Certainly! Here are some additional facts about manholes:

1. Purpose: Manholes are access points to underground utility and infrastructure systems, such as sewer lines, storm drains, water mains, electrical conduits, and telecommunications cables. They provide entry for maintenance, inspections, repairs, and cleaning of these systems.

2. Construction: Manholes are typically made of durable materials like concrete or cast iron. The cover or lid is often made of heavy-duty materials to withstand traffic loads and prevent unauthorized access.

3. Components: A typical manhole consists of three main components:
   - Cover: The topmost part of the manhole, designed to prevent debris, water, and people from falling into the underground system. Covers can be round, rectangular, or square, depending on the design and application.
   - Shaft: The vertical section that provides access to the underground system. It is usually cylindrical in shape and varies in depth depending on the specific infrastructure it serves.
   - Base: The lower section that connects to the underground utility lines or pipes. It contains various features like channels, steps, or ladders to facilitate descent into the system.

4. Sizes and Dimensions: Manholes come in different sizes to accommodate the specific utility or infrastructure they serve. Their dimensions can vary based on factors like pipe size, depth, and accessibility requirements. Common diameters for manholes range from 2 to 4 feet (0.6 to 1.2 meters), although larger manholes can be found in certain applications.

5. Safety Measures: Manholes are designed with safety in mind. They often feature locking mechanisms or special covers that require tools to open, preventing unauthorized access. Manholes in public areas may have warning signs or markings to increase visibility and reduce the risk of accidents.

6. Ventilation: Manholes may have vents or small openings to allow gases to escape, ensuring proper ventilation within the underground systems. This helps prevent the buildup of potentially harmful or flammable gases.

7. Maintenance and Inspections: Regular maintenance and inspections are essential for manholes to ensure the integrity and functionality of the underground infrastructure. This includes clearing debris, checking for structural damage, monitoring water levels, and addressing any necessary repairs.

8. Manhole Covers and Urban Art: Manhole covers often feature unique designs and patterns specific to the city or region they are located in. Some cities embrace manhole cover art as a form of urban expression, featuring intricate designs or local symbols that add aesthetic value to the streetscape.
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