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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
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Publication Number:  FHWA-HRT-17-047    Date:  September 2017
Publication Number: FHWA-HRT-17-047
Date: September 2017


Appendix F. TRL Scale

Table 11. TRL Scale: Descriptions and requirements.



To achieve the given TRL, you must answer yes to EVERY question. Discuss any uncertain answers.

Basic Research


Basic principles and research

  • Do basic scientific principles support the concept?
  • Has the technology development methodology or approach been developed?


Application formulated

  • Are potential system applications identified?
  • Are system components and the user interface at least partly described?
  • Do preliminary analyses or experiments confirm that the application might meet the user need?


Proof of concept

  • Are system performance metrics established?
  • Is system feasibility fully established?
  • Do experiments or modeling and simulation validate performance predictions of system capability?
  • Does the technology address a need or introduce an innovation in the field of transportation?

Applied Research


Components validated in laboratory environment

  • Are end-user requirements documented?
  • Does a plausible draft integration plan exist, and is component compatibility demonstrated?
  • Were individual components successfully tested in a laboratory environment (a fully controlled test environment where a limited number of critical functions are tested)?


Integrated components demonstrated in a laboratory environment

  • Are external and internal system interfaces documented?
  • Are target and minimum operational requirements developed?
  • Is component integration demonstrated in a laboratory environment (i.e., fully controlled setting)?



Prototype demonstrated in relevant environment

  • Is the operational environment (i.e., user community, physical environment, and input data characteristics, as appropriate) fully known?
  • Was the prototype tested in a realistic and relevant environment outside the laboratory?
  • Does the prototype satisfy all operational requirements when confronted with realistic problems?


Prototype demonstrated in operational environment

  • Are available components representative of production components?
  • Is the fully integrated prototype demonstrated in an operational environment (i.e., real-world conditions, including the user community)?
  • Are all interfaces tested individually under stressed and anomalous conditions?


Technology proven in operational environment

  • Are all system components form-, fit-, and function-compatible with each other and with the operational environment?
  • Is the technology proven in an operational environment (i.e., meet target performance measures)?
  • Was a rigorous test and evaluation process completed successfully?
  • Does the technology meet its stated purpose and functionality as designed?



Technology refined and adopted

  • Is the technology deployed in its intended operational environment?
  • Is information about the technology disseminated to the user community?
  • Is the technology adopted by the user community?




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