Mechanically stabilized earth (MSE) walls are rapidly becoming more common than conventional cast-in-place concrete walls for a variety of highway and other civil applications. MSE walls and reinforced soil slopes (RSSs) consist of a geosynthetic material layered with compacted earth. Easily constructed and highly durable, these structures are inexpensive when compared with other more traditional wall or slope-construction methods, and can tolerate large differential settlements. However, failures of MSE walls and RSSs have occurred. Most of these failures can be traced to poor construction practices and inadequate inspection. There is a shortage of well-trained construction inspectors for MSE walls / RSSs and an associated lack of systematic training materials to produce qualified inspectors. To counter this trend, Geosyntec was selected as part of a teaming arrangement by the Federal Highway Administration (FHWA) and National Highway Institute (NHI) to prepare a training course for various state Departments of Transportation (DOT) construction personnel.
Geosyntec's Scope of Services
Geosyntec worked with the FHWA and NHI to develop a thorough curriculum for a course on MSE wall inspection. The curriculum included: (i) an overview of MSE walls/RSS design; (ii) a description of construction methods and sequencing; (iii) guidance for how to interpret the important aspects of reports relating to site and geotechnical conditions; (iv) detailed instructions for reviewing design plans, shop drawings, and specifications; (v) administrative procedures for compliance review of technical submittals and pay requisites from the contractor; and (vi) detailed procedures for all aspects of performing field inspections during MSE wall/RSS construction. We presented the course to various agencies and eventually transitioned the course materials to NHI for their instructors to teach.
The FHWA and NHI retained Geosyntec due to our well-earned reputation for pioneering work in the design and construction of MSE walls and RSS around the United States, having worked on dozens of such projects during the past several years. The training curriculum and associated testing requirements will ensure that state DOT inspectors now have a deeper understanding of what may cause MSE walls or RSSs to fail, and a clear set of procedures in place to scrutinize all aspects of construction with the ultimate goal of preventing such failures.