Explained: How The Internet Physically Travels Around Nashville

The fibers — a fraction of a millimeter each — are separated into color-coded tubes and tinted to keep track of each strand. Credit: Emily Siner / WPLN

Todd Oney with the Nashville Electric Service is pointing to a utility pole next to I-40. There’s electricity at the top, then telephone at the bottom, and in the middle, three black cable lines.

“One’s Comcast, one’s our own cable, and … I’m not sure who owns the third one,” he says, as cars zoom by.

This past year, Nashville has been abuzz with talk about fiber-optic Internet. Google Fiber says it will decide early next year whether it’s expanding to Nashville. AT&T says it plans to launch GigaPower here but hasn’t yet given a timeline. Both promise to send data at gigabit speeds to computers.

As much as that process seems virtual and wireless, the Internet is, for the most part, a very physical series of cables around the world. They’re even laid under the ocean. In Nashville, you just have to look up — they’re strung on utility poles across the city.

Some cities have Internet lines buried underground, so they’re not visible. That’s more expensive than it’s worth in Nashville, Oney says.

“Nashville’s on solid rock, just about the entire city. So anywhere you’re going to go to dig, you’re going to dig up rock,” he says.

Nashville Electric Service started installing fiber optic cables on utility poles in the early ‘90s, as a way to transmit its own data around the city. Instead of being made out of metal, like older cable lines, fiber is made out of glass. It’s very thin, almost microscopic glass.

Oney opens up a tube in his office. Inside, there’s a small section of cable with 72 little tinted see-through fibers — 12 fibers in six colored tubes. The whole thing isn’t even the size of his index finger, but it could connect thousands of homes or businesses.

“The thing that blows my mind,” Oney says, “is how tiny it is, but it can transmit all that information over that little tiny piece of glass.”

And it transmits it really fast. Fiber uses light to transmit data: A box of equipment turns data into laser impulses, shooting through the glass. It’s not quite as fast as the speed of light, but it’s the same concept. Oney says the theoretical limit on fiber is 50 terabits per second — estimates differ, because no one has ever actually tested the Internet at those speeds.

Still, 50 terabits is 50,000 times faster than a gigabit. So why isn’t the Internet nearing the speed of light yet?

The holdup, Oney explains, is the equipment on the end of the fiber, converting data into light and back. It’s getting faster, but it hasn’t gotten anywhere near fiber’s limit. Even with Google or AT&T advertising superfast fiber-optic Internet, the reality is that they haven’t even scratched the surface of what’s possible.