2,700-mile TVA fiber blitz passes quarter-way mark in effort to modernize the electric grid.

NOVEMBER 20, 2020—TVA is stretching 2,700 miles of high-speed fiber across the Tennessee Valley in an effort to build a modernized electric grid. The $300-million investment is enhancing both transmission capability and security through the integration of emerging technologies.

The elaborate fiber network is positioning the Valley as a hub for large manufacturers and job producers whose operations hinge upon automation, robotic assembly and sustained power quality.

TVA Helicopter Lineman Matt Townsend grounds 144-strand fiber-optic cable on a TVA transmission structure.
Photo Credit: Lyn Burks, Rotorcraft Pro Magazine

“We want to make every electron flowing through our transmission lines count,” said Aaron Melda, senior vice president, TVA Transmission & Power Supply. “This project is going to increase our remote switching capability. This new system will give us the ability to predict versus react, which will help us prevent transmission failures and load-not-served conditions. That’s an immediate cost benefit for our customers and stakeholders.”

In addition to maintaining system reliability and bolstering the region’s economic development potential, TVA’s fiber efforts are creating information superhighways that are now helping local power companies and third-party providers connect homes and businesses to high-speed internet.

According to Senior Program Manager for Strategic Fiber Shane Beasley, all new fiber-line paths are being re-analyzed to current National Electric Safety Code reliability and loading standards. Structural upgrades are being implemented where required.

“As a design team we made a conscious decision from the beginning to bring all impacted lines up to current design code,” Beasley said. “An effort of this magnitude needs to meet the most current engineering standards, and a side benefit to that is increased system reliability and a reduced maintenance burden in the future.”

To date, TVA linemen have strung more than 700 miles of new 144-strand fiber cable and have replaced a slew of wooden power poles with galvanized transmission structures. Comprised of 12 line crews and two helicopter teams, the agency’s linemen are capitalizing on the autumn window as temperatures continue to lower system demand and create favorable opportunities for planned work outages.

Regardless, the daunting task of hanging fiber-optic cable across the 80,000-square-mile service territory will not be complete until 2027 due to the sheer scope of the project. For reference, 2,700 miles is the equivalent distance between New York City and Las Vegas, Nevada.

“All our linemen have a hand in it, but it’s a joint effort,” said TVA Helicopter Line Foreman Andy Reagan. “We leave a little extra on the end of each pull and the telecom guys come in behind us and connect all the fibers in the splice cans. The big deal is getting our entire transmission system interconnected, but when we’re finished it’s gonna open up a lot of doors for these rural communities.”

Dark Fiber

COVID-19 exposed a clear communications crisis as public health precautions made telework and remote learning essential. America’s students, teachers and parents who are isolated in broadband deserts are part of a stark reality: only 20 percent of U.S. households have access to reliable high-speed internet, according to the Federal Communications Commission.

In March, the CARES Act — a $2-trillion coronavirus-relief package — added $100 million to the U.S. Department of Agriculture’s $700-million annual budget to connect rural communities to broadband. And the USDA’s telecommunications programs will soon expand by another $600 million. The addition will make everyday access to fiber a $1.3 billion federal priority.

As a federal agency, TVA has allowed interested LPCs and third-party providers to lease surplus capacity on its extensive fiber-optic network for more than 30 years. The TVA Dark Fiber program allows these entities to use a portion of TVA’s 4,100-mile infrastructure as private-information superhighways to connect rural regions to the digital world.

When all upgrades are complete, TVA fiber will blanket more than 6,200 miles across a seven-state service region.

“High-speed internet access is as critical in today’s world as electricity was in 1933. We’re not in the commercial broadband business, but we are here to make life better for the 10 million people we serve,” said Kristie Goodson, TVA’s Dark Fiber Specialist. “TVA is building an information interstate. If we don’t need the entire capacity and somebody needs a couple of fibers to connect point-A to point-B, we’re happy to work with them because we know it will benefit everyone between here and there.”

To effectively use fiber technology, two strands are required — one to transmit and another to receive. TVA’s 144-strand fiber-optic cable is about the diameter of a wedding band and can be paired into 72 superhighways for high-speed communications. These paths of information are what connect cities, towns and rural communities to the major metropolitan data hubs.

“It’s just like a county road,” Goodson said. “You can put all the fiber you want in a town, but it doesn’t go anywhere if you don’t have an interstate that can connect you to rest of the world. That’s what our Dark Fiber program has always been about — simply connecting people.”

TVA is currently serving 23 of its 153 LPC partners with dark fiber. Headquartered in Columbus, Mississippi, 4-County Electric Power Association is on the outermost band of the agency’s service territory. The LPC serves nine rural counties in the east-central region of the state, including Oktibbeha County and the area around the metropolitan of Starkville, which is the home of Mississippi State University.

4CEPA is using TVA fiber to cross a 600-foot span of river and connect an isolated community. “We’ve just come to a point in our lives where you really can’t survive without technology,” said 4CEPA CEO Brian Clark. “Using TVA’s fiber paths are going to help us bridge the gap to the areas of our membership that would have taken years to get to otherwise.”

Meriwether Lewis Electric Cooperative, an LPC that serves five counties in Middle Tennessee, contracted a TVA fiber line in 2014 to connect Cumberland City to West Nashville. Cumberland City is a rural town with a population of 307, a median household income of $22,143 and a 39.4 percent poverty rate, according to the U.S. Census Bureau. The tiny municipality is the home of the Stewart-Houston Industrial Park.

“There are a lot of players in the fiber field that are helping us connect our customers to high-speed internet and TVA is one of those trusted partners,” said MLEC CEO Keith Carnahan. “TVA’s grid upgrades are creating new opportunities for LPCs. It gives us another option when we’re trying to get fiber paths to a particular point of service.”  

Capability

The blitz to fiber optic technology is due to its superiority over traditional phone lines and microwave paths. TVA’s microwave systems are highly reliable but, unlike fiber optic technology, it has lower bandwidths. Additionally, TVA’s microwave paths can be interrupted by moisture in the atmosphere and by temperature.

Fiber, however, is more secure because it is embedded in aluminum casing that serves as a ground wire to protect the channel from lightning strikes and other induced forms of energy that could potentially cause communication outages.

According to Christine Bertani, a senior program manager for TVA Telecom Planning, a typical phone line can only transmit a single signal at about 64 kilobits-per-second. A microwave path is capable of 191 megabits-per-second. This means a microwave signal is equivalent to approximately 2,984 phone lines.

However, more than 11,250,000 phone lines are required to match the speed of a single pair of fiber.

Bertani says the big difference with fiber is that multiple wavelengths, or “channels”, can be transmitted across an individual strand at variable speeds. Typical industry rates are 10, 40, and 100 gigabits-per-second. Although manufacturers are continuously making advanced telecom-fiber equipment that can produce faster speeds, Bertani prefers to use the 10-Gbps rate when defining fiber’s potential.

Picture this: 144-strand fiber is capable of streaming 28,800 high-definition movies simultaneously.

“In the real world, the capacity of fiber cannot be defined by a definitive number because of many variable factors. It depends on your end equipment and the span between them because the signal gets weaker over distance,” Bertani said. “It’s also limited by the inherent characteristics of the fiber and how it is spliced together. Mathematically, fiber can pass high rates of traffic, but we manage capacity based on what the end equipment can handle as well as our customer requirements and priorities.”

Although it’s impossible to quantify how fast future technology will send bits buzzing around the world, the medium on which digital information will travel is certain. And that is why TVA is building tomorrow’s grid with fiber — to provide reliable connectivity throughout the Valley.