Effects of Debris on Bridge-Pier Scour

Waterborne debris, composed primarily of tree trunks and limbs, often accumulates on bridges during flood events. Debris accumulations can obstruct, constrict, or redirect flow through bridge openings resulting in flooding, damaging loads, or excessive scour at bridge foundations. The size and shape of debris accumulations vary widely, ranging from a small cluster of debris on a bridge pier to a near complete blockage of a bridge waterway opening. Debris accumulation geometry is dependent on the characteristics and supply of debris transported to bridges, on flow conditions, and on bridge and channel geometry. Little information is available to state highway agencies for predicting the size and geometry of typical debris accumulations. The effects of debris accumulation can vary from minor flow constrictions to severe flow contraction resulting in significant bridge foundation scour. In order to make prudent decisions in designing bridge-pier foundations, state highway agencies need reliable, accurate methods of predicting pier scour caused by debris accumulations. During flood events, decisions also have to be made about the stability of existing bridges and public safety, but current methods for assessing bridge-pier scour caused by debris accumulations are inadequate to make these decisions with confidence. There is a need for accurate methods of quantifying the effects of debris on scour at bridge-pier foundations, for use by highway agencies in the design, operation, and maintenance of highway bridges. The objectives of this research are to develop (a) guidelines for predicting the size and geometry of debris accumulations at bridge piers and (b) methods for quantifying scour at bridge piers resulting from debris accumulations.


  • English


  • Status: Completed
  • Contract Numbers:

    Project 24-26

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Reynaud, David

  • Performing Organizations:

    Owen Ayres Associates, Incorporated

  • Principal Investigators:

    Lagasse, Peter

  • Start Date: 20040618
  • Expected Completion Date: 0
  • Actual Completion Date: 20100131
  • Source Data: RiP Project 9017

Subject/Index Terms

Filing Info

  • Accession Number: 01463109
  • Record Type: Research project
  • Source Agency: National Cooperative Highway Research Program
  • Contract Numbers: Project 24-26
  • Files: RiP, USDOT
  • Created Date: Jan 3 2013 2:16PM