Scale and Scope of Safety Assessment Methods in the Project Development Process

Long Description

Equations for calculating CMFs for median width, lighting, and automated speed enforcement are as follows:

Crash modification factor for Median Width

• The crash modification factor for median width equals 0.99. (Median width = 20 feet)

Crash modification factor for Lighting

• The crash modification factor for lighting equals the product of the proportion of total crashes for unlighted roadway segments that occur at night and the difference between 1.0 and the product of 0.72 and the proportion of total nighttime crashes for unlighted roadway segments that involve a fatality or injury and the product of 0.83 and the proportion of total nighttime crashes for unlighted roadway segments that involve property damage only; the resultant value is subtracted by 1. (HSM Equation 12-34, p. 12-42)
• The crash modification factor for lighting equals the product of 0.410 and the difference between 1.0 and the product of 0.72 and 0.364 and the product of 0.83 and 0.636; the resultant value is subtracted by 1 equals 0.913. (HSM Table 12-23, p. 12-42 (4D))

Crash modification factor for Automated Speed Enforcement

• The crash modification factor for Automated Speed Enforcement equals 0.95. (Automated Speed Enforcement Present per HSM, P. 12-43)

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