The I-77 ‘whirlpool’ — a decade in the works — reaches final stage in Statesville
A massive interchange that state transportation officials deem critical to North Carolina’s highway system has entered its final phase of construction at Interstates 40 and 77 in Statesville after a decade of work.
The “whirlpool” or, as the state calls it, “partial turbine” interchange is replacing a woefully outdated cloverleaf interchange built in the late 1960s. The old interchange “has outlived its original purpose,” N.C. Department of Transportation officials say on the I-40/I-77 interchange project page.
The cloverleaf configuration was harrowing for drivers, The Charlotte Observer reported in 2012 when work was about to begin on bridges and roads near the planned new interchange.
Westbound I-40 drivers trying to head onto I-77 South, for instance, contended with southbound I-77 drivers spilling off a ramp and onto their short exit lane.
The interchange, about 42 miles north of Charlotte, is a key component of North Carolina’s highway network because it links two of the most heavily traveled interstates crisscrossing the state, NCDOT officials say.
About 70,000 drivers a day use the interchange, a number expected to leap to 110,000 a day by 2035, according to NCDOT.
“The importance of this project is that it will improve congestion as well as safety for the I-40/I-77 interchange in Statesville,” NCDOT spokesman Marcus Thompson told the Observer last week.
Other NC turbine interchanges
In 2015, NCDOT completed transforming the existing I-85/I-485 interchange near Charlotte into a turbine interchange.
The $98.7 million project was the first of its kind in the state “and uncommon in the United States,” according to general contractor Lane Construction. Lane’s crews also are transforming the Statesville interchange.
The planned construction of a turbine interchange south of Raleigh reached a milestone in early July with the closure of a ramp that will send some drivers on a detour for more than a year, The News & Observer reported.
N.C. 540, also known as the Triangle Expressway, will meet I-40 south of Garner at the spot where the U.S. 70 Bypass now splits off heading east into Johnston County, according to the N&O.
How a whirlpool interchange works
The whirlpool interchange design spreads entrance and exit ramps much farther out. Vehicles from one interstate no longer spill into the lane used by others trying to access the other highway.
The design also typically eliminates left-lane exit ramps, highway officials said. Drivers use far-safer and longer right-lane exits and loop ramps.
Lane Construction describes the design this way on its website, LaneConstruct.com:
“The turbine interchange design circles all high-speed ramp traffic around central mainline bridges in a counter clockwise direction, creating a seamless movement between the two highways. It also requires fewer levels and has smaller bridges with smaller columns.”
Completion delayed
The NCDOT I-40/I-77 project page says work is expected to wrap up by year’s end, but Thompson said delays have pushed completion to late 2023.
Work has taken so long because of the many nearby bridge, ramp, road and other improvements involved in the project, officials said.
Crews completed the first half of the work in 2018, including 11 bridge, ramp, road and other improvements, according to a July 14 update on NCDOT.gov and Thompson.
The state widened I-40 from four to six lanes in each direction from Old Mocksville Road, just east of the I-40/I-77 interchange, to near N.C. 115 west of the interchange, according to NCDOT.
And highway workers transformed the nearby I-40/U.S. 21 interchange into a diverging diamond layout that’s also been shown to curtail bottlenecks and wrecks.
Invented by the French, diverging diamonds are increasingly common in North Carolina. The diverging diamond that opened in 2014 at I-77 Exit 28 in Cornelius at Lake Norman cut wrecks by 60% in its first year, the Observer reported at the time.
Crews completed about a dozen other projects, including reconstructing a stretch of U.S. 21, replacing or building several bridges and building several interstate ramps.
Work is well underway on the second half of the project, which also includes bridge replacements, highway widening and the centerpiece of all of the work — the interchange, according to NCDOT.
Officials divided the second half of the project into three phases to better manage traffic, Thompson said. Work on the final phase started in the spring, he said.
‘Nightmare’ for truckers
Trucker Darleen Willis calls the I-40/I-77 construction zone “a real nightmare,” especially considering the project started so long ago, in 2012.
“I don’t know why it took that long,” Willis told the Observer at the Pilot truck stop at I-77 Exit 42 in Troutman last Wednesday. “The money’s there. It should have been done a long time ago. But we’re very glad it’s going to be done. And hopefully it’s done correctly and they won’t have to redo it in another year.”
Willis, husband, Tony, and their 13-week-old Texas heeler, Smokey, were on their way to visit family in Warren, Ohio, before traveling to Indianapolis, then back to their home near Punxsutawney, Pennsylvania, then to Miami with a load.
“We like to hit these kinds of interstates late in the evening, after rush hour,” Tony Willis said. “The less traffic the better.”
“Construction in itself is a nightmare for truckers,” his wife said. “Not only do you have to worry about construction sites, but you have to worry about the other drivers that are trying to pay attention to the construction zones and not paying attention to the other drivers merging.”
About the I-40/I-77 project, she said, “I’m glad they’re finally getting something done with it, but we’ll see. Usually, the more lanes, the more traffic anyway, just like in California. So we’ll see how it goes.”
For real-time closures regarding the I-40/I-77 interchange project, check NCDOT Eastern Mountains on Twitter.
This story was originally published August 2, 2022 at 5:30 AM.