How Slope Failures Can Lead to Critical Highway Collapses

CEE Associate Teaching Professor Craig Shillaber says that highway failures like the recently collapsed section of Teton Pass only happen under certain circumstances. These collapses are caused by slope failures, which depend on the stress of loading conditions and the strength of the foundation soil.

This article originally appeared on Northeastern Global News. It was published by Tanner Stening. Main photo: This photo provided by Wyoming Highway Patrol shows a damaged section of Teton Pass near Jackson, Wyo., that officials said had “catastrophically failed.” Wyoming Highway Patrol via AP

A section of critical highway collapsed in Wyoming. Could it happen anywhere?

The partial collapse of a roadway in Wyoming as a result of a landslide that occurred over the weekend raises serious questions about the state of the nation’s infrastructure — echoing concerns aired recently over a range of issues, from frequent water main breaks to the Baltimore bridge collapse in March.

The Teton Pass is a “critical” link between Victor, Idaho, and Jackson, Wyoming. There’s no timeline for the reopening, which could take “weeks to months,” says Daniel Aldrich, director of Northeastern University’s Security and Resilience Program and co-director at the Global Resilience Institute.

Aldrich, who studies resilience and preparedness, says the incident illustrates just how vulnerable the nation’s roadways are to potential catastrophe.

“The Teton Pass roadway is one of the few roads connecting these hard-to-reach areas, and for those trying to get to hospitals — this could be one of the only roads possible,” he says.

“We don’t recognize how important these systems are until there is a major issue. We assume the roads are going to work; we assume the bridges are going to work — until they don’t,” Aldrich says.

Craig Shillaber, an associate teaching professor of civil and environmental engineering at Northeastern University, says that slope failures, or landslides, typically occur “when the shear stress imposed by a loading condition exceeds the shear strength of the foundation soil.”

“These failures don’t happen everywhere. The conditions have to be right,” Shillaber says. “For example, you need a road on top of a slope, and then the slope must have a loading that exceeds the shear strength of the foundation soil. That typically happens as a result of changes in water conditions, such as groundwater levels rising higher than anticipated.”

Shillaber adds that sometimes a slope failure is the result of a failure to identify a weak soil layer in the subsurface. “We hear about these types of failures along California’s coastal Highway 1, for example, with some frequency,” he says.

Read full story at Northeastern Global News

Related Faculty: Craig Shillaber

Related Departments:Civil & Environmental Engineering