Metal or Plastic?

From England comes the fairly amazing details of that country’s metal-theft problems – an international crime ring costing authorities around a million dollars a month – and one relatively novel idea for tackling manhole cover theft: making covers and grates out of plastic, which has very, very little value – if any – as scrap.

It seems like an obvious solution, on the surface, so you have to wonder why it hasn’t been tried before. My educated guess is that there are rather a number of problems with this plan that haven’t been fully examined: tensile strength of the new lids, for one; is the plastic as strong as cast iron? If it’s overweighted, how does it fail: flexing and cracking, or completely shattering? Does the plastic degrade with exposure to sunlight? Exhaust fumes? Hydrogen sulfide? How abrasion resistant is it, compared to iron?

Equally important is the weight of the plastic covers. The weight of steel lids helps keep them from being “sucked off” by passing cars and trucks, and helps keep them from “blowing off” (this, obviously, is a [freaking awesome] worst-case example, but this is much more typical) during a storm. How are plastic lids and grates going to fare during events like these? (I think the phrase you’re looking for is “low earth orbit”.)

I mean, it’s a drastic measure to combat metal theft, yes. I don’t think it’s going to stop the theft, or even slow it down, just force the thieves to move on to other targets; I also question whether the rush to combat metal thieves means the whole plastic manhole cover idea hasn’t been thought through as well as it should have.

Ah, well; we’ll find out sooner or later, it appears. In the meantime, let’s not even go into how great a boon this is for urban explorers: why yes, local government, I would like manhole covers that weigh eighty percent less, thank you very much…

Published in: Geekiness, General, Urban Exploration | on September 23rd, 2008| Comments Off on Metal or Plastic?

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