Interstate 540 (North Carolina)

Interstate 540 (I-540) and North Carolina Highway 540 (NC 540) are part of a partially completed beltway around the city of Raleigh in the US state of North Carolina, forming the Raleigh Outer Loop. When complete, the route will completely encircle the city, meeting its parent route of I-40 in two locations.

The initial phase of construction is designated I-540 and was completed in January 2007. It runs from I-40 near the Raleigh–Durham International Airport to I-87/U.S. Highway 64 (US 64)/US 264 south of Knightdale. The original plan was for the entire route to be designated as part of the Interstate Highway System, possibly renumbering the route to I-640 when the beltway was complete. When it became financially unfeasible to construct the entire route with public funds within a reasonable timeframe, it was decided that the remaining portion of the route (approximately two-thirds of the total completed mileage) would be constructed as a toll road and designated as a North Carolina highway rather than an Interstate Highway. The tolled portion is known as the Triangle Expressway. The first section of NC 540 was opened in July 2007, extending westward from the western terminus of I-540. Further extensions have carried NC 540 around the western side of Wake County to its current southwestern terminus south of Apex. Future projects are planned to complete the southern leg, from Apex to Garner, and eastern leg, from Garner to Knightdale, under the same toll system. In particular, the portion south of Garner has been held up due to conflicting interests in choosing a path for the route. The southern extension is currently under construction and is expected to be completed in spring 2024. Construction on the eastern extension is projected to begin around the time the southern extension is opened with a completion date of 2028.