSM-R Network Management (NMG) and European Network Integration for Railways (ENIR) are working intensely on harmonising GSM-R border crossing and roaming operations.
As seen on the map, 11 European railways are interconnected, with 19 direct interconnections and more than 15 transit routing paths in operation.
Such GSM-R network inter-connections normally take place based on a peer-to-peer roaming agreement, between two such networks.
In 2010 the GSM-R Operators in the NMG decided on a Transit Routing Agreement, signed by all of them, stating the general conditions and obligations for transparent support of roaming operations.
Since GSM-R implementation in Europe is a long process, each new implementer, when activating its network, expects that roaming will be possible. This results in a continuous expanding interconnection network with regular updates of GSM-R signalling and traffic routing facilities.
This is why the ENIR group decided to study the integration of each new GSM-R network into the international GSM-R Overlay Network. The outcome of this study was the UIC Common Design Document (CDD) version 1.0, which also covers the routing guidelines to build the individual Routing Data Sets (RDS) – which establish the main and backup routes for the international GSM-R network interconnection – based on the current physical network status.
The RDS databases are calculated and generated by DB Systel, in the frame of the UIC Project GSM-R Network Management. However, the changing of an international RDS if not synchronised can result in unavailability of routing for roaming GSM-R mobiles. So the next step was to decide on a very challenging operation: implementing a unique RDS database in all networks in Europe, at the same moment.
A complete schedule of routine checks was put in place. The GSM-R Implementers (Austria, Belgium, Czech Republic, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden and Switzerland), represented in the NMG and ENIR agreed that there was a strong need for all of them to accept this concept and apply the update at the same moment. With this decision the outage of routing facilities was minimised. However, in case of failing the update process in one country could affect GSM-R roaming facilities in all GSM-R networks, with impact on train operation. Given the experienced staff and the robustness of procedures, the risk was calculated as almost zero.
This moment was chosen for 25 September 2011 at 2am CEST (central European summer time).
With all previous steps described achieved, the operation took place as scheduled, lasted 2 hours and was successful, with just some minor consequences to be solved in the next period and no impact on train operation.
Therefore, since together with the impressive implementation and roaming operations figures European GSM-R networks currently use a common RDS database, we can now say that the GSM-R networks are proven to be integrated and well managed in Europe.