Mapping out a new route

June 28, 2022

Terracon helped many communities reduce congestion, improve safety, and support future population and economic growth on a 13-mile stretch of new highway in Pennsylvania—while preserving natural, cultural, and socioeconomic resources.

The trip through Pennsylvania on US Route 15 is a scenic drive along the Susquehanna River on mostly four-lane, limited-access highway. One major exception is a winding stretch of highway that slows traffic below 50 miles per hour, clogging the region’s central business district with large trucks and other traffic “passing through” the area. In fact, a project study determined that at least 50 percent of the cars and 90 percent of the trucks traveling through the business district did not have a local origin or destination.

The resulting congestion and safety concerns prompted the Pennsylvania Department of Transportation to take action with the intent to separate commuter traffic from the vehicles actively wishing to stop to deliver goods, shop, or simply get from point A to point B. The goal: to return the local roadway network to the local drivers.

The Central Susquehanna Valley Transportation (CSVT) project was the answer. Originally conceived in the 1970s, and proposed again in the mid-1990s, this bypass experienced several delays due to the complex nature of the environmental and infrastructure improvements. Finally breaking ground in 2019, the CSVT project features the new highway routed through farmland and environmentally sensitive areas and includes four interchanges with local roadways and the new, nearly mile-long new crossing over the West Branch of the Susquehanna River. The team in Terracon’s Harrisburg office led the way in making this project a reality.

Terracon’s environmental planning takes the lead on CSVT

Environmental planning for CSVT was a large puzzle with multiple pieces and different concerns. All had to be considered to find a solution. Some of the issues addressed included:

  • Potential relocation of impacted homes and businesses
  • Natural resources including wetlands, waterways, and forested areas
  • Floodplains and flood-prone areas
  • Local farms and the impact of CSVT on their operations
  • Archaeology, including Native American and Colonial artifacts
  • Above-ground historic resources
  • Noise considerations
  • Recreational resources like local parks and regional boating and fishing access points along the river

Not only were impacts determined for each identified resource but mitigative measures such as the creation of a new boating and fishing launch area and the design of replacement wetlands were developed.

Environmental firms like the team in Harrisburg (which originated as Skelly & Loy and joined Terracon in 2020) are typically sub-consultants on projects like this, providing the lead firm with specialized information needed to keep the project progressing on-budget. CSVT, however, is no ordinary project.

Terracon served as the lead firm on CSVT because the multitude of natural, cultural, and social resources were driving planning for the route and its ultimate construction. The corridor that was  selected is the route of least environmental impact—striking the right balance between meeting the local and regional needs of the new highway and the social, natural, and cultural impacts.

Bridging the Susquehanna

The largest obstacle on CSVT, both literally and metaphorically, was finding the best route for crossing the West Branch of the Susquehanna River. It’s the second-longest river in Pennsylvania, the longest non-commercially navigable river in the country and is protected by Section 404 of the Clean Water Act.

The new bridge stretches nearly a mile and is about 200 feet above the river’s surface at its highest point. It’s one of the largest bridges in the state outside of Pittsburgh and Philadelphia, and the first new bridge across the Susquehanna in many years. Construction of the bridge took almost three years to complete. Our work was essential in determining the bridge’s final location and pier placement, assessing the potential impacts to nearby homes, and estimating the effect on the aquatic ecosystem and the impact to fishing and boating uses.

Environmental planning services from coast to coast

We can apply the knowledge and expertise of Terracon’s environmental planning experts to projects of all sizes – from new highway or transmission line routes to lane additions, road realignments, bridge repair or replacement, and everything in between. We have environmental experts across the country who are familiar with federal, state, and local regulations. We’re ready to partner with you provide the environmental services needed to keep projects on track.

Find an office location

More than 175 offices from coast to coast.