Cost effective improved rail safety
The European Rail Traffic Management System (ERTMS) is a major industrial project developed by a number of major manufacturers in close cooperation with the European Union, railway stakeholders and the GSM-R industry.
ERTMS has two basic components:
- ETCS, the European Train Control System, is an automatic train protection system (ATP) to replace the existing national ATP-systems;
- GSM-R, a radio system for providing voice and data communication between the track and the train, based on standard GSM using frequencies specifically reserved for rail application with certain specific and advanced functions.
ERTMS aims at replacing the different national train control and command systems in Europe. The deployment of ERTMS will enable the creation of a seamless European railway system and increase European railway’s competitiveness.
ERTMS is specified at different levels, and the definition of the level depends on how the route is equipped and the way in which information is transmitted to the train. At Ådalsbanan in Sweden, Banverket together with Bombardier provided a section of railway with ERTMS Level 2. An application that is unique as it is the first level 2 installation ever to include equipment such as railway crossing barriers. In an ERTMS Level 2 system the engine driver can receive basic track and rail information via the GSM –R radio network. This driver information is sent from Banverket’s control centre via an IP network, which is connected to control and monitoring devices along the railway.
The equipment along the trackside has been linked to Banverket’s IP network using pre-existing twisted pair copper cables and the Westermo DDW-225. The DDW225 uses SHDSL technology that allows data to be sent at a maximum speed of up to 5.7 Mbit/s at shorter distances and up to 15 km at lower speeds. In this installation however, network resilience and reliability were prioritised rather than bandwidth. The best balance between range and signal to noise ratio was achieved at 2.3 Mbit/s over distances from 2 to 7 km.
The requirements for high reliability called for a redundant network solution, which is why the National Rail Administration created two individual networks connected to duplicated control equipment. The different networks are completely separate and connected to the backbone network by separate routers. Even if one network should fail full access to the entire route can be achieved through the redundant network. In addition, the DDW-225 supports a number of features that allow configuration for optimal control. VLAN, QoS, SNMP, SSH, and extended diagnostics were part of the requirements from the Rail Administration.
The DDW-225 is a robust Ethernet Extender with EN 50121-4-EMC approval for apparatus in trackside applications. The unit is designed for harsh environments and can operate in an extended temperature range (-40°C to +70°C). The DDW-225 has contributed to significant cost savings as new fibre installation could be avoided. The DDW-225 is also future-proofed as it can be upgraded to support future networking standards as and when they are required.