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How FMCSA Calculates BASIC Measure

Five million truck and bus drivers share the road with more than 250 million motorists in the U.S. Commercial drivers and their violations need to be monitored and assessed to ensure the safety of everyone on the road.

The Safety Measurement System (SMS) is a component of the Compliance, Safety, Accountability (CSA) program by the Federal Motor Carrier Safety Administration (FMCSA). The system collects two (2) years’ worth of roadside inspections and crash reports, and data from investigators to analyze and mediate motor carriers that endanger the public. The data collected is, then, organized into seven Behavior Analysis and Safety Improvement Categories (BASICs).

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These BASICs are used to give a better indication as to the types of violations drivers incur. Also, this overview helps to improve safety performance and compliance. The infographic below shows the seven BASICs and the incident rate per 100 trucks in each category. How the BASIC measure is calculated for each motor carrier is also explained below.

  Crash Rate by BASIC Prioritized in the SMS Preview

Crash Rate by BASIC Prioritized in the SMS Preview.

Image by FMCA (

What is the science used by FMCSA to measure BASIC performance? 

  • The SMS determines a motor carrier’s prioritization status (i.e., prioritized or not prioritized) in each BASIC based on the motor carrier’s on-road performance and investigation results.
  • A motor carrier’s relative on-road performance is indicated by its BASIC percentile. Investigation results reflect if any Acute and Critical Violations are found in a given BASIC during investigations.
  • A motor carrier can be prioritized for interventions because its percentile is at or above the Intervention Threshold as described in the table below, and it has one or more Acute and Critical Violations related to a BASIC.

BASIC Intervention Thresholds Table


Intervention Thresholds


Passenger Carrier



Unsafe Driving, Crash Indicator, HOS Compliance




Vehicle Maintenance, Controlled Substances/Alcohol, Driver Fitness




Hazmat Compliance





Calculation of a BASIC Measure

The measures for a BASIC are calculated as the sum of severity and time-weighted applicable violations divided by a motor carrier average Power Units (PUs) multiplied by a Utilization Factor, as follows:

BASIC Measure =

Total of time and severity weighted applicable violations


Average PUs x Utilization Factor

In this equation, the terms are defined as follows:

An Applicable Violation is a violation recorded in any Driver Inspection (Level 1, 2, 3, or 6) that matches the Federal Motor Carrier Safety Regulations (FMCSRs) and Hazardous Materials Regulations (HMRs) cites listed in Table A–1: SMS Unsafe Driving BASIC Violations that can be found at  for incidents during the past 24 months. In cases of multiple counts of the same violation, the SMS uses each violation cite only once per inspection.

Note: Some roadside inspections are performed following a traffic enforcement stop for a moving violation. Violations reported on the inspection form during such stops do not always result in issuing a citation/ticket to the driver but are used in the SMS whether a citation/ticket is issued.

A Severity Weight from 1 (less severe) to 10 (most severe) is assigned to each applicable violation. See Table A–1 for the severity weights corresponding to each violation. The severity weighting of each violation cites accounts for the level of crash risk relative to the other violation cites used in the BASIC measurement. 11 The sum of all violation severity weights for anyone inspection in any one BASIC is capped at a maximum of 30. This cap of 30 is applied before the severity weights are multiplied by the time weight. Out-of-service (OOS) weights are not assigned for Unsafe Driving violations as most violations in this category are not considered OOS violations.

Note: The severity weights of violations outside of the BASIC being calculated do not count towards the violation cap.

A Time Weight of 1, 2, or 3 is assigned to each applicable violation based on how long ago it was recorded. Violations recorded in the past six months receive a time weight of 3. Violations recorded over six months and up to 12 months ago receive a time weight of 2. All violations recorded earlier (older than 12 months but within the past 24 months) receive a time weight of 1. This time-weighting places more emphasis on recent violations relative to older violations.

A Time and Severity Weighted Violation is a violation’s severity weight multiplied by its time weight.

Average PUs are used in part to account for each motor carrier’s level of exposure when calculating the BASIC measure. The number of owned, term-leased, and trip-leased PUs (trucks, tractors, HM tank trucks, motor coaches, and school buses) contained in the Census data are used to calculate the PU totals. The average PUs for each motor carrier is calculated using the:

(i)              Motor carrier’s current number of PUs,

(ii)            Number of PUs the motor carrier had six months ago, and

(iii)          Number of PUs the motor carrier had 18 months ago.

The average PU calculation is shown below:

AveragePU =

PU Current + PU 6 Months + PU 18 Months



The Utilization Factor is a multiplier that adjusts the average PU values based on the utilization in terms of Vehicle Miles Traveled (VMT) per average PU, where VMT data in the past 24 months are available.

The primary sources of VMT information in the Census are (1) Form MCS-150, filled out by the motor carrier, and (2) Form MCS-151, filled out by law enforcement as part of an investigation.

Motor carriers are required to update their MCS-150 information biennially.

In cases where the VMT data have been obtained multiple times over the past 24 months for the same motor carrier, the most current positive VMT figure is used.