A handwritten or spreadsheet-based PDF cannot be "fixed" directly; it must be re-modeled. The gold standard fix is to re-enter the corrected geometry and loads into FEA software (e.g., STAAD.Pro, SAP2000) or dedicated culvert design tools (e.g., CASTON, AASHTOWare BrR).

Often neglected, but crucial for large spans. Step 3: Structural Modeling The culvert is typically modeled as a rigid frame .