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Part 2 Traffic Accident Investigation

Chapter 8


Traffic accidents are extremely confusing events. How they occur, who or what causes them, and why they occur are factors the Military Police must determine. This section provides information and guidance on how to fulfill the Military Police mission of reporting and investigating traffic accidents.

Provost Marshal

The provost marshal is the principal staff officer concerned with traffic accidents. The PM's responsibilities include:

Advising the commander on plans, policies, procedures, and equipment needed to insure traffic accident investigation and reporting, and traffic safety.

Preparing, coordinating, and implementing traffic accident investigation/reporting; safety; control; and information programs.

Maintaining up-to-date statistics on accident and enforcement programs, with the aim of improving safety, and reducing the number of traffic accidents.

Coordinating desired safety programs with the installation safety office, information office and schools.

Military Police

Every MP must know the fundamentals of traffic accident investigation and know how to prepare traffic accident reports. It is recommended that traffic accident investigation teams, provided for in TOE 19-510H, be responsible for investigation of all accidents. Each team of one MP supervisor (E5, 95B20, ASI Q9) and one senior MP (E4, 95B10, ASI Q9) will be able to properly and uniformly investigate and report traffic accidents. The duties of MP traffic accident investigators are as follows:

Conduct traffic accident investigations.

Complete reports.

Enforce traffic regulations, rules and orders.

Develop recommendations to reduce traffic accidents and promote safety.

Provide the provost marshal and commanders with necessary information to take appropriate action against traffic offenders.

MP Operations Section

  • Supervise the overall traffic accident investigation program.
  • Recommend to the PM information on procedures for gathering traffic information, training requirements and traffic control/circulation plans.
  • Review reports for completeness and correctness.
  • Coordinate safety and prevention programs with other offices and agencies.
  • Inform personnel on changes in speed limits, traffic control devices, traffic flow and other traffic information.
  • Desk Sergeant

  • Receive reports of traffic accidents/incidents and dispatch investigators, if necessary.
  • Insure correctness of completed forms.
  • Insure appropriate entries are made on records maintained at the MP desk, such as the blotter and radio log.
  • Patrol Supervisor

  • Proceed to scene of traffic accidents and insure necessary traffic control is established.
  • Assist the investigation team, if necessary, or provide supervision to individual shift patrol members.
  • Military Police Investigators And CID Special Agents

    Investigators or special agents may assume investigative responsibility in accidents in which other offenses contributed to or resulted from the accident. Military Police will notify the supporting USACIDC element whenever a traffic accident involves a fatality or an offense within CID investigative responsibility as described in AR 195-2. In all cases, MPs will complete the investigation of the actual accident and provide a copy of the report to the USACIDC element.

    Since the installation commander has ultimate responsibility for traffic accident investigation, reporting, and safety, other persons on his staff will also be involved in traffic programs. This may be the primary and special staff (such as facilities engineer, staff judge advocate, transportation officer, surgeon, information officer and explosive ordnance officer).

    Essential Elements Of an Investigation

    DA Form 3946, Military Police Traffic Accident Investigation Report, when properly completed, contains the essential investigation elements--who, what, when, where, why and how. Alone, or supported by scaled diagrams, photographs and statements, it provides this necessary information. The following guidelines may be used to determine the required depth of an investigation. This information can provide for maximum effective use of MP resources in investigating traffic accidents.

    Use DA Form 3946 only under the following conditions:

  • No government vehicles involved and no government property damaged.
  • No incapacitating or fatal injuries.
  • No evidence of a related serious offense.
  • Extensive investigative effort is required to support the conclusion of Form 3946 in the following situations:

    • Government vehicle involved or government property damaged. When the accident occurs off-post or outside US jurisdiction, coordination with civilian authorities is necessary.
    • Fatal injury.
    • Incapacitating injury. This is an injury which prevents the injured person from walking, driving or continuing normal activities. It does not include momentary unconsciousness, broken fingers or toes, or simple complaint of pain.
    • There is evidence that a serious offense has been committed, such as driving under the influence, hit and run, or reckless driving.
    • There is extensive damage to private vehicle(s), making it impossible for the vehicle(s) to be driven away safely and normally.

