Manhole

Template:Short description Template:Other uses

A manhole (utility hole, maintenance hole,<ref>Template:Cite book</ref> or sewer hole) is an opening to a confined space such as a shaft, utility vault, or large vessel. 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, sewers, telephone, electricity, storm drains, district heating, and gas.

Manholes are generally found in urban areas,<ref name="function">Template:Cite web</ref> 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 used to get access from a room or hallway into the ceiling cavity of a building.<ref>Template:Cite web</ref><ref>Template:Cite web</ref> These manholes are typically around Template:Cvt square.

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,<ref name="function" /> 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.<ref>Template:Cite web</ref>

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.<ref>Template:Cite book</ref> 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).<ref>Template:Cite web</ref>

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<ref name=" Manhole inverts ">Template:Cite web</ref>
Flumes<ref name=" Flow measuring flumes ">Template:Cite web</ref>
Drop structures from higher elevation flows to lower elevation discharge pipes
Weirs<ref name="Manhole weirs ">Template:Cite web</ref>
Storm water screening structures<ref name=" Storm water structures ">Template:Cite web</ref>
Sewage grinders<ref name=" Sewage grinders ">Template:Cite web</ref>
Energy absorbing structures to dissipate undesirable flow stream turbulence or velocity<ref name=" Energy absorbing structures ">Template:Cite web</ref>

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 electrocuted after stepping on a metal manhole cover, while walking her two dogs in New York City.<ref>Template:Cite news</ref>

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.<ref>Template:Cite web</ref>

Sewer manhole location

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

Gallery

A round manhole in New Orleans, and its cover
Manhole cover in Belo Horizonte, Brazil
Manhole cover in Sawston, Cambridgeshire
Installation of a sewer manhole. Upon completion, typically only the top ring and cover (not pictured) would be visible.
Manhole cover of precast concrete in Germany
Storm drain manhole without cover in France
"Man Hole Door" at Girard College, Philadelphia, constructed in the 1840s
An open packaged metering manhole made of fiberglass before installation
Manhole cover in Kibbutz Sasa, Israel
Manhole cover in downtown of Haifa, Israel
Painted gold Manhole cover in Tel Aviv, Israel