The station’s studios are like a control centre: the animators always have one eye on the monitors showing the focal points of the roads leading into the city

With the pandemic, traffic had plummeted and the ratings of Radio Circulation, Montreal’s traffic radio station, had declined. But since the renovation of the Louis-Hippolyte-La Fontaine tunnel (opened in 1967) began, the station has become very popular again. The tunnel to be renovated, to ensure its operation for another 40 years, passes under the St. Lawrence River and connects the island of Montréal with the south bank of the river in Longueuil, Quebec. It is a vital access route to the city and since three of the six lanes will remain closed until November 2025, many have thrown in the towel and opted for the train or the metro (+15%), while those in cars rely on the radio to seek alternative routes.

A bet won

The futuristic Turcot interchange, a vital local and regional link as it is located on a key route between Montreal-Trudeau International Airport and the city centre

Moreover, Radio Circulation owes its fortune to traffic jams: it opened in 2011, a year before the opening of the major construction site for the Turcot interchange, a multi-level elevated road system linking three motorways: Autoroute 15, 20, and 720. The station broadcasts on 98.5 FM and 730 kHz mediumwave, and in the studio, two editors take turns every half-hour in conducting and answering listener calls, never losing sight of the twenty or so monitors that show the hot spots at risk of traffic jams. The radio competes with online navigation platforms but manages to give faster and more up-to-date information than Google Maps and Waze, both in the portfolio of Alphabet, the web giant.

Written by Fabrizio Carnevalini


A mobile RAI vehicle conducting tests for digital radio reception in the tunnels

With the development of DAB comes the question of how to add services to an existing system. A study conducted in Italy in 2017 by the RAI-Radiotelevisione Italiana Research Centre, in anticipation of the development of digital radio, highlighted the criticalities of using the structures built to broadcast the channel over Isoradio traffic. It would be necessary to intervene on the device that mixes the signals before conveying them on the slit cable: a costly and complex operation. It was therefore suggested, in order to drastically reduce costs, to use the radio wave system by re-transmitting the signal from an antenna placed at one end of the tunnel, or, in longer tunnels, at both ends.

A leading country…

On the BPC website, you can find in-depth technical information on tunnel diffusion systems

Italy, due to its orography, is the second largest country in the world in terms of the number and length of tunnels, second only to China and followed by Japan, Norway, Switzerland, Austria and France. And it can count on world-leading companies in tunnelling, underground construction and transmission systems with a high level of integration such as those used in the Frejus (12.8 km) and Mont Blanc (11.6 km) international motorway tunnels. More than 30 channels are available in these tunnels for the services of Italy and France: fire brigade, border police, Carabinieri, Gendarmerie, medical emergency vehicles and FM broadcasting with RDS. The systems are managed by a control centre that can interrupt radio programmes to broadcast emergency messages.

…but Switzerland also has its leadership

On the website of SRG SSR, the company that runs Switzerland’s public radio and television service, you can find a list of the 193 road tunnels where you can listen to digital radio

Switzerland is well advanced on DAB. Network expansion has been going on since 2014: the country had given itself a ten-year horizon for the switchover to digital radio, which will take place at the end of 2024 when the analogue FM transmitters will be switched off. Currently, SSR network coverage for indoor reception is 98%, while for outdoor reception and car radios it even exceeds 99%. Today, therefore, Switzerland boasts the best DAB+ coverage in the world, with some 193 tunnels longer than 300 metres being illuminated by the signal already in 2018 with an investment of around CHF 30 million. The areas not covered are mainly located in peripheral regions, a problem that will be solved in the coming years.
(Writteb by Fabrizio Carnevalini)


In the latest technical bulletin (December 2021), SRG SSR takes stock of the expansion of the DAB+ digital transmission network

Despite the fact that DAB+ signals already reach 99 % of the population in Switzerland, as required by the Federal Office of Communications (OFCOM), the public broadcaster has further expanded the digital network in Italian and French-speaking Switzerland. Between 2020 and 2021, ten new transmitters were activated and twelve others were optimized. Improvements were made in the cantons of Jura, in the northwest of the country, and Ticino, located almost entirely south of the Alps, where the network was further expanded at the beginning of 2021 with the activation of the installation in Cardada. In Switzerland, the digital signal is also broadcast in tunnels longer than 300 meters: the list of the 193 road tunnels covered by DAB+ signals can be consulted on

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