|Research Home | Hydraulics Home|
|This report is an archived publication and may contain dated technical, contact, and link information|
Publication Number: FHWA-HRT-07-026
Date: February 2007
PDF Version (3.67 mb)
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 (MDSHA) in a partnership arrangement in which MDSHA shared the cost of the study. A primary objective of this study was to validate or improve an existing methodology developed by MDSHA for estimating scour in bottomless culverts. The study included experiments to determine stability of rock riprap and to test effectiveness of rock cross vanes and other measures to reduce scour at the foundations of bottomless culverts. This report will be of interest to hydraulic engineers and bridge engineers who are involved in selection and design of structures for small stream crossings. It is being distributed as an electronic document through the Turner-Fairbank Highway Research Center Web site (www.fhwa.dot.gov/research/tfhrc/).
Gary L. Henderson, P.E.
Director, Office of Infrastructure
Research and Development
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof. This report does not constitute a standard, specification, 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.
The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.
|1. Report No.
|2. Government Accession No.
||3. Recipient's Catalog No.
|4. Title and Subtitle
Bottomless Culvert Scour Study: Phase II Laboratory Report
|5. Report Date
|6. Performing Organization Code|
Kornel Kerenyi, J. Sterling Jones, and Stuart Stein
|8. Performing Organization Report No.
|9. Performance 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 and Address
Office of Engineering Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296
|13. Type of Report and Period Covered
May 2002–November 2005
|14. Sponsoring Agency Code|
|15. Supplementary Notes
Contracting Officer’s Technical Representative (COTR): J. Sterling Jones, HRDI-07
The Maryland State Highway Administration (MDSHA) 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. Larry Arneson and Jorge E. Pagán-Ortiz provided technical review of this document.
Bottomless culverts are three-sided structures that use the natural channel for the bottom. These structures could be used to convey flows from one side of a highway to the other. As such, they are an environmentally attractive alternative to box, pipe, and pipe arch culvert designs. Bottomless culverts range in size from less than a meter (1.5 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 represents a significant portion of the cost of this type of structure, overdesign of these elements can add significantly to the cost of the project.
Several dozen physical modeling configurations of bottomless culverts were tested, and the resulting scour at the entrance along the foundation and outlet was measured. Predictive equations for estimating scour depth were developed and compared to MDSHA methodology. These equations will provide guidance for the design of footing depths for bottomless culverts.
The study was conducted in two phases. The first phase focused on measuring maximum scour depths at the culvert entrance and developing an analysis procedure using methods found in the literature to approximate prescour hydraulic parameters that drive the analysis. No fixed-bed experiments were conducted in the first phase to measure actual prescour hydraulic parameters. No submerged entrance experiments were conducted in the first phase. The second phase expanded the investigation to include scour measurements at the outlet, submerged entrance scour measurements, and detailed velocity and depth measurements with a prescour fixed bed at locations where maximum scour occurred. Additional tests were conducted to evaluate the use of various measures to reduce scour including wingwalls, pile dissipators, riprap, and cross vanes.
Phase I results are reported in Kerenyi, K., Jones, J.S., and Stein, S., Bottomless Culvert Scour Study: Phase I Laboratory Report, FHWA-RD-02-078, 2003.
|17. Key Words:
Scour, culverts, 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 Classification (of this report)
|20. Security Classification (of this page)
|21. No. of Pages
Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
Topics: research, infrastructure, hydraulics
Keywords: research, infrastructure, hydraulics, Scour, culverts, hydraulics, physical model
TRT Terms: research, hydraulics, hydrology, fluid mechanics, earth sciences, geophysics