Consideration of Roadside Features in the Highway Safety Manual (2022) / Chapter Skim
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Pages 26-35
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From page 26... ...
26 METHOD RUN-OFF-ROAD CRASH PREDICTION MODEL FORM The functional form of the Run-off-Road (ROR) prediction model includes two crash modification functions: CMFROADWAY and a CMFROADSIDE.
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27 Where: XSHLD = Proportion of the segment edge where longitudinal barriers are installed where 0 ≤ XSHLD ≤ 1. XUNSHLD = Proportion of the segment edge where there are unshielded ditches or roadside slopes and other unshielded fixed objects where 0 ≤ XUNSHLD ≤ 1.
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28 This dataset is available within RSAPv3.
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29 increasing milepost direction will hereafter be noted as the primary direction of travel and the decreasing milepost will be the opposing direction. The outside right edge in the increasing milepost direction is therefore the primary right edge (PRE)
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30 crash because it was traveling primary direction and exited the road to the left just before hitting a fixed object. Another example would be if the vehicle traveling in the opposing direction entered the median of a divided road then crossed through the median and became involved in a head-on collision in the opposite (i.e., primary)
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31 A longitudinal barrier (LB) crash subset of the complete (ROR)
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32 A higher p-value only indicates that the results have not proven the null hypothesis false, not that the null hypothesis is true. The p-value cannot be relied on alone.
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33 The Full Bayes (FB) method is a modeling approach comparable to Generalized Linear Regression.
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34 A negative binomial regression model of the edge crashes was estimated for both divided and undivided highways. The model relates the explanatory variables to the response variable using the method of maximum likelihood to quantify the magnitude of the relationship.
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35 an OC crash. Therefore, 𝑆𝑆(𝐿𝐿𝐿𝐿 ∪ 𝑂𝑂𝐶𝐶)
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