TENTATIVE CRITERIA FOR DESIGN OF SAFE SLOPING CULVERT GRATES

SOME HIGHWAY DRAINAGE STRUCTURES HAVE A GEOMETRICAL CONFIGURATION THAT CAN CAUSE AN ERRANT AUTOMOBILE TO COME TO AN ABRUPT STOP OR VEER OUT OF CONTROL. ONE SUCH STRUCTURE IS THE END CULVERT INLET WITH OR WITHOUT HEAD-WALLS. IN RECENT YEARS, HIGHWAY ENGINEERS HAVE USED SLOPING INLET AND OUTLET GRATES THAT ALLOW AN AUTOMOBILE TO TRAVERSE THE CULVERT OPENING RATHER THAN COME TO AN ABRUPT STOP. SLOPING GRATES ARE CURRENTLY DESIGNED ON THE BASIS OF JUDGMENT AND EXPERIENCE BECAUSE OBJECTIVE CRITERIA ARE PRACTICALLY NONEXISTENT. A MATHEMATICAL SIMULATION TECHNIQUE, WAS USED TO INVESTIGATE THE DYNAMIC BEHAVIOR OF A SELECTED STANDARD- SIZE AUTOMOBILE TRAVERSING A MEDIAN CONTAINING A CROSSOVER AND A SLOPING CULVERT INLET GRATE. TWENTY-THREE COMPUTER SIMULATIONS WERE MADE. IT WAS DETERMINED THAT 8:1 DITCH SIDE SLOPES AND 10:1 CULVERT GRATE SLOPES PRODUCED TOLERABLE AUTOMOBILE ACCELERATIONS TO AN UNRESTRAINED OCCUPANT. STEEPER COMBINATIONS OF SIDE AND GRATE SLOPES WERE FOUND TO PRODUCE SEVERE ACCELERATIONS AND/OR ROLL-OVER AND SHOULD BE AVOIDED WHERE POSSIBLE. FOR PURPOSES OF STRUCTURAL DESIGN, IT WAS FOUND THAT THE DYNAMIC TIRE LOAD ON 8:1 AND FLATTER GRATE SLOPES WAS ABOUT FIVE TIMES THE AUTOMOBILE CURB WEIGHT. FOR 6:1 AND STEEPER GRATE SLOPES, THE DYNAMIC TIRE LOAD REACHED VALUES OF ABOUT 10 TIMES THE AUTOMOBILE CURB WEIGHT. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1972/386/386-0010.pdf
• Supplemental Notes:
  • Sponsored by Committee on Traffic Safety Barriers and Sign, Signal and Lighting Supports. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
• Authors:
  • Ross Jr, Hayes E
  • Post, Edward R
• Conference:
  • 51st Annual Meeting of the Highway Research Board
  • Location: Washington District of Columbia, United States
  • Date: 1972-1-17 to 1972-1-21
• Publication Date: 1972

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: pp. 101-110
• Monograph Title: Traffic safety barriers, lighting supports and dike slopes
• Serial:
  • Highway Research Record
  • Issue Number: 386
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Automobiles; Computers; Culverts; Drainage structures; Grates; Simulation; Slopes
• Subject Areas: Bridges and other structures; Design; Highways;

Filing Info

• Accession Number: 00203661
• Record Type: Publication
• Report/Paper Numbers: No 386
• Files: TRIS, TRB
• Created Date: Oct 15 1972 12:00AM