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 Minutes later, emergency responders were hovering over the
71-year-old as he lay unconscious on the ground. Police said an
underground blast had blown a cast-iron manhole cover skyward and
the heavy metallic disk came crashing down on his head.
While the seriousness of Grillo's injury is unusual, manhole
"events" have become all too common in the country's largest
metropolis. In the snowy first week of February, Consolidated Edison
Inc, the local utility, tallied about 600 "smokers," fires and
occasional explosions involving manholes, part of a seasonal surge
that plagues New York every winter.
Manholes are entry points to a labyrinth of electric cables, many of
them aged and decaying, that snake underneath the city streets. In
winter melting snow mixed with de-icing salt can seep through,
causing frayed low-voltage cables to fail. That can trigger fires,
smoke and explosions that can send manhole covers flying.
"These incidents are yet another example of New York City's outdated
infrastructure. It's well-known that saltwater and exposed
electrical wires are a dangerous combination," said New York's
Public Advocate Letitia James. "If we want a safer city, we must do
more to address this issue."
Cables have an expected lifetime of about 40 years, but in
Manhattan, 5 percent of low-voltage distribution cables were
installed before 1930, according to a 2014 analysis. In addition,
overheating and even gnawing rats can hasten the deterioration. It
is the oldest electrical system in the nation.
"Everything that’s electrical has a certain limit, a certain
lifetime," said William Black, a professor emeritus of mechanical
engineering at the Georgia Institute of Technology.
In any single year, New York has 2,100 manhole incidents a year, or
nearly six of them every day, Con Ed estimates.
The problem is so much larger in New York than elsewhere in part
because the city has the country's largest underground electrical
system, with its 98,000 miles (157,716 km) of cable and 264,000
manholes and service boxes.
To be sure, most manhole incidents are relatively harmless
"smokers," but about 10 percent in the first week of February were
more dangerous.
Earlier this month, a smoking manhole exploded in Brooklyn, sending
a worker scrambling for safety in an incident caught on video. On
the same day, a parked Mazda was torched after a manhole beneath it
started spouting fire.
"Con Ed has a rather difficult situation because if you proceed to
dig underneath the street you’ll see how congested it is," Black
said.
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The problem is attracting attention. Donovan Richards, chair of the
New York City Council's Environmental Protection Committee, is
considering legislation to push Con Ed to spend more on modernizing
its underground infrastructure.
In 2014, Con Ed invested $1.3 billion in modernizing its electrical
infrastructure, including the installation of nearly 1,600 miles
(2,575 km) of underground electric cable. But that is just a
fraction of the tens of thousands of miles in the system.
Manhole events "take a considerable amount of time and resources,"
said Con Ed spokesman Allan Drury. "But our emphasis is on public
safety and we are always looking for new technologies and methods to
improve our system."
For instance, the utility has been installing vented covers that
allow for trapped combustible gases to dissipate more easily.
Con Ed has teamed with the Massachusetts Institute of Technology and
Columbia University to develop a tool that predicts manhole
incidents through statistical modeling, taking into account factors
such cable age and failure history.
But Cynthia Rudin, associate professor of statistics at MIT who
worked on the project, warns against focusing too much energy and
money on replacing cables.
"It is not a reasonable scenario to think of replacing the whole
distribution network every few years or so," Rudin said.
(Editing By Frank McGurty and Lisa Lambert)
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