OK, this pisses off my highly honed sense of order:
The Parkway West from the Fort Pitt Tunnel to Interstate 79 has been redesignated as Interstate 376, the Pennsylvania Department of Transportation announced today.And here's why. From der Wikipedia:
Its former designation as Interstate 279 now applies only to the Parkway North.
I-376 now stretches from the Pennsylvania Turnpike in Monroeville to the I-79 interchange in Robinson. Eventually, PennDOT will extend I-376 along Routes 22, 30 and 60 on the Airport Expressway and Beaver Valley Expressway to Mercer County,
Auxiliary Interstate Highways are circumferential, radial, or spur highways that principally serve urban areas. These types of Interstate Highways are given three-digit route numbers, which consist of a single digit prefixed to the two-digit number of a nearby primary Interstate Highway. Spur routes deviate from their parent and do not return, with a few exceptions; these are given an odd first digit. Circumferential and radial loop routes return to Interstate Highways, and are given an even first digit. Due to the large number of these routes, auxiliary route numbers may be repeated in different states along the mainline.
So, if you caught all that, PennDOT has assigned a circumferential route number to what will now be a spur route and a spur route number to what will eventually (I presume) be a circumferential route. Really the numbers should be changed to I-379 and I-276! They could have at least kept it I-279/I-376 to the I-79 interchange, rather than making a complete switch.
I mean, what the point of a system if you're just going to throw out numbers willy-nilly! Might as well just call the damned things "Interstate Sunday in the Park with George Wentz" and "Interstate Be like the seventh level donkey in space: PING!".