Rise of Aerial Fiber Could Increase Risk of Wireless Outages

Placing fiber above ground increases the risk of wireless outages, possibly preventing people from calling 911, warned an official from the infrastructure industry. Aerial fiber is going up in risky places, including areas of Florida known for hurricanes, he said. Ice storms took down poles in Kentucky and Ohio last winter, knocking out power, the source noted. If fiber is attached to poles, a storm could kill cellphone communications just as easily, he said. Restoring service isn’t always quick, since it requires putting the poles back up and re-stringing the wires, he said.

The Hurricane Katrina independent panel cited aerial fiber vulnerabilities in its June 2006 report to the FCC. “Katrina demonstrated that in many areas there may be a lack of multiple fiber routes throughout the wireline network and that aerial fiber was more at risk than underground fiber,” the report said. The FCC declined to comment for this story.

What public safety risks come with different wireless backhaul approaches is a “very valid” question, especially “as more and more folks are moving to a wireless existence and the number of wireless 911 calls coming in outstrip the number of wireline 911 calls coming in,” said National Emergency Number Association President Brian Fontes in an interview. NENA estimates that at least half of all 911 calls are wireless and the number is higher in many communities. CTIA estimates more than 20 percent of households use only wireless for voice, and cellphone users make more than 290,000 calls daily to 911 and other emergency services.

“What we really need to do is sit down and have a better understanding in conversations with these network architecture folks to see … what method will be the most effective restoration method in the event of a catastrophe,” Fontes said. Outages might be alleviated if satellite or other backup connections can be activated while service is restored, for example, he said. Discussions between industry and public safety would ensure industry has the right preparations in place, and public safety knows what to expect in a disaster, such as how quickly service is likely to be restored, he said.

There is “a desperate move afoot to try and get … increased bandwidth at cell sites using a variety of technologies,” especially buried and aerial fiber, said Karl Strohmeyer, Level 3 senior vice president of wholesale markets. As carrier demand for fiber increases, “you're going to see a lot more enthusiasm for aerial fiber,” said Frost & Sullivan analyst Mike Jude. “Trend is probably too strong a word,” but there is certainly “increased interest,” because aerial lacks buried fiber’s expensive trenching and right-of-way costs, he said.

Upgrading to fiber can cost carriers $65,000 to $75,000 per tower, so carriers commonly seek out the fiber provider that can offer the lowest price, said the broadband infrastructure industry official. Many of the companies winning bids for cell site backhaul are cable companies, which tend to face lower costs since they often already have aerial fiber near wireless towers to provide TV service, the official said. However, even many traditional backhaul providers are realizing that aerial is the most cost- effective option for deploying to the 500-some towers a carrier may have in a single market, he said.

“Lashing a fiber to another cable or stringing it pole to pole and suspending the optical splitters up there is a lot easier and cheaper than all the trenching, building pedestals, restoring driveways and lawns, etc., that buried cable requires,” said Verizon media relations director Jim Smith. Buried fiber “installation methods inherently cost more than aerial techniques,” though right-of-way and regulatory costs can vary considerably, and “complexities” may arise during installation that may affect the cost of either approach, agreed Ken Dunn, project tech support manager of engineering services for Corning. “Aerial construction also proceeds more quickly. [Buried] is far less likely to sustain physical damage, though.”

“The likelihood of environmental damage to aerial plant is far greater than to buried plant,” Dunn said. The main risk to buried fiber is construction machinery like backhoes, he said. Underground fiber is built to survive flooding without problem, and earthquakes are infrequent, he said. That said, aerial is more easily accessible for repairs because it’s above ground, he said. The difficulty of restoring underground fiber varies depending on how deep it’s buried, he said.

Saving money is probably the most common reason for choosing aerial over buried fiber, said Jude; however, “sometimes cost is secondary to physical or political constraints.” In Colorado, for example, aerial fiber is the only practical way to serve the many upscale communities in the Colorado foothills, “unless you are willing to blast solid rock to trench in a cable,” he said. And there are places in the Denver area “where it is politically impossible to trench up the ground and put in more fiber,” he said. “Not because it isn’t possible physically, but because of the disruption to traffic, etc.”

Most local governments favor buried facilities, said President Ken Fellman of the National Association of Telecommunications Officers and Advisors. New neighborhoods often require buried utilities for aesthetic and public- safety reasons, he said. In existing neighborhoods, most local governments allow aerial infrastructure as long as it doesn’t require putting up new poles, but companies installing aerial infrastructure usually are subject to rules requiring them to move the utilities underground if a government project demands it, he said. Local governments often have public safety concerns about aerial facilities for critical infrastructure, because snow storms or even a truck crashing into a pole could result in an outage, Fellman said. Also, poles can deteriorate over time due to exposure to salt, making them more vulnerable to strong winds, he said. “The more of that stuff that goes underground, the more you minimize that risk for those kinds of accidents.”

Aerial fiber “certainly has the ability to get there faster and to more towers,” said Level 3’s Strohmeyer. But aerial is “more susceptible to damage or hurricanes or weather or other kinds of accidents, and potential downtime,” he said. Level 3 provides mostly buried fiber, he said. The company takes “a conservative stance when it comes to network infrastructure requirements,” he said. The company’s competitors are using “a mix of approaches, and speed is something that is definitely of consideration, however, we pride ourselves on the long-term viability of our infrastructure.”

Verizon’s “experience is that aerial fiber is for the most part as safe and secure as any facilities,” Smith said. Most routes have built-in redundancy, and Verizon response time to problems is fast, he said. “The facilities are monitored 24/7 and we see and correct problems often before the customer carrier knows about them.” Underground fiber has its own unique vulnerabilities, Smith added. “Imagine, for example, the complex service issues that can develop in manholes,” including fire, flooding and electrical damage, he said.

“If you stick aerial plant of any sort in a hurricane path, it’s probably not going to do too well,” said Jude. But companies have automated processes for restoring aerial fiber, he said. “If [companies are] down there doing it and putting it in the path of a hurricane, then they've probably done the numbers and figured out that if this stuff is wiped out, it’s probably not more expensive, maybe even a little bit cheaper to repair and replace it.”

Even if companies have protocol for restoring service, they may encounter “extraordinarily out of the normal” situations like Hurricane Katrina when plans break down, Fontes said. “I don’t know if anybody totally prepares for 70, 80, 90 percent or 100 percent of the network being destroyed over such a vast geographic area that could be several hundreds of miles.”