Temporary Manhole Cover Grid Design for Fall Prevention
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Solution Overview
Problem
Existing manhole covers do not adequately prevent the entire body from falling into a manhole while allowing workers' hands and tools to pass through, posing a risk of severe injury.
Innovation Solution
A temporary manhole cover design featuring an annular perimeter with vertically-extending cylindrical walls and radially-extending shelves, along with parallel cross-members that create multiple openings allowing hand passage but preventing body entry, ensuring safety and access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a temporary manhole cover is designed to allow light and air to pass through, then visibility and ventilation are improved, but the risk of workers' bodies falling into the manhole increases
Solution Approach 1:
The manhole cover is segmented into multiple functional components: an annular perimeter portion with vertically-extending walls, a horizontally-extending shelf, and cross-members forming a grid pattern. This segmentation creates multiple openings for light and air passage while the vertically-extending walls and shelf structure prevent body passage, resolving the contradiction between visibility and safety.
2Object-affected harmful factors
If the manhole cover structure is made more robust to prevent body falls, then safety is improved, but the ability of workers to reach through and pass tools is reduced
Solution Approach 1:
Different portions of the manhole cover have different structural qualities tailored to their specific functions. The annular perimeter portion has vertically-extending walls for body fall prevention, while the center area has a grid pattern of cross-members that creates openings large enough for hands and tools but small enough to prevent body passage. This local differentiation resolves the contradiction between safety and operational access.
Data Source
AI summary
A temporary manhole cover and its methods of use are configured to prevent an entire person from falling into a manhole, while providing a unique structure, adjustable in some embodiments, that allows access for a user to simultaneously reach through and/or pass objects through the temporary manhole cover when it is installed in a manhole. The structure may include an annular perimeter portion optionally having an L-shaped cross-section defining a circular interior opening there-through, a first set of two parallel laterally-separated cross-members each attached with and extending across the circular opening, and a second set of two parallel laterally-separated cross-members each extending perpendicularly between and attached with the first set of two parallel laterally-separated cross-members.