With a total length of 57 km the Gotthard Base Tunnel will be the world’s longest railway tunnel. The project is actually running slightly ahead of schedule, with the official opening due to take place on June 1, 2016. Scheduled operation is set to start on December 11, 2016. The Gotthard Base Tunnel links Erstfeld in the Uri Valley with Bodio near Biasca in the Canton of Ticino. Together with the Ceneri Tunnel, the new tunnel will cut journey times from Zurich to Milan from 3 hours 40 minutes to below 3 hours.
As part of this major project, the Scada system Simatic WinCC Open Architecture solution described here will be contributing towards the achievement of more efficient and safer European rail transfer.
Architecture and structure of the tunnel management system
The tunnel management system is responsible for ensuring the remote control and monitoring of relevant data points across the electromechanical systems. Using the information being constantly supplied, the tunnel management system prepares a graphic system overview which indicates not only the statuses of the various electromechanical systems, but also the locations of trains within the Gotthard Base Tunnel alongside additional information.
Ensuring the availability of the overall system in a project of this enormous scale is an exciting challenge. The entire infrastructure is displayed, monitored and operated at two Tunnel Control Centers, one at the North and the other at the South Portal. The individual infrastructure subsystems encompass the power supply, catenary system, ventilation and air conditioning, lighting, operation and surveillance of wide-ranging different doors and gates. All of these systems are managed by the overriding tunnel management system on the basis of Simatic WinCC Open Architecture.
To achieve an integrated solution concept for all the electromechanical systems through to the tunnel management system level, a hierarchical concept was drawn up encompassing overriding functions and defined performance features. Standardized display and operation across all the different applications was achieved by using the same general specifications, such as the style guide, visualization concept, OPC UA communication and other.
OPC UA as a standardized interface across the whole project
Given the need to integrate sixteen different facilities from different suppliers, it was vital to use a platform-neutral, standardized and uniform protocol. OPC UA was defined as the standardized interface between the tunnel management system and the electromechanical systems. There were several reasons for choosing OPC UA.
Because high availability is paramount in a project of this nature, a redundant configuration was set up both for the OPC UA client and server, and the OPC UA feature Heartbeat was used for monitoring the connection in both directions.
An additional requirement is reliable data exchange. It was possible to guarantee this using OPC UA, which supports authentication and authorization both on the server and the client side. The security is based on current standards (SSL/TLS specification) and allows use of standardized X.509 certificates. These same certificates are also used in IT for safeguarding the https connections. This allows the use of a standardized infrastructure (CA). To safeguard all OPC UA communication, encryption and a digital signature were used. Configuration of the firewall was simple as only one port was needed.
With a project of this scale encompassing several hundred thousand data points, high performance is vital. By using the binary protocol (OPC UA Binary, UA TCP), it was possible to ensure high-performing communication.
The benefit of the binary protocol is that it requires few overheads, consumes minimal resources, offers outstanding interoperability and uses only a single TCP port for communication. As a result, it allows simple tunneling or activation in a firewall.