Have you ever wondered how manhole covers are tested for durability? Me neither, but that's not going to stop me from telling you about it.

French manufacturer Saint-Gobain PAM makes ductile iron manhole covers—sorry, "access covers" in industry parlance—as well as grating and surface boxes, and must ensure these "meet the many performance and quality criteria demanded by municipal authorities, network managers and local residents." To that end they've constructed this 8-metric-ton beast called the Carrousel, which endurance-tests a circular array of access covers at high speed:

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I have an idea to help offset the cost of whatever the Carrousel cost them to build: They could kill three birds with one stone by simultaneously testing out tires and, in between the manholes, reinforced-toe boots.

via Jalopnik