Manhole is a type of junction used for connecting several networks and lines. For example, in sewage systems, manhole is used to connect several sewage pipes and to conduct them towards a single direction. in telecommunication systems, manhole is used to access underground cable routes. However, we have all witnessed manholes in cities, manholes are valves on the ground level which are used for different applications (water and sewer, telephone, electricity, etc.) manhole is actually used to provide easy access to the canals and is covered with lid. Manhole is made of concrete, brick, polyethylene and plastic depending on their application and their lids are made of polyethylene, steel, and cast iron and so on.
Manholes should be divided into two categories according to their application places: small diameter Manholes used in the sub-network lines for the following reasons:
- Low pipe diameter.
- Low flow rate.
- High number of input pipes.
Large diameter Manholes used in the main network lines for the following reasons:
- In The main lines and transmission lines
- Large pipe diameter.
- High flow rate.
- Limited number of input pipes.