1. 1 Superelevation and Spiral Curves

2. 2 Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4 th Ed.

3. 3

4. 4

5. 5 Source: CalTrans Design Manual online, http://www.dot.ca.gov/hq/oppd/hdm/pdf/chp0200.pdf

6. 6 Maximum Relative Gradiant (G) Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4 th Ed.

7. 7 Source: Iowa DOT Standard Road Plans RP-2 With Spirals Same as point E of GB

8. 8 Source: Iowa DOT Standard Road Plans RP-2 With Spirals Tangent runout (A to B)

9. 9 Source: Iowa DOT Standard Road Plans RP-2 With Spirals Removal of crown

10. 10 Source: Iowa DOT Standard Road Plans RP-2 With Spirals Transition of superelevation Fully superelevated

11. 11 Length of Components (Cont.) Length of Runoff: function of design speed, rate of attainment, and width of lanes – See Exhibit 3-29 p. 174 for two and four lane highways (based on appearance and comfort) Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4 th Ed.