Yesterday, friends sent me the news that somebody in Japan has built a road that plays music as a car rolls upon it. There's a video available.
I was talking about this in the Eighties. I've been scooped.
I'm going to go off and sulk.
While I'm doing that, you can read an essay I wrote, originally for a book
George Ewing was proposing. When that fell through, I tried peddling it to a magazine, without success.
For George, I entitled it "The Roads Must Rock 'n' Roll," an allusion to the title of a Heinlein story. Later, I called it "Song of the Highway." I can't remember exactly when I wrote this, but the file I pulled it from indicates that it was earler than July, 1988.
When I was a kid I loved to ride over bridges. When Dads would drive our Studebaker wagon over a bridge's metal latticework roadway, a mysterious and wonderful hum would fill the car. Perhaps the bridge was singing to us.
After getting my own car and moving to Chicago, I discovered that the roadway spoke to me every time I approached a tollbooth. The builders had embedded a series of bumps, maybe an inch apart, in the road, which generated a burst of deep sound. Each zone of bumps was a few feet long, and there were three zones. So sounds of "Brrp... brrp... brrp" came to mean, "You'd better have your forty cents ready!"
The principle of these bumps could be applied more generally. The frequency of the resulting tone depends upon the spacing between the small bumps: Two inches between bumps would generate a tone half the frequency of the tone from a one-inch spacing. Thus by laying down little bumps in the road with varying spacings, you could play music as your car drove over them.
Think of highways that play tunes. Think of roads named, not by route number, but by song titles: The Stars and Stripes Forever Freeway. The Hallelujah Chorus Toll Road. The Stardust Turnpike. You wouldn't have to make the whole road musical, just a short cheery signature stretch, maybe a block or two long, in the right lane following entrance ramps. This little song would let you know what road you're on.
Because of the harmonic relationships of the bumps, the songs would always be "in tune," as long as you drove over them at constant speed. The duration of a note would depend on the length of a zone of bumps. If the zone is shorter than your wheelbase, you'd hear two distinct notes, one from the front tires, then another from the rear tires. So it would be best to make the zone longer than the wheelbase of the longest car expected to travel the road. Ten or twelve feet should do nicely. Then every driver will hear a single note from each zone of bumps. By the same token, the spacing between notes (zones) should be longer than this wheelbase to assure that individual notes are distinct.
(I can hear you asking, "What about semis?" I contend that the driver of a semitrailer truck can hear the notes coming from his tractor's tires, but that the rear wheels of the trailer are too far behind him for him to hear their music. So the zones and spacings should be only as long as the tractor's wheelbase.)
A spacing between the small bumps of 3.78 inches will give middle C (256 Hertz) at 55 mph. Of course, going over the same stretch at 11 mph will play a note five times lower in frequency, and at one-fifth the tempo. A car crosses a ten-foot stretch of road in .6 seconds at 11 miles per hour, .13 seconds at 55 miles per hour. Even the first speed is enough for a slow, dirgelike tune. At 55 mph, the notes can be short enough that we can play brisk and lively music.
We could exploit the symmetry of our vehicles to create polyphonic music. In a given lane, the right half could have a pattern of bumps different from the left half. Then the right tires would sing a different sequence of notes, and two-part harmony would be possible. Motorcyclists, alas, would not enjoy this benefit, unless they had sidecars.
How about percussion? We could put loosely fastened metal plates into the pavement. They would make a satisfying "CLANK" as you rolled over them. There are all kinds of ways to vary the sound of such plates.
I don't imagine that state highway agencies will follow my suggestion right away. Probably amusement parks or shopping malls would install Musical Roads to entertain customers while they search for a parking place. Once they began to catch on ("Daddy! Can we drive over the Music again? Please?"), some cities might see them as catchy promotions for tourism.
Imagine that as you approach the exit for downtown Chicago on I-80, the road begins to hum: "Chicago! Chicago! That toddlin' town!..." What about San Antonio Rose? The Lullaby of Broadway? Hurray for Hollywood? Alma maters and fight songs might appear on the outskirts of college towns. State songs or national anthems as you cross borders. And think of crossing the Golden Gate Bridge, as the fog lifts from the Bay, while under you your tires play, "I left my heart, In San Francisco..."