Page 106 - Highway Engineering Handbook Building and Rehabilitating the Infrastructure

HIGHWAY LOCATION, DESIGN, AND TRAFFIC 89

Figure 2.8 shows a graphic comparison of the various methods. Method 5 is most
commonly used on rural and high-speed [50 mi/h (80 km/h) or higher] urban high-
ways. Method 2 is used on low-speed urban streets and temporary roadways.
Recommended minimum radii for a given range of design speeds and incremental
superelevation rates are given in Tables 2.7 through 2.11, where each table represents

DEGREE OF CURVE (or 1/R)

DEGREE OF CURVE (or 1/R)

DEGREE OF CURVE (or 1/R)

FIGURE 2.8 Methods of distributing superelevation and side
friction. (a) Superelevation. (b) Corresponding friction factor at
design speed. (c) Corresponding friction factor at running speed. (From
A Policy on Geometric Design of Highways and Streets, American
Association of State Highway and Transportation Officials, Washington,
D.C., 2004, with permission)