SECTION 1 INTRODUCTION
This geotechnical Technical Guidance Manual (TGM) provides technical guidance for
geotechnical work performed by the Federal Lands Highway (FLH). It provides guidance for
understanding and applying policies, standards and criteria in recognition of the need to
manage financial and public safety risk and accomplish the missions of FHWA, FLH and partner
agencies. Specific topics include geotechnical reconnaissance, site and subsurface
investigation, analysis and design, reporting, PS&E involvement, construction support,
performance monitoring, emergency response and consultant roles.
The guidance in this TGM supports the policies, standards and standard practices presented in
Chapter 6 of the Project Development and Design Manual (PDDM). Additionally, the TGM
provides guidance for activities where standards and standard practices do not exist and it
provides access to and guidance for the use of new technologies. Chapter 6 of the PDDM is
the source for general direction on “what” should be performed, whereas guidance herein
provides recommendations and options for “how” to perform these tasks.
Like the PDDM, the TGM is intended to be used primarily as a web-based electronic reference
document. Not all guidance is presented directly in the manual. When published sources
present guidance that satisfies the requirements of FLH, or does so with only minor modification
required, the TGM provides citations and links to those sources. If necessary, commentary on
the application of these sources is provided here. This is done to keep the TGM small and more
manageable, and also to allow easy and timely incorporation of new guidance as it is developed
and published by FLH, FHWA and others.
Technical guidance references cited and linked in this manual are classified as either “Primary”,
or “Secondary”. Primary sources either present preferred guidance on how to accomplish a
task or, when equal guidance is available through many sources, the Primary source is most
widely available. “Secondary” sources are additional documents that are often relied on for FLH
work; they present guidance to augment the Primary source.
The PDDM presents work requirements through the official statement of policy and standards
so it is an essential companion manual to the TGM. The TGM does not stand alone; policies
and standards are repeated here only as necessary to offer guidance on their application. If
discrepancy in the statement of policy or standards exists, the PDDM has precedence.
