Meadow Lands Interchange Project wins ESWP award

Harrisburg, Pa. — The Engineering Society of Western Pennsylvania (ESWP) honored the I-79 Meadow Lands Interchange Improvements project with the 2013 Transportation Project of the Year Award. Each year, ESWP names a Project of the Year for commercial, industrial, sustainable, and transportation categories. Qualifying projects must have been performed by an ESWP member within the last five years and can be located anywhere in the world.

Gannett Fleming performed preliminary engineering, final design, and construction consultation services for the project in partnership with the Pennsylvania Department of Transportation. Swank Associated Companies was the prime contractor.

The Pennsylvania interchange is located at Exit 40 of I-79 at the intersection of S.R. 1009 and S.R. 1047 in South Strabane and Chartiers Townships, Washington County. The $23 million project covered 1.42 miles and was completed in July 2013.

The design and construction efforts faced the challenge of reconfiguring the 50-year-old partial interchange into a full-access interchange with I-79 to meet the needs of the surrounding area in response to regional commercial and industrial growth, increasing truck traffic, and anticipated future development. Using a split diamond interchange configuration, the existing ramps were reconstructed to meet current design standards for acceleration and deceleration. In addition, new northbound entrance and southbound exit ramps were constructed, and new connector roadways and ramps were built. With the split diamond interchange configuration, four new signalized intersections were created.

The project faced numerous challenges that affected both design and construction including avoiding impacts to Chartiers Creek and relocating more than 800 feet of a tributary to the creek. A key element to eliminating impacts to the Chartiers Creek's stream channel was the construction of a reinforced concrete retaining wall approximately 530 feet long having a maximum height exceeding 20 feet. The tributary relocation involved coordinating with environmental agencies and integrating mitigation features, such as a meandering low flow channel, mud sills, boulders, and plantings.

During construction, the project maintained two lanes of traffic on I-79 in each direction and significantly reduced any impacts to the I-79 travel lanes while erecting new dual bridges. This was achieved by constructing the new northbound mainline bridge first to a width of 60 feet to accommodate four lanes of traffic when the southbound bridge was constructed. Short-term single-lane restrictions were occasionally required, but two lanes were open in each direction during peak periods.

Other obstacles facing the project included relocating a side road, avoiding an archaeological site, avoiding impact to a golf course, closing off an old mine pond to re-establish low flow back into the tributary, mitigating noise with a noise barrier, grouting mine voids, and rehabilitating the bridge carrying Pike Street over Chartiers Creek.

Completion of the interchange project provided full access, which simplified navigation in the area, reduced through traffic, created direct access to I-79 from areas south and east of the interchange, improved access for existing and future commercial and industrial facilities in the surrounding area, and improved operation at a major intersection in the community of Meadow Lands, Pa.

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