RadioActive wrote:

We don't have this here in Southern Ontario as far as I know, but I once heard a story about how CKLW managed to get its signal to come in when motorists crossed the long tunnel between Detroit and Windsor back when AM 800 was a "rock" star. It was, if memory serves, the only station you could get for those long minutes spent commuting underground.

All that was brought back to mind by this terrific article about the places where radio can still be heard inside those lengthy concrete-covered commutes, and the news that - in the U.S. at least - there are no government regulations needed to put in the equipment to make it all work. 

Tunnel Radio: How Signals Reach Drivers Underground

You are correct CKLW was the only station you could get in the Windsor - Detroit tunnel. That is no longer the case, I believe WJR 760 now has that distinction. Maybe the purchased the CKLW equipment and retuned it.

turkeytop wrote:

When we go through the D W tunnel, it always amazes me how deep into the tunnel we get until the SXM drops out.

There is more than likely a terrestrial booster in the tunnel.  SXM has boosters in all the larger city centers due to large tall buildings and such blocking signals.