I-79 Missing Ramps

Pittsburgh, Pennsylvania

To help improve regional connectivity, the Pennsylvania Department of Transportation (PennDOT) called for the construction of two direct connection ramps at the existing interchange of Interstate 79 and Interstate 376 (Parkway West), to provide a direct link between the interstate and the Pittsburgh International Airport. This new connection would eliminate the need for daily commuters to use the overcrowded and increasingly congested two-lane State Route 60. The first ramp would connect I-79 southbound with I-376 westbound toward the Pittsburgh International Airport and the second ramp would connect I-376 eastbound toward Pittsburgh to I-79 northbound.

This project presented structural design, traffic analysis and roadway geometric design challenges which were further complicated by the high volume of traffic on I-79 and I-376.  In addition, the new ramps needed to fit into the existing complex interchange configuration and account for existing terrain. To accommodate the new ramps, lanes were added in each direction of I-376. To make room for the additional lanes and to avoid impacts to businesses adjacent to the highway, more than a mile of the highway was shifted up to 50 feet from the original centerline alignment while maintaining all lanes of traffic to reduce delay and congestion.

Michael Baker provided engineering services to support the addition of both ramps at the interchange of I-79 and I-376 west of Pittsburgh. Services included roadway and bridge design, drainage design, aerial mapping, traffic analysis, signal design, lighting design, intelligent transportation system design, complex maintenance and protection of traffic plans and environmental site assessments.

The new ramps enable traffic along I-79 traveling south to go nonstop out to I-376 west, and inbound traffic on I-376 east to travel I-79 north without being diverted to a congested business district with its signalized intersections and commercial driveways.