| 摘要 |
A number of rectangular cover elements (3) set into the frame (11, 12) of the manhole are formed of trapezoidally sectioned shallow troughs (4) to which side sheets (5) of parallelogram or trapezoid shape are welded. The shells thus formed are filled approximately to the brim with concrete (6) to increase their rigidity. They are supported at their four corners on cantilever plates (4). An overlay (10) can be added to match the surrounding road surface according to local circumstances.
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