U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
Scale and Scope of Safety Assessment Methods in the Project Development Process
Long Description
Estimated Crash Modification Factor for proposed curve for Total Crashes and All Severities calculated as:
- CMF for proposed curve for Total Crashes and All Severities equals the product of 1.55 and the length of curve plus 80.2 divided by the radius of curve minus the product of 0.012 and S; the whole of this is then divided by the product of 1.55 and the length of curve. (HSM Equation 10-13, p. 10-27)
- S equals 1 if a spiral transition curve is present; 0 if spiral transition curve is not present; 0.5 if spiral transition curve is present at one but not both ends of the horizontal curve.
- CMF for proposed curve for Total Crashes and All Severities equals the product of 1.55 and 230 divided by 5280 plus 80.2 divided by 250 minus the product of 0.012 and 0; the whole of this is then divided by the product of 1.55 and 230 divided by 5280 equals 5.71. (Length of curve (converted from feet to miles) – calculates CMF for proposed curve)
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Page last modified on November 18, 2016