As most here probably know, much of Europe went to DAB (Digital Audio Broadcasting) a few years ago. It's why if you took a North American radio over to the Continent, you may not be able to get much on it. But there was one big problem in a place that has a lot of underground tunnels connecting one place to another - the already weak signals wouldn't penetrate the underground passages. 

Now, in Belgium, they've fixed that issue, installing strategically located repeaters and antennas inside those long tunnels so motorists can continue to get their signals even if they're away from the great outdoors during their drive. 

Didn't CKLW do this once a long time ago in the Detroit-Windsor tunnel, ensuring the Big 8 was virtually the only radio station you could hear as you traversed that enclosure? Interesting to see history repeater-ing itself. 

Flanders Bringing DAB+ to Tunnels