Usually, if a research project is evaluated, key metrics like publications in peer reviewed scientific journals or conference contributions get assessed. In the case of a transdisciplinary project, these metrics are not enough to cover and reflect the whole approach. The evaluation, then, becomes rather complex.
Three questions to become familiar with the broad field of evaluating TDR projects are:
WORKING PAPER BY TD-NET
Pohl C et al., 2011. Questions to evaluate inter- and transdisciplinary research proposals.
Working paper, td-net for Transdisciplinary Research, Berne. [pdf]
SYSTEMATIC LITERATURE REVIEW
Belcher, B. M., Rasmussen, K. E., Kemshaw, M. R., & Zornes, D. A. (2016). Defining and assessing research quality in a transdisciplinary context. Research Evaluation, 25(1), 1–17.
Table: Transdisciplinary research quality assessment framework [pdf]
Hansson S., Polk M. (2018). Assessing the impact of transdisciplinary research: The usefulness of relevance, credibility, and legitimacy for understanding the link between process and impact. Research Evaluation, 27(2), 2018, 132–144.