Department of Transportation


I-80 Rockfall Mitigation Photo

PRELIMINARY ENGINEERING 2013-2021

The Preliminary Engineering phase includes an environmental analysis of the Preliminary Preferred Alternative (PPA), initiates project design work in support of the environmental document, and initiates the right-of-way acquisition process for temporary or permanent construction easements. In the case of rockfall mitigation projects, a detailed rock characterization and engineering study is also completed at this time. Federal funding from the Federal Highway Administration (FHWA) for preliminary engineering work was authorized in July 2013 and a design agreement was executed in October 2013.

Rock Characterization and Engineering

The existing rock cut areas along the westbound direction of Interstate 80 (I-80) within the Project limits have physical and geological hazards. The primary modes of rock instability identified during the data collection and site characterization of the area are planar sliding, wedge sliding, toppling, rock mass failure, and discrete rockfall as evidenced by the large overhangs, steep vertical faces, loose boulders, and rock blocks, which have resulted in rock toppling down and landing on the shoulder and roadway lanes and washouts along the I-80 roadway. A series of large open fissures exists in the area near the steep vertical rock wall, and if not stabilized, there is the potential for a major rockfall event to occur.

Although the original conceptual alternatives were intended to incorporate more localized removal and stabilization techniques, the detailed rock study revealed more areas of rockfall and safety concerns than first assessed. Rockfall modeling revealed the need for more aggressive stabilization strategies and consideration of source material from areas much farther upslope within areas under the jurisdiction of the National Park Service (NPS).

Environmental Resources

The Delaware Water Gap National Recreation Area (DWGNRA) was established in 1978 and straddles a stretch of the Delaware River on the New Jersey and Pennsylvania border which slices through the Kittatinny Ridge. Worthington State Forest is encompassed by the DWGNRA as well. The Appalachian National Scenic Trail enters New Jersey from the south on a pedestrian walkway along the I-80 bridge over the Delaware River, ascends from the Delaware Water Gap to the top of Kittatinny Mountain in Worthington State Forest and continues north through the DWGNRA and Stokes State Forest.

A 40-mile section of the Delaware River, entirely within the DWGNRA, has been granted protected status as the Middle Delaware National Scenic River under the National Wild and Scenic Rivers System and is also administered by the NPS.

Tribal nations from the Delaware Nation, Oklahoma; Delaware Tribe of Indians; Shawnee Tribe; Shawnee Tribe of Indians of Oklahoma; and Stockbridge Munsee Mohican Tribe, Wisconsin have a cultural interest in the area.

In addition, there are documented threatened and endangered (T&E) plant and animal species present in the DWGNRA.

Several documented T&E plant and animal species are present in the DWGNRA as well.

Environmental Assessment

An Environmental Assessment (EA) is prepared when it is unclear if a project will cause significant adverse environmental impacts. Intensive studies are only performed for those social, economic, and environmental resources that might experience significant adverse impacts. In May 2018, after conferring with the Federal Highway Administration (FHWA), the National Park Service (NPS), and the New Jersey Department of Environmental Protection (NJDEP), NJDOT determined that preparation of an EA would appropriate for the I-80 Project due to its unique location and to allow for additional public involvement. This process is currently underway.

If the EA concludes that the Project will not result in significant individual or cumulative environmental impacts, a Finding of No Significant Impact (FONSI) will be prepared for FHWA approval. FHWA’s issuance of a FONSI will conclude the NEPA process.

Coordination efforts have been ongoing with many representatives of the U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service (USFWS), NPS, NJDEP, New Jersey State Historic Preservation Office, Pennsylvania Historic Preservation Office, Appalachian Trail Conservancy, Warren County, Knowlton Township and Hardwick Township representatives.


Last updated date: August 26, 2020 8:06 AM