Scale and Scope of Safety Assessment Methods in the Project Development Process
Long Description
Lane and shoulder width calculations for segments that do not match base conditions. Segment-related lane width crash modification factors are calculated as:
- Lane width crash modification factor equals the product of the crash modification factor for segment-related crashes minus 1 and the proportion of the segment-related crashes that make up all crashes plus 1. Â (HSM Equation 11-13, p. 11-26 with Table 11-11 values and default value of 0.27 for PRA)
- Lane width crash modification factor equals the product of 1.00 minus 1 and 0.27 plus 1 equals 1.00. (≥ 12' Lanes (Existing))
- Lane width crash modification factor equals the product of 1.04 minus 1 and 0.27 plus 1 equals 1.01. (11' Lanes (Alternative))
Segment-related shoulder width crash modification factors are calculated as:
- Shoulder width crash modification factor equals the product of the crash modification factor for segment-related crashes based on shoulder width and the crash modification factor for segment-related crashes based on shoulder type minus 1.0 and the proportion of the segment-related crashes that make up all crashes plus 1.0. (HSM Equation 11-14, p. 11-27 with Table 11-12 and Table 11-13 values and default value of 0.27 for PRA)
- Shoulder width crash modification factor equals the product of the 0.87 and 1.00 minus 1.0 and 1.0 plus 1.0 equals 0.96. (8' paved shoulder (Existing))
Shoulder width crash modification factor equals the product of the 1.00 and 1.00 minus 1.0 and 1.0 plus 1.0 equals 0.96. (6' paved shoulder (Alternative))
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