After about three years of construction, York County commuters are enjoying a smoother drive across the new U.S. 21 bridge.
With four traffic lanes, the 1,000-foot long bridge is one of two ways to cross the Catawba River between Rock Hill and Fort Mill.
The majority of the bridge construction finished July 1.
Senior bridge inspector Russ Carroll of KCI Technologies said he ranks the U.S. 21 bridge as one of the top bridge construction projects he’s worked on.
The project took longer than planned, he said, because of some right-of-way acquisition issues.
With some road widening on either side of the bridge, engineering and right-of-way land costs, the S.C. Department of Transportation finished the project at an expense of about $20.5 million.
The bridge may continue to see enhancements over the next few years if leaders decide to add public transportation or connect the river crossing to the Carolina Thread Trail – a network of about 117 miles of greenways and walking trails.
Stairs leading to the bridge from the river area could be built in the future to connect U.S. 21 to the greenway network.
The Rock Hill-Fort Mill Area Transportation Study has endorsed U.S. 21 as an appropriate route to put public transportation in the future, said David Hooper, RFATS coordinator.
The RFATS group started in the early 1960s to address a booming York County population, mainly growing around the Rock Hill area.
Since then, the group has expanded its scope to include the Fort Mill and Tega Cay areas, assisting with transportation planning in eastern York County.
A third Catawba River crossing is on RFATS’ “planning radar screen,” Hooper said.
From the U.S. 21 bridge, commuters can see the other river crossing – an Interstate 77 bridge.
Given the frequent traffic congestion along U.S. 21, Celanese Road and parts of I-77, Hooper said consideration of a third bridge to connect Fort Mill and Rock Hill “is a fair question to ask.”
Traffic on many parts of I-77 alone, he said, has grown by 20,000 daily commuters consistently every 10 years.
Officials expect the U.S. 21 bridge to serve the area’s transportation needs for the next 30 to 40 years before it’s due for replacement or major repair.
For now, the bridge is a “significant improvement” for the area, Hooper said.
About 18,500 vehicles use the bridge daily, according to RFATS estimates.
Over the next 20 years, transportation officials predict the number of cars crossing the U.S. 21 bridge will more than double to about 40,000 vehicles.
Contractors used an innovative technique during construction of the 68-foot high bridge, Carroll said.
Because of the shallow depth of this stretch of the Catawba River, barges couldn’t be used to haul in cranes for the project.
A “girder lifting frame” was used instead – the first time such equipment has been used in the Southeast to build a bridge, he said.
Carroll’s “top focus” on the project site was to ensure that contractors were using only American-made products – a requirement during all bridge construction, he said.
“And, safety is paramount, of course,” he added.
Construction was challenged, Carroll said, by the hard surface rock found on the river bed.
It was a “very difficult undertaking” to install 35 drill shafts into the rock to ensure the bridge’s structural integrity, he said.
The bridge has seismic restrainers that ensure it can withstand a certain amount of seismic activity in the event of an earthquake.
Designers also paid attention to the bridge’s aesthetics, he said, with requests from local leaders to install decorative lighting on both sides and a finish giving the appearance of brick.
The 108-foot-wide bridge includes bicycle lanes and a 15-foot median for emergency service vehicles in case of a traffic accident.
Earlier this year, the American Council of Engineering Companies of South Carolina awarded an “engineering excellence” honor to Triplett-King & Associates and KCI for the U.S. 21 bridge project.
The new bridge replaces a two-lane bridge that has been demolished.
The old bridge was “showing signs of age” and had some “structural inadequacies,” Hooper said.
With expected development in the area, he said, U.S. 21 will continue to be a “gateway facility” for the Fort Mill and Rock Hill areas.
Anna Douglas • 803-329-4068