TRUCKING GUIDE

MASTERING FMCSA SAFETY MEASUREMENT SYSTEM

Every day, the Federal Motor Carrier Safety Administration (FMCSA) works toward a simple yet critical mission: to reduce crashes, injuries, and fatalities involving large trucks and buses on our nation’s roads.

While that may sound like a tall order, FMCSA uses a powerful prioritization tool to help carry out this mission—the Safety Measurement System (SMS).

This guide explores how the SMS works, why it matters to motor carriers, how it directly affects your compliance standing and risk of intervention, and the coming SMS changes.

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FMCSA SMS

WHAT TO KNOW

01 What Is the Safety Measurement System (SMS)?

The SMS is part of FMCSA’s broader Compliance, Safety, Accountability (CSA) program. Its main function is to help the agency identify motor carriers with potential safety problems and prioritize them for interventions—whether that’s a warning letter, investigation, or roadside inspection.

Put simply, SMS is the FMCSA’s way of turning large volumes of safety data into actionable insights, focusing their resources where they’re needed most.

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How SMS Works

SMS gathers and analyzes safety data from multiple sources:

Roadside inspections
Crash reports
Investigations and audits

Based on this data, the system evaluates a motor carrier’s performance and assigns scores in seven categories known as BASICs (Behavior Analysis and Safety Improvement Categories). These are:

Unsafe Driving
Crash Indicator
Hours-of-Service (HOS) Compliance
Vehicle Maintenance
Controlled Substances/Alcohol
Hazardous Materials (HM) Compliance
Driver Fitness

Each carrier’s performance in these categories is compared to others with similar operation sizes and event counts (e.g., crashes or inspections). The result? A percentile score from 0–100, where a higher score indicates worse safety performance.

What Triggers an FMCSA Intervention?

SMS doesn’t just stop at scoring—it actively identifies carriers for intervention based on two major criteria:

High BASIC percentile scores
Presence of Acute and Critical Violations (serious or repeat violations found in investigations)

If a carrier shows issues in one or more BASICs—especially with alerts or major violations—they’ll likely be flagged for further monitoring or enforcement.

Does SMS Work?

Yes—and multiple studies support its effectiveness:

FMCSA’s 2014 SMS Effectiveness Test found that carriers with BASIC alerts had a 79% higher future crash rate than those without.
A 2012 ATRI report showed crash risks increase as the number of BASIC alerts increase.
An independent 2011 evaluation confirmed that five of the seven BASICs strongly correlate with crash risk.

These findings reinforce why understanding and managing your SMS data isn’t just about compliance—it’s about protecting your drivers and business.

Looking Ahead in the Series

In the next article, we’ll take a closer look at how each of the seven BASICs are structured, what data feeds into them, and how a carrier’s percentile scores are calculated. Understanding this breakdown is essential for managing risk and staying ahead of potential interventions.

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02 Inside the Design of FMCSA’s SMS BASIC Prioritization System

In Part 1 of this series, we introduced the Safety Measurement System (SMS), the Federal Motor Carrier Safety Administration’s (FMCSA) primary tool for identifying and prioritizing motor carriers that may pose safety risks.

Now in Part 2, we take a deep dive into how SMS prioritization is designed and why certain carriers are flagged for intervention. This understanding is crucial for fleets aiming to reduce violations, avoid investigations, and ultimately improve their safety scores.

A motor carrier is considered high-risk based on many sources of information, and when they are, the FMCSA wants to understand why.

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What is BASIC Prioritization?

FMCSA uses SMS to evaluate commercial motor vehicle (CMV) carriers based on their performance in seven Behavior Analysis and Safety Improvement Categories (BASICs). These BASICs measure compliance with federal safety regulations and help FMCSA prioritize which carriers may need interventions or inspections. The system is data-driven, relying on information from roadside inspections, crash reports, and investigations that uncover Acute or Critical Violations.

The seven BASICs are:

Unsafe Driving – Examples: speeding, texting while driving, not wearing seatbelts.
Crash Indicator (not public) – A pattern of reportable crashes.
Hours-of-Service (HOS) Compliance – Examples: driving beyond 11 hours, incomplete RODS.
Vehicle Maintenance – Examples: brake defects, lighting issues, load securement failures.
Controlled Substances/Alcohol – Examples: drug/alcohol use or possession.
Hazardous Materials (HM) Compliance (not public) – Examples: improper placarding or leaking containers.
Driver Fitness – Examples: no valid CDL, medically unqualified drivers.

FMCSA also tracks an Insurance/Other Indicator (not publicly displayed) related to registration, financial responsibility, and crash reporting requirements.

