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PTC Southern Beltway Interchange SR0576 55C2-1

Location: Canonsburg, Pennsylvania

Award: Durability

Project Team

Owner: Pennsylvania Turnpike Commission Contractor: Walsh Construction Designer: MS Consultants Construction Manager: CDR Maguire Concrete: Stone & Company Slag Cement: Skyway Slag Cement

The Southern Beltway, located in Canonsburg, PA, USA, is an all-new, limited access toll road under construction in Pittsburgh, PA’s southern and western suburbs, linking the Pittsburgh International Airport at its western terminus to its future eastern terminus with the Mon Fayette Expressway. This section of the current 13 mile (20 km) segment under construction is the Southern Beltway interchange with I-79, a key element of this toll road and the last portion to complete a direct 19 mile (15 km) link from I-79 and points south from the Pittsburgh International Airport.

Section 55C2-1 is a $180 million project, consisting of a full interchange between I-79 and Toll Road 576 (Southern Beltway), which includes a half interchange with Morganza Road. In addition to the 2 mile (3.2 km) of new eastbound and westbound mainline highway, the construction includes nine new ramps totaling 7.5 mile (12 km) in length, and a bi-directional third lane widening of 3.5 mile (5.5 km) of I-79 within the existing median. The project includes 6.6 million yd3 (5 million m3) of excavation; 360,000 yd2 (301,000 m2) of concrete paving; 214,000 yd2 (180,000 m2) of temporary asphalt; 475,000 yd2 (400,000 m2) of subbase; and 50,000 ft (15,000 m) of drainage.

Two overhead bridges (over I-79) are to be removed; while six new bridges, three retaining walls, and one box culvert are to be constructed.

The project includes two permanent and two temporary soldier pile retaining walls, three mechanically stabilized earth walls, and a temporary reinforced soil slope. A decorative masonry sound wall was also constructed adjacent to the National Cemetery of the Alleghenies. Concrete paving consists of 360,000 yd2 of concrete, produced from an on-site batch plant. Most of the pavement is specified as long life pavement, requiring only the most durable materials and accessories.

Application Type

% Slag Cement Replacement


% Portland Cement


% Portland Limestone Cement

% Other SCM (if applicable)


Natural sand & crushed limestone

Water/cement ratio


7-day strengths

4100 psi

28-day strengths

6700 psi


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