What purposes do manhole covers serve?

• A. To allow drainage
• B. To provide strength to support loads, keep runoff from entering, and prevent unauthorized entry
• C. To provide lighting
• D. To seal gas

Answer: (B)

Manhole covers are safety and control devices for underground networks. They must be heavy enough and properly shaped to distribute surface loads so traffic won’t crush the opening or cause subsidence. They also serve to keep surface runoff and debris from entering the sewer, which helps prevent clogs and reduces unwanted drainage into the system. Additionally, a sturdy cover acts as a barrier to prevent unauthorized entry, protecting workers and the public from falls or hazardous conditions inside the manhole.

Lighting is not a function of the lid, and while seals can influence odors or gas movement to some extent, sealing gas is not the primary purpose of a manhole cover. The combination of withstanding loads, limiting inflow of water and debris, and preventing unauthorized access is what makes this option the correct description.