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Overcoming environmental challenges on the Mon/Fayette Expressway

For nearly two centuries, U.S. Route 40 – also known as the National Road – served as the main thoroughfare for drivers traversing Fayette and Washington counties in southwestern Pennsylvania.

But as the years progressed, traffic volumes steadily increased to nearly 7,000 vehicles per day, and the hilly two-lane road’s varying speed limits, inadequate passing zones, and limited sight distances resulted in higher-than-average accident rates. The historic road just wasn’t meant to support the ever-increasing volumes of traffic. It was time for an alternative.

Expansion of the National Road was out of the question. The storied road was the first federally funded highway in the U.S., and since its construction in 1811, the road created a westward passage for settlers headed to the frontier. Countless homes, businesses, and structures eligible for the National Register of Historic places would be adversely affected by improvements to the existing roadway.

A new road was the answer, and the Mon/Fayette Expressway, PA Turnpike 43, Uniontown to Brownsville, was born. The expressway is part of a 60 mile, four-lane toll road that connects I-68 east of Morgantown, West Virginia, with Pennsylvania state Route 51 and the southern suburbs of the Steel City.

However, the geography and historic structures of the southwestern Pennsylvania landscape had the design team dodging several hurdles.

Mind the Gap: The Hazard Below the Surface

Like many of our nation’s highways, the 17-mile expressway spans steep valleys and numerous streams. Posing a unique obstacle for the design and construction teams was the Pittsburgh Coal Seam, which stretches beneath the entire length of the expressway. The thickest and most economically important coal bed in the eastern U.S., the seam spans 11,000 square miles and 53 counties in Pennsylvania, Maryland, Ohio, and West Virginia. Because this 10-foot-thick coal bed was mined extensively during the mid 1900s, large voids existed beneath the earth’s surface and posed a threat to the stability of 37 bridges.

To ensure solid footing, a fluid material that hardens with time was pumped into each of the mine voids. This material, consisting of flyash – a fine-grained byproduct of coal combustion – combined with grout, hardened to form a stable bearing platform for the foundations.

Flyash is a durable and environmentally friendly material used in roadway and highway construction since the early 1950s. The use of flyash also reduces the amount of coal byproducts disposed of in landfills.

Keeping Up Appearances

The project required extensive coordination with environmental review agencies to facilitate compliance with the National Historic Preservation Act of 1996. The project team developed plans consistent with stipulations requiring construction to be “compatible with historic and architectural qualities of the National Road.”

As a nod to the history of the road it parallels, structures throughout the corridor contain specific aesthetic treatments, such as the application of field stone-colored staining, which complements the materials that were predominant in the era of the National Road’s construction.

Paving the Way for Economic Development

Since the new expressway’s opening in July 2012, the need to use the National Road as a major transportation artery has diminished. The improved travel efficiency has helped the region’s economy, an area which suffered a severe downturn with the dramatic decrease of the coal and steel industries. As the natural gas industry emerged, it became imperative to provide the growing number of area motorists – including oversized drilling equipment that has become a regular sight on area roadways – with a safer, more expedient thoroughfare.

The new expressway offers emergency services a faster route, allowing them to reach their destinations 10 minutes faster. Driving the expressway also has reduced fuel consumption and vehicle wear and tear and allows goods hauled via truck to arrive at their destinations sooner, saving time and money for individuals and businesses alike.

While protecting the National Road’s viewshed, the new expressway features signage directing motorists to sites of interest along the historic route, such as the Searights Tollhouse, in an effort to promote tourism in the region.

The road’s impact was summed up by Pennsylvania Governor Tom Corbett: “This represents a major engineering and construction achievement, but it means something much more to the citizens of the Mon Valley. It represents renewed hope and opportunity for the people in an area where coal and steel once dominated – people looking for a brighter tomorrow for themselves and their families.”

Contact Francis P. Nese, PE, via email for more information.

This expressway is carrying us into the future… connecting a nation and bringing us into the new industrial revolution.

Pennsylvania Governor Tom Corbett