The state of the practice of MSE wall design for highways has become more
complex as more and more systems, engineers and researchers have become
involved. There are correct ways to design MSE walls, to apply traffic surcharge, to
select design parameters and backfill, to assess service life, to address special design
conditions such as bridge abutments, traffic barriers and earthquakes, and to select the
wall design method itself. Yet the complexity persists, arising from policy changes
and from the multitude of conflicting design choices.
Designers are forced to be familiar with the Coherent Gravity, the Simplified
(Tieback Wedge) and occasionally other methods, with the ASD and LRFD design
platforms, with metric and U.S. customary units, with design guidelines issued by
AASHTO and NHI, and with numerous, differing governmental specifications.
Designers are understandably confused by the conflicting guidance and clarification
is needed. This clarification can be achieved through the following steps:
• Continued and exclusive use of AASHTO specifications for MSE wall design
• NHI courses should teach material consistent with AASHTO
• Require the Coherent Gravity Method for design of MSE walls with
inextensible reinforcements
• Require the Simplified Method for design of MSE walls with extensible
reinforcements
Today's challenge is to restore basic principles to the design of MSE walls for
highways to ensure that Mechanically Stabilized Earth structures continue to meet the
structural and economic needs of transportation infrastructure for years to come