The Authority concluded in early 2007 that it would be financially feasible to build the western section (along with an extended Durham Freeway, which combined would be called the "Triangle Expressway") using toll funds. The NCTA apparently never wanted an interstate designation for the Western Wake Parkway. To lessen motorist confusion about where I-540 ended, the route was truncated to the I-40 interchange. All I-540 signs that were put up along the unopened stretch between I-40 and NC 55 were taken down in early July 2007; the new section is now signed as NC 540. (In addition, I-540 as a completed loop would violate the Interstate numbering convention regarding three-digit routes, as spurs begin with an odd number and loops with an even number, and at one point, I-640 — the last remaining available number within the state, as I-240, I-440 and I-840 are already taken — was proposed for the loop.)