The bottomless culvert study described in
this report was conducted at the Federal Highway Administration (FHWA) hydraulics laboratory in response to a request by the Maryland State Highway Administration (SHA) in a partnership
arrangement in which the Maryland SHA shared the cost of the study. Two
suppliers, CONTECH® and CONSPAN®, agreed
to provide models of the typical configurations that are used for highway
applications. Part of the study objective was to compare results from a
simple rectangular shape to the results from shapes that are typically
available from the suppliers. This report presents the results of laboratory experiments; it
does not represent FHWA policy or endorsement of design concepts. This report
is being distributed as an electronic document through the Turner- Fairbank Highway
Research Center web Web site (www.tfhrc.gov).
T. Paul Teng, P.E.
Director, Office of Infrastructure
Research and Development
This document is disseminated under the sponsorship of the U.S. Department of OTransportation in the
interest of information exchange. The United StatesU.S. Government assumes no liability for its
contents or use thereof. This report does not constitute a standard, specification,
policy, or regulation.
The U.S. Government does not endorse products or manufacturers. Trade and manufacturers' names appear in this report only because they are considered essential to the object of the document.
|1. Report No.|
|2. Government Accession No.||3. Recipient's Catalog No.|
|4. Title and Subtitle|
BOTTOMLESS CULVERT SCOUR STUDY: PHASE I LABORATORY REPORT
|5. Report Date|
|6. Performing Organization Code|
Kornel Kerenyi, J. Sterling Jones, and Stuart Stein
|8. Performing Organization Report No.|
|9. Performing Organization Name and Address|
GKY and Associates, Inc.
5411-E Backlick Road
Springfield, VA 22151
|10. Work Unit No. (TRAIS)|
|11. Contract or Grant No.|
|12. Sponsoring Agency Name and Address|
Office of Infrastructure Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, Virginia 22102-2296
|13. Type of Report and Period Covered|
March 2000-December 2000
|14. Sponsoring Agency Code|
|15. Supplementary Notes|
Contracting Officer's Technical Representative (COTR): J. Sterling Jones, HRDI-07The Maryland State Highway Administration (SHA) provided technical assistance and partial funding for this study. Dr. Fred Chang was instrumental in setting up the experimental plan and provided a data analysis strategy. Dr. Xibing Dou provided numerical model results.
Bottomless culverts are three-sided structures that have sides and a top and use the natural channel for the bottom. As such, they are an environmentally attractive alternative to box, pipe, and pipe arch culvert designs. Bottomless culverts range in size from a few feet to more than 10 meters (35 feet) in width. The failure of such a structure could have severe consequences similar to the failure of a bridge. On the other hand, since the cost of the foundation and scour countermeasures represent a significant portion of the cost of the structure, overdesign of these elements can add significantly
to the cost of the project. The Maryland SHA funded a study of scour at bottomless culverts. Several dozen physical modeling configurations were tested and the resulting scour was measured. The results were evaluated
and predictive equations for estimating scour depth were developed. These equations will provide guidance for the design of footing depths for bottomless culverts. Additional tests were conducted to determine the riprap sizes needed to prevent the deep scour that was observed near the upstream corners of the culvert when there was substantial approach
flow blocked by the roadway embankments. These tests were preliminary and are not an indication that the Federal Highway Administration endorses the concept of using a countermeasure to reduce foundation depth.
|17. Key Words
hydraulics, physical model.
|18. Distribution Statement|
No restrictions. This document is available to the public through
the National Technical Information Service (NTIS), Springfield, VA 22161.
|19. Security Classif. (of this report)|
|20. Security Classif. (of this page)|
|21. No. of Pages
LIST OF ACRONYMS AND ABBREVIATIONS
|AASHTO||American Association of State Highway and Transportation Officials|
|COTR||Contracting Officer's Technical Representative|
|DOT|| Department of Transportation|
|FHWA|| Federal Highway Administration|
|MSE||Mean Square Error|
|NTIS||National Technical Information Service|
|RSQ ||Correlation Coefficient|
|SG|| Specific Gravity|
|SHA|| State Highway Administration|
|SI||International System of Units (metric system)|
|SMB|| Shields, Manning, and Blodgett|
|TFHRC|| Turner-Fairbank Highway Research Center|
|VI|| Virtual Instruments|
|VR||Representative Velocity |
|W.S.|| Water Surface|