Clear zones, barriers/end treatments, breakaway hardware — the forgiving-roadside doctrine.
Why: traffic engineers touch it via sign/signal pole placement (breakaway? shielded?), clear zone checks in reviews.
When:
- fixed-object crash patterns
- pole placement review
- barrier warrant sanity checks
Example question:
- clear zone for 45 mph, 4:1 slope, given ADT?
- does this signal pole location need protection?
Related: SPM Plan Review Checklist · Highway Safety Manual (HSM)