How SMS Measures and Prioritizes Safety Risks

SMS turns inspection and crash data into BASIC measures and percentile scores to rank carrier safety relative to peers. Here’s how it works:

Data Sources Feeding the SMS

Roadside Inspections: Most common data input. Includes all violations found, with added weight for Out-of-Service (OOS) violations.
Investigations: Includes Offsite and Onsite inspections, identifying Acute (severe, one-time) and Critical (pattern-based) violations.
Crash Data: State-reported crashes that meet FMCSA criteria.
Motor Carrier Census Data: Collected via Form MCS-150 and MCS-151, providing context like number of power units and VMT.

Violation Severity & Time Weighting

Each violation is assigned a severity weight (1–10) based on its correlation to crash risk—higher weights for more dangerous violations.
Violations also carry time weights, so more recent events have a bigger impact. Events older than 24 months drop off.

Normalization

To ensure fair comparisons across carriers of different sizes, FMCSA normalizes BASIC scores using metrics like:

Number of inspections
Vehicle miles traveled (VMT)
Type of power units (straight trucks vs. combination vehicles)

Segmentation & Safety Event Groups

Carriers are segmented by the types of vehicles they operate and grouped by the number of safety events (e.g., inspections, crashes). This prevents small carriers from being unfairly penalized due to limited data.

Percentile Ranking

Each BASIC gets a percentile score from 0 to 100, with 100 being the worst. Carriers are only scored if they meet data sufficiency thresholds. These percentiles help FMCSA determine intervention eligibility.

Special Considerations in Scoring

Crash Preventability Determination

If a carrier believes a crash was not preventable, they can submit evidence through the Crash Preventability Determination Program (CPDP). If accepted, the crash is labeled “Reviewed — Not Preventable” and excluded from the Crash Indicator BASIC.

Adjudicated Citations

If a violation is dismissed in court, carriers can submit proof via FMCSA’s DataQs system. The violation may be removed or downgraded in severity depending on the outcome.

Investigation-Based Prioritization

Beyond on-road data, Acute and Critical Violations found during investigations can also trigger prioritization—even if the carrier has few inspection violations. These violations highlight severe issues such as:

Using a disqualified driver (Acute)
A pattern of falsifying logs (Critical)

FMCSA will display a symbol in the corresponding BASIC on the public SMS site if a recent Acute or Critical Violation is found.

What This Means for Carriers

Understanding how FMCSA prioritizes carriers gives fleet managers and safety professionals the knowledge to:

Focus efforts on high-risk areas like vehicle maintenance or HOS compliance.
Monitor and correct behaviors that drive up BASIC percentiles.
Use tools like DataQs and CPDP to challenge inaccurate or unfair data.

03 BASIC Prioritization Status Assessment

We explore how FMCSA interventions are triggered, what types of interventions exist (e.g., warning letters, compliance reviews), and how carriers can reduce intervention risk through proactive compliance strategies.

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HOS Compliance BASIC Prioritization Status Assessment

The sections below describe how a carrier’s Hours-of-Service (HOS) Compliance BASIC percentile and investigation results are determined and how they both affect the carrier’s prioritization status.

Definition:
The HOS Compliance BASIC includes operation of CMVs by drivers who are ill, fatigued, or in noncompliance with HOS regulations. This includes violations such as:

Driving beyond the 11-hour limit
Operating a CMV while ill or fatigued
Failing to preserve Records of Duty Status (RODS) for 6 months
Failing to preserve supporting documents

On-Road Performance

This BASIC is assessed using roadside inspection data. Each motor carrier’s performance is scored and then compared against carriers with a similar number of relevant inspections.

BASIC Measure Calculation:

BASIC Measure =
(Total Time- and Severity-Weighted Applicable Violations) ÷ (Total Time Weight of Relevant Inspections)

Applicable Violations: Violations in Driver Inspections (Levels 1, 2, 3, or 6) as listed in Appendix A.
Relevant Inspections: Any Driver Inspection in the past 24 months, even those without violations.
Severity Weight: Each violation has a weight (1–10) based on crash risk; Out-of-Service (OOS) violations get +2 additional points.
Time Weight: Based on how recent the violation is (3 = within 6 months, 2 = 6–12 months, 1 = 12–24 months).
Maximum violation severity per inspection is capped at 30.

BASIC Percentile Rank

Carriers are grouped by the number of relevant inspections:

Group	Relevant Inspections
1	3–10
2	11–20
3	21–100
4	101–500
5	501+

Percentiles are calculated within each group. Carriers with no violations in the last 12 months and none during the most recent inspection are removed.

