A manhole (utility hole, maintenance hole, or sewer hole) is an opening to a

confined space A confined space is a space with limited entry and egress and not suitable for human inhabitants. An example is the interior of a storage tank, occasionally entered by maintenance workers but not intended for human occupancy. Hazards in a confined ...

such as a shaft,

utility vault A utility vault is an underground room providing access to subterranean public utility equipment, such as valves for water or natural gas pipes, or switchgear for electrical or telecommunications equipment. A vault is often accessible directly fro ...

, or large vessel. Manholes are often used as an access point for an underground

public utility A public utility company (usually just utility) is an organization that maintains the infrastructure for a public service (often also providing a service using that infrastructure). Public utilities are subject to forms of public control and r ...

, allowing inspection, maintenance, and system upgrades. The majority of underground services have manholes, including

water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

, 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 e ...

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as describ ...

, storm drains,

district heating District heating (also known as heat networks or teleheating) is a system for distributing heat generated in a centralized location through a system of insulated pipes for residential and commercial heating requirements such as space heating a ...

, and

gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

. Manholes are generally found in urban areas, in streets and occasionally under sidewalks. In

rural In general, a rural area or a countryside is a geographic area that is located outside towns and cities. Typical rural areas have a low population density and small settlements. Agricultural areas and areas with forestry typically are descri ...

and undeveloped areas, services such as telephone and electricity are usually carried on

utility pole A utility pole is a column or post typically made out of wood used to support overhead power lines and various other public utilities, such as electrical cable, fiber optic cable, and related equipment such as transformers and street lights. I ...

s 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.

Construction

Manhole covers in sidewalk (42839905802)

Manhole closings are protected by a

grating A grating is any regularly spaced collection of essentially identical, parallel, elongated elements. Gratings usually consist of a single set of elongated elements, but can consist of two sets, in which case the second set is usually perpendicul ...

manhole cover A manhole cover or maintenance hole cover is a removable plate forming the lid over the opening of a manhole, an opening large enough for a person to pass through that is used as an access point for an underground vault or pipe. It is designed t ...

, 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 Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast bea ...

glass reinforced plastic Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clot ...

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 Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene. Polypropylene belongs to the group of polyolefins a ...

, or

fiberglass Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...

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 (

) manholes are commonly used in applications where infiltration, exfiltration, or corrosion by hydrogen sulfide (from

sewer gas Sewer gas is a complex, generally obnoxious smelling mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage. Sewer gases may inc ...

) 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 t ...

s * Drop structures from higher elevation flows to lower elevation discharge pipes *

Weir A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...

s * Storm water screening structures * Sewage 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 flo ...

issues have become a significant concern for utilities. On January 16, 2004, Jodie S. Lane was

electrocuted Electrocution is death or severe injury caused by electric shock from electric current passing through the body. The word is derived from "electro" and "execution", but it is also used for accidental death. The term "electrocution" was coined ...

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 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 Northamptonshire to the ...

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, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

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 area ...

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 ...

Philadelphia Philadelphia, often called Philly, is the List of municipalities in Pennsylvania#Municipalities, largest city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, the List of United States cities by population, sixth-largest city i ...

, 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

Sasa, Israel Sasa or Sassa ( he, סָאסָא) is a kibbutz in the Upper Galilee area of northern Israel. Located one mile from the border with Lebanon, it falls under the jurisdiction of Upper Galilee Regional Council. In it had a population of . History ...

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