Jonathan White
Almost 600 pivoted turnbuckle manhole risers were used to raise …
Texas State Highway 183 from Euless to Dallas/Fort Worth underwent a $1.6 billion major reconstruction in 2014. On projects of this size, even small changes can lead to a great deal of extra work. Such was the case when an unexpected grade change was required to correct drainage issues.
“It was a surprise; the road was raised up to 4 inches after utility manholes had been installed,” says Jonathan White, operations manager at Cheyenne Construction Co. of Mansfield, Texas, a concrete subcontractor for the project. “That meant that 300 to 400 manholes needed to be uncovered and raised to grade.”
Raising that many manholes could have added weeks to the completion timeline, not to mention higher costs and many more lane closures than had been anticipated. Fortunately, the company found a solution that was acceptable to lead contractor Bluebonnet Contractors LLC of Fort Worth and the project’s owner, the Texas DOT (TxDOT).
Taking a chance on a new product
A solution based on custom sonotube forms was initially considered, but would have taken too long.
“When we started to look into alternatives, almost right away, manhole risers from American Highway Products appeared to be the right method for us,” White says. “We hadn’t used them before, but they directly addressed our need, had a good reputation, and certainly seemed to be fast to install and cost effective.”
The company also provides same-day service at no additional charge if the order is placed by 10 a.m. EST.
Still, given the project’s size, using the risers amounted to a big bet on a new product. To satisfy themselves and other stakeholders, the subcontractor decided to test the solution on three manholes before committing to several hundred.
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American Highway Products Ltd. has manufactured steel manhole risers, catch basin risers, and water/gas valve risers in Bolivar, Ohio, since 1978. The pivoted turnbuckle risers that Cheyenne Construction chose are heavy-duty galvanized steel rings that are slipped into existing manhole frames. The turnbuckle is tightened with a screwdriver to fit snugly into even worn or out-of-round rims. The riser, now at grade, becomes a new rim for the original manhole lid.
The product can be used in asphalt or concrete. Some customers report virtually zero failures after almost two decades. One person can easily handle a riser; and the only installation tools required are a crowbar or pry bar, sledgehammer, and Phillips screwdriver. Risers are generally safer than manual raising methods because strain injuries are less likely and traffic exposure is reduced. They’re also a common solution for water and wastewater districts.
On Highway 183, the plan was to sawcut a 4-foot square around the manholes, remove the covering asphalt, set the risers, and then pour new concrete around the lid and new riser, leaving the manhole and a neat concrete border, both flush with the new asphalt grade (this was due to the surprise nature of the work — adjustable risers are usually set just before final paving lifts). The three test manholes proved the method was practical; total time to raise the manholes with a four-man crew was about three hours. Installing the risers was less than 10 minutes of that. “Anything else would have taken two to three times as long,” White says.
The risers are ordered in precise, custom sizes to fit any rim and match grade precisely. They can also be stacked if needed, a fact that Cheyenne leveraged to its advantage.
“All the manhole rim diameters were the same, but the asphalt varied from a little over an inch up 4 inches,” White says. “We ordered 1.5- and 2.5-inch frames and combined them to match different pavement thicknesses.”
Crews were able to adjust the concrete final grade about half an inch as needed. The risers can also be adjusted a bit vertically before tightening. That meant the two different risers could be stacked to match pavement thicknesses of 3 inches or more, and individual risers could be used in thinner pavement.
TxDOT inspected visually.
“We were able to match grade at every manhole,” White says. “They all worked perfectly.”
And they were convenient to order and use. White would typically establish lead times and order in batches of 30 to 40; in all, 556 were used. They’ve been bearing traffic for several months with no failures.
“They’re heavy-duty ribbed steel,” White says. “They’re not going anywhere.”
Angus Stocking is a licensed land surveyor who has written about infrastructure since 2002. E-mail angusstocking@gmail.com.
