By the ASCE Awards Committee

The South Junction Interchange project, designed by HDR (prime consultant) and constructed by Golden Triangle Construction (prime contractor), was an integral part of PennDOT District 12-0’s ongoing initiatives to make safety and capacity improvements to the entire I-70/I-79 corridor.

The project’s primary safety improvement was the elimination of the previous substandard loop ramp that was used to maintain the I-79 northbound movement. This loop ramp contributed to many significant accidents over many decades – and was the primary reason that Reader’s Digest Magazine once labeled the South Junction Interchange as one of the seven most hazardous interchanges in the United States.

The elimination of the previous substandard loop ramp by way of the new high-speed flyover eliminated the need for unassuming drivers to reduce traveling speeds from in excess of 60 mph hour to 20 mph just to maintain travel on the I-79 northbound direction. Through the reconfiguration of this ramp, the South Junction interchange no longer requires appreciable reductions in speed in order to maintain the continuous northbound I-79 movement. It is much more aligned with driver expectations, and, consequently, a much safer facility through which to travel.

During the construction phase, Golden Triangle, in collaboration with their construction engineering partner Mackin Engineering, conceived the innovative idea of constructing a tunnel underneath the existing I-70 overpass structures that would maintain the ramp traffic without disrupting the four lanes of I-70 traffic.

Since the tunnel would be continuous and much wider than the old bridge decks, there would be enough room to shift I-70 traffic lanes from side to side in order to completely remove the old superstructures and rebuild the interstate without the use of conventional temporary median crossovers. Golden Triangle’s outside-the-box innovation saved over $1 million in construction costs – and improved work zone traffic control safety by eliminating the need for high-speed median cross-overs within a curved portion of the I-70 interstate.

PennDOT District 12-0 staff worked very closely with designer and contractor throughout all phases of the South Junction project delivery to ensure a much needed, cost-effective, and innovative improvement to this Washington County transportation facility.

PROJECT TEAM

Owner: PennDOT District 12-0

Prime Design Consultant: HDR, Inc. Subconsultant Design

Team Members: Burns Engineering, Inc., Raudenbush Engineering, Inc., Santangelo & Lindsay, Inc., Pedersen & Pedersen, Inc., Christine Davis Consultants. Inc.

Contractor: Golden Triangle Construction Construction Engineering: Mackin Engineering, Inc. Construction Inspection: JMT