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
The CMF for left side barrier, based on HSM equation 19-38, p.19-51, is calculated as:
- Crash modification factor for left side barrier on a site of type w, cross section x, crash type y, and severity z equals the product of 1.0 minus the proportion of segment length with a barrier present on the left side and 1.0 plus the product of the proportion of segment length with a barrier present on the left side and the exponential of a divided by the distance from the edge of left shoulder to barrier face, where
- The distance from the edge of left shoulder to barrier face equals the summation of the length of left side lane paralleled by barrier i divided by the summation of the length of left side lane paralleled by barrier i divided by the horizontal clearance from the edge of the traveled way to the face of left side barrier minus the paved left shoulder width. (HSM equation 19-76, p.19-72)
- The distance from the edge of left shoulder to barrier face equals the summation of 0.02 plus 0.05plus 0.10 divided by the summation of 0.02 divided by the sum of 8 minus 7 and 0.05 divided by the sum of 8 minus 7 and 0.10 divided by the sum of 8 minus 7 equals 1.
- Crash modification factor for left side barrier on a C-D road, one-lane, multi-vehicle, and fatal and injury severity equals the product of 1.0 minus 0.17 divided by 0.50 and 1.0 plus 0.17 divided by 0.50 multiplied by the exponential of 0.210 divided by 1. (HSM Table 19-29, p.19-51)
- Crash modification factor for left side barrier on a C-D road, one-lane, multi-vehicle, and fatal and injury severity equals 1.079.
- Crash modification factor for left side barrier on a C-D road, one-lane, multi-vehicle, and property damage severity equals the product of 1.0 minus 0.17 divided by 0.50 and 1.0 plus 0.17 divided by 0.50 multiplied by the exponential of 0.193 divided by 1. (HSM Table 19-29, p.19-51)
- Crash modification factor for left side barrier on a C-D road, one-lane, multi-vehicle, and property damage severity equals 1.072.
- Crash modification factor for left side barrier on a C-D road, one-lane, single-vehicle, and fatal and injury severity equals the product of 1.0 minus 0.17 divided by 0.50 and 1.0 plus 0.17 divided by 0.50 multiplied by the exponential of 0.210 divided by 1. (HSM Table 19-29, p.19-51)
- Crash modification factor for left side barrier on a C-D road, one-lane, single-vehicle, and fatal and injury severity equals 1.079.
- Crash modification factor for left side barrier on a C-D road, one-lane, single-vehicle, and property damage severity equals the product of 1.0 minus 0.17 divided by 0.50 and 1.0 plus 0.17 divided by 0.50 multiplied by the exponential of 0.193 divided by 1. (HSM Table 19-29, p.19-51)
- Crash modification factor for left side barrier on a C-D road, one-lane, single-vehicle, and property damage severity equals 1.072.
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Page last modified on November 18, 2016