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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation
FHWA Highway Safety Programs

The National Definition For Serious Injuries MMUCC 4th Edition

The Federal Highway Administration's (FHWA) Safety Performance Management Measures Final Rule (23 CFR 490) and the National Highway Traffic Safety Administration's (NHTSA) Uniform Procedures for State Highway Safety Grants Program Interim Final Rule (23 CFR 1300) establish a single, national definition for States to report serious injuries per the Model Minimum Uniform Crash Criteria (MMUCC) 4th Edition "Suspected Serious Injury (A)" attribute found in the "Injury Status" element. This document highlights the requirements for State compliance with this new definition.

Why did the Federal government establish a national definition?
Congress, through the Moving Ahead for Progress in the 21st Century (MAP-21) Act, mandated the establishment of safety performance measures, which includes a requirement that all States report serious injuries resulting from motor vehicle crashes. States and Metropolitan Planning Organizations (MPOs) must set annual targets for safety performance measures in order to implement the FHWA Highway Safety Improvement Program (HSIP) and the NHTSA Highway Safety Grants Program activities. As a means of standardizing serious injury data, the United States Department of Transportation (US DOT) established a single national definition for reporting serious injuries. This action will ensure a consistent, coordinated, and comparable serious injury data system.

What is the benefit to establishing a national definition?
Law enforcement, engineers, safety specialists, researchers, planners, and others rely on accurate and consistent data to determine effective countermeasures. When States and law enforcement agencies use different definitions and coding conventions to report serious injuries, it leads to inconsistent reporting. Inconsistent reporting results in poor data quality. A national definition will improve the data at the State and National levels and will assist stakeholders in addressing highway safety challenges.

What is MMUCC?
The Model Minimum Uniform Crash Criteria Guideline, or MMUCC, is a voluntary, standardized, minimum data set used to describe motor vehicle crashes and the vehicles, persons, and environments involved in them. MMUCC assists Federal, State, and local partners in generating information necessary to improve highway safety by creating consistent crash reporting data.

What is the national definition for serious injuries?
The US DOT defines a serious injury using the MMUCC 4th Edition "Suspected Serious Injury (A)" attribute found in the "injury status" data element. A suspected serious injury is defined in the MMUCC 4th Edition as any injury other than fatal that results in one or more of the following:

The National Definition For Serious In

  • Severe laceration resulting in exposure of underlying tissues/muscle/organs or resulting in significant loss of blood
  • Broken or distorted extremity (arm or leg)
  • Crush injuries
  • Suspected skull, chest, or abdominal injury other than bruises or minor lacerations
  • Significant burns (second and third degree burns over 10% or more of the body)
  • Unconsciousness when taken from the crash scene
  • Paralysis

When must a State comply with the new definition?
States are required to comply with the new definition by April 15, 2019. However, it is recommended that States begin using the MMUCC 4th Edition definition and attribute beginning January 2019 or earlier in order to have a complete and consistent crash data file for the entire 2019 calendar year.

What are the criteria for compliance with the new definition?
A State is considered compliant with the serious injury definition requirement if it:

  • (a) Maintains a statewide crash database capable of accurately aggregating the MMUCC 4th Edition injury status attribute for "Suspected Serious Injury (A)";
  • (b) Ensures the State crash database, data dictionary and crash report user manual employs the terminology and definitions for the MMUCC 4th Edition injury status attribute "Suspected Serious Injury (A)";
  • (c) Ensures the police crash form employs the MMUCC 4th Edition injury status attribute for "Suspected Serious Injury (A)"; and
  • (d) Ensures that the seven serious injury types specified in the "Suspected Serious Injury (A)" attribute are not included in any of the other attributes listed in the States' injury status data elements.

While States are required to adopt the "Suspected Serious Injury (A)" attribute, they are strongly encouraged to adopt the full "Injury Status" data element for clarity and ease of use.

What if a State does not currently use the MMUCC 4th Edition definition for serious injuries?
States that are not currently using the MMUCC 4th Edition definition for "Suspected Serious Injury (A)" shall use the State Serious Injury Conversion Tables to convert the equivalent definition and attributes from their State's Motor Vehicle Crash Database to report serious injuries. These conversion tables are located on the FHWA Safety Performance Management website at States may use the conversion tables until April 15, 2019.

Who are the State stakeholders that need to be involved in helping the State achieve compliance with the new national definition?
Stakeholders that should be involved to achieve compliance of the new serious injury definition include State departments of transportation (DOT), State highway safety offices (SHSO) and State law enforcement agencies–all of which play a key role. Additional stakeholders may include traffic records coordinating committee members, State DOT administrators, and representatives of the Governor's Highway Safety Association.

What Federal Agencies require States to report serious injuries using the national definition?
Several Agency reports require the new definition of serious injuries. Each State DOT submits its Highway Safety Improvement Program Annual Report to FHWA by August 31. State highway safety offices also submit their Highway Safety Plans to NHTSA each year by July 1. FMCSA requires reporting of all personal injury crashes involving commercial motor vehicles if a person immediately receives treatment away from the scene of the accident. All serious injuries would be reportable because they would involve immediate treatment away from the scene of the crash. FMCSA therefore supports the national definition of serious injury as the industry standard.

Is there technical assistance and training available to help States meet the requirement?
Yes, technical assistance is available. FHWA Division Offices and NHTSA Regional Offices stand ready to assist States. For specific questions, please contact your FHWA Division Office ( or your NHTSA Regional Office ( FHWA and NHTSA have developed a law enforcement roll call video that will help officers completing crash reports understand the new definition and how to report suspected serious injuries. The video will be distributed to law enforcement agencies by FHWA and NHTSA with assistance from law enforcement partners and other stakeholder groups.

Last updated: Tuesday, June 28, 2022