Simple Design Alternatives to Improve Drainage and Reduce Erosion at Bridge Abutments

Bridge approach settlement and the formation of the bump at the end of the bridge is a common problem that draws upon considerable resources for maintenance. Recently, a field and laboratory investigation was carried out to investigate bridge approach performance problems identified by Iowa DOT personnel. Field inspections of seventy-four existing and under construction bridges in Iowa revealed that inadequate drainage, wetting, induced soil collapse, and erosion are among the primary factors contributing to the approach slab performance problem. By characterizing backfill materials used behind bridge abutments, it was found that the specified granular backfill gradation is within the range of most erodible soils and is susceptible to increased compaction resistance due to the moisture bulking phenomenon. In addition, it was determined that a large portion of granular backfill particles are smaller than the perforation size in commonly used subdrain tile. To eliminate these problems, alternative backfill materials and drainage systems were evaluated in the laboratory using the newly developed scaled Bridge Approach Drainage Model (BADM). Using the BADM, measurements of void size, approach slab settlement, and drainage capacity were determined for thirteen different drainage/backfill designs. The results indicate that drainage performance can be greatly improved with the use of porous backfill, granulated tire chips, or geocomposite drainage systems. This paper presents a summary of the field investigation and simple design recommendations that can be implemented immediately to minimize problems associated with poor drainage, erosion, and void development at bridge approaches.


  • English

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: 13p
  • Monograph Title: Proceedings of the 2005 Mid-Continent Transportation Research Symposium

Subject/Index Terms

Filing Info

  • Accession Number: 01004249
  • Record Type: Publication
  • ISBN: 9780965231084
  • Files: TRIS
  • Created Date: Sep 23 2005 10:38AM