Design and analyze walls following accepted geotechnical engineering industry standards. In analyses, use earth pressures that follow governing sections of the current edition of the AASHTO

Standard Specifications for Highway Bridges

. For load conditions or walls that are not specifically covered by AASHTO, refer to the for recommendations.

The project engineer must ensure that the retaining wall system is appropriate for its location. Check walls to ensure minimum factors of safety are met for all potential modes of failure. These include sliding, overturning, bearing pressure, and global stability. Consult governing wall standard sheets for assumptions and minimum factors of safety for various modes of failure. The minimum global factor of safety is set at 1.3 for conditions where the designer has adequate soils laboratory and field testing data on which to base the analysis. 

Make the global safety factor 1.5 or greater

 where the data obtained for the design and analysis is based primarily on strength correlations 

or walls that support abutment, buildings, critical utilities, or for other installations with a low tolerance for failure

. If a TxDOT retaining wall standard is used for the wall design, it is the designer's responsibility to validate the strength values shown on the retaining wall standard used. If the actual soil conditions show a strength weaker than that shown on the governing standard the designer must determine what modifications, if any, are necessary to the standard and if any ground improvements are necessary to ensure wall performance.

Avoid perching walls on slopes. When walls must be placed on slopes, conduct both short- and long-term stability analyses using appropriate soil strengths, geometry, and loading conditions (live load surcharge, hydrostatic, etc.).