Within the Triad, real-time measurement technologies are technologies that provide and manage results quickly enough to affect the course of ongoing field work. The Triad does not try to define "real-time" in terms of the absolute number of seconds or minutes required for the result to be generated, because such a distinction is necessarily arbitrary. Also, as technologies evolve, the expectations of data users for what is considered "real-time" are also evolving. Finally, since the Triad grounds all concepts in the goal of confident decisions, use of the term "real-time" is also grounded in what is required to support project decision-making while work is underway. One outcome of this definition is that a particular measurement or analytical technology may produce results that are "real-time" for the purposes of one field activity (e.g., site characterization), but not for another (e.g., remediation support).

Since Triad terminology defines "real-time" in terms of supporting on-site decision-making, and not in terms of minutes for result turn-around, the term "near real-time" is not typically used in the context of the Triad. Since "real-time" can be measured in days, hours, minutes, or can truly be instantaneous, technologies considered "real-time" within the Triad context encompass a wide range of tools used to evolve the conceptual site model simultaneously with field work. Other environmental practitioners may have equally justifiable reasons to define the term "real-time" differently than Triad usage, and to make distinctions between the terms "real-time" and "near real-time". As with all environmental terminology for which standardized usage does not exist, participants in a particular project should clarify their terminology usage within a specific project to facilitate non-ambiguous communications and consensus.

Although real-time measurement technologies are usually associated with field-based measurement techniques, standard fixed-laboratory methods that have an expedited turnaround are also included by the Triad approach in this broad category of real-time analytical options. The added cost for quick turn-around from a fixed lab can be cost-effective if it leads to more efficient field activities that produce greater savings.

The term "real-time measurement technologies" also includes a variety of rapid turnaround geophysical, geochemical, geotechnical, and global positioning system (GPS) techniques, as well as a range of tools for managing data in real-time. Real-time data management tools usually involve software (and the hardware needed to run them). Not all of the tools need be physically present on-site if provision is made to transfer data electronically between the field and office-based systems. Databases, graphical programs, and statistical algorithms facilitate real-time data storage, retrieval, quality review, display, reduction (i.e., calculations), mapping, and sharing between field and office and among data users. Computer-based data manipulation technologies are critical when large numbers of data points must be rapidly and reliably handled in real-time. Software tools that are used to statistically manipulate or graphically present data rapidly enough to support data users in their decision-making process are frequently termed "decision support software (DSS) tools." The integration of data gathering, processing, and interpretation technologies into an efficient, intercommunicating network can be called a "real-time measurement system."