Manhole cover
Manhole covers date back at least to the era of ancient Rome, which had sewer grates made from stone.
[citation needed] The weight helps to keep them in place when traffic passes over them, and makes it difficult for unauthorized people without suitable tools to remove them.
According to Remo Camerota, the author of a book on the subject titled Drainspotting, 95% of Japanese municipalities have their own cover design, often with colorful inlaid paint.
[2] Despite their weight and cumbersome nature, manhole covers are sometimes stolen, usually for resale as scrap, particularly when metal prices rise.
On January 16, 2004, Jodie S. Lane was electrocuted after stepping on a metal manhole cover, while walking her dog in New York City.
[13] As result of this and other incidents, increased attention has been focused on these hazards, including technical conferences on stray voltage detection and prevention.
As of 2022, local utility company Eversource is replacing 38,000 maintenance hole covers, starting in high-traffic areas, with a safer design.
A rail allows the cover to lift up to 4 inches (100 mm) and let gases escape, but prevents it from flying into the air and damaging buildings or cars or injuring pedestrians.
To prevent and mitigate safety problems, the company is also installing monitoring equipment to detect dangerous gases and fires, and increasing inspection frequency.
[15] Because of their aerodynamic design, some modern racing cars create enough vacuum to lift a manhole cover off its recess.
As darkness fell, they levered up the iron covers and sold them to local merchants, who cut them up and loaded them onto ships to China.
From Montreal to Gloucester to Kuala Lumpur, unsuspecting pedestrians stumbled into holes.In Newham, East London, nearly 200 grates and covers were stolen in 2004.
If by some stroke of luck the manhole cover had made it into orbit, it would have been the first man-made object to do so, as it pre-dated the launch of Sputnik 1 by 38 days.
After the event, Dr. Robert R. Brownlee described the best estimate of the cover's speed from the photographic evidence as "going like a bat out of hell!
It would typically be restricted to light duty applications in pedestrian areas, gardens, patios, driveways and similar.
By contrast, the heaviest class F900 manhole cover can withstand a maximum weight of 90 tons, making it suitable for docks, airports, and other extreme heavy-duty applications.
It has a similar scope as the EN 124, focuses on wheel loadings and is based on the European standards for structural steelwork.
