Recreation
SR 944 Underpass on the Appalachian Trail
* 2010 American Council of Engineering Companies' Diamond Award Winner
Hikers navigating the Appalachian National Scenic Trail (AT) in Cumberland County had to cross a very busy arterial highway carrying 13,600 vehicles per day across Route 944 (known locally as Wertzville Road). The Appalachian Trail Conservancy (ATC) identified this as the most dangerous highway crossing of the trail in Pennsylvania and wanted to improve its safety. Of six alternatives prepared by the Army Corps of Engineers, the ATC preferred the design of an “underpass” beneath the highway.
Challenge 1: the desire for an aesthetically pleasing trail experience. Though safety was the primary goal, the ATC wanted to preserve the trail experience for its users by providing an aesthetically pleasing design for the underpass approaches. However, a study by the Army Corps of Engineers suggested the 350 foot long approaches to the underpass be confined by retaining walls.
Solutions:
HRG worked closely with the ATC and the Cumberland Valley Appalachian Trail Club to lay out a new design for the underpass approaches. This design eliminated the retaining walls and laid back the slopes to blend with the natural contours of the surrounding land.
HRG worked closely with the ATC to select native plantings for landscaping along the approaches.
HRG specified the use of form liners to simulate a stone facing appearance on the underpass’s exposed concrete. When airbrushed with penetrating stains, the result is a very natural stone look with the strength and low maintenance of concrete.
Challenge 2: Constructing the bypass on a high traffic highway with no reasonable detour options. The surrounding topography eliminated any possibility of a temporary runaround roadway, and a road closure would’ve required a 20-mile detour, drastically inconveniencing the high volumes of commuter traffic.
Solutions:
HRG completed a Critical Path Method schedule analysis during the project planning stages and concluded that the underpass could be constructed beneath the roadway in 58 hours – if crews worked around the clock.
In order to minimize disruption to drivers, HRG specified that this portion of the project be constructed over Labor Day weekend when traffic levels and the impact of the detour would be dramatically less.
The contractor, Hempt Bros., agreed and developed a well-orchestrated, hour-by-hour work plan to support HRG’s requirement.
Construction crews worked non-stop from 7 p.m. Friday evening to construct the underpass and opened Wertzville Road to traffic ahead of schedule Sunday night – finishing the construction in just 50 hours!
View a time lapse video of photographs showing the innovative, expedited approach to construction here.
Challenge 3: Cost. The original cost estimate prepared by the Army Corps of Engineers for the underpass was more than $1.3 million.
Solutions:
HRG produced substantial cost savings by eliminating the extensive retaining walls and specifying the very efficient, compressed construction schedule.
The underpass design was successfully bid at $572,000 – well below the initial estimate.
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