The Oklahoma Turnpike Authority’s “heavy reinvestment” in diamond grinding dowel bar retrofit projects on state toll roads has produced positive, measurable results, the agency’s governing board was told recently.
Approximately 57 miles of H.E. Bailey Turnpike pavement were rehabilitated in dowel bar retrofit projects during the past six years in three contracts totaling about $32 million.
Those contracts smoothed three segments of pavement between mile marker 45, the Medicine Park exit north of Lawton and Fort Sill, and mile post 101.6 approximately a mile north of the SH-9 spur leading to Norman.
Meanwhile, a dowel bar retrofit project on the southern leg of the Bailey – between mile marker 5 at the US-70/ Randlett junction and mm 20 at Walters – is expected to start early next year.
That project is scheduled to go out for bids on Nov. 20 and a contract is slated to be awarded at the Turnpike Authority’s Dec. 9 meeting, according to Jessica Lyle with OTA Public Relations. The engineer’s estimated cost of the job is $13.6 million.
In such a project, a series of grooves are cut into the concrete paving, a metal bar is placed into each groove and covered with concrete, and then a diamond grinder smooths the driving surface.
A dowel bar retrofit restores load transfer across joints and cracks by installing metal dowel bars that link the adjoining slabs. “By linking slabs, the traffic load is shared, preventing differential vertical movement of the slabs at the joints and cracks,” which in turn eliminates “the formation of faults or step-offs,” explained Interstate Improvement, a contractor on one of the H.E.Bailey jobs.
“It is these faults that cause the rough ride and wheel slap that is sensed when traveling on a concrete roadway that has lost its ability to transfer load from one panel to the next,” the Minnesota company said.
The subject arose during the Turnpike Authority’s monthly meeting Nov. 4, after the board approved a multimillion- dollar contract for another diamond grind pavement rehab project on a 22-mile segment of the Indian Nation Turnpike that stretches for 105 miles between Henryetta and Hugo.
The transportation industry has developed a “pavement condition index” (PCI) that is “part of the story when you talk about ride quality,” said Jimmy Sparks, a consulting engineer who works for Olsson Engineering. The PCI is “an international roughness index” (IRI) that is “basically the measure of bumps per mile,” he said.
The Oklahoma Turnpike Authority reports its pavement conditions to the Federal Highway Administration.
A “good” IRI is less than 95 inches per mile, while a “poor” IRI is more than 170 per mile, Sparks said.
In 2021, he said, 27% of the Indian Nation Turnpike pavement was rated as good, 57% was considered fair, and 9% was rated poor. By 2024, after multiple diamond grind projects were performed on sections of the toll road, 89% of the pavement condition was rated good, 4% was deemed to be fair, and 7% was rated poor.
The OTA’s “continual series of reinvestments” in diamond grind projects “has had an impact” on Oklahoma’s turnpike system, Sparks said.