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Level II scour analysis for Bridge 25 (BRNATH00290034) on Town Highway 29, crossing Locust Creek, Barnard, Vermont

Open-File Report 96-642
Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration
By:  and 
https://doi.org/10.3133/ofr96642

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Abstract

This report provides the results of a detailed Level II analysis of scour potential at structure BRNATH00290034 on Town Highway 29 crossing Locust Creek, Barnard, Vermont (figures 1-8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D.

The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 11.5-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest, except for pasture on the downstream right overbank.

In the study area, Locust Creek has an incised, generally straight channel with a slope of approximately 0.03 ft/ft, an average channel top width of 64 ft and an average channel depth of 7 ft. The predominant channel bed materials are gravel and cobble with a median grain size (D50) of 89.3 mm (0.293 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 13, 1994 and December 16, 1994, indicated that the reach was stable.

The Town Highway 29 crossing of Locust Creek is a 37-ft-long, one-lane bridge consisting of one 32-foot concrete span (Vermont Agency of Transportation, written communication, August 23, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 25 degrees to the opening while the opening-skew-to-roadway is 25 degrees. There was no observable scour protection measure at the site. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Level II scour analysis for Bridge 25 (BRNATH00290034) on Town Highway 29, crossing Locust Creek, Barnard, Vermont
Series title Open-File Report
Series number 96-642
DOI 10.3133/ofr96642
Year Published 1996
Language English
Publisher U.S. Geological Survey
Description iv, 50 p.
Country United States
State Vermont
City Barnard
Other Geospatial Locust Creek
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