Saturday, November 30, 2013

Manhole Covers and Japanese Manhole Cover Art, Part 1

What started off, below, as a quick introduction to Japanese Manhole Cover Art ended up developing a life of its own. As I read up on the most mundane of objects, manhole covers, I became more and more fascinated by some of the information I came across. That information has become Part 1 of this post; Part 2, the art part, will be posted next week.  There may even be some more posts about manhole covers.

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According to the Online Etymology Dictionary "manhole" not surprisingly means a hole through which a person may pass. What is surprising is that it dates from 1793 by a conjunction of the words “man” + “hole”. 

An alternative explanation is that the term manhole comes from the 19th century and originally referred to a small access hole in the top or side of a boiler that was covered with a heavy metal plate bolted in place. These holes were not meant to provide access for a man to pass through, but for an arm and hand to reach the inner parts of the boiler. “Man” in this case refers not to the gender of the worker, but is from the root word that means “hand,” as in the word “manual.” Indeed, some old boiler manuals use the words “manhole” and “handhole” synonymously. Sewer manholes were probably so-called as an extension of the general term that meant “an access hole” and the gender-specific meaning followed naturally, albeit somewhat erroneously.

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The push for non-gender specific and gender-neutral language has removed a lot of the bias and stereotype reinforcement inherent in sexist language. As long as police officers were called policemen, and firefighters were called firemen, there was both a recognition that these were masculine occupations and a corresponding unspoken gender exclusion for women. Removing the sexist bias inherent in the words also removes the unspoken exclusion. There is a parallel in Orwell’s 1984 where Winston Smith works in the Ministry of Truth continually rewriting and revising history, including deletion of words from dictionaries so as to remove the concept. Words such as “manhole”, however, are more difficult to rework into gender-neutral language in that the term also denotes function and size. Nonetheless the word “manhole” and similar usages as in signs “Men at Work” reinforce the notion that such activities and activities are male activities. Alternatives that have been suggested for manhole covers are “sewer access cover” and ‘stormwater access cover”.

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Ancient Roman sewer grate made out of lime sandstone, 1st century AD, excavated at Vindobona.

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Why are manhole covers usually round?

That is the only shape that will not fall in on itself.

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The problem with that explanation is that a lot of manhole covers are not round and there are additional reasons for being round:

  • Round tubes are the strongest and most material-efficient shape against the compression of the earth around them, so it is natural that the cover of a round tube assume a circular shape.

  • A round manhole cover has a smaller surface than a square one, thus less material is needed to cast the manhole cover, meaning lower cost.

  • The bearing surfaces of manhole frames and covers are machined to assure flatness and prevent them from becoming dislodged by traffic. Round castings are much easier to machine using a lathe.

  • Circular covers do not need to be rotated to align with the manhole.

  • A round manhole cover can be more easily moved by being rolled.

  • A round manhole cover can be easily locked in place with a quarter turn (as is done in countries like France). They are then hard to open without a special tool. Also then they do not have to be made so heavy, because traffic passing over them cannot lift them up by suction.

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Because of their aerodynamic design, modern racing cars create enough vacuum to lift a manhole cover off the ground. During races on city streets, manhole covers must therefore be welded or locked down to prevent injury. 

On September 23, 1990 while participating in a world sports championship car race in Montreal, Quebec, Canada, Team Bruns driver Jesus Pareja (of Spain) had a close encounter with a manhole cover. 

Driving fairly close behind a Jaguar in his Porsche 962C, Pareja discovered the effects of the 'suction' effect race cars have on the track. The 'updraft' of the Jaguar in front of him dislodged a manhole cover and sent it flying through the air, causing it to smash through the Porsche's windshield, narrowly missing Pareja and piercing through the rear of the car, tearing the fuel tank apart. Both this and the impact with the wall caused the $750,000 car to burst into flames. Luckily Pareja came out alive. The manhole covers are now welded down for race day at that track. 

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Some manhole covers:

Modern manhole cover in Rome.
The initials SPQR come from the Latin phrase from Roman Republic days, Senatus Populusque Romanus (“The Senate and People of Rome”). It was used as an official emblem of the municpality of Rome. Its use has been revived in modern times, throughout Europe and beyond. In Rome today sewage and water supply accesses contain the label "SPQR" in recognition of the innovation in sewage and water supply realised during the Roman times.






New York






Makes one proud to come from Oz.  Eat your heart out, world!

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