St. Louis, Missouri ordered and installed 76 Pivoted Turnbuckle Manhole Risers (made in Ohio by American Highway Products) in 2020, a huge amount for a small midwestern town with a population of just 7,500.
“We’ve been using the AHP adjustable risers occasionally for 15 years or so—but only in particular situations, where I think they’re cost-effective,” Director of Public Works Mark Abbott explained. “In 2020, we just happened to have 3 miles of a project where they were the best solution available.”
In production since 1978, the American Highway Products Pivoted Turnbuckle Manhole Riser is a uniquely efficient adjustable riser based on the “pivoted turnbuckle,” a patented mechanism that enables fast, durable, and totally secure melding of the riser to the original utility rim. Essentially, the riser itself is a strong-but-flexible strip of shaped galvanized steel, joined at the ends by the turnbuckle to form a ring. To install, the riser is simply set into the original rim, then expanded with the turnbuckle, which is easily cranked with a screwdriver or similar tool, used as a lever. The turnbuckle provides sufficient mechanical advantage to generate thousands of pounds of force and form a strong and permanent attachment between riser and rim.
Risers are made to order to precise diameter and thickness dimensions, always suited to project needs. “Ordering the project-specific risers we need has always been effective for us, and we’ve never had any issues with the process,” Abbott said. “Even when the order is complicated, we get exactly what we need within a couple of weeks, right on schedule.”
Adjustable risers are not used exclusively to raise manholes to grade in St. Louis, as the public works department still routinely rebuilds utility accesses with concrete rings when needed. Rather, Abbott views the AHP riser as a “tool in the toolbox” to be used as needed in certain situations. The large 2020 order was for a 3-mile long, surface repair paving project where the overlay was relatively thin and many of the manholes were hinged or otherwise complicated. “For this project, it just made sense to use a quality riser that could be installed quickly without digging up any pavement,” Abbott said. “And of course they’re more cost-effective and less labor-intensive, relative to cast iron risers. A big win for us.”
