Opening to a confined space
A
manhole
(
utility hole
,
maintenance hole
,
[1]
or
sewer hole
) is an opening to a
confined space
such as a
shaft
,
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
,
sewers
,
telephone
,
electricity
,
storm drains
,
district heating
, and
gas
.
Manholes are generally found in urban areas,
[2]
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.
[3]
[4]
These manholes are typically around 450 mm × 450 mm (18 in × 18 in) square.
Construction
[
edit
]
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,
[2]
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 manufacture than square or rectangular shapes, they are easier to move by rolling, and they can't fall into the opening.
[5]
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
[
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. 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
[6]
- Flumes
[7]
- Drop structures from higher elevation flows to lower elevation discharge pipes
- Weirs
[8]
- Storm water screening structures
[9]
- Sewage
grinders
[10]
- Energy absorbing structures to dissipate undesirable flow stream turbulence or velocity
[11]
Hazards caused by stray voltage in manholes
[
edit
]
In urban areas,
stray voltage
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.
[12]
Sewer manhole location
[
edit
]
The location of a sewer manhole must be carefully considered to ensure that the drainage system is effective and easy to
maintain
.
[13]
[14]
According to design standards, the distance between two manholes is typically between 7 and 20 meters, depending on the specific characteristics of the project.
[15]
[16]
In cities, the distance is 20 meters per manhole,
[17]
while in industrial or commercial settings it is 10-15 meters per manhole.
[18]
[19]
The distance between manholes in homes or restaurants is typically 7-10 meters.
[20]
[21]
[22]
Gallery
[
edit
]
See also
[
edit
]
Wikimedia Commons has media related to
Manholes
.
References
[
edit
]
- ^
Nemerow, Nelson L.; Agardy, Franklin J.; Salvato, Joseph A. (2009).
Environmental Engineering: Environmental Health and Safety for Municipal Infrastructure, Land Use and Planning, and Industry
(6, illustrated ed.). John Wiley & Sons.
ISBN
978-0470083055
. Retrieved
2019-07-19
.
- ^
a
b
Singh, Kanwarjot (2023-06-30).
"What is a Manhole- Function, Construction, Materials, and Types of Manhole - Civil Engineering Portal"
.
Civil Engineering Portal - Biggest Civil Engineering Information Sharing Website
. Retrieved
2024-04-22
.
- ^
Attribus Innovation (17 January 2019).
"Assessment Requirements for CPCCPB3027 Install ceiling insulation products"
(PDF)
.
Department of Education and Training
(1st ed.). Commonwealth of Australia
. Retrieved
5 July
2019
.
- ^
"How to install a manhole"
.
Bunnings Warehouse
. Retrieved
5 July
2019
.
- ^
Scheckel, Larry (December 2013).
Ask a Science Teacher: 250 Answers to Questions You've Always Had About How Everyday Stuff Really Works
. The Experiment.
ISBN
9781615190874
.
- ^
"Manhole inverts"
(PDF)
. Containment Solutions. Archived from
the original
(PDF)
on 2015-04-03
. Retrieved
2013-03-07
.
- ^
"Packaged Fiberglass (FRP) Flume Manholes"
. Openchannelflow. Archived from
the original
on 2013-03-25.
- ^
"Packaged Fiberglass (FRP) Weir Manholes for Flow Monitoring"
. Openchannelflow. Archived from
the original
on 2013-09-19.
- ^
"Fiberglass (FRP) Storm Water Manholes for Initial Oil, Grease, Sediment, and Debris Collection"
. Openchannelflow. Archived from
the original
on 2013-03-07.
- ^
"Fiberglass (FRP) Grinder Manholes integrating grinders from JWC, Franklin Miller, MonoFlo, and more"
. Openchannelflow. Archived from
the original
on 2013-08-28.
- ^
"Fiberglass Energy Absorbing Manholes for Controlling Excess Line Velocities"
. Openchannelflow. Archived from
the original
on 2013-03-07.
- ^
Ramirez, Anthony (January 19, 2004).
"East Village Woman Was Electrocuted on Street With Metal Plate, Medical Examiner Says"
.
New York Times
. Retrieved
2009-12-03
.
- ^
"Tai di?n tinh tr?ng h? ga m?t n?p gi?a long đo th? thong minh Thai Nguyen"
.
laodong.vn
(in Vietnamese). 2023-06-13
. Retrieved
2023-12-20
.
- ^
"C?n c?nh v? tri cac "lo c?t" s?p l?p đ?t tren đ??ng Nguy?n Trai"
.
suckhoedoisong.vn
(in Vietnamese). 2023-05-30
. Retrieved
2023-12-20
.
- ^
danviet.vn.
"Am ?nh v?i h? ga m?t n?p, "nu?t tr?n" xe may c?a ng??i đi đ??ng"
.
danviet.vn
(in Vietnamese)
. Retrieved
2023-12-20
.
- ^
"đ??ng m?i m? va "đi?p khuc" m?t n?p h? ga"
.
vovgiaothong.vn
(in Vietnamese)
. Retrieved
2023-12-20
.
- ^
Bao cao chuyen đ?: M?c đ? bao ph? c?a cac ch??ng trinh y t? cong c?ng
(in Vietnamese). Nha xu?t b?n Y h?c. 2003.
- ^
Le, Thanh Chau (2002).
Tim hi?u quy đ?nh v? quy ho?ch, xay d?ng, & c?p gia?y ch?ng nh?n quy?n s? h?u nha ?: ap d?ng t?i thanh ph? H? Chi Minh va cac t?nh, thanh ph? tr?c thu?c Trung ??ng
(in Vietnamese). Th?ng ke.
- ^
Tuy?n t?p cac tac ph?m bao chi Vi?t Nam th?i k? đ?i m?i, 1985-2004
(in Vietnamese). H?i nha bao Vi?t Nam. 2005.
- ^
"Cach s? d?ng h? ga ng?n mui hi?u qu?"
. 2013-10-31
. Retrieved
2023-12-20
.
- ^
Minh, Huy.
"N?p h? ga"
.
thanhanco.vn
. Retrieved
2023-12-20
.
- ^
Phan, Thanh Khoi; L??ng, Xuan Hie?n (2006).
M?t so? va?n đe? kinh te? - xa h?i trong tie?n trinh cong nghi?p hoa, hi?n đ?i hoa vung đo?ng ba?ng song Ho?ng
(in Vietnamese). Nha xua?t b?n Ly lu?n chinh tr?.
- Isles, Paul (2010). "Dover Engineering Works".
Dover Life Magazine
Further reading
[
edit
]
- Ascher, Kate; Marech, Wendy (2007).
The works: anatomy of a city
. New York: Penguin Press.
ISBN
978-0-14-311270-9
.