    Preparing for Investigation

    As an MP investigator or CID special agent, your preparation begins with yourself. You must meet these criteria:

  • Present a favorable appearance and bearing.
  • Be technically proficient.
  • Remain calm and guard against injecting personal opinions and emotions while investigating.
  • You should have the following investigative equipment:

    The following protective and first aid equipment is needed:

    • Blankets
    • Flashlight
    • Flares or fuses (red signal flares)
    • Portable reflector or flashing lights
    • Warning flags and stanchions
    • Engineer tape
    • Reflectorized vests
    • First aid kit
    • Traffic cones
    • Fire extinguisher (dry chemical)

    You need these items of equipment on your vehicle:

    • Warning lights
    • Public address system
    • Spotlight
    • Siren.

    The following rescue items are needed:

    • Pinch bar
    • Heavy scissor-type jack
    • 25-foot (8 m) tow chain or cable
    • Shovel
    • Axe
    • Wrenches.

    For office equipment you'll need:

    • Office space
    • Drawing board and instruments
    • Filing cabinets
    • Wall space for accident maps and diagrams.

    Training Courses

    Motor Vehicle Traffic Management/Accident Investigation and Prevention Course--A three-week course for commissioned officers conducted by the Traffic Institute of Northwestern University.

    Traffic Management/Accident Investigation Course--A Three-week course for enlisted personnel given by the Department of Security Police Training, Lackland Air Force Base. (The award of Additional Skill Identifier Q9 is authorized upon successful completion of this course).

    Traffic Accident Investigation Course--A three-week course conducted by the Seventh Army Combined Arms Training Center, US Army Europe. (ASI Q9 is authorized for award upon successful completion of this course.)

    Classification, Terminology, Factors and Stages

    Traffic accidents are classified by type and severity.


  • Overturned
  • Other noncollision
  • Collision with pedestrian
  • Collision with motor vehicle
  • Collision with motor vehicle on other roadway
  • Collision with parked motor vehicle
  • Collision with railway train
  • Collision with pedalcycle (2 or 3 wheels--no motor)
  • Collision with animal
  • Collision with fixed object
  • Collision with other object.
  • Severity

  • Fatal (within 12 months)
  • Incapacitating injuries
  • Nonincapacitating evident injuries
  • Possible injuries
  • Disabling damage to vehicle (cannot be moved)
  • Functional damage to vehicle (can move, but would not be safe)
  • Other damage to vehicle (minor damage, not unsafe).
  • Terminology

    These definitions are provided to insure standardized definition and reporting which aid in analysis:

    Trafficway--The entire width between property lines, or other boundary lines, of every way or place of which any part is open to the public for purposes of vehicular travel as a matter of right or custom. All highways are trafficways, but trafficways also include some areas on private property such as shopping centers.

    Highway--The entire width between the boundary lines of every way publicly maintained when any part thereof is open to the use of the public for purposes of vehicular travel; a street; a publicly maintained trafficway.

    Road--The part of a trafficway which includes both the roadway, which is the travelled part, and any shoulder alongside the roadway. Where there are uncountable curbs, the road and roadway are the same. If there is a guardrail, the road is considered to extend to the guardrail.

    Roadway--That portion of a highway improved, designed, or ordinarily used for vehicular travel, exclusive of the berm or shoulder. In the event a highway includes two or more separate roadways the term roadway as used herein, shall refer to any such roadway separately, but not to all such roadways collectively.

    If there is a curb, the roadway is considered to extend to the curb, hence roadway may include lanes commonly used for parking. If there is a paved shoulder, the roadway may be distinguished from the shoulder mainly by a painted line marking the edge of the roadway.

    Shoulder--That portion of the road contiguous with the roadway for accommodation of stopped vehicles, for emergency use and for lateral support of the roadway structure. The line between the roadway and the shoulder may be a painted edge line, a change in surface color or material, or a curb. On some modern trafficways, there may be a surfaced shoulder on the right side, and frequently a narrow shoulder on the left side of a one-way roadway.

    Motor Vehicle--Every vehicle which is self-propelled and every vehicle which is propelled by electric power obtained from overhead trolley wires, but not operated on rails.