Intervention Thresholds

Carrier Type	Threshold
Passenger Carrier	50%
HM Carrier	60%
General Carrier	65%

A carrier is prioritized if it:

Exceeds the percentile threshold and/or
Has one or more Acute or Critical Violations related to this BASIC within the past 12 months

Vehicle Maintenance BASIC Prioritization Status Assessment

The sections below describe how a carrier’s Vehicle Maintenance BASIC percentile and investigation results are determined and how they affect the carrier’s prioritization status.

Definition:
The Vehicle Maintenance BASIC includes violations for failure to properly maintain a CMV or prevent shifting loads, spills, or overloading. Example violations include:

Inoperative brakes or lights
Defective tires or wheels
Improper load securement
Failure to repair defects noted on a DVIR

On-Road Performance

This BASIC is assessed using violations found during vehicle-related roadside inspections.

BASIC Measure Calculation:

BASIC Measure =
(Total Time- and Severity-Weighted Applicable Violations) ÷ (Total Time Weight of Relevant Inspections)

Applicable Violations: Found in Vehicle Inspections (Levels 1, 2, 5, or 6) per Appendix A.
Relevant Inspections: All Vehicle Inspections within the past 24 months, regardless of violation presence.
Severity Weight: Based on crash risk (1–10); OOS violations receive +2 points.
Time Weight: Recency-weighted (3, 2, or 1 as described above).
Maximum violation severity per inspection is capped at 30.

BASIC Percentile Rank

Carriers are grouped based on the number of relevant inspections:

Group	Relevant Inspections
1	5–10
2	11–20
3	21–100
4	101–500
5	501+

Only carriers with five or more relevant inspections and at least one BASIC violation are included in percentile calculations. Those with no violations in the last 12 months and none in the most recent inspection are excluded.

Intervention Thresholds

Carrier Type	Threshold
Passenger Carrier	65%
HM Carrier	75%
General Carrier	80%

A carrier is prioritized if it:

Exceeds the percentile threshold and/or
Has one or more Acute or Critical Violations related to this BASIC within the past 12 months

Controlled Substances/Alcohol BASIC Prioritization Status Assessment

This BASIC focuses on driver impairment related to alcohol, illegal drugs, and the misuse of prescription or over-the-counter medications. It also includes violations related to the absence or failure of a required drug and alcohol testing program.

Common Violations Include:

Possession or use of drugs or alcohol while operating a CMV
Failing to implement a DOT-compliant drug and alcohol testing program
Refusing a drug test or returning a positive test

On-Road Performance

The Controlled Substances/Alcohol BASIC measure is calculated using:

(Sum of time- and severity-weighted applicable violations) ÷ (Sum of time-weighted relevant inspections)

Applicable Violations: Based on Level 1, 2, 3, or 6 inspections over the past 24 months
Severity Weight: Ranges from 1 to 10 (OOS weights are not used, as these are mostly OOS by default)
Time Weight:
- 3 (for violations within 6 months)
- 2 (6–12 months old)
- 1 (12–24 months old)
Violation cap: 30 points max per inspection, even if multiple violations occurred

Prioritization: Percentile and Thresholds

Carriers are grouped based on the number of inspections with violations (from 1 to 4+), then ranked within their group and assigned a percentile score (0–100).

Carrier Type	Intervention Threshold
Passenger	65%
Hazardous Materials (HM)	75%
General Freight	80%

Additionally, Acute and Critical Violations found in investigations within the last 12 months can trigger prioritization—even if the percentile is below the threshold.

HM (Hazardous Materials) Compliance BASIC Prioritization Status Assessment

This BASIC is not publicly visible, but is heavily scrutinized during inspections. It targets the unsafe handling and transportation of placardable quantities of hazardous materials.

Common Violations Include:

Improper marking, labeling, or placarding
Failure to secure HM packages
Transporting leaking containers
Missed inspections/tests on HM cargo tanks

On-Road Performance

The HM Compliance BASIC measure is calculated similarly to other categories:

(Sum of time- and severity-weighted applicable violations) ÷ (Sum of time-weighted relevant inspections)

Applicable Violations: Must occur during Level 1, 2, 5, or 6 inspections while transporting placardable quantities of HM
Severity Weight:
- 1 to 10, based on crash risk
- +2 if the violation caused an out-of-service (OOS) condition
Time Weighting and Violation Cap: Same as other BASICs (30-point cap per inspection)

Prioritization: Percentile and Thresholds

Carriers are grouped by total number of relevant inspections (5+), then ranked and scored by percentile.

