Covering Manholes for Safer Cities
You drive and walk over them every day and probably never give them a second thought. But if those manholes did not have heavy duty manhole covers when you tried to pass over them, you would definitely notice. They’re a portal to another part of the system that makes our society tick, but must be kept separate for safety reasons. However choosing a manhole cover that will stay in place and safely allow drivers and pedestrians to pass over it can be a difficult task.
Why the covers of the past won’t cut it
Many older manhole covers are heavier, as they are cast iron. One problem with this is the difficulty in lifting or moving them for maintenance purposes. But perhaps the larger problem is the issue of their value. Many covers have been stolen for their material, leaving gaping manholes dangerously open for anyone to stumble into. And the theft of these covers is not just a problem in the United States, but worldwide. In one city in India, over 10,000 of the covers for manholes were stolen in just two short months. And even when those were replaced with covers made of concrete, those new ones were also taken for the rebar on the interior.
So what’s the solution?
Many cast iron covers are now being replaced with composite covers. They have absolutely no scrap value, so as soon as a potential thief realizes it is not what he or she is looking for, the cover will be left right where it was found — in place over top of the manhole where it should be. And on top of that, their overall quality rates right up there with its cast iron predecessor, if not higher. Composite covers can be lighter in weight, which is better for the overall health of workers handling them, but they are also heavy duty enough to support pedestrians and heavy vehicles. They stay in place, and can last upwards of 30 years. While cast iron systems can also last that long, they often require more time, energy and money to be poured into them for maintenance or repairs during that time period.
Covers for manholes are not something to shrug off in terms of the safety of a city and its citizens. Using composite covers in place of the traditional cast iron could make all the difference.