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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

A manhole (alternatively utility hole, cable chamber, maintenance hole, inspection chamber, access chamber, sewer hole 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 978-0143112709. 

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.

31260 news items

 
The Denver Post
Sat, 25 Apr 2015 19:56:57 -0700

Denver police blocked off 13th Avenue access to downtown after apparent manhole explosions near 13th Avenue and Pennsylvania Street Saturday night. Residents and bar patrons, who were told to evacuate the area, said they heard explosions. "Power ...

New York Daily News

New York Daily News
Wed, 22 Apr 2015 06:07:30 -0700

An agoraphobic British woman bravely left her house for only the third time in ten years — and then promptly plunged down an open manhole. Janet Faal had only just started beating her crippling decadelong fear of the outside when the horrific accident ...

Daily Mail

Daily Mail
Tue, 21 Apr 2015 02:59:34 -0700

This is the incredible moment a man narrowly missed being burnt alive by a massive fireball which erupted from the pavement. Father-of-two Shiraz Nawaz said he felt lucky to be alive after the 15-foot flames shot out of the manhole just seconds after ...

New York Daily News

New York Daily News
Sat, 18 Apr 2015 06:43:41 -0700

A quiet Saturday morning turned disastrous for residents of one Queens block when three manhole explosions set three parked cars on fire, officials said. Firefighters were called to Metropolitan Ave. and 69th Ave. in Forest Hills after the 6:30 a.m ...

WGRZ-TV

WGRZ-TV
Mon, 13 Apr 2015 14:56:15 -0700

BUFFALO, NY – National Grid Corp. hopes to learn within a few days what sparked a fire involving some underground electrical cables, which resulted in an explosion that sent a manhole cover soaring several stories in the air in downtown Buffalo on ...

BBC News

BBC News
Wed, 22 Apr 2015 13:03:45 -0700

A pedestrian has captured an underground explosion in a manhole in Birmingham where flames leaped several feet in the air. Electrical equipment exploded underneath Stratford Road in Shirley on Monday, causing smoke and then flames to repeatedly ...

Greater Greater Washington

Greater Greater Washington
Fri, 24 Apr 2015 07:50:55 -0700

The manhole was almost surely for below-the-street electrical power access. A&P was the last company to switch from horse-cars to electric power, making the switch in 1900, so we can reasonably assume this cover to be from between 1900 and 1912.

WLWT Cincinnati

WLWT Cincinnati
Tue, 21 Apr 2015 14:41:19 -0700

Fortunately, no one was injured when gas built up around the underground electrical cables shooting three manhole covers straight into the air. Cellphone video shot from the Atrium building captured flames coming from the manhole. Duke Energy has spent ...
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