Work on the arterial road will also include a traffic circle under the bridge–the first of its kind in Round Rock—designed to direct local traffic with continuous flow on and off Chisholm Trail Road.
The collaborative effort among the city, Williamson County and the Texas Department of Transportation will likely break ground in summer 2019, said Gary Hudder, director of the Round Rock Transportation Department.
Plans for the project show RM 620 will be widened to eight lanes of traffic, six of which will traverse the train tracks along Chisholm Trail Road via a new overpass.
Westbound and eastbound frontage roads will be added to either side of the six-lane bridge and will connect to the roundabout at the Chisholm Trail Road intersection. Local traffic on the traffic circle will have to stop for trains on the Union Pacific line, though traffic counts shows more than 80 percent of traffic at that intersection is not local and will use the overpass, per Hudder.
“[RM] 620 has just become more and more and more crowded every year,” Hudder said. “When you’ve got those kind of numbers impacted by a [railroad track] conflict, it makes sense to remove that conflict.”
The planned overpass will stretch from west of Brentwood Street to the I-35 frontage road on RM 620.
The city of Round Rock’s website states the project will cost $35 million, though Hudder estimates the project will ultimately cost anywhere from $40 million to $45 million.
Williamson County is contributing $4 million of those funds, and Round Rock will contribute up to $12 million, Hudder said. TxDOT is scheduled to pay for the rest of the bill for the project.
TxDOT will send the project out to bid in April, and Hudder expects officials to break ground on the overpass construction shortly thereafter.
Four lanes of traffic will remain open to residents throughout the length of construction, Hudder said.