A manhole (utility hole, maintenance hole, or sewer hole) is an opening to a confined space such as a

shaft Shaft may refer to: Rotating machine elements * Shaft (mechanical engineering), a rotating machine element used to transmit power * Line shaft, a power transmission system * Drive shaft, a shaft for transferring torque * Axle, a shaft around whi ...

, utility vault, or large vessel. Manholes 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 Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

, sewers,

telephone A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into el ...

, electricity, storm drains, district heating, and gas. 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. In Australia, ''manhole'' also commonly refers to an

access hatch A trapdoor is a sliding or hinged door in a floor or ceiling. It is traditionally small in size. It was invented to facilitate the hoisting of grain up through mills, however, its list of uses has grown over time. The trapdoor has played a pivot ...

used to get access from a room or hallway into the ceiling cavity of a building. These manholes are typically around square.

Construction

Manhole covers in sidewalk (42839905802)

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 material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...

s (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 manufacture than square or rectangular shapes, they are easier to move by rolling, and they can't fall into the opening. 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, UK, and surrounding villages).

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 *

Flume A flume is a human-made channel for water, in the form of an open declined gravity chute whose walls are raised above the surrounding terrain, in contrast to a trench or ditch. Flumes are not to be confused with aqueducts, which are built to ...

s * Drop structures from higher elevation flows to lower elevation discharge pipes * Weirs * Storm water screening structures *

Sewage Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residenc ...

grinders * Energy absorbing structures to dissipate undesirable flow stream turbulence or velocity

Hazards caused by stray voltage in manholes

In urban areas,

stray voltage Stray voltage is the occurrence of electrical potential between two objects that ideally should not have any voltage difference between them. Small voltages often exist between two grounded objects in separate locations, due to normal current fl ...

issues have become a significant concern for utilities. On January 16, 2004, Jodie S. Lane was electrocuted after stepping on a metal manhole cover, while walking her dog in New York City.

Gallery

Open Manhole and Cover Mid-City New Orleans.jpg, A round manhole in New Orleans, and its cover Bueirocemig.JPG, Manhole cover in Belo Horizonte,

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Cambridgeshire Manhole.jpg, Manhole cover in

Sawston Sawston is a large village in Cambridgeshire in England, situated on the River Cam about south of Cambridge. It has a population of 7,260. History Prehistory Although the current village of Sawston has only existed as anything more than a ha ...

Cambridgeshire Cambridgeshire (abbreviated Cambs.) is a Counties of England, county in the East of England, bordering Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and North ...

Manhole.jpg, Installation of a sewer manhole. Typically only the top ring and cover (not pictured) would be visible. - Manhole cover in Germany -.jpg, Manhole cover of precast concrete in

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

Manhole without manhole cover in Villebon-sur-Yvette 4.jpg, Storm drain manhole without cover in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...

ManHoleDoorFoundersHallGirard1840.jpg, "Man Hole Door" at

Girard College Girard College is an independent college preparatory five-day boarding school located on a 43-acre campus in Philadelphia, Pennsylvania. The school was founded and permanently endowed from the shipping and banking fortune of Stephen Girard upon hi ...

Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...

, constructed in the 1840s Openchannelflow-domed-metering-manhole.JPG, An open packaged metering manhole made of fiberglass before installation Sasa manhole cover.jpg, Manhole cover in

Kibbutz A kibbutz ( he, קִבּוּץ / , lit. "gathering, clustering"; plural: kibbutzim / ) is an intentional community in Israel that was traditionally based on agriculture. The first kibbutz, established in 1909, was Degania. Today, farming h ...

Sasa, Israel

References

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

Construction

Composite manholes

Hazards caused by stray voltage in manholes

Gallery

See also

References

Further reading