Carrier Type	Intervention Threshold
Passenger	80%
Hazardous Materials (HM)	80%
General Freight	80%

Carriers may be prioritized for intervention if they exceed the percentile threshold or if an investigation identifies Acute or Critical Violations within the past 12 months.

Driver Fitness BASIC Prioritization Status Assessment

This BASIC assesses whether drivers are legally and medically qualified to operate a CMV. It includes everything from medical certificates to driver qualification file maintenance.

Common Violations Include:

Operating a CMV without a valid CDL
Driver is medically unqualified
Missing or incomplete driver qualification files

On-Road Performance

The Driver Fitness BASIC measure uses this calculation:

(Sum of time- and severity-weighted applicable violations) ÷ (Sum of time-weighted relevant inspections)

Applicable Violations: From Level 1, 2, 3, or 6 inspections
Severity Weight: 1–10 based on crash risk, with +2 for OOS violations
Time Weight and Cap: Same methodology applies (weights of 1–3; 30-point cap per inspection)

Prioritization: Percentile and Thresholds

Carriers are sorted into five Safety Event Groups (5–500+ inspections), then ranked within their group to determine a percentile.

Carrier Type	Intervention Threshold
Passenger	65%
Hazardous Materials (HM)	75%
General Freight	80%

Just like the other BASICs, an Acute or Critical Violation discovered during an investigation can result in prioritization—even if the percentile score is below the threshold.

04 How FMCSA Assigns Violation Severity in the Updated SMS Methodology

In Part 4 of our series analyzing the FMCSA’s September 2024 updates to the Safety Measurement System (SMS), we’re diving into Appendix A—a critical component that explains how individual violations are weighted and categorized, and how these weights contribute to the overall scoring that flags carriers for interventions.

This section lays the foundation for how BASIC scores are calculated and how violations are judged in terms of crash risk. Understanding this methodology helps safety managers and compliance professionals prioritize their efforts more effectively.

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The Purpose of Appendix A

Appendix A includes a downloadable SMS Appendix A spreadsheet, which serves as a master list of every violation used in the SMS. For each Behavior Analysis and Safety Improvement Category (BASIC), the spreadsheet provides two tables:

All applicable violations used in the BASIC, along with severity weights.
Acute and Critical Violations, which are especially important for compliance reviews.

Each violation is linked to the relevant section of the FMCSRs or HMRs and is grouped by type (e.g., brakes, hours of service logs, drug/alcohol violations). These groupings are key to assigning severity weights, which indicate how closely each violation correlates with crash risk.

How Violation Severity is Scored

Each violation in a BASIC is assigned a severity weight from 1 to 10:

1 = Lowest crash risk
10 = Highest crash risk (within that BASIC)

Important: These severity scores are only meaningful within their BASIC category. A violation rated as a “5” in Driver Fitness isn’t necessarily equal in seriousness to a “5” in Unsafe Driving. Each BASIC has its own internal scale based on different risk factors and behaviors.

What Influences Severity Weights?

The FMCSA uses a rigorous five-step methodology to determine severity weights:

BASIC Mapping
All safety violations are assigned to the appropriate BASIC category (e.g., Vehicle Maintenance, Controlled Substances, etc.).
Violation Grouping
Violations are clustered into similar groups using expert judgment. This helps account for rare violations that might not show up frequently in data but are still important to evaluate.
Crash Occurrence Analysis
Using data from the Driver Information Resource (DIR) developed by the Volpe Center, the FMCSA examines how often certain types of violations are associated with actual crashes. This is done using statistical modeling based on multivariate regression.
Crash Consequence Analysis
Severity weights are adjusted based on how severe the resulting crashes typically are. Federal and state enforcement experts weigh in to ensure that the scoring reflects not just crash likelihood but also crash impact.
SMS Effectiveness Test
FMCSA runs a simulation to test how well the violation weights identify carriers that are involved in future crashes. This step helps validate and fine-tune the severity model.

Dismissals and Adjudicated Violations

Not all violations carry the same weight forever. If a citation is:

Dismissed or marked “Not Guilty” through court adjudication, it is removed from SMS scoring.
Convicted of a different charge, its severity weight is reduced to 1, and no out-of-service (OOS) penalty is applied.

To change a violation’s weight in SMS, carriers or drivers must submit certified court documents through the FMCSA’s DataQs system.

Note: This only applies to inspections conducted on or after August 23, 2014.

New Software, New Codes

As of February 1, 2023, FMCSA began using updated inspection software that introduced new violation codes. Appendix A reflects these updates, but only violations cited on or after February 1, 2023, are counted in SMS calculations.

