Choices range from free academic tools to subscription-based services—which calculators do experienced engineers rely on for critical structural checks?
For formal load ratings, AASHTOWare Bridge Rating is what most DOTs lean on; I pair it with a small Mathcad sheet to ‘trust, but verify’ axle groups and distribution factors. Free online calculators (e.g., SkyCiv’s beam tool) are fine for quick sanity checks, but I wouldn’t base LRFD/LRFR sign‑off on them — belt and suspenders. Are you after preliminary sizing or a full LRFR check?