In March and April 2012, Ajax, Ontario and Niagara Falls, Ontario[25] had dozens of manhole covers stolen.
Types of Manholes:
1. Shallow Manhole:
A shallow manhole typically refers to a manhole that is not very deep or has a relatively shallow depth compared to standard manholes. Manholes are access points built into underground utility systems, such as sewer lines, storm drains, or telecommunications networks, to allow maintenance workers to access and inspect these systems. The depth of manholes can vary depending on the specific infrastructure they access and the regulations or standards in a particular region. Standard manholes are usually several feet deep to allow workers to descend safely and perform their tasks.
ductile iron manhole cover
11. Ventilation covers
1. Stability They provide robust support, minimizing vibrations and movement that could lead to wear or failure.