Geotechnical investigation, comprising sampling and
in situ
testing, provides ground truthing at specific locations and is, therefore, a key input into ground model development. This article presents the author's perspective on key
in situ
and sampling developments, in chronological order. These geotechnical investigation developments, which have been primarily driven by oil and gas companies, are discussed in the context of their contribution to the four key development drivers, which are “reducing time and cost,” “improving quality,” “increasing capability and durability,” and “improving safety.” The article concludes with summaries of “game changers” and “useful developments that, for assorted reasons, are not currently mainstream.”