Many shales exposed in roadway cut-sections are susceptible to weathering, slaking, and erosion; fallout and taluses clog drainage; benches overflow; and occasionally landslides or rockslides develop. Presently, in design, certain types of shales and even named formations are afforded wider benches than others; soil mantles at the tops of cuts are being stripped back farther; and, of course, sound ledge-rock offers the preferred type of bench-cap. Pre-splitting methods of blasting have greatly enhanced the appearance of cuts and have minimized the shattering of cut faces. The resulting surfaces frequently are quite smooth when first exposed and remain so if the materials are resistant to weathering and erosion. However, erosive shales interbedded between sound rock ledges may eventually cause trouble.

Report Date


Report Number

No. 261

Digital Object Identifier