Ernie Nelson, transportation operations chief for Tampa, Fla., has relied on the same brand of manhole risers for 20 years because they've consistently resisted buckling, loosening, rattling, and popping out.
The expanding pivoted turnbuckle manhole riser—manufactured by Bolivar, Ohio-based American Highway Products—are made to order. Customers specify five dimensions and orders are filled within five days. Nelson, for example, ordered four different configurations to accommodate the various adjustments needed for Tampa's manholes.
While having tailor-made risers can be nice, old manhole frames can vary in size and wear unpredictably, or even become misshapen. The risers' pivoted turn-buckle adjusts to accommodate variances of up to ±½ inch in diameter for a total diametric adjustment of 1 inch. The turn-buckle makes it easy for even minimally trained workers to apply 5600 pounds of pressure evenly around the circumference, using a screwdriver as a lever. The force 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 2600 lane miles to maintain, Nelson's department is lifting grade on city streets most days of the year. The risers' durability, efficiency, and ease of installation are furthering that effort.
Starting in 2005 and ending this summer, Baltimore's DOT is rehabilitating 2½ miles of Wabash Avenue, one of the city's busiest roads. Wabash is six lanes wide, with 9 inches of 30-year-old concrete. The city considered reconstruction, but, according to project manager Kevin Livingston, the option proved 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, establishment and upgrade of curb ramps, and raising of bus pads as needed to match a new 2-inch-thick asphalt overlay. Further complicating matters, the stretch of road was home to 195 manholes and 210 catch basins.
Baltimore's lead contractor, P. Flanigan and Sons Inc., used the pivoted turn-buckle manhole risers for all of the apertures, installing them just ahead of the paver. By prepping, installing, and paving around the risers in one day, traffic control issues were avoided, as was possible damage to manually adjusted castings. The city specified the company's catch-basin risers, which were custom-made to the city's measurements and also installed just ahead of paving operations. The department saved time and money, and compaction around the utility frames was not disturbed, eliminating “dishing” around the castings in years to come.
— Angus Stocking is a Paonia, Colo.-based business writer.