By: Angus W. Stocking
"They do not fail; we'll never stop using them," said Ernie Nelson, the transportation operations chief in Tampa, Fla. He's talking about the expanding Pivoted Turnbuckle Manhole Riser made by American Highway Products. He's been ordering the risers since 1986, and purchased 614 in 2005 alone. And in all that time, as he emphatically stated, they've never buckled or loosened, and manhole lids have never rattled or popped out.
AHP Manhole Risers are made to order. Customers specify five dimensions and orders are filled within five days, and one-day service is available. In 2005, for example, Tampa ordered four different configurations to accommodate different adjustments needed for manholes.
Made to order is nice, but old manhole frames can vary in size, wear unpredictably or even be out of round. AHP's pivoted turnbuckle (a patented feature) adjusts to accommodate variances from provided dimensions of up to plus or minus 1/2 in. in diam. for a total of 1-in. diametric adjustment. The turnbuckle makes it easy for minimally trained workers, using a screwdriver as a lever to apply 5,600 lb of pressure evenly around the entire circumference of the riser; this enormous force easily and permanently fits the riser to the existing frame. Even before new asphalt is applied, the riser is sturdy enough to stand up to trucks and paving machines.
With 2,600 lane miles to maintain, Ernie Nelson's department is lifting grade on city streets most days of the year. The durable, efficient and quick-to-install AHP Manhole Riser is an important part of that continuing effort.
Beginning in 2005 and finishing up this summer, Baltimore's Department of Transportation is rehabilitating 2.5 miles of Wabash Avenue, one of the city's busiest roadways. Wabash is six lanes wide, with a 9-in.-thick roadway of 30-year-old concrete. Reconstruction was certainly considered, but according to Kevin Livingston of the department, it was too expensive and would tie up a main artery for far too long. Instead, Livingston proposed cement base repairs to the existing road, repairs as needed to curbs and sidewalks, the establishment and upgrade of handicap access ramps, and the raising of bus pads as needed to match a new 2-in.-thick asphalt overlay. And oh yeah: there were 195 manholes and 210 catch basins in that 2.5 mile stretch of road.
The city's lead contractor, P. Flanigan and Sons Inc., used Pivoted Turnbuckle Manhole Risers for all manholes, installing them just ahead of the paver. By prepping, installing and paving around the riser in one day, unnecessary traffic control was avoided, as was possible damage to manually adjusted castings. Similarly, American Highway Products' Catch Basin Risers were pre-ordered, custom made to the city's measurements (in riser height increments as fine as 1/4 in. and 1/16 in. in all dimensions) and also installed just ahead of paving operations. Time and money were saved, and compaction around the utility frames was not disturbed, eliminating "dishing" around the castings in years to come.
Excavating and resetting utility castings is expensive and time consuming, and never an option for the Wabash Avenue project. Other riser products are available, and the city of Baltimore has tried them, but they weren't an option either.
