Manhole Explosion Incidents – A Disaster Documentary
The in-depth story of Manhole Explosion Incidents.
A deadly trap lurks on the streets of large cities throughout the United States. It strikes without warning, and it hits hard. As there have been more and more incidents recently, we’re looking at exploding manholes! We’ll explain manhole explosion accidents and sewer fire disasters with real footage.
A deadly trap lurks on the streets of large cities throughout the United States.
It strikes without warning, and it hits hard. As there have been more and more incidents recently,
we’re looking at exploding manholes! Manhole cover explosions can produce large
bursts of flame; they can shoot the hatches high in the sky only to come crashing back down like
a cannonball. They can throw a person into the air and be so powerful to blow up an entire sidewalk.
New York cab driver Osman Bah experienced first-hand how dangerous these accidents can be.
While driving his cab, a nearby manhole exploded and sent the heavy lid flying – straight through
Osman’s windshield. Luckily the paramedics arrived in time to save his life. However, the injuries
caused by the manhole cover were so severe that they left one side of his body crippled.
When researching this episode, I wanted to understand: Why are manhole covers
exploding? And is there something that can be done to prevent these accidents?
Manholes are maintenance holes for underground infrastructure. They are used as access points
to pipes leading to underground structures like a sewer. Below the surface lies a small
confined room that houses installations such as power cables, communication lines and gas
and water pipes. Some manholes are isolated access points, but they can be connected, forming a row.
In order to restrict unauthorized access to manholes, heavy lids weighing 85 to
300 pounds (35 to 136 kilograms) are used that can be opened using special cranks.
In the city of New York, reports of manhole fires date back to the early 1900s.
Unfortunately, the incidents are on the rise. Manhole fires more than doubled in 2021, when 6104
incidents were recorded. On 281 occasions, the lid was dislodged by the force of the explosion.
So what makes the manhole a deadly contraption? One of the main culprits for the explosions is
salt. During the winter, when most explosions occur, road service crews spread salt to melt
ice on the streets to keep them safe for driving. After melting, the ice and snow
turn into salt water. Then, the water flows into manholes and onto electric wiring. This
causes the insulation to corrode and exposes the 13,000-volt power cables. The exposed wires cause
the damaged insulation to smoulder, which releases flammable gasses into the manhole. Because it is
sealed with a heavy lid, gasses can not escape the manhole, and it becomes a high-pressure-explosive
chamber. It only takes a spark from the naked power wire to trigger an explosion.
But salt is not the only thing that damages cables. The insulation can deteriorate
because it is too old or because rats ate it. The result of what can be understood as neglect is
significant material damage and severe injuries. Jeffrey Lide, another New Yorker, was seriously
injured when his car got hit by a lid from below. Lide was parking his car on Nostrand Avenue,
just above a manhole, when the manhole exploded. The car was lifted into the air,
and Mr Lide ended up with extensive injuries to his spine and shoulder.
There have been numerous reports of such accidents. A car driving down the street
suddenly gets hit by a manhole explosion and flips forward while still in motion.
However, probably the most notorious manhole explosion was the 2014 Kaohsiung Gas explosion.
On July 31, 2014, the Firefighter Brigade in this large Taiwanese city responded to reports
of a series of manholes emitting white smoke. Unfortunately, even though they intervened by
spraying the manholes with water, they couldn’t prevent what happened next.
An underground gas pipeline had ruptured, causing an enormous amount of propylene gas
to fill the stormwater trench. When the gas came into contact with an ignition source,
the street and everything on it were blown into the air. A powerful explosion threw cars from
the road onto the roofs of nearby buildings. All glass surfaces in the area shattered. Countless
pieces of the road were thrown into the air, injuring bystanders and damaging nearby buildings.
In a flash, the entire route along three large streets was destroyed as the remains
of the roads collapsed into the stormwater trench. 32 people died, and 321 were injured
with the damage totalling 60 million dollars. So is it always neglected maintenance or faulty
installation that leads to manhole fires and explosions? No, there’s also human carelessness:
In a series of videos originated in China, kids are seen dropping firecrackers into manholes.
One shows a kid dropping a firecracker into a sewer. But an explosion much bigger than
anticipated sends the boy flying. The kid didn’t know that the sewer was filled with an explosive
mix of methane gas and air. Luckily, none of the children
sustained any serious injuries. Now that we know the causes – is
there any way to prevent manhole explosions? To reduce the risk of fires, New York City
manholes are regularly inspected using infrared imaging to identify and repair hot spots.
Con Ed, the city’s largest electric provider, also started a campaign to replace solid manhole
covers with ventilated ones, letting heat and gas escape before they build up. However, vented lids
allow more water and salt to enter the system, which can cause cables to corrode more quickly.
Some newer manholes even have latches to prevent lids from flying off into the air.
What might surprise you is that all explosions until now, as terrifying as they are, pale in
comparison to this final incident. A manhole cover explosion that sent the lid into space.
Truth be told, the manhole was not ordinary. In the first decade of the United States’
nuclear weapon development program, bombs were detonated in the deserts of Nevada and New Mexico.
There was a problem with these trials since nuclear fallout could travel through the air
and into urban areas. Because of this, the Pentagon decided to move tests underground.
Scientists behind the project believed that all harmful materials would be contained
below the surface if the detonation just happened in a deep enough hole.
In late July 1957, the first such test, codenamed Pascal, was conducted. The borehole was dug 485
feet deep (150m) and four feet across (121cm). A nuclear bomb was placed at the bottom. At the top,
a 4-inch-thick iron lid (10 cm), weighing 1,984 pounds (900 kg), was welded.
Dr Robert R. Brownlee, the scientist in charge of the project, mounted a high-speed camera
to record the event at the surface. The explosion blew off the heavy cap,
but post-test examinations showed the cap only in one frame of the slow-motion video.
Dr Brownlee calculated that the cap must have been travelling at about 125,000 miles per hour
or five times the escape velocity of Earth. A theory suggests that the lid was blown all
the way into space, becoming the fastest man-made object as well as the first man-made object to
enter space two months before the launch of the Soviet Sputnik satellite.
Dr Brownlee said the scenario was plausible but assumed the cap disintegrated before reaching
space. Even though there is no definite proof that the lid went off to space,
there is no evidence that it landed either.
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