The stretch of Route 66 that travels east out of Albuquerque, New Mexico and heads to the small town of Tijeras is desolate at best. Besides a handful of gas stations and a spider web of power lines that cast their shadows onto the two-lane roadway, there’s not a whole lot to see. But for one quarter-mile stretch, there’s plenty to hear.
Two years ago, the New Mexico Department of Transportation (NMDOT), along with the National Geographic Channel, had the idea to make a roadway that sings—literally. Enlisting the help of San Bar Construction Corp., a New Mexico-based company that designs and constructs traffic control devices and signs, NMDOT created a length of roadway between mile markers four and five that plays music whenever a vehicle drives over it. But there’s a catch—the tune, in this case “America the Beautiful,” only works when cars are traveling at exactly 45 mph. The road’s purpose is twofold: to encourage drivers to stay the speed limit and to bring a little excitement to an otherwise monotonous highway.
“Route 66 is a very historical roadway and [NMDOT] thought it would be neat to do something like this on such a unique piece of highway,” Matt Kennicott, director of communications for NMDOT, tells Smithsonian.com. “We chose this stretch for its historical and travel value. Albuquerque has several classic car clubs that date back to when Route 66 was in its heyday that like to cruise the roadway, so it seemed like a good fit.”
Souped up Ford Mustangs and Pontiac GTOs aren’t the only vehicles getting their kicks on Route 66. At one time, the historic roadway was one of the main arteries linking Chicago to Los Angeles, serving as a lifeline for farmers and ranchers fleeing the drought-ridden region in search of work during the Dust Bowl. After World War II, automobile ownership grew and Route 66 did too, becoming an icon of road trip freedom for cross-country travelers. Over the years, driving along the more than 2,400-mile “Mother Road” has remained a bucket-list item for road-weary travelers of all stripes, and the musical highway is just one more reason for drivers to keep this endangered roadway on their GPS.
Exactly how does the musical highway work? Using a series of perfectly spaced rumble strips (similar to the ones that wake you up if you’re nodding off behind the wheel) and a mathematical equation, engineers at San Bar Construction Corp. were able to figure out how the distance of each rumble strip affected the pitch that was produced once a tire drove over it. Even being off by as little as a millimeter could throw the entire song out of whack.
“The road works by the simplest bit of science, Kennicott says. “All of the sounds and music notes that we hear in day-to-day life are just vibrations through the air. For instance, anything that vibrates 330 times in one second will produce an E note—a guitar string, a tuning fork or even a tire. To produce an E note with a car, we had to space the rumble strips such that if driven at 45 mph for one second, the car would hit 330 strips. A bit of math tells us this is 2.4 inches between each rumble strip. After that, it’s a case of breaking down the music into exact chunks of time and applying the same technique to each space depending on what note is needed and for how long.”
Once engineers had spacing in mind, they welded metal bars together to make a template, heated up the asphalt in sections using massive blowtorches and pressed each template into the pavement. All told, it took about a day for workers to install the rumble strips into the highway and paint musical notes on the pavement. A few signs mark the musical stretch and instruct drivers to stay the speed limit if they want to hear the song.
What drivers hear depends on the car or truck—the size of a vehicle’s tires can affect the tone of the song. “The width of the tires, what they’re made out of and the ambient noises coming from under the car’s carriage can change the way the song sounds,” Frank Sanchez, operations manager for San Bar Construction Corp. tells Smithsonian.com. “The song sounds different in every single vehicle.”
Currently there are only a handful of rhythmic roadways around the world, including highways in Denmark (called the “Asphaltophone”) and Japan (“Melody Road”). Automobile manufacturer Honda also had one built near Lancaster, California as part of an ad campaign that remains popular with motorists. Perhaps one day every highway will play a song. After all, what's a road trip without an epic playlist?