MMUCC C9 Manner of Crash

Executive Summary: You may have never heard of the MMUCC (Model Minimum Uniform Crash Criteria; a set of federal guidelines), it trickles down into every state’s motor vehicle crash reporting system. It’s somewhat analogous to the relationship between the UVC and state’s vehicle codes. The problem, I should say one problem, is non-motorists tend to get overlooked. One obvious example is delved into here — the “Manner of Crash”, e.g. angle, rear-end, sideswipe, etc. is ONLY defined when it involves two motor vehicles, leaving that data-field undefined when a crash is between a MV and bicyclist. Since bicyclists are vehicle drivers, the MMUCC should reflect that. Read on for a proposed change that’s on the table, and how you can vote/comment officially:

UPDATE Sept 2016. There is a PROPOSED CHANGE similar to the change I submitted a year or two ago (they’ve added animal-drawn vehicles; I think it would be better described as …or other non-motorized vehicle). You can support or otherwise comment on the proposed changes here. The deadline for responses is 5:00 p.m. ET on Friday, October 7, 2016!!

Here’s the change, extracted from Page 10 of this document, with the additions highlighted in yellow:

Issue C9: Modify definition The following is a proposal from a public stakeholder to modify the definition of “C9. Manner of Crash/Collision Impact.”
The identification of the manner in which two motor vehicles or a motor vehicle and a bicycle/animaldrawn vehicle in transportinitially came together without regard to the direction of force. This data element refers only to crashes where the first harmful event involves a collision between two motor vehicles or a motor vehicle and a bicycle/animal-drawn vehicle in transport.


Dear Highway Safety Expert:

The Model Minimum Uniform Crash Criteria (MMUCC) is a voluntary guideline developed jointly by NHTSA and GHSA to help states determine what crash data to collect at the scene and include in their state databases. The guideline is currently undergoing a complete review, with the goal of releasing the 5th edition in 2017. The review has been led by an Expert Panel of approximately 30 participants, including representatives of law enforcement, state traffic records coordinators, state and local departments of transportation, researchers, EMS and federal officials.

The panel has made a number of initial decisions, including the creation of separate sections for fatal crashes, large motor vehicles and non-motorists. It has recommended that states be given more flexibility in the way in which they collect data and has also proposed a few new data elements, including ones for automated vehicles and ignition interlocks.

Following the first meeting, the Expert Panel formed small working groups to review particular data elements and their attributes and recommend changes. In addition, respondents to an online forum (conducted in May) and to a Federal Register notice proposed additional changes to MMUCC. We have created a second online forum to solicit your opinions about these proposals.

The forum is now open at

You will need to create a login account to access the forum. This account enables you to save your work in progress and return to the survey at a later time. Please make note of your username and password, as you will need them to log in each time you return. Full instructions for completing the forum are provided on the first page after you log in. Please note that all comments submitted to the forum will be posted without change at, including any personal information provided. The deadline for responses is 5:00 p.m. ET on Friday, October 7, 2016.

If you would like to review the full list of proposals and questions prior to completing the forum, you may download them here:

It should take between 30-60 minutes to complete the online forum. Your input is invaluable to ensure that the proposals will yield collectable and useful data that State Highway Safety Offices can use in their planning processes. I strongly encourage you, your traffic records coordinator or a member of the state Traffic Records Coordinating Committee to complete the forum.

Should you have any technical questions about the online forum, please contact Amadie Hart at

Thank you for sharing your time and expertise with us as we seek to improve MMUCC and crash data collection, management and analysis.

UPDATE Sept 2017

For reasons that are not clear, issue C9 (a.k.a. proposal 4.2) was rejected, and will not be made to the MMUCC 5th Edition. The voting was 43 to approve vs. 17 to reject (20 were no opinion). There’s a breakdown by “Public Stakeholders”, 27 approve / 9 reject. Whereas “Expert Panel” was 16 approve / 8 reject.
I have no idea what the process within DOT is ??


Below is a proposed change to the MMUCC to clarify data collection when the first harmful event in a motor vehicle crash involves a bicycle…

Discussion / Reason for change:

Bicycles are legally defined as vehicles, or bicyclists are legally defined as the driver of a vehicle, throughout the United States. Crashes between motor vehicles and bicycles should therefore be fully documented in the same way as a crash between two motor vehicles. Currently, the crash data element C9. Manner of Crash / Collision Impact is only defined when two motor vehicles collide.

