Custom curb inlet risers save hundreds of man-hours on IDOT asphalt overlay

Asphalt Case Studies April 12, 2017
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Asphalt overlays are one of the most common and well-studied roadway projects, so innovation seems unlikely, especially the kind of new idea that saves significant time and money without a major capital investment. But Rowe Construction, an Illinois paving firm, recently saved about 400 man-hours on an asphalt overlay project. “This was a 3-mile stretch of U.S. Highway 51 near Bloomington, and mostly standard mill and overlay,” explains Superintendent Ben Donovan. “But the curb and gutter area was a little different—IDOT (Illinois Department of Transportation) wanted a slope here, from 2.5 in. at the edge of pavement down to an inch in the flowline of the gutter pan. And there were 42 grated curb inlets in this 3-mile stretch.”


Raising curb inlets to grade can be laborious, requiring jackhammering and excavation of asphalt and concrete, new concrete utility frames, removal by truck of heavy debris (with associated waste management and sustainability costs), and patching and refilling prior to paving. And the gutter slope added a finicky element that could compromise final grade match. Donovan estimates that conventional replacement would have taken a two-man crew five to six hours, per inlet, for a total of up to 250 man-hours spent on what really amounted to a detail. Donovan decided to opt out. “My company has used risers from American Highway Products, mostly manhole risers, on many previous projects, and we also had some experience with their catch basin risers,” he says. “Their representative, Dan Peterson, met with me, and we figured out a way to customize the catch basin risers for this project, and it turned out to be a great decision.”


American Highway Products Ltd. catch basin risers and monument box risers are simple, sturdy frames that slip snugly into original utility frames and provide a new, at-grade rim for the original grates. Risers are made to order to precisely fit particular risers and project specifications.


In this case, Peterson met with Donovan on site and measured the curb inlets, then ordered and delivered test risers in two different styles. “After the first round of testing in the actual curb inlets, Dan and I figured out which styles needed some adjustments," Donovan says. "After these corrections were made, we ordered and all 42 were delivered within a couple of weeks.”


During the actual project, risers were installed just prior to new paving, and took one man 10-15 minutes per inlet to install. “Most of that time was spent on grate removal,” Donovan says. “Some had been in place for years and were really stuck.” The project was completed in October 2016 and when reviewed in winter all risers had performed well with no failures. “We were able to pave right around them,” Donovan says. “It all worked out really well, and IDOT was happy too. We’ll certainly be using them again.”


Overlay Init