• The first step in determining a CSA BASIC (Behavior Analysis and Safety Improvement Category) Score is to look at the BASIC Measure formula.
• More recent safety events have a greater capacity to impact a motor carrier’s HOS Compliance BASIC Measure.
• The number of inspections (exposure) is factored into the formula.
  

The Hours-of-Service (HOS) Compliance BASIC Measure is calculated as the sum of the severity and time weighted applicable violations divided by the number of time weighted relevant (driver) inspections.

Basic Measure = Total of time and severity weighted applicable violations ÷ Number of time weighted relevant inspections

In order to fully understand the formula, the individual components must be defined and explained.

Applicable violation

An applicable violation is any violation recorded in any Driver Inspection (Level 1, 2, 3, or 6) that matches the FMCSRs listed for HOS Compliance BASIC during the past 24 months. The Safety Measurement System (SMS) only uses each violation cite once per inspection in cases of multiple counts of the same violation.

See Hours-of-Service Compliance BASIC Severity Table

Relevant inspection

A relevant inspection is any Driver Inspection (Level 1, 2, 3, or 6), including those that do not result in a violation in the BASIC.

Severity score

When a violation enters a BASIC in the SMS for scoring, a “value” is assigned to each. The value for each safety-related violation will be determined by its level of crash risk in relationship to other violations in this BASIC. It is given a severity weight of 1 to 10, and 2 points are added if the event involved being placed out of service. The sum of all violation severity weights from any one inspection for one BASIC is capped at a maximum of 30. The severity weights of violations outside of the BASIC during the same roadside inspection do not count towards the violation cap.

Time weight

After the violations from the roadside inspection are assigned a BASIC based on severity (i.e., likelihood to factor into an accident), all safety events are assigned a time weight. The time weight of an event decreases with time, resulting in more recent events having a greater impact on an entity’s BASIC than events from the more distant past.

Events occurring:

• In the past 6 months are time-weighted at 3;
• In the past 7 to 12 months are given a time weight of 2; and
• More than 12 months ago but within 24 months are time-weighted at 1.

Events older than 24 months are assumed irrelevant and no longer used.

In order to arrive at a violation’s time and severity weighted value, you take the severity score for a BASIC from a specific roadside inspection and multiply it by 1, 2, or 3 based on when it occurred.

Normalization using relevant inspections

The total of the time weighted relevant inspections is used to account for each carrier’s level of exposure when calculating the HOS Compliance BASIC Measure. This number is divided into the total time weighted applicable violations.

For example, suppose a carrier had six relevant inspections in the past six months. You multiply the total relevant inspections for the time period by the time weight (6 inspections x 3 time weight = 18). It had four inspections after six months, but within twelve months. Again, multiply the total relevant inspections for the time period by the time weight (4x2=8). Finally, the carrier had just one relevant inspection older than twelve months, but within the 24 months. You once again multiply the total relevant inspections for the time period by the time weight (1x1=1). You then add the 18, 8, and 1 to arrive at 27 for the total time weighted relevant inspections.