TTI Research Supervisor:
Chiara Silvestri, Ph.D.
Texas Transportation Institute
Texas A&M University System
College Station, Texas 77843-3135
(979) 845-8971 [email protected]
Pooled Fund Technical Representative:
Jeff Jones, Director
Tennessee Department of Transportation
James K. Polk State Office Building
Nashville, TN 37243-0348
(615) 741-2221 [email protected]
The purpose of this study was to suggest and explore a crashworthy design option of median barriers for use as grade separation on split level highways. The median barrier had also to perform as a retaining wall. Geo-technical analysis included determining the stability of the retaining median wall by both evaluating factors of safety, that is, with respect to sliding, bearing capacity, and overturning, and by verifying the stability according to the Load Resistance Factor Design (LRFD) method suggested by the American Association of State Highway and Transportation Officials (AASHTO).
Researchers optimized the barrier segment lengths with the scope to maintain the capability of the barrier to resist forces causing sliding and overturning. The authors optimized the minimum barrier segment length needed to resist soil forces and MASH TL-3 and TL-4 impact conditions. The crashworthiness and stability of the sloped median wall were evaluated using finite element analyses. These analyses resulted in acceptable barrier performance according to the criteria set forth in MASH for longitudinal barriers, and soil retention according to AASHTO 2007.