Several years ago, the city of Milwaukee was experiencing issues with their cast-iron manhole risers installed throughout the area. “They’re usually fine, but on occasion they would slip or rattle out, and that led to car damage and claims—there was definitely room for improvement,” said Milwaukee’s Engineer in Charge Samir Amin, P.E.
A few years ago, Amin was approached by a representative from American Highway Products (AHP), who demonstrated the company’s adjustable riser, the pivoted turnbuckle manhole riser. Implementing the adjustable risers seemed like a good idea to Amin, so he organized a pilot project. Milwaukee transportation officials picked a street near the city's municipal yards that sees heavy truck traffic for the pilot, according to Amin. Seeing that the adjustable risers were able to handle heavy loads, the team decided that they would work well for the city's streets.
The city could not specify a particular brand of riser. Instead, Milwaukee wrote specifications for riser use that required adjustable risers with a mechanism similar to the pivoted turnbuckle. Since the specifications were put into effect four years ago, the city has been pleased with the results. “At the very beginning we faced some resistance from contractors, who were used to the readily available cast-iron risers,” Amin says. “But really, that went away quickly, and now nobody mentions it.”
City crews also install AHP risers, including the firm’s catch basin risers, and keep about a hundred risers in inventory for use as needed. The pivoted turnbuckle manhole risers are sturdy galvanized steel risers that feature a turnbuckle. Using a screwdriver as a lever, the turnbuckle transmits thousands of pounds of force to the flexible rim, seating the riser into original utility rim securely. And unlike risers that depend on set screws or other mechanisms for adjustment, the pivoted turnbuckle riser connects tightly around its entire circumference, like a pressed-in bearing.
By now, close to 1,000 adjustable risers are installed in the city. Milwaukee has emphasized milling and repaving in recent years, and Amin estimates that between 200-300 risers are installed annually. And in all that time, none have rattled out or failed in any way.
