Traffic modeling is guided by a series of professional and administrative guidelines. In the case of the proposed $7.5 Interstate Bridge Replacement Project, IBR and Metro modelers did not follow or violated these guidelines in many ways as they prepared their traffic demand modeling. IBR modelers:
- Didn’t assess accuracy of their previous modeling
- Failed to calibrate their models to observed traffic levels
- Failed to accurately account for capacity constraints
- Ignored other models and more accurate data that contradicted their conclusions
- Failed to exhibit scientific integrity
- Failed to document their data and methods
- Failed to commission an independent review of their analysis
Each of these errors constitutes a violation of professional standards for traffic forecasting, and invalidates the claims made the the IBR Draft Supplemental Environmental Impact Statement.









