Reports

Allegany County Highway Rock Cut Inventory and Slope Failure Potential

2023, Brezinski, D.K., Kavage Adams, R., and Sylvia E.R.

Report of Investigations 89

Executive Summary

• One hundred ninety-five MDOT-maintained highway embankments in Allegany County, Maryland were catalogued in an effort to gain insight into the effects of climatic, vegetative, and geology factors on embankment slope stability.
• Information was collected in real-time in ArcGIS Survey123.
• In total, more than 7,000 data observations were made.
• Each exposure was categorized as to location, dimensions, weathering condition, and geologic structure.
• Based on these data, summary evaluations were made as to the potential for rockfall, rock roll, rockslide, or slumping and rotational failures.
• Rockfalls were considered to be most prone to occur in slopes of >60º, composed of massive sandstone or limestone lithologies, and exhibiting major levels of differential erosion.
• The rockfall failure type was identified for twenty-four percent of the slopes studied.
• The most common type of potential slope failure was rock roll, a type of potential failure that was assessed to be present for fifty-one percent of the studied exposures.
• Rock roll potential was typical of exposures comprised of interbedded lithologies, and for slopes of between 30º to 60º.
• Rockslide potential was identified for fourteen percent of the exposures studied, and this failure type was largely confined to strata that were inclined into the roadway.
• Slump or rotational dislocations were identified in eleven percent of the outcrops studied, and their potential tended to be present on highly weathered outcrops that were covered by vegetation.

Downloads and Data

Report of Investigations 89 (pdf, 26 MB)