As cities strive to make their transport systems more efficient and user-friendly, they are increasingly turning to GNSS-based solutions. The Czech capital Prague, which has already leveraged GNSS to modernise its tram fleet, is now turning to a Galileo-enabled solution to improve drivers’ experience in the city’s road tunnels.
Drivers using the tunnels on Prague’s Ring Road can’t have failed to notice that satnav does not work in a large section of the tunnels, as they receive the message ‘GPS Signal Lost’. This is not usually a problem in classic tunnels with only one entrance and one exit, but in more complex tunnel systems drivers can get confused.?
To deal with this issue, the Prague Technical Road Administration (TSK) commissioned a study into possible solutions to navigation signal loss in tunnels. Based on the findings of this study, a GNSS signal retransmission solution using Galileo is now being tested in the Bubene? Tunnel, part of the city’s Blanka Tunnel Complex.
“GNSS is an important tool for any forward-looking city looking at modernizing its transport systems and making them better adapted to the needs of urban dwellers,” said GSA Executive Director Rodrigo da Costa. “By supporting solutions ranging from mobility as a service to parking support and passenger information systems, GNSS is helping to build the urban transport systems of the future,” he said.?
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The first stage of Bubene? Tunnel project will see repeaters installed at three locations in the tunnel. The GNSS signal will be routed from an antenna above ground to the repeaters in the tunnel via a short cable line. Although initially the entire tunnel will not be covered by the signal, the retransmission between the individual stations will nevertheless increase the accuracy of the navigation solution, increasing driver comfort. This pilot project will verify the functionality, performance and coverage of the transmitted signal in the tunnel.
Interesting technical challenge
"This is great news for all drivers, they will no longer have to hesitate about which tunnel exit to use, and which direction to take at the next junction if the navigation signal has not yet been recovered. TSK has started testing three GNSS repeaters in the Bubene? Tunnel, which can transmit the signal of all available navigation systems and thus ensure functional navigation in the first parts of the Blanka tunnel complex,” said Adam Scheinherr, Prague’s Deputy Mayor for Transport.
“This is also an interesting technical challenge. We need to install an antenna on the surface above the tunnel that receives the GNSS signal from the satellites, which we transfer to the equipment in the tunnel, located at exactly the same place as the antenna on the surface,” Scheinherr said.
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Once the functionality is tested, a decision will be reached on whether to extend the technology to the entire Blanka Tunnel and to other tunnels in Prague. The advantage of this system is that it allows operation of standard on-board navigation equipment or mobile phones, which makes the solution more versatile and accessible for all users.
Prague is one of many EU cities that is turning to GNSS to upgrade its transport system. The city of Madrid has also using GNSS-based intelligent transport solutions to improve user experience on the city’s buses. By enabling intelligent transport solutions of this kind, GNSS is supporting Europe’s cities in their efforts to become smarter and more sustainable, thereby contributing to EU’s priorities for a greener, more digital Europe.
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