Traffic Violations Indicator (TVI) Methodology
Using (1) traffic violation (TV) data collected in conjunction with Level 1, 2, and 3 roadside inspections within the last 24 months and (2) the average number of power units from the Motor Carrier Census, SafeStat calculates the TVI for each carrier with a minimum of three TVs from three different inspections. SafeStat assigns a weight to each TV by its age and whether it is a specified TV, (see table below), or an unspecified TV, i.e., 392.2 (General/Local Law). The sum of the weighted TVs is normalized by the number of average power units to obtain the Traffic Violations Measure (TVM). Carriers with similar numbers of power units are grouped, compared to one another by their TVMs, and ranked by percentile within each group. SafeStat assigns a percentile number to each carrier’s TVI, based on that rank.
Traffic Violation Data
In calculating the TVI, SafeStat uses traffic violations recorded in conjunction with Level 1, 2, and 3 roadside inspections over the last 24 months. There is a minimum number of three inspections with TVs for SafeStat to consider the data sufficient to calculate a TVI for a carrier.
SafeStat uses the following data elements from roadside inspections in its calculations of the TVI:
Specified Traffic Violations are identified as follows:
Unspecified Traffic Violations are identified as 392.2 (General/Local Law)
Census Driver Data
SafeStat computes the TVI using the number of traffic violations normalized by the average number of power units contained in the Census data. The primary sources of power unit information in the Census are Forms MCS-150 and MCS-151. When the Census data on the average number of power units for a carrier are suspect, specific state/federal organizations are contacted to obtain the most accurate value.
Calculation of the Traffic Violations Measure (TVM)
SafeStat calculates the TVM by adding the weighted number of traffic violations and dividing by the average number of power units. The equation for the TVM is:
SafeStat time weights violation data by assigning a value of 1,2, or 3 to each violation data to give more relevance to recent violations. The following steps detail SafeStat’s calculation of the TVM.
Calculation of the Traffic Violations Indicator (TVI)
SafeStat uses the TVM to calculate the TVI. The following steps detail SafeStat’s calculation of TVI.
Calculation of the Driver SEA Value
The Driver SEA Value establishes the carrier’s safety status concerning driver operations. SafeStat uses the Driver Inspections Indicator (DII) and the Driver Review Indicator (DRI) and the Traffic Violations Indicator (TVI) with their associated indicator weights to calculate the Driver SEA Value.<>
The Driver SEA Value calculation is the maximum of the DRI, DII, and TVI.
If none of the indicators exist (DRI, DII, or TVI) then the carrier has insufficient data for SafeStat to calculate a Driver SEA Value.