American motorists are familiar with the rumble strip. Designed to alert distracted drivers that they are nearing the edge of the road, this grooved section of asphalt creates a harsh, thunderous, grating sound.
Now engineers in South Korea and Japan have one-upped the rumble strip by creating "singing" highways.
Also known as melody roads, these new thoroughfares use cars, specifically their tires, as tuning forks to play music as they barrel along. The musical roads are created by a series of grooves, cut at very specific intervals, in the surface of the asphalt.
Much like the vibrations and rumbles produced on a bumpy or poorly maintained street, engineers discovered that different notes were produced when grooves were placed at certain intervals along the surface. Depending on how far apart the grooves are, tires moving over them produce a series of high or low notes, enabling designers to create a distinct tune.
With 68 percent of highway accidents in Korea caused by inattentive, sleeping or speeding drivers, the Korean Highway Corp., as well as the Hokkaido Industrial Research Institute in Japan, came up with the idea of musical road surfaces to keep motorists entertained but also to reduce their speed and help them stay alert.
Referring to a particularly treacherous section of South Korea's singing highway, Seung-Hwan Shin, manager of the Korean Highway Corp., said, "That place is in a downhill, S-curved road, so there's been lots of accidents from dozing and speeding."
Shin, along with other Korean highway officials, hope these new roads significantly reduce the number of accidents caused by distracted drivers every year.
But creating these singing streets isn't easy. It takes thousands of grooves carved into a road to create even one song. Shin said construction for one song took four days. On Korean highways, the song of the streets is the simple, yet sweet "Mary Had a Little Lamb."
Transforming those vibrations into a melody, however, depends on the distance between the grooves, which may vary between 5.3 centimeters and 10.6 centimeters. The rhythm, on the other hand, is controlled by the length of the groove. For example, to get one second of the C, or "do" note, the groove must be stretched to 28 meters.
But the makers of the iPod have little to worry about this new competitor. The optimal speed for listening to these songs from the road is a safe 62 mph. At faster speeds, motorists still hear the music, but instead of an easy-listening song, they hear the annoying Alvin and the Chipmunks version, and slower speeds have a slow-mo effect on the song, making it virtually impossible to decipher.
The idea behind the singing highways is a good one, and officials hope that version 2.0 of this new technology will have all the kinks worked out.
Joohee Cho and Rebecca Lee contributed to this report.