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The hole is greater than the sum of its parts


A highway tunnel like the Pfänder Tunnel in Bregenz, Austria, is more than just a hole in a mountain – it is also a complex network of very important technology. If you have ever driven through one, you surely noticed the lighting and ventilation units, and maybe even the signaling equipment and life-saving emergency systems. Behind these lie state-of-the-art automation systems like those provided by Dürr Austria, built using Automation PCs and X20 control systems from B&R and the XAMControl process control system. Seamless integration into this process control system from Dürr's subsidiary, evon GmbH, including automatic code generation, helped minimize the amount of engineering required.

In mountainous regions, more and more roads are being routed through tunnels. In exchange for their convenience, these tunnels place heightened demands on safety and reliability. Fresh air and light need to be delivered deep into the mountain, and noxious exhaust fumes must be allowed to escape. Signaling and monitoring systems are needed to regulate the flow of traffic. In the event of an accident or other emergency, the technology must also help people exit the tunnel quickly and safely. Disasters like those in the Mont Blanc and Tauern tunnels and the Kaprun funicular serve as dramatic and painful reminders of the importance of tunnel safety.

The technology installed in the tunnel must provide reliable safety over decades of operation. This, in turn, relies on durable and reliable control components equipped to handle both present and future requirements.

Highway tunnel no small undertaking

A second tunnel was added next to the 30-year-old original, which was subsequently upgraded to equally state-of-the-art technology. The project included the installation of 300 emergency exit guide lights and 200 video cameras as well as 100 emergency call stations and alarm systems.

Tunnel automation systems can easily take on immense proportions, as was the case with the Pfänder Tunnel that bypasses Bregenz, capital of the Austrian state of Vorarlberg. The 6.7-kilometer, two-lane tunnel first opened to traffic over thirty years ago. In June of 2012, after nearly five years of construction, a second two-lane tunnel featuring state-of-the-art electrical and safety technology was opened adjacent to the original one, which was then upgraded to match its new neighbor by July of the following year.

The project, commissioned by the Austrian highway operator ASFINAG in April 2011, encompassed a low-voltage distribution system and emergency power supply with five UPS units, lighting provided by 2100 LED bulbs, air quality sensors, 120 variable message signs and traffic lights, 1750 curb reflectors, 300 emergency exit guide lights and 200 video cameras.

In addition, 100 emergency call stations and alarm systems were also installed. Connecting these to the 141 tunnel controllers and to the master control station required more than 60 kilometers of fiber optic cable, 140 network switches and 14 kilometers of fire alarm cable.

Like all seven tunnels on the highways and expressways of Vorarlberg, the Pfänder Tunnel is controlled and monitored from the master control station in Hohenems, Austria. There, the 45,000 data points that represent the Pfänder Tunnel are managed in 200 process diagrams.

Long-term reliability in a harsh environment

As the general contractor for the approximately €25 million project, ASFINAG selected Dürr Austria GmbH. This innovative organization of 80 highly-skilled and motivated employees has an excellent reputation for developing solutions that pull together all of the necessary individual systems into a seamlessly coordinated whole. For the integration of this overall solution, Dürr called on the 23 employees of its subsidiary evon, who specialize in software development.

"The individual systems that comprise this project are relatively straightforward in themselves," explains Andreas Leitner, managing director of evon, "yet the extensive interconnections and long distances between them, as well as the task of making the systems failsafe and redundant at all levels, made the overall solution quite complex indeed. On top of all that, we faced the challenge of fitting all the control equipment into a very limited space and ensuring that it would operate reliably for many years in a dusty environment exposed to constant exhaust fumes."

Compact and robust

Control is provided by distributed X20 controllers from B&R and a redundant pair of B&R Automation PCs positioned in each section of the tunnel. With no moving parts such as fans and hard drives, they ensure maintenance-free functionality for many years of operation.

To control the individual systems throughout the tunnel, evon selected I/O systems from B&R's compact and robust X20 series. The 98 controllers distributed throughout the tunnel are networked via a redundant ring of fiber optic cable. Control of the X20 systems is provided by 43 B&R Automation PCs, positioned out in the open in redundant pairs with each assigned to a particular section of the tunnel.

These controllers send data directly from the Pfänder Tunnel to the master control station in Hohenems. Shock, vibration, heat and continuous operation in industrial environments are no problem for B&R's Industrial PCs. With no hard drives or fans, they were designed for just such inhospitable conditions. HMI devices installed include Automation Panels, Power Panels and PANELWARE tablets.

Openness in process control

These systems are all connected to ASFINAG's master control station in Hohenems.

The distributed B&R control system operates within, and seamlessly intertwined with, evon's XAMControl process control system. Also at home in processing and building control applications, XAMControl is built on a database platform and can be adapted simply by setting parameters rather than by tediously rewriting code. The X20 controllers in the Pfänder Tunnel are managed and programmed centrally via this process control system.

XAMControl scans and automatically detects the hardware configuration and generates C# code for specific control tasks. This code is tested on virtual PLCs and then converted by the B&R compiler directly into machine code that can be executed by the X20 systems.

This homogeneously integrated system architecture made it possible – for the first time ever in a traffic control solution – to follow a consistent top-down approach to system development, where the software is fully tested and simulated prior to being assigned to the actual hardware configuration.

"The decision to work with B&R was an easy one. Not only do their products provide thorough openness and compatibility with an excellent price/performance ratio, they were accompanied by outstanding support from B&R's local technical office in Graz and direct communication between our development departments," says Leitner, citing some of the most significant advantages of the cooperation. "The ability to derive the control code from database-supported, object-oriented programming in the management system helps users avoid unnecessary redundant work and eliminate potential errors caused by interfacing issues."

45,000 data points keep traffic flowing smoothly

Developing control technology and process control systems to provide lighting, fresh air and traffic safety in highway tunnels is no small undertaking. The Pfänder Tunnel in Bregenz, Austria boasts a dizzying 45,000 data points.

The successful cooperation between Dürr, evon and B&R produced an overall system whose performance goes beyond simply providing reliable, safe operation. The seamless continuity, from the master control station down to each and every data point, makes work easier and faster for maintenance technicians and supervisory bodies. This was enough to fully satisfy the operator of Austria's highways and expressways, ASFINAG, that control of the tunnel's automation is in good hands with B&R.


"The ability to transfer code directly to the X20 control system from B&R is a huge relief for traffic control system engineers," says evon's managing director Andreas Leitner. "The advanced software technology behind evon's process control system, in combination with the powerful, open and robust B&R systems, provides the long-term reliability required for many years of operation."

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