Up to that point, Ethernet protocol had been used onboard only for CCTV (Close Circuit Television) and tertiary systems such as Information and Entertainment. Most of the different systems in a train have traditionally had separate interconnection or networks. For train operation, a railway-specific network called TCN was used. Bombardier Transportation teams developed a new system where Ethernet provides connectivity and management for all of the vehicles on board equipment. In the first projects, the old and new networks – Ethernet rings and TCN – will coexist, but Ethernet will fully replace the TCN. The Bombardier Transportation system was the first to integrate all the intelligent devices onboard into one Ethernet network.
For the regional trains currently delivered in Germany and the Netherlands, the Ethernet network is able to determine the composition of a train e.g. what kind of coaches constitute the train, in which order they are coupled together, and in what direction they run (to be able to open the correct set of doors, etc). The TCN is kept for train-wide communications.
“We have a project where the TCN will be kept only for local connections whereas the train-wide communication will be carried out on the ETB (Ethernet Backbone). They will start commissioning after the summer. This is the next step on the way to the full Ethernet train. The network carries all data types needed for control, security and passenger information e.g. data from surveillance cameras, passenger announcements, data to control the operation of the train and coaches (doors, propulsion, lighting….). All except signalling and Internet access will be managed through the Ethernet protocol.” Says Klas ENGLUND, TCMS Product Manager at Bombardier Transportation Sweden.
Westermo supplied various network components: managed ring switches, managed train switches, train repeaters and unmanaged switches. There is an average of 2 to 4 switches per car, and 2 to 8 cars per train set with 400 switches delivered. Additional switches which serve as a repeater are necessary in long train sets as Ethernet segments can only operate over a 100m distance.
Reducing costs and improving functionalities are the two main reasons to change traditional low-speed train networks into Ethernet networks. Hardened Ethernet products and knowledge are now common even with higher data transmission rates and bandwidth, whereas the rail-specific network knowledge and equipment are very specific, leading to high costs. Furthermore, there is an increased demand for larger bandwidth, necessary to respond to improved diagnostics function requirements and to handle audio/video security functions and safety systems such as Driver Controlled Operation (DCO).
”There were many candidates for cooperation around these products that will probably become the new train standard. The main reasons for us to go with Westermo were, firstly, that they had an interesting and promising concept which could serve as a platform for implementation of our add-on functionality. Together we saw the possibility for adaptation to our needs and the integration of our special software solutions into the products. Westermo also demonstrated an open mind about the way to cooperate, and a strong involvement in customisation for railway needs.” Adds Mr Englund.
Westermo rail specific products have been designed and certified to meet, and in most cases exceed the railway specific standards regarding EMC (Electromagnetic Compatibility) and other environmental requirements resulting in a very resilient product. On Bombardier’s side, engineers have developed a specific software that has been integrated into the switches.
Westermo have a dedicated series of switches and routers approved and certified for railway usage according to EN50155. Westermo Rail products support 10/100/1000 data rates with all ports supporting auto-negotiation of speed and duplex connectivity, auto crossing and auto polarity.
The latest Gigabit Train Backbone Routing Switch supports line-speed routing with no loss in throughput capability in conjunction with a Gigabit bypass function where the switch will pass-through communication in case of a loss of switch / carriage power or switch malfunction. Management and setup can easily be done using the Windows based WeConfig configuration tool.
Westermo rail products support network redundancy by the well-proven FRNT protocol from Westermo for fast re-configuration of ring topology. The RSTP/STP protocol can alternatively be used in case of a complex topology. Excellent real time properties are offered through both layer 2 and 3 priority support with four priority queues.
”In the future Westermo products will be on all types of rail vehicles from trams to locomotives,” concluded Mr Englund.
WESTERMO Contact Details
Rolling Stock Networking. 61 Charlotte Street, Birmingham B3 1PX
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