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For other uses, see Manhole (disambiguation).
PMG manholes in a city street, Perth, Western Australia.
Manhole in Belo Horizonte, Brazil.
This is a sewer manhole, exposed during construction. Typically, only the top ring and manhole cover (not pictured) would be visible.
Manhole cover of precast concrete in Germany
Manhole being used to access sewer

A manhole (alternatively utility hole, cable chamber, maintenance hole, inspection chamber, access chamber, sewer hole, smellhole, flabhole, ding-dong or confined space) is the top opening to an underground utility vault used to house an access point for making connections, inspection, valve adjustments or performing maintenance on underground and buried public utility and other services including sewers, telephone, electricity, storm drains, district heating and gas.

Usage[edit]

Manhole closings are protected by a manhole cover, a flat plug designed to prevent accidental or unauthorized access to the manhole. Those plugs are traditionally made of metal, but may be constructed from precast concrete, glass reinforced plastic or other composite material (especially in Europe, or where cover theft is of concern).

Manholes are usually outfitted with metal, polypropylene, or fiberglass steps installed in the inner side of the wall to allow easy descent into the utility space. Because of legislation restricting acceptable manual handling weights, Europe has seen a move toward lighter weight composite manhole cover materials, which also have the benefits of greater slip resistance and electrical insulating properties.

The access openings are usually circular in shape to prevent accidental fall of the cover into the hole.

Manholes are generally found in urban areas, in streets and occasionally under sidewalks. In rural and undeveloped areas, services such as telephone and electricity are usually carried on utility poles or even pylons rather than underground.

Composite manholes[edit]

Composite (fiberglass) manholes are commonly used in applications where infiltration, exfiltration, or corrosion by hydrogen sulfide (from sewer gas) are a concern, or where structures need to be factory integrated into a manhole before placement.

Structures commonly integrated into composite manholes include:

  • Flow inverts[1]
  • Flumes[2]
  • Drop structures from higher elevation flows to lower elevation discharge pipes

Occasionally, composite manholes will integrate:

  • Weirs[3]
  • Storm water screening structures[4]
  • Sewage grinders[5]
  • Energy absorbing structures to dissipate undesirable flow stream turbulence or velocity[6]

Hazards caused by stray voltage in manholes[edit]

In urban areas, stray voltage issues have become a significant concern for utilities. In 2004, Jodie S. Lane was electrocuted after stepping on a metal manhole cover, while walking her dog in New York City.[7]

See also[edit]

Notes[edit]

References[edit]

  • Isles, Paul (2010). "Dover Engineering Works". Dover Life Magazine

Further reading[edit]

  • Ascher, Kate ; researched by Wendy Marech (2007). The works : anatomy of a city (Reprint. ed.). New York: Penguin Press. ISBN 978-0-14-311270-9. 

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Manhole — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.

72448 news items

NBC New York

NBC New York
Wed, 03 Feb 2016 18:01:05 -0800

Weather is believed to be the culprit of an underground transformer explosion in Midtown Manhattan sent sparks flying and smoke billowing from a manhole Wednesday evening. The manhole fire at Lexington Avenue and East 56th Street knocked out traffic ...

NBC New York

NBC New York
Mon, 25 Jan 2016 11:24:12 -0800

A 6-year-old girl out for a walk in the snow in the Bronx Saturday afternoon tumbled down a manhole, authorities said. The girl was walking with her mother at about 3:30 p.m. on Westchester Avenue in Woodstock when she fell down the snow-covered ...
 
Flathead Beacon
Wed, 10 Feb 2016 10:11:15 -0800

10:15 a.m. A concerned Kalispell resident called police to report a missing manhole cover. They were worried someone would fall in it. 2:29 p.m. A Glacier National Park ranger found one of the park's chainsaws at a Kalispell pawnshop. 2:34 p.m. Someone ...

Tech Insider (blog)

Tech Insider (blog)
Fri, 05 Feb 2016 05:45:45 -0800

It wasn't like that. This manhole cover was shot into space with a nuclear bomb. Robert Brownlee, an astrophysicist who designed the nuclear test in question, told Tech Insider the unbelievable story. He refutes his critics and asserts that yes, it ...

New York Magazine

Gothamist
Thu, 28 Jan 2016 08:45:26 -0800

Indeed, the season of Exploding Manholes is once again upon us—NBC reports that as of yesterday evening, there have been 400 manhole fires in the city since Friday, thanks to the Saturday's nearly record-making blizzard. The fires are leading to power ...

Parade

Parade
Thu, 04 Feb 2016 07:22:30 -0800

A round manhole cover will not fall through a round opening only when the opening is made smaller than the cover. This is also the case for other geometric shapes, but the difference in the size of the cover and the size of the opening needs to be ...

WABC-TV

WABC-TV
Mon, 25 Jan 2016 08:45:07 -0800

While walking in the snow Saturday afternoon, her little girl fell 8 feet into an opening where the ground had eroded around a manhole at the NYCHA-run St. Mary's Houses in the Bronx. "She's trapped down there, screaming help me mommy, mommy help me ...

Mid-Day

Mid-Day
Sun, 07 Feb 2016 20:07:30 -0800

In a freak accident, Jameela Khan (35) lost her life after a manhole lid, and the surrounding area, caved in the moment she stood on it. The incident occurred around 9.45 pm on Saturday night, behind Thane Central Jail while Khan was on her way home ...
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