Vertical alignment design covers grade selection, vertical curves, and sight distance. Maximum grades are determined by terrain classification and design speed per AASHTO Green Book Table 3-3. ADOT maximum grades: Level terrain 3-5%, Rolling terrain 4-7%, Mountainous terrain 6-10%. Crest vertical curves require minimum K-values for stopping sight distance. Sag vertical curves require minimum K-values for headlight sight distance and rider comfort (A/46.5).
All work under this section shall comply with ADOT current standards and applicable AASHTO, ASTM, and federal requirements. The Engineer has authority to accept or reject materials and workmanship that do not conform to the specifications.
Source: ADOT Highway Design Manual, 2024 Edition. Pages 7–8 of 37.