    Traffic--Pedestrians, ridden or herded animals, vehicles, streetcars, and other conveyances, either singly or together, while using any highway for purposes of travel.

    Pedestrian--Any person not in or upon a motor vehicle or other road vehicle.

    Driver--Person who drives or is in control of a vehicle.

    Motor vehicle traffic accident (crash)--An unintended event involving one or more moving vehicles, occurring on, but not limited to, a trafficway, which results in property damage, personal injury or death.

    Pedalcycle--A vehicle operated solely by pedals, propelled by human power, such as a bicycle or tricycle.

    Accident factors--Combinations of simultaneous and sequential (in sequence) circumstances which cause an accident.

    Accident investigation--Detailed systematic search to uncover facts (who, what, when, where, why and how) and determine the truth of the factors.

    Collision diagram--A plan of an intersection or section of roadway on which an accident occurred. It is drawn by means of arrows showing the manner of collision. Date, time and road conditions are entered on one of the arrows representing each collision.

    Property damage--A loss suffered by a person, firm or other entity when property is marred, defaced, spoiled, ruined or destroyed.

    Simultaneous factors--Factors which must be present at the same time to cause an accident.

    Sequential factors--Factors which are away from the crucial event of the accident. Certain actions that set up situations which may increase the probability of an accident.


    The three factors involved in traffic accidents are operational, condition and remote condition.

    Operational factor is any unconventional or hazardous behavior or negligence by a road user which contributes directly to the accident. This can be any of the following:

    Speed--Greater or lesser than a safe normal speed:

    Making it impossible to follow a desired curve.

    Making it impossible to take successful evasive action.

    Presenting unusual surprise to other traffic units.

    Initial Behavior--

    Unusual action (skidding or spinning out).

    Illegal actions (driving on wrong side of road).

    Hazardous actions (excessive lane changing).

    Delayed Perception--The failure to perceive and safely respond to the impending danger of a possible accident, caused by inattention or distraction.

    Faulty Evasive Action--Evasive action is taken when the road user reacts to a dangerous situation after the perception of the danger. This may be slowing, stopping, accelerating or turning. It is faulty and can be an operational factor when it is not taken or wrongly taken.

    Condition Factor is a condition which contributes to an operational factor. There may be one or more condition factors, such as skidding on a curve (an operational factor) and slippery pavement (a condition factor).

    Remote Condition Factor is an act or condition which sets up an operational factor.

    A road with severe potholes in it is a remote condition factor. If a vehicle with bald tires hits a pothole and a tire blows out, that's a condition factor. If a car swerves into the opposite lane and another car collides with it, that is an operational factor.


    Each traffic accident has a number of stages or chain of events. Every accident will have a key event; however, not all accidents will include all possible stages.

    1. Point of Possible Perception--time and place at which the unusual or unexpected movement or condition could have been perceived by a normal person.

    2. Point of Perception--time and place at which the danger is perceived or actually seen. This point comes after the point of possible perception. Perception time is the period between these two points. (This point does not exist in all cases--as when a driver falls asleep at the wheel.)

    3. Point of No Escape--time and place, after which the traffic accident cannot be avoided. It may occur before or after the point of perception.

    4. Key Event--the most important stage of an accident. There is only one key event--it is determined by the first harmful event. It determines the exact time, place and type of accident. It may be one of the following:

  • Collision on the road--When traffic units have made their first contact (point of initial contact)
  • Noncollision on the road--When only one traffic unit is involved, and the key event occurs on the road.
  • Collision or Noncollision Off the Road--When the first harmful event occurs after the traffic unit leaves the roadway.
  • 5. Point of Maximum Engagement--the time and place in a collision at which traffic units are forced together as much as they will be. It follows the point of impact.

    6. Final Position--place where the objects involved in a traffic accident finally come to rest. Any collision following this stage should be considered as another traffic accident.

    7. Other Events--The following are other events or stages which appear to a lesser degree in a traffic accident:

    • Encroachment - Movement into the lane, path or area designated to another traffic unit.
    • Start of Evasive Action - When first action to avoid accident occurs.
    • Disengagement - The separation of units involved in a collision.

    Stages of Accident of Chain of Events

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