Roadway Geometric Design: max grade
grade local mountain to grade local rolling
AASHTO Green Book 7th Edition (2018) roadway geometric design standards — stopping sight distance (15–80 mph), passing sight distance (20–70 mph), minimum horizontal curve radius by design speed and emax (4%/6%/8%), K-values for crest and sag vertical curves (25–80 mph), maximum grade limits by terrain type (level/rolling/mountainous) and road class (freeway/arterial/collector/local), superelevation standards, lane and shoulder width standards, and design vehicle dimensions (P, SU, WB-40, WB-62, WB-67).
| parameter type | record id | description | unit | value max (varies) | value min (varies) | value typical (varies) |
|---|---|---|---|---|---|---|
| max grade | grade local mountain | Max grade — local road mountainous terrain | Rural local road; mountainous terrain; absolute maximum steep grade | % | 14 | 15 |
| max grade | grade local rolling | Max grade — local road rolling terrain | Rural local road; rolling terrain | % | 12 | 12 |
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