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  • Writer's pictureFront Range Compliance

FMCSA's New Segment for Driver Fitness in SMS

One of the ways the Federal Motor Carrier Safety Administration (FMCSA) Safety Measurement System (SMS) accounts for differences in carrier operations is by segmenting

carriers by whether their company operates primarily Straight vehicles or Combination vehicles.

Currently, this segmentation only applies when calculating percentiles for the Unsafe Driving

and Crash Indicator safety categories. FMCSA decided to explore whether extending

segmentation to the rest of the safety categories would provide better carrier-to-carrier

comparisons and improve the methodology’s ability to identify carriers with high crash rates for interventions.


The proposed methodology would extend Straight and Combination segmentation to the Driver Fitness safety category in addition to retaining segmentation in the Unsafe Driving and Crash Indicator safety categories. The table below provides the SMS’ criteria for Straight and Combination carriers, which would carry over to the proposed methodology.

Straight and Combination Carrier Criteria

Extending segmentation to Driver Fitness would ensure motor carriers are treated fairly by

comparing them to other carriers with similar operations and patterns of violations.

Analysis Method

The FMCSA explored extending Straight and Combination segmentation to the HOS Compliance, Vehicle Maintenance: Driver Observed, Vehicle Maintenance, and Driver Fitness safety categories by following the process below. Segmentation was applied after establishing the violation severity weights.

  1. Apply Straight and Combination segmentation for each safety category above.

  2. Compare violation rates among Straight and Combination carriers in each safety category to determine whether segmentation is justified.

  3. Run ET to assess the impact on crash rates of carriers prioritized and number of Straight and Combination carriers prioritized.

Evaluation Results

The FMCSA’s analysis shows that Straight and Combination segmentation would improve the effectiveness of the Driver Fitness safety category. There are large differences in the violation rates of Combination and Straight carriers in Driver Fitness. As shown in the below table, the violation rates of Straight carriers are nearly four times as high as Combination carriers. Based on these results, segmentation is justified to ensure carriers are compared to others with similar operations and violation rates.

Driver Fitness Violation Rates for Straight and Combination Carriers

Applying segmentation to the Driver Fitness safety category would identify prioritized carriers with higher crash rates in both the Straight and Combination segments. While it does decrease the number of carriers prioritized in the Driver Fitness, the carriers that are removed have a lower crash rate, which would sharpen the focus on carriers at higher risk for crashes.

Carriers Prioritized in Driver Fitness With and Without Straight and Combination Segmentation

FMCSA also tested segmentation in the HOS Compliance, Vehicle Maintenance: Driver

Observed, and Vehicle Maintenance safety categories, but the addition of segmentation lowered the crash rate of prioritized carriers in these safety categories.

All information in this post was retrieved from the FMCSA New Prioritization Methodology: Foundational Document, Version 1.5, March 2022.

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