Danger: cast iron discs of death

Living in New York could be considered dangerous. Odds are you’ll hear about a mugging, stabbing or shooting somewhere in the city every day, but for the most part, they can be avoided by applying a little common sense: avoid starting a gangland drug war, not exploring the ghetto with a guidebook and map at midnight, don’t insult anyone holding a blood-covered machete — and so on. It’s even possible to cut down the chances of being pushed in front of an oncoming subway train by a psychotic, homeless schizoid by simply standing away from the platform edge.

None of this really came as a surprise when I moved to New York, after all, I’ve lived in the Middle East, Los Angeles and I call East London home. All have their rough spots.

But recently I’ve become aware of a new deadly threat in New York, not terrorism no, but exploding manholes. Yes, really. And what makes this worse is that apparently it happens every year. Along with mountains of dirty snow and rock-hard ice that stand by the roadside and huge puddles created by melt-water, it’s one of this city’s indications that Winter is nearly over and Spring is on its way.

Many of the electrical cables underground are old and frayed, so when melted water that’s mixed with the salt that’s spread on the roads drips down, it erodes the insulation on the wires and conducts electricity. This can cause them to spark and create little fires, which release combustible gas and build pressure inside the hole. When the sparks ignite the gasses, you get an exploding manhole. Apparently, it’s not necessarily related to NYC’s aging infrastructure. Some cables are old and some are new, and either can be affected by corrosion due to salt and snow.

These cast iron discs of death can fly anywhere from one to 50 feet and they weigh up to 300 pounds (that’s 136 kg).


According to Reuters, Consolidated Edison — or Con Ed, which is the electricity company for most of New York — has counted about 600 manhole incidents this year and the Brian Lehrer Show reported that there have been over 1000 so far this year. Most of those are explosions, though some just smoke or catch fire. Last week, three firefighters were injured by an explosion and a 71-year-old man was hurt near Prospect Park last month.

In 2009, three research scientists from Columbia University’s Center for Computational Learning Systems collaborated with Con Ed engineers to create a manhole profiling tool that ranked the structures in order to help predict when serious events like smoke, fire or an explosion occur in a manhole. In a later publication of the paper in 2011, titled 21st-Century Data Miners Meet 19th-Century Electrical Cables the researchers said, “New York City has the world’s oldest grid, and we computed that over five percent of Manhattan’s low-voltage underground cables were installed before 1930.” The article also reveals that NYC alone has more than 94,000 miles of underground cable, enough to wrap around the Earth three and a half times. “There is simply too much cable to replace or individually monitor — we’re not even close,” it reads.

Two incidences were recently reported in Park Slope, Brooklyn. The first explosion, at 11:20am on February 2, sent a 70-pound manhole cover flying into the head of 71-year-old Sal Grillo, who was out with his dog. Grillo was rushed to the Lutheran Medical Center; fire department officials say he’s lucky to be alive. Another victim of the incident was Marge Contorno, 93, who was cut by flying shards of glass after the violent blast shattered her window.

A second explosion occurred at 4am on February 3. No one was hurt, but six nearby buildings were evacuated owing to high levels of carbon monoxide in the area.

Ah, Spring is in the air.

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