Horizontal alignment design shall follow AASHTO Green Book criteria for design speed, radius, superelevation, and sight distance. Minimum curve radius is determined by the design speed and maximum superelevation rate. GDOT uses a maximum superelevation rate of 10% for rural highways and 6% for urban facilities. Compound curves require a ratio of long radius to short radius not exceeding 1.5:1. Broken-back curves (closely spaced curves in the same direction) are discouraged per GA design policy.
All work under this section shall comply with GDOT 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: GDOT Highway Design Manual, 2024 Edition. Pages 5–6 of 37.