Ever since the automobile became a driving force in American and global culture, road designers and highway planners have been looking for ways to curb the risks associated with driving.
Some cities use dynamic speed limits and flexible lanes (that can run in either direction depending on the time of day) to adjust the flow of traffic during the busiest times of travel. Others widen lanes in a misguided attempt to reduce congestion and collisions.
Many highways feature rumble strips to make cars vibrate, warning of impending curves or sudden stops and alerting drivers who veer too close to the shoulder.
There are a few stretches of highway, however, all across the world, where designers have retuned rumble strips for a different effect, transforming ordinary pavement into musical roads.
By controlling the depth and spacing of rumble strips, engineers and designers can control the pitch and rhythm of the vibrations they produce as a driver passes over the indentations. Assuming a car is traveling at a constant speed, spacing the grooves closer together increases the pitch and spacing them farther apart lowers the pitch.
Producers of National Geographic’s television series Crowd Control used this approach to set up an experiment to encourage drivers to reduce their speed on one of America’s most iconic roads: a stretch of Route 66 near Tijeras, New Mexico. The target area was outfitted with a series of strips, spaced in such a way that motorists would hear America The Beautiful as they drove over.
The design came with a calculated catch: drivers had to slow to 45 miles per hour to hear that tune at the intended tempo and in the appropriate key. Go too fast and the pitch is transposed higher and the tempo is increased (think: chipmunks from Alvin And The Chipmunks); go too slow and the inverse happens (think: any non-chipmunk from the Alvin And The Chipmunks).
Not all musical roads, however, are designed to modify behavior. The first recorded use of a musical road was in Denmark in 1995. It was created by two artists and dubbed the Asphaltophone. Unlike most musical roads, this one used raised bumps on the surface of the road to create vibrations as cars drove over instead of impressions into the pavement. The same physical principles apply, though: the closer the bumps, the higher the resulting pitch of the note.
About a decade later in Japan, a bulldozer operator accidentally etched some grooves into the road and realized that with the proper planning and spacing of the grooves, the technique could be used to create music. A national research institute refined the operator’s design approach to create four stretches of Melody Roads across the country in hopes they would attract tourists. The one in the video above can be found on a major road to Mount Fuji.
More complex pieces are also possible with the right planning. The Okinawa Melody road has two distinct sets of strips in the lane, one for the left and right set of wheels. In addition to allowing more complexity in rhythm, it also creates a stereo effect since different notes can be played from the right and left side of the car.
Unfortunately, not all musical roads turn out equally well. In Lancaster, California, there is a stretch of highway that was supposed to play the finale of the William Tell Overture. But something seems to have gone wrong in their calculations—or perhaps the tune was overly ambitious. The video above shows a couple going over the stretch at the recommended speed of 35 mph and at the posted speed of 55 mph. Still, no matter their speed, the song doesn’t sound right.
There are probably a few factors at play. First, this piece of music is pretty upbeat, with a lot of notes to hit in a very short amount of time. If one of those notes is off at all, it throws off the rhythm of the others as well. The rhythm, however, turned out far better than the pitch. The intervals (the “jumps” in pitch between the musical notes) is totally off in multiple places, making the melody bare little semblance to the original piece. Most likely, they made a miscalculation (or a series of miscalculations) in the spacing between the grooves for several of the notes which led to these distortions.
Whether well or poorly designed, these musical roads do seem to be grabbing the attention of drivers as evinced by all of shaky YouTube footage that exists from around the world. One does have to wonder, though, if these roads are actually improving driving habits.
Obeying the speed limit to get a musical reward might slow people down, but it can also increase temptation to pull out a phone and capture the moment. A tip for would-be musical road drivers: bring a passenger if you want to record the experience.
I was surprised to find out that folk musician and activist Pete Seeger had this idea in the late 1930’s. From his biography “How Can I keep From Singing?” (p. 194), “I remember driving with him one time;’ Bess continued, “and we went over a long section of metal grating. We hit this road and the pitch of the tires went way up. Pete started speculating on how an engineer could grade the surface of the road so that you could play a tune on coming into a city – the right song to put you in the right mood, with a sign that said ‘Hit this at 42 miles per hour and you’ll hear …’.””
For the mathematically inclined, here’s an article about what went wrong at Lancaster:
Love that a guy with a tape measure and a welding clamp is described as ‘precision engineering ‘ in the first video.
If you drive in reverse do you hear Satanic incantations?
Critics are everywhere: