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. CDOT 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 CDOT 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: CDOT Highway Design Manual, 2024 Edition. Pages 7–8 of 37.