For inanimate, tough objects, manhole covers seem to find themselves in a lot of trouble. Or trouble finds them. They can explode, be stolen, or just weigh as much as 500 pounds, which makes moving them for repairs a project in itself. Manhole covers have been around since the time of the Roman Empire, but they are still a work in progress. Current designs for manhole covers are focussed on using lightweight, composite materials that are strong enough to take the stresses demanded by the rough job.
Throughout the year, summer and winter, different types of pressures and stresses create dangerous conditions underground. Smoking manhole covers are a common sight in urban areas, but it’s when they begin sp