A $67.5 million project through Spring 2009 expanded Parkway West to six and eight lanes along a 1.5-mile stretch in the vicinity of Carnegie. Construction also lowered a hill by as much as eight feet to improve safety and added two ramps omitted from the mid-1970s construction of the interchange linking I-79 and 279. The original $17 million exchange was one of the most expensive in the state at the time and two ramps were dropped from the final design to cut costs. Their removal was also based upon traffic being directed onto PA 60 (Steubenville Pike) from I-79 south to Pittsburgh International Airport. Steubenville Pike was vastly more rural then with upgrades planned to handle airport bound traffic.4,5
Opened in November 2008, the new ramp connecting Interstate 79 south to the Parkway West westbound includes a 640 foot long flyover over Campbells Run Road. The new ramp linking Parkway West eastbound with Interstate 79 north includes a 1,500 foot long flyover over both freeways. Opening of these ramps was forecast to bring a 35% reduction in traffic on nearby PA 60 (Steubenville Pike).4
Several changes were made to the Pittsburgh’s Interstates during the first 15 years of the system. For Interstate 279, the route was initially proposed as a western bypass of Pittsburgh, with the I-79 mainline looping east to Downtown via the Fort Duquesne Bridge and Penn Lincoln Parkway West to Carnegie. A succeeding change took place on June 30, 1970, with AASHTO approval of the following:
- Reroute Interstate 79 onto its current alignment west of Pittsburgh
- Reassign I-279 to the Parkway North section of the urban loop between the Fort Pitt Bridge at the Point and I-79 at Franklin Park
- Renumber Parkway West as a westward extension of Interstate 76 (the Pennsylvania Turnpike mainline northwest from Monroeville was still a part of Interstate 80S).
Interstate 279 was extended westward over Parkway West the following year as approved by AASHTO on December 3. I-279 overtook I-76 west from the Fort Pitt Bridge to I-79, as I-76 was reassigned to the remainder of the PA Turnpike northwest to Ohio and Parkway East was renumbered as new Interstate 376. This configuration remained in place until 2009, when I-376 was designated over Parkway West as part of its 70-mile extension to I-80 near the borough of Wheatland.