This report presents the results of a research project to determine the hydraulic characteristics of and to develop design equations for two types of stormwater drainage structures: flush depressed curb inlets and bridge deck drains. Flush depressed curb inlets are so named because the lip of the inlet opening is flush with the curb line and the gutter section adjacent to the inlet opening is depressed. Bridge deck drains consist of grated openings in the bridge deck supported by a drain pan. All of the drainage structure designs tested in this project are used by the Texas Department of Transportation (TxDOT) in the State of Texas. Except for one of the bridge deck drains, no empirical design information existed previously for any of the drainage structures tested in this project. One of the bridge deck drains had been tested previously in a different orientation. To determine the hydraulic characteristics of the drainage structures, models of the structures were tested on a large roadway model. Curb inlets were tested at 3/4 scale; bridge deck drains were tested at full scale. The measurements made during the model studies were correlated to the capacity of the inlets and drains to develop empirical design equations. The performance of curb inlets is usually divided into the following two categories: (1) 100% efficiency, in which the inlet is capturing all of the approach flow, and (2) less than 100% efficiency, in which there is carryover flow. The design method developed in this project for flush depressed curb inlets utilized a new empirical equation for the 100% efficiency capacity of the inlets on the basis of the effective length of the inlet. For less than 100% efficiency, an existing TxDOT design equation was used, also on the basis of the effective inlet length. Two types of bridge deck drains were tested. Empirical design equations were developed for both drains. The equations are a function of the roadway geometry and approach flow conditions.

  • Supplemental Notes:
    • Research study title: Hydraulic Characteristics of Recessed Curb Inlets and Bridge Drains: Phase 2.
  • Corporate Authors:

    University of Texas, Austin

    Center for Transportation Research, 3208 Red River Street
    Austin, TX  United States  78705

    Texas Department of Transportation

    Research and Technology Transfer Office, P.O. Box 5051
    Austin, TX  United States  78763-5051

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Hammonds, M A
    • Holley, E
  • Publication Date: 1995-12


  • English

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 170 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00724959
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/TX-96/1409-1, Res Rept 1409-1, CTR 1409-1
  • Contract Numbers: Study 0-1409
  • Created Date: Aug 26 1996 12:00AM