Interstate 40 has been the backbone of the Triangle's transportation web for years, with traffic volumes surging as the region's economy booms.
Keeping up with highway infrastructure in a fast-growing area is a constant challenge for engineers with the North Carolina Department of Transportation. With I-40, the pressure is always high, as just one confusing lane shift or rush-hour collision can snarl traffic for hours.
Here are three busiest stretches of the interstate in the Triangle and their average daily traffic estimates for 2022:
Here's what the projections are by 2050:
To accommodate the growth, NCDOT is working on major construction projects along stretches of I-40. The goal is a more efficient highway and, hopefully, a better commute for drivers.
Here are five projects set to transform I-40 in the Triangle.
Crews are now working to finish massive widening projects on two ends of the Triangle — Johnston County and Orange County.
In Orange County, crews are working to widen nearly 11.5 miles between I-85 and the Durham County line from four to six lanes. The $236.5 million project is scheduled for completion in 2026.
In Johnston and Wake counties, the finish line is even closer. The goal is to widen the interstate between the I-42 interchange and I-440 in Raleigh, adding two lanes of capacity in each direction. Lanes from I-440 to U.S. 70 opened last year. It's made a huge difference, according to Brandon Jones, an NCDOT engineer covering Wake and Durham counties,
“We’re continuing to work to get the lanes open,” Jones said.
The $350 million project involves modernizing interchanges, such as the diverging diamond interchange that recently opened in Garner and another planned at N.C. 42.
A heavy maintenance project is underway in Cary, with crews milling the surface of the roadway between Wade Avenue and I-440. The project involves crews removing the entire road surface, exposing the underlying concrete.
“When you take off the surface … you don’t exactly know what you’re going to run into,” Jones said, adding that his team feels “really good about that project now.”
But there are complications, as the material crews are laying down has temperature restrictions, meaning the weather can, and has, caused delays. But the project is expected to be finished later this year.
Further out, crews see opportunities to build more auxiliary lanes in Wake County between Aviation Parkway and Harrison Avenue, a project that would require widening bridges. But that project, and another that would widen Wade Avenue from the Beltline to I-40, have not yet been funded.
Even after completing modifications of the Aviation Parkway Interchange, work continues in the I-40 area near the airport as crews work to convert the Airport Boulevard interchange into a diverting diamond. Right now, crews are building twin bridges at the site. The first bridge has had traffic running for a few months, and the second has its girders up. The goal is to substantially complete the project later this year.
Altogether, the project is a $100 million investment in I-40’s two main airport interchanges. But Jones said it will make a huge difference in airport traffic. Drivers used to have to merge into mainline traffic via ramps. But the ramps at Airport Boulevard and I-540 have been connected with auxiliary lanes to make travel less confusing.
Other maintenance projects planned for I-40 in the region include a pavement rehabilitation and bridge project from 15/501 to I-885 that's expected to begin next year.
One of the most complex projects in the coming years has yet to break ground. NCDOT wants to simplify the complex clover of loops at U.S. 1 through a number of connected projects under one contract.
The goal is to widen I-40 from Lake Wheeler Road to I-440 and add auxiliary lanes to ease mergers. Between Lake Wheeler and Gorman Street will be a connecting auxiliary lane. Another will connect Gorman Street and I-440.
“As you know, there’s some difficult maneuvers out there today with those four loops that create weaving issues, so the key was, how do we eliminate that?” Jones said. “If you want to go southbound on U.S. 1, instead of having to get out of here and enter the traffic in this loop to get into this other loop … we’re going to create a flyover lane.”
The Crossroads Boulevard access to U.S. 1 North in Cary will be eliminated.
Altogether, it’s a $300 million project that's further complicated by heavy traffic volume, a creek and nearby development. The design-build project won’t kick off until 2027.
“If you’ve kept up with what’s happening with South Hills, the redevelopment planned there, it’s just getting more dense with development,” Jones said.
Another project in its planning stage could tackle Durham commutes, though it is also not planned to kick off until 2027.
Currently, it’s complicated during rush hour when traveling from the Durham Freeway to I-40, where you merge only to have to get back off the highway if you want to go to 55.
The plan is to build an auxiliary ramp from I-885 south to I-40 west.
“Right now, it merges back into 40, so basically we’re going to take that and continue that … and tie it into where the exit goes into that loop,” Jones said.
The $12 million operational improvement is one part of the plan. Crews will also widen I-885 from I-40 all the way to the East End Connector.
“A part of that project … it’s how do we improve 885 southbound to I-40 eastbound?” Jones said. “If you’ve ever done that movement … it’s dual lanes that merge into one lane that then become a lefthand ingress onto I-40.”
The plan is to figure out how to get two full lanes coming southbound. NCDOT is now working through scenarios, such as bringing I-40 eastbound traffic in, hugging I-40 westbound. Then the existing eastbound I-40 would be used as an exit for Davis Drive, with I-885 coming south and tying back in on the right hand side.
Current estimates tag the project at $150 million, but actual construction is not scheduled until 2029, meaning a lot could change, Jones said.
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