What is the minimum diameter for round access openings in a manhole?

The minimum diameter for round access openings in a manhole is significant for ensuring safe and effective access to underground utilities and infrastructure. A diameter of 650 mm is appropriate as it provides ample clearance for personnel to enter and exit safely, while also accommodating the necessary equipment for maintenance and repairs.

This standard dimension is often established to facilitate the movement of tools, equipment, and personnel within the manhole, reducing the risk of injury or operational difficulties. Smaller diameters may hinder access, making it challenging for workers to navigate the space effectively, especially in emergency situations when quick access is critical.

In comparison, specified larger diameters exceeding 650 mm could allow for easier access but may not be strictly necessary for all applications, which is why the standard for minimum access is correctly set at 650 mm to balance safety, functionality, and resource efficiency.