This fifth edition of AASHTO's "Green Book" contains the latest design practices in universal use as the standard for highway geometric design and has been updated to reflect the latest research on superelevation and side friction factors as presented in NCHRP Report 439. New exhibits in Chapter 3 will help designers to quickly and accurately determine the side friction factor used for horizontal curve design, the superelevation rates for various curve radii, and the minimum radii with normal crown for each of the five maximum superelevation rates.