<p>This paper aims to present a model for measuring urban transportation sustainability in Tehran (capital of Iran) with an uncertainty approach. The study is applied in nature, with a cross-sectional data collection period and a mixed-methods research design. The qualitative sample consists of 22 experts in the fields of transportation, environment, and industrial engineering, selected purposively until theoretical saturation was achieved. In the quantitative section, data were collected from 140 managers and experts in the field of public transportation sustainability. Data collection tools included semi-structured interviews and questionnaires. The validity of the qualitative section was assessed and confirmed according to Lincoln and Guba’s criteria. Reliability for the qualitative section was estimated at 0.652 using Holsti’s formula. For measuring the validity of the questionnaire, both convergent and divergent validity, as well as composite reliability and Cronbach’s alpha, were applied. Data analysis for the qualitative section was conducted using grounded theory and MAXQDA software, while the quantitative section employed Partial Least Squares (PLS) and SMART PLS software. The results showed that the economic dimension, with factor loadings ranging from 0.504 to 0.852 and a reliability coefficient of 0.938, demonstrates high reliability. The social dimension, with factor loadings ranging from 0.405 to 0.825 and a reliability coefficient of 0.915, indicates its adequacy in evaluating social aspects. The environmental dimension, with factor loadings between 0.549 and 0.748 and a reliability coefficient of 0.923, also shows high reliability. In this model, the relationships between all three dimensions and the concept of public transportation sustainability are strong and significant, highlighting that each of these dimensions plays an important role in achieving sustainability in public transportation.</p>