TERRACED HIGHWAY SIDE SLOPES IN LOESS, SOUTHWESTERN IOWA

Abstract

Research Article| December 01, 1950 TERRACED HIGHWAY SIDE SLOPES IN LOESS, SOUTHWESTERN IOWA CHARLES S GWYNNE CHARLES S GWYNNE IOWA STATE COLLEGE, AMES, IOWA Search for other works by this author on: GSW Google Scholar GSA Bulletin (1950) 61 (12): 1347–1354. https://doi.org/10.1130/0016-7606(1950)61[1347:THSSIL]2.0.CO;2 Article history received: 29 Dec 1948 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation CHARLES S GWYNNE; TERRACED HIGHWAY SIDE SLOPES IN LOESS, SOUTHWESTERN IOWA. GSA Bulletin 1950;; 61 (12): 1347–1354. doi: https://doi.org/10.1130/0016-7606(1950)61[1347:THSSIL]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract In 1940 the Iowa State Highway Commission made use of an experimental terraced type of design for highway side slopes along a 4-mile east-west route through the loess of Harrison County, Iowa. Relief along the route is 250 feet, and road cuts as deep as 80 feet were required. Terraces were 15 feet high and 15 feet wide; treads were sloped along the length and toward the base of the risers. It was believed that this design would have advantages over the conventional side slopes of 1-to-l to 3-to-l ratio. The risers, being in loess, would tend to maintain verticality, but the hazard involved in single vertical cuts of as much as 80 feet would be avoided. Such slopes would be less subject to raindrop and rivulet erosion.Spalling of risers, principally the result of changing stress conditions, commenced within a year. Almost all risers have now been affected to some extent. The greatest changes have been the result of rivulet erosion down the risers, presently developing as a consequence of the accumulation of sloping piles of material on the treads. Deterioration has been greatest on the slopes of the south side of the road; the loess does not dry out as readily, and freezing becomes more effective; more debris accumulates on the treads, and slope wash increases.Although the slopes now have a ragged appearance, the design is considered reasonably successful as far as maintenance requirements are concerned. Further experimentation is being considered. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.