Manhole

A manhole, also known as an inspection chamber, provides access to underground utilities, most commonly sewer systems. This enables operatives to undertake inspections, make modifications, and carry out cleaning and maintenance.

A manhole usually consists of a chamber or ring – a vertical circular pipe – of varying sizes and depths, which is used to access inspection points.

Manholes are generally constructed where there is a change of direction and/or a change in gradient of the utilities, or where access is required for a specific maintenance purpose. They are typically positioned 0.5 m away from curb lines, preferably with the manhole cover positioned away from the wheel line of traffic.

The cover acts as a plug to protect the manhole and prevent unauthorised access. Covers can be circular, rectangular or square, and are typically made from metal or, less commonly, precast concrete, glass reinforced plastic, or a composite material.

Older manholes are usually fitted with steps on the inner side of the wall to allow easy access. Generally, if the manhole depth is less than 1 m, a step ladder is mandatory, whereas if it exceeds 2.5 m, a regular ladder must be fitted. More modern manholes may be designed so that physical entry is not required.

For more information, see Manhole chambers.

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