Improving Motor Carrier Safety Measurement (2017) / Chapter Skim
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Appendix B: Details of the Safety Measurement System Algorithm
Appendix B: Details of the Safety Measurement System Algorithm
Pages 135-144
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From page 135... ...
Inspection data include: date/time of the inspection, truck or bus carrier, vehicle configuration, cargo body type, gross vehicle weight range, date, state and county, inspection level, number of violations, and whether the vehicle had enough hazardous material to require a placard. Violation data -- which are able to be linked to the relevant inspection -- include violation code, whether a citation was issued, whether the violation has been adjudicated and the result, whether the violation is a postcrash violation, whether the violation resulted in an out-of-service order, the associated Behavior Analysis and Safety Improvement Categories (BASICs)
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From page 136... ...
, and a lower weight is assigned other ise. The crash severity weights are as follows: w Crash Type Crash Severity Weight Involves tow-away but no injury 1 Injury or fatality 2 Involves an HM release Crash Severity Weight + 1 Time Weights.
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From page 137... ...
. Third, for the Unsafe Driving BASIC, for behaviors that usually prompt an inspection, such as speeding or swerving, the normalization TABLE B-1 Definition of Utilization Factors for Combination Segment Combination Segment Vehicle Miles Traveled (VMT)
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From page 138... ...
Example violations include: speeding, reckless driving, improper lane change, texting while operating a CMV, not wearing safety belts.2,3 The measure is defined as follows: Total of time and severity weighted violations Unsafe Driving Measure = Average PUs × Utilization Factor • HOS [Hours of service] Compliance BASIC -- This BASIC mea sures "Operation of CMVs by drivers who are ill, fatigued, or in noncompliance with the HOS regulations.
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From page 139... ...
Example viola tions include: inoperative brakes, lights, and other mechanical defects, improper load securement, failure to make required repairs." The equa tion used to calculate the BASIC is as follows: Total of time and severity weighted violations Vehicle Maintenance Measure = Total time weight of relevant inspections • Controlled Substances/Alcohol BASIC -- This BASIC measures "Operation of CMVs by drivers who are impaired due to alco hol, illegal drugs, and misuse of prescription or over-the-counter medications. Example violations include: use or possession of con trolled substances or alcohol, failing to implement an alcohol and/or controlled substance testing program." The measure is defined as follows: Total of time and severity weighted violations Controlled Substances/Alcohol Measure = Total time weight of relevant inspections (Since all such violations are considered to be out-of-service vio lations, it is not the case that two additional severity points are added to any violations for this BASIC.)
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From page 140... ...
, being medically unqualified to operate a CMV, failing to maintain driver qualification files." The measure is computed as follows: Total of time and severity weighted violations Driver Fitness Measure = Total time weight of relevant inspections • Crash Indicator BASIC -- This BASIC measures "Historical pat tern of crash involvement, including frequency and severity. The BASIC is based on information from state-reported crashes that meet reportable crash standards.
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From page 141... ...
STRATIFICATION BY TYPE AND SIZE OF CARRIER SMS makes use of two types of stratifications in the sense that its computations and rankings are carried out separately within these strata: Type of Carrier. Unsafe Driving and Crash Indicator BASICs are stratified (referred to as being segmented)
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From page 142... ...
142 TABLE B-3 Definitions of Combination Safety Event Groups Hours-of- Controlled Hazardous Unsafe Service Vehicle Substance/ Materials Crash Safety Event Driving Compliance Maintenance Alcohol Compliance Driver Fitness Indicator Group BASIC BASIC BASIC BASIC BASIC BASIC BASIC Number of Inspections with Unsafe Number of Number of Number of Number of Number of Driving Relevant Relevant Relevant Relevant Relevant Number of Violations Inspections Inspections Inspections Inspections Inspections Crashes 1 3–8 3–10 5–10 1 5–10 5–10 2–3 2 9–21 11–20 11–20 2 11–15 11–20 4–6 3 22–57 21–100 21–100 3 16–40 21–100 7–16 4 58–149 101–500 101–500 4+ 41–100 101–500 17–45 5 150+ 501+ 501+ 101+ 501+ 46+
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From page 143... ...
TABLE B-4 Definitions of Straight Safety Event Groups Hours-of- Controlled Hazardous Service Vehicle Substance/ Materials Crash Safety Event Unsafe Driving Compliance Maintenance Alcohol Compliance Driver Fitness Indicator Group BASIC BASIC BASIC BASIC BASIC BASIC BASIC Number of Inspections with Unsafe Driving Number of Violations Crashes 1 3–4 See above for See above for See above for See above for See above for 2 combination combination combination combination combination 2 5–8 3–4 segment segment segment segment segment 3 9–18 5–8 4 19–49 9–26 5 50+ 27+ 143
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From page 144... ...
In addition, because the consequences of any resulting crashes are greater, the thresholds are lower for passenger carriers and for HM carriers. There are a few additional rules regarding computation of percentile ranks.
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