It's true that, ordinarily, radio waves bounce off the sides of mountains like common sense off Rick Santorum's skull. But commuters to and from the eastern suburbs have been getting FM radio signals inside the tunnel for much of the past five years now.
"It got started because in college, my oldest son Brian had a summer job that required him to drive through the Squirrel Hill Tunnel," says Dan Stancil, an electrical and computer engineering professor at Carnegie Mellon University. "And he got irritated every time he lost his favorite song when he went through."
For most Pittsburghers, this is a minor nuisance: Judging from what I hear on the radio, all of our favorite songs are either by AC/DC or Led Zeppelin, and we only have to wait 15 minutes before they get played again. But Brian Stancil had an advantage over the rest of us: His father was an engineering prof at CMU. As we all know, those people are capable of doing almost anything -- from unleashing killer robots to ensuring that commuters can savor every note of "Black Dog."
The Stancils proposed having college students wire the tunnel as a school project. Brian "started calling people at PennDOT, the FCC, and all over," Dan Stancil says, pitching the idea of wiring the tunnels as a student project. Everywhere he went, "he found enthusiastic support." After all, installing such a system commercially would have cost at least $100,000; having CMU students do the work meant PennDOT would pay one-tenth that in parts and labor.
Traffic engineers were so enthusiastic that PennDOT was even willing to block off one lane of the tunnel -- and we all know that if there's one thing PennDOT hates, it's restricting traffic. "When we were first starting, they shut one lane down for us so we could make measurements," Stancil says. "Of course, they only did so on certain nights, and during certain hours. But grad students are at their peak at around 2 or 3 in the morning anyway."
The system the students designed was fairly straightforward. As explained on the project's Web site, www.tunnelradio.net, it consisted of an antenna mounted atop the hillside, with an amplifying device beaming it down cables to a wire loop that runs the length of the tunnel. The loop is stowed in a crawl space directly above the roof of the tunnel, and so remains invisible to the commuter.
Once the students had a chance to study the tunnel ("The air ducts above the tunnel were ... like straight out of Ghostbusters," the Web site reports) PennDOT electricians installed it. The system was up and running by October 2000, and while Stancil says it "operated for a year or two, we had some trouble keeping it going." The problem was in the cables joining the aboveground antenna to the equipment tucked away in the tunnel crawlspace. The cables had been threaded through air-changing ducts, but Stancil says, "The air going through those ducts was moving at a pretty high speed. It's like being in a gale in there. When you go in front of where the fan opening is, you have to lean into it from being blown over." The original cables hung in the shafts "like clotheslines, and they would flap around in the wind and break."
Earlier this summer, the old cable was replaced with shielded cable, which means the line is encased in a protective sheath. So if you're hearing only stations on your FM dial now, that may be why.
Nor is that the extent of CMU's tunnel vision. Stancil and his students -- nearly two dozen of whom have worked on the project over the past five years -- also installed a similar FM system in the Fort Pitt tunnel while it was closed for repairs. Fort Pitt already had an AM antenna installed, though Stancil has plans to upgrade that system, and add an AM antenna to Squirrel Hill someday.
So if you want to avoid having to listen to AC/DC and Led Zeppelin, your only commuting option is the Liberty Tubes. Or a CD player.