by Angus W. Stocking, L.S.
Hickory is a nice small town, population 40,000, in Catawba County, North Carolina. Like any town, anywhere, the public works department has to keep up with annual road maintenance and resurfacing, and as part of that work they need to raise about 200 manhole lids to new grades every single year. For twelve years, they’ve used adjustable manhole risers from American Highway Products to do that work, rather than the cast iron risers that were the department’s previous choice. “The drop in rings were economical, but they tended to pop out in heavy traffic,” explains Assistant Public Services Director Steve Miller. “And they’re hard to get customized to match the slope of the superelevation or crown on our roadways.”
Miller says that the cast iron risers were easy to set, and ended up level since they were set into the original, level, utility rims. But since newly paved roadway surfaces are typically sloped, some part of the level cast iron riser would stick up where snowplows could catch it, or traffic would rattle it out. The method for securing the non-adjustable risers was also problematic. “The cast iron risers are held in place by just set screws, and they aren’t really secure until the asphalt is poured in around them. And even they could rattle and pop out. The adjustable risers are a better quality solution.
The American Highway Products Pivoted Turnbuckle Manhole Risers are sturdy rings of galvanized steel available in precise sizes to match any rim diameter and paving lift. They’re also routinely made to match sloped grades—about half of the risers that Hickory orders are sloped in this fashion, eliminating manholes with protruding edges. Instead of set screws providing just three points of contact with original utility rims, the AHP riser uses the patented pivoted turnbuckle to expand the riser with 1,000s of pounds of force, tightly joining the entire rim and riser circumferences.
After the paving schedule is set for the season, Hickory crews measure the manholes that will need raising and order the risers as needed. They also keep risers on hand for emergencies and manhole repairs. The AHP risers are then provided to paving contractors to install, which is usually done just before new paving. “The contractors like using them, and our staff like them,” says Miller. “They’ve been a good solution for us, and don’t pop out—we’re glad they’re available.”
Angus W. Stocking is a former licensed land surveyor who has been writing about infrastructure since 2002