There is some evidence that most law enforcement officers already, perhaps unconsciously, conform to the changes proposed below — in Arizona, which has very similar definitions as element C9, investigators assigned a value besides ‘Other’ to about 80% of motor vehicle – bicyclist crashes.

The changes proposed below are all additions, no deletions, and shown in ALL CAPS:

C9. Manner of Crash/Collision Impact

The identification of the manner in which two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE in transport initially came together without regard to the direction of force. This data element refers only to crashes where the first harmful event involves a collision between two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE in transport. See Appendix F for a diagram of the manner of collision.


  • Front to Rear
  • Front to Front
  • Angle
  • Sideswipe, Same Direction
  • Sideswipe, Opposite Direction
  • Rear to Side
  • Rear to Rear
  • Other
  • Unknown

Important for evaluation of occupant injuries and structural defects. This data element can be used in conjunction with Motor Vehicle Maneuver/Action (V18) to describe the crash.


Arizona seems to be generally consistent with the MMUCC. Unlike the MMUCC, and a better approach in my opinion, Arizona defines the notion of a traffic unit, which can be any vehicle (motorized or otherwise), bicyclist, or pedestrian — in other words, instead of having vehicle level data, in Arizona it is simply unit level data. In Arizona a unit action, e.g. going straight, turning left, turning right, etc, is completely consistent for bicyclists as well as motorist, so there’s no confusion and no data is lost. The equivalent element in MMUCC is V18. Motor Vehicle Maneuver/Action which needlessly restricts the data to a motor vehicle.

In Arizona, a person riding a bicycle has the same rights and responsibilities as the driver of a vehicle,   §28-812.  The relevant data field on the Arizona Crash Report is block 17 see Arizona Crash Form Manual, Rev. 8/2010 , [archived copy] page 37.

The way Arizona defines the manner of crash impact, though, by definition still has the same troubles as the MMUCC as noted above. Also note, Arizona defines two extra values: Single Vehicle (which makes sense to me, however it’s inconsistent with the definition) and Left Turn (which also makes sense to me.  A left turn is really just a special case of Angle).

Thus the proposed changes  in ALL CAPS:

17 – MANNER OF CRASH IMPACT- Identifies the manner in which two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE in transport initially came together, OR A SINGLE MOTOR VEHICLE CRASH NOT INVOLVING ANY OTHER TRAFFIC UNITS.

1. Single Vehicle – There is not a collision between two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE in transport.

2. Angle (front to side) (other than left turn) – Two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE approaching from an angle; usually resulting in a “T-bone” crash.

3. Left Turn – Two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE are traveling in opposite directions, prior to the crash, where at least one vehicle is making a left turn.

4. Rear End (front to rear) – A crash where the front of one motor vehicle OR BICYCLE impacts the rear of another motor vehicle OR BICYCLE AND AT LEAST ONE UNIT IS A MOTOR VEHICLE.

5. Head-On (front to front) (other than left turn) – A crash where the front ends of two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE impact together.

6. Sideswipe, Same Direction – Crashes where two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE are traveling the same direction and impact on the side….

7. Sideswipe, Opposite Direction – Crashes where two motor vehicles OR A MOTOR VEHICLE AND A BICYCLE are traveling the opposite direction and impact on the side…

8. Rear-to-Side – A crash where the back of one motor vehicle OR BICYCLE impacts the side of another motor vehicle OR BICYCLE. Vehicle #1 backing out of a parking space and striking vehicle #2 in the side

9. Rear-to-Rear – A crash where the backs of two motor vehicles impact together. This impact type could occur as in the first example below where the car loses control and spins 180 degrees impacting the rear of the truck. Another possible scenario would be two vehicles backing from roadside parking and impacting rear-to-rear.

97. Other… If “Other” is used it must  (emphasis in original) be listed on the line provided or described in the narrative.

99. Unknown – This would indicate that the Investigating Officer could not determine which Manner of Collision occurred.

Some more random thoughts

Animal-drawn wagons, e.g. horse and buggy, should probably be included somewhere; again, they are typically, as are animal riders, defined as vehicles or assigned driver’s rights and responsibilities.

I would think it would be appropriate to set a special value for pedestrian — i.e. when the first harmful event is pedestrian, there should be a specific/new value.