A stretch of Interstate 80 on the New Jersey side of the Delaware Water Gap has been a flashpoint for years over plans by the state’s transportation department to build a massive wall to prevent rocks from falling onto the road.

A long list of people and organizations hate that idea, from nature lovers who say the wall will spoil the natural beauty of the gap to safety advocates who contend the curving of the highway on the Warren County stretch poses a far greater danger to motorists than falling rocks.

Now, another problem has cropped up. A New Jersey Department of Transportation committee says a retaining wall that supports the highway for a quarter mile may be “subject to sudden failure.” According to the New Jersey Herald, the committee approved $5.5 million study to inspect the wall and determine how to fix its deterioration and cracks, which would cost an estimated $55 million.

The wall’s failure would endanger motorists and lead to the closing of the interstate, an entryway to the Poconos and a major Pennsylvania-to-New York commuting artery. For the Lehigh Valley, that means the potential for heavier traffic on a highway system already strained by truck traffic from the enormous growth of warehousing in the region — thought state and federal officials say that probably won’t be the case.

“This is talking about sending I-80 traffic down through the Lehigh Valley for years,” said Tara Mezzanotte of Knowlton Township. She is a founding member of the I-80 Rockfall Fence and Safety Concerns at the Delaware Water Gap Coalition, a citizen’s group demanding, among other things, an independent engineering study of the rockwall project.

Possible traffic diversion plans during the yearslong rock wall construction include sending eastbound I-80 traffic south on Route 33 to Interstate 78. Motorists would then head east to Route 287 in New Jersey and follow that road north back to I-80. Westbound traffic would be routed south on 287 to I-78 west, then north on 33 to I-80.

NJDOT says it is premature to offer many details about traffic or other aspects of the projects, because both are still in the design phase.

In response to emailed questions, NJDOT spokesman Stephen Schapiro said the retaining wall repair will likely begin before the rock wall construction but both projects will be coordinated as closely as possible to reduce cost and duration. Generally, the department tries to minimize traffic disruption by working overnight and leaving a lane open to let traffic through.

I-80 passing through the Delaware Water Gap in New Jersey (Shutterstock)

The part of the highway at issue, in Knowlton and Hardwick townships, is narrow and configured with an S-curve that make driving difficult, especially for tractor-trailers. It passes through a rock cut that nature has been grinding down since the highway was built at the base of Mount Tammany in the 1950s. As a result, rocks sometimes fall onto the road. More than two dozen rockfalls occurred between 2001 to 2017 and caused 14 crashes, one of them fatal.

NJDOT wants to solve that problem by building a 60-foot metal wall. Mezzanotte’s group says that’s a bad idea, not only because the wall would mar the beauty of the area but because the greater danger by far is the curvature of the road. A wall would only exacerbate that threat by eliminating the road shoulder, thus making the S curve even narrower.

NJDOT, however, has no plans to straighten the curve, Schapiro said in the email.

“As noted on the I-80 project website and presented during public outreach efforts, options that involve straightening the S-curve would result in significant adverse environmental impacts and are estimated to cost in excess of several hundred million dollars,” he said.

Because of Mezzanotte’s group, news about the coming changes to I-80 have spread far and wide and caught the attention of officials who fear the potential ripple effect on surrounding communities. Last year, state Rep. Rosemary Brown, who represents Monroe and Pike counties, suggested the money proposed for the project might be better spent on a proposed Pennsylvania-New Jersey commuter rail service, which would alleviate highway congestion.

U.S. Rep. Susan Wild, who represents the Lehigh Valley, and U.S. Sen. Bob Casey took their concerns about the rockwall to the Federal Highway Administration.

About $200 million in federal funds are earmarked for the project. In April of last year, Wild and Casey asked about the impacts on traffic, the environment and safety. FHA assured them that all potential effects were being studied under environmental assessments.

The agency said it expects no major traffic disruptions.

“The proposed project can be completed within the existing right of way with four lanes of traffic open (two lanes in each direction) for the most part,” the FHA said. “One exception will be blasting once a week (Monday through Thursday) that will close I-80 for about 15 minutes at a time during periods of low traffic volumes.”

Most other lane closures would potentially occur in the westbound direction, primarily overnight, FHA said. Apart from that, “the project would not affect traffic on I-80 or roads in the communities surrounding the project area.”

Mezzanotte is skeptical of all such assurances. She said the poor condition of the retaining wall has been common knowledge for a long time — residents took video of cracks and “erosion caves” in 2020 ― and she questions the idea of putting the weight and strain of all traffic on the outer lane of the highway during the projects.

“If you put that kind of language on a bridge,” she said — meaning NJDOT’s warning about sudden failure — “nobody would go over it.”

“Their messaging doesn’t match what our eyes have seen,” she added. “This is where the big push is going to be now. We’re screaming for an absolutely independent review.”

Morning Call reporter Daniel Patrick Sheehan can be reached at 610-820-6598 or dsheehan@mcall.com