Manhole

 ( Public Utilities ) 

A manhole ( utility hole, maintenance hole,

or sewer hole) is an opening to a confined space such as a shaft, utility vault, or large container. Manholes, typically protected by a manhole cover, are often used as an access point for an underground public utility, allowing inspection, maintenance, and system upgrades. The majority of underground services have manholes, including Water industry, sanitary sewer, telephone, electricity, , district heating, and natural gas.

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

In Australia, manhole also commonly refers to an access hatch used to get access from a room or hallway into the ceiling cavity of a building. These manholes are typically around square.

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

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.

Manholes are usually round, primarily because roundness is the best shape to resist the compression of the earth; covers are round because they are easier to move by rolling, and they can't fall into the opening.

Larry Scheckel (2013). 9781615191796, The Experiment. . ISBN 9781615191796

But in the United Kingdom they are nearly always square, or rectangular, in shape, at least at street level. Manholes can also be found in a triangular shape (e.g. in Cambridge, and surrounding villages).

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Composite manholes 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. In these manholes, the entire underground enclosure is constructed of some composite material, in addition to the cover.

Structures that can be integrated into composite manholes include:

• Flow inverts
• Drop structures from higher elevation flows to lower elevation discharge pipes
• Storm water screening structures
• Sewage grinders
• Energy absorbing structures to dissipate undesirable flow stream turbulence or velocity

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Hazards caused by manholes In urban areas, damaged or uncovered manholes and stray voltage issues have become a significant concern.

On January 16, 2004, Jodie S. Lane was electrocution after stepping on a metal manhole cover, while walking her two dogs in New York City.

On December 3, 2020, Justin Carey, a 49-year-old special education teacher, was injured after stepping on a broken manhole cover on Route 111 in Smithtown. As he exited his parked car near the Route 347 intersection, the split cover gave way, causing his left leg to fall into the hole. He suffered a strained Achilles tendon and a bruised knee.

Failures of underground electrical lines Why Manhole Explosions Happen in the Summer can cause fires and sudden releases of energy that blow manhole covers into the air and may injure pedestrians or cause property damage. Two manholes explode in downtown Boston during morning rush hour Some utilities have installed safer covers that can vent hot gas while remaining attached to the ground, using metal rails. The solution to Boston’s manhole explosions is an engineering ‘game changer’

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Sewer manhole location The location of a sewer manhole must be carefully considered to ensure that the drainage system is effective and easy to Maintenance. According to design standards, the distance between two manholes is typically between 7 and 20 meters, depending on the specific characteristics of the project. In cities, the distance is 20 meters per manhole, while in industrial or commercial settings it is 10-15 meters per manhole. The distance between manholes in homes or restaurants is typically 7-10 meters.

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Gallery File:Open Manhole and Cover Mid-City New Orleans.jpg|A round manhole in New Orleans, and its cover File:Bueirocemig.JPG|Manhole cover in Belo Horizonte, Brazil File:Cambridgeshire Manhole.jpg|Manhole cover in Sawston, Cambridgeshire File:Manhole.jpg|Installation of a sanitary sewer manhole. Upon completion, typically only the top ring and manhole cover (not pictured) would be visible. File:- Manhole cover in Germany -.jpg|Manhole cover of precast concrete in Germany File:Manhole without manhole cover in Villebon-sur-Yvette 4.jpg|Storm drain manhole without cover in France File:ManHoleDoorFoundersHallGirard1840.jpg|"Man Hole Door" at Girard College, Philadelphia, constructed in the 1840s File:Openchannelflow-domed-metering-manhole.JPG|An open packaged metering manhole made of fiberglass before installation File:Sasa manhole cover.jpg|Manhole cover in Kibbutz Sasa, Israel File:HAIFA DOWN TAWN.jpg|Manhole cover in downtown of Haifa, Israel File:Golden manhole cover Tel Aviv.jpg|Painted gold Manhole cover in Tel Aviv, Israel File:Gas manhole in Dnipro.jpg|Small gas manhole in Ukraine.

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See also

• Packaged metering manhole
• Sanitary manhole

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

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Further reading

• (2026). 9780143112709, Penguin Press. ISBN 9780143112709

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