Future looking up for Prague's lookout tower

With a steadily increasing flow of tourists, it's important to have an infrastructure that takes them safely, reliably and quickly from A to B. In Prague, automation technology from B&R now helps them visit one of its major attractions without the crowds and long waits.

The Czech Republic's capital city of Prague is one of the most popular tourist destinations in Europe. As the number of visitors continues to increase, the city's infrastructure – particularly around the most popular attractions – must continually be upgraded and expanded. The daily strain of mass tourism has also taken its toll on the cable railway that carries visitors up the hill to the Petřín Lookout Tower, one of the city's main attractions. Prague-based PEG was therefore tasked with giving it a complete overhaul. With the newly installed B&R controls and HMI technology, the cable car is now more safe and efficient.

PEG is a system integrator based in Prague. To modernize the cable car, PEG turned to its trusted partner B&R. "We've always had positive experiences with B&R as a supplier. So it was natural for us to rely on them once again for this big project," says PEG Software Manager Jan Maštera. "In terms of both technology and price, the Austrian automation specialist was best choice for us."

The famous cable car to the Petřín Lookout Tower was built in 1891. It had been technically renovated twice over the past century, but replacement parts were becoming increasingly difficult to come by. "We transport around two million guests each year," reports Pavel Kejha, the cable car's operations manager. "In 2018, the time had come to renew the aging drive and control system. It's important to us that we get our guests up to the tower quickly and safely."

And so it was clear that they needed a powerful, more reliable new system. The new system would need to be much easier to upgrade to meet future requirements. It was also important to provide cable car conductors more sophisticated, intuitive controls. As always, a key concern during the modernization project was safety. The new system would need to transport the guests up the hill safely and reliably.

Together, PEG and B&R developed a concept for a new and improved cable car system. "We have experience with comparable systems in both Austria and the Czech Republic," says Martin Větrovský, project manager from B&R Czech Republic. "Our advanced mapp View HMI system follows the HTML5 standard and fully satisfied all the requirements." Inside the cabin of the cable car, the system runs on two touch screen panels: a large 24" panel for the conductor and a smaller 15" panel for operation via the control cabinet.

"Our cable car completes its journey up and down the Petřín hill more than 80 times a day. We transport as many as 1,400 people per hour," notes Kejha. "So, of course, passenger safety is our top priority."

Fault protection on the control computer continuously monitors the state of the cable car. The control computer sends commands like start, stop or speed setpoints to an autonomous controller via the MODBUS RTU protocol. The safety system can detect and report more than 100 abnormal states, providing the conductor with a complete overview of what's going on with the system.

The safety system differentiates between three categories of faults. Depending on the category of the fault, the controller sends one of three different commands. In the event of acute danger, a command is sent to apply an emergency brake to stop the cable car. If unexpected obstacles are encountered along the way, a command is sent to stop the cable car before it reaches the affected track segment. The third type of fault is one that does not endanger operation. The safety system simply reports a warning that notifies operators so that they can perform the necessary maintenance.

Centralized data acquisition with the X20 control system collects and evaluates large volumes of data. Any faults are quickly localized and corrected. The new design also helps limit the extent of damage: If a fault occurs in one part of the system, it doesn't cause damage in subsequent parts. This increases reliability while simultaneously minimizing the amount of downtime in the event of a problem.

"The new solution detects faults sooner for increased reliability and delivers more computational power," says Project Architect Pavel Novák. "The newly installed system has better diagnostics, and the mapp View HMI is much cleaner and more intuitive, which is great news for the conductor."

The days of aging infrastructure and long lines of tourists wrapping around Prague's Petřín hill are over. With B&R technology, the cable car operator has made a decisive leap forward. A system that can be updated and expanded at any time is sure to always be up to date. "The only thing left of the original electrical system is the motor. The rest of the system has been replaced and upgraded," Kejha. "This solution puts us right at the cutting edge of today's technology. And it puts us in a position that we can continue to build on into the future."