For decades, the Public Works Department of Salem, Oregon was content to use cast iron risers when raising manholes to grade; they weren’t completely happy with this solution, but it was certainly good enough. That attitude changed in the early 2000s, as Salem embarked on an ambitious repaving program. “We had a lot of roadway issues, and our mindset was too put a lot of asphalt down in a hurry,” says Public Works Project Leader Ken Waller. “We noticed that precast risers were a factor that slowed us down.”
The main problem was the weight and bulk of cast iron risers. “They’re very labor intensive to install, and extremely heavy. We even had a few injuries, mainly pinching and straining,” Waller explains. “We tried everything to lift them into place mechanically, including magnets, but nothing worked well.” Excessive labor and injuries weren’t the only problem with cast iron—they were also becoming hard to find locally, weren’t cheap, and only came in a limited number of sizes.
So in 2008, the department began using adjustable steel manhole risers made by American Highway Products. The Pivoted Turnbuckle Manhole Riser is a compact, lightweight riser that features a patented turnbuckle linkage that is used to expand the riser. A simple screwdriver, applied to the turnbuckle as a lever, applies 1,000s of pounds of force, seating risers securely and permanently, even when original utility rims are worn or out of round.
Setting the riser and expanding it is a one-person job that takes less than five minutes, ending Salem’s time and labor worries—for that reason alone, the department never looked back and now installs up to a hundred annually. But they soon learned there were other advantages. “They come in 1/4” height and diameter increments, so it’s easy to always have the correct size on hand,” Waller says. “We keep about a hundred in stock, for our own use and to give to other departments as needed.”
Precise sizing facilitates a very efficient paving workflow. Manhole risers are now typically installed after paving lifts—while asphalt is still hot, Salem crews uncover manholes in the roadway, measure the difference between rims and newly paved surface, and quickly set a riser that exactly matches grade. Waller says, “It only takes a minute or two, and then we rake the asphalt back in place—it could hardly be more efficient.”
And they’re reliable too. “We’ve never had one fail, and customer service from American Highway Products is always excellent. I don’t know how they can be better, and we’ll be using them for as long as I have anything to say about it.”
Editor's Note: Scranton Gillette Communications and the SGC Infrastructure Group are not liable for the accuracy, efficacy and validity of the claims made in this piece. The views expressed in this content do not reflect the position of the Roads & Bridges' Editorial Team.