A Vital Tool for Compliance Strategy

Understanding Appendix A is not just for policy wonks. For carriers and safety managers, it offers direct insights into which violations carry the most weight and thus demand the most attention. Knowing how violations are scored—and how to challenge incorrect ones—can directly affect your fleet’s prioritization status in the FMCSA’s eyes.

To explore the full list of violations, groupings, and severity weights, access the official Appendix A spreadsheet available through the CSA website.

05 Future Changes to SMS

In January 2025, the FMCSA hosted a detailed webinar on the upcoming final updates to the Safety Measurement System (SMS) — the heart of the CSA (Compliance, Safety, Accountability) program.

These changes are the culmination of years of feedback, research, and public comment, and they mark a pivotal shift in how the FMCSA identifies and prioritizes carriers for safety interventions.

Here’s what carriers, safety managers, and compliance professionals need to know.

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🚛 Why Is the SMS Changing?

FMCSA’s mission is clear: reduce crashes and save lives. To do that effectively, they’re updating the SMS to make it:

Fairer – so similar carriers are held to the same standards.
More Accurate – by using better data groupings and analysis.
Easier to Understand – making results and risk factors clearer for carriers.

🔄 Key Changes to the SMS

Let’s break down the biggest structural changes coming to the SMS.

Reorganized Compliance Categories

The old seven BASICs are being streamlined into more precise compliance categories:

Old BASIC	New Category (2025)
Unsafe Driving	Unsafe Driving (now includes Controlled Substances/Alcohol + Operating While OOS)
Hours of Service (HOS)	Hours of Service
Driver Fitness	Driver Fitness
Vehicle Maintenance	Split into 2 categories: • Vehicle Maintenance • Vehicle Maintenance: Driver Observed
Controlled Substances/Alcohol	Merged into Unsafe Driving
Hazardous Materials (HM)	Hazardous Materials
Crash Indicator	Crash Indicator (remains the same)

Why it matters:

This allows FMCSA to more accurately target high-risk behaviors.
Separating “Driver Observed” violations helps carriers and inspectors pinpoint what’s likely visible during a pre-trip inspection vs. a full mechanical inspection.

Reorganized Roadside Violations Into Violation Groups

FMCSA has created around 100 Violation Groups, each containing similar violations that point to the same safety issue.

What changes:

If multiple violations from the same group are cited during one inspection, they’ll be counted as a single violation for SMS calculations.

Example:
If a driver is cited for four different HOS infractions during an inspection, they will now count as one violation in the “HOS Requirements” group, not four separate strikes.

Why it matters:

Prevents carriers from being unfairly penalized multiple times for one underlying issue.
Promotes consistency in enforcement and prioritization.

Simplified Severity Weights

Previously, SMS assigned a 1–10 severity weight to each individual violation, which could vary even for similar issues. The new system assigns 1 or 2 based on the violation group, not individual violations.

Severity Weight	When Applied
1	Non-OOS and non-disqualifying violations
2	Out-of-Service (OOS) violations – Applies to all categories except Unsafe Driving
2	Driver Disqualifying violations – Applies only to Unsafe Driving (per 49 CFR 383.51)

Why it matters:

Creates a simpler, clearer weighting system.
Easier for carriers to understand why a violation carries weight.
Focuses more on the presence of a safety issue rather than how many sub-violations were found.

📍 Real-World Example

A single inspection may include:

Hazmat placard violation (Severity 1)
Brake system out-of-adjustment, OOS-level (Severity 2)
Brake wear issue, not OOS (Severity 1)

Previously, each of these could have different and confusing weights. Now, you’d be assigned a 1 or 2 per violation group, based on severity and OOS status.

🛠 What’s Next: Rollout Timeline

We are now in Phase 3 of the FMCSA’s rollout:

✅ Phase 1 (Completed): Launch of the CSA Prioritization Preview Website, public feedback collection.
✅ Phase 2 (Completed): Review of public comments, refinement of changes.
🔜 Phase 3 (Now): Full implementation, including website redesign and integration of changes into CSA enforcement.

Enforcement officials will soon begin using these updates in prioritizing interventions, and the revamped SMS will be the new standard.

✅ Final Thoughts: What Carriers Should Do

Review your current SMS data on the CSA website.
Check your status under the Prioritization Preview to see how your performance is measured using the new system.
Train your safety team to understand the new Violation Groups and how severity weights are applied.
Prioritize OOS and disqualifying violations, as these now universally carry more weight.

Bottom Line:
These SMS changes are designed to create a more balanced, understandable, and impactful safety monitoring system. Staying ahead of the curve now could mean fewer interventions, better scores, and ultimately, safer roads for everyone.