Aerial view of the Complete 540 interchange under construction.

Complete 540 Construction Project


Our Client’s Challenge

Addressing transportation, mobility, social, and economic demands in southeastern Wake County, the North Carolina Department of Transportation (NCDOT) is undertaking a multi-segmented highway construction project to complete the 540 Outer Loop around the greater Raleigh area.

The Complete 540 project, also known as the Southeast Extension, will extend the Triangle Expressway from the NC 55 Bypass in Apex to US 64/US 264 (I-87) in Knightdale, linking Apex, Cary, Clayton, Garner, Fuquay-Varina, Holly Springs, and Raleigh. The project will also ease congestion on the nearby I-440, I-40, NC 42, NC 55, and Ten Ten Road roadways.

Our Solution

Gannett Fleming serves as the lead design firm for the Flatiron-Branch Joint Venture (JV) to design and construct a section of the Complete 540 project. This consists of a new, six-lane, limited-access highway connecting NC 55 Bypass near Apex to US 64/US 264 in the Knightdale area.

This 4.6-mile project west of NC 55 Bypass to the east of Pierce Olive Road (SR 1389) will complete a partial circumferential highway, or outer beltline, around greater Raleigh. The work scope includes:

  • Roadway.
  • Bridges.
  • Hydraulics.
  • Erosion control.
  • Permitting.
  • Geotechnical services.
  • Utility design and coordination.
  • Traffic management.
  • Pavement marking plans.
  • Signing.
  • Pedestrian tunnel and sidewalk design.
  • Traffic signals.
  • Communication plans.
  • ITS and tolling services.
  • Highway lighting.
  • Monthly erosion inspections.
  • Noise design.

The structural project scope includes nine bridges with a diverging diamond interchange (DDI), 11 single and multi-barrel reinforced concrete box culverts (RCBC), more than 2.5 miles of brick noise walls, overhead signs, and all-electronic tolling gantries.

Gannett Fleming is performing design and production work for the DDI interchange and three other grade separations consisting of 2-span bridges with girder superstructures using conventional and integral end bents with mechanically stabilized earth wall abutments with aesthetic treatments. The interior bents are aesthetic columns on pile-supported footings.

The firm is also responsible for designing and producing seven RCBCs, including a pedestrian tunnel, noise walls, sign structures, and the aesthetics package. Design services include the development of preliminary general drawings for 25% review by the contractor and NCDOT, bridge designs, and final request for comments plans.

This project included unique ecological concerns in adjacent bodies of water, which include Middle Creek, Swift Creek, and the Neuse River along the project area, each home to endangered species. Swift Creek contains the dwarf wedgemussel and the yellow lance, both federally endangered freshwater mussel species. Biological assessments were conducted for the U.S. Fish and Wildlife Service, leading to the design of diverting stormwater spills and runoff of the highway away from Swift Creek to protect the conditions for these mussels’ species.

Key Features

  • Increases the current loop by 28 miles to complete the 70-mile multimodal 540 circle.
  • Links the cities of Apex, Cary, Clayton, Garner, Fuquay-Varina, Holly Springs, and Raleigh.
  • Improved access to Raleigh-Durham metro area and Research Triangle.
  • Tolled, limited-access roadway with three, 12-foot lanes in each direction.

Awards & Recognition

  • Awards list here.


  • Outcomes listed here.


North Carolina Department of Transportation (NCDOT)


Wake County, N.C.



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