1. Michigan Comprehensive Crash Data Analysis
TRAFFIC RECORDS FORUM 2016
Prabha Narayanaswamy
University of Michigan Transportation Research Institute
Ann Arbor, MI

2. Michigan Fatalities
11% decrease in 2015 compared to 2006, but 10% increase from 2014 to 2015

3. Michigan Serious Injuries
36% decrease in 2015 compared to 2006

4. Michigan Crashes
6% reduction in 2015 compared to 2006
Source:

5. Increase in Fatalities - Mutually exclusive and exhaustive categories
Analytical Approach
Increase in Fatalities
- Mutually exclusive and exhaustive categories
- 14 categories to address causal factors
- Primary cause – specific order to categories
- All comparisons made to 2006
A set of mutually exclusive and exhaustive categories was developed to characterize the crash experience of crash-involved occupants who either died or were seriously injured. These categories were designed to address causal factors in either the crash or the injury outcome of the occupant, though cause cannot be identified with certainty in all cases. Since the characteristics of interest varied across the crash, vehicle, and occupant levels, the approach was used to assign categories to the most specific level: the individual occupant.

6. Crash Categories Deer Involved Winter Weather Alcohol Drugs
Unrestrained
Commercial Vehicles
Motorcycles
Pedestrians
Bicyclists
Young Drivers
Senior Drivers
Rear-End Crashes
Single-Vehicle Crashes
All Other Crashes
Because categories such as “deer involved” and “occupant unrestrained” are not mutually exclusive, we also defined an order of assignment to the categories. This was based on the notion of “primary cause.” That is, if there had been no deer, then a deer crash wouldn’t have happened, and it would have been irrelevant whether the occupant was restrained or not. Thus, Deer is a more primary cause than Unrestrained.

7. Fatalities due to Deer-involved Crashes
In 2015, deer related fatalities have reduced by 8% relative to Lowest # of deer involved fatalities was in 2014 with a count of 6

8. Seasonal Pattern of Deer Crashes
Deer crashes highest during fall months. 20% of total deer crashes occur in October

9. Winter Weather Fatalities

10. Alcohol
2014 had the big drop in alcohol inv crashes. Thus , there has been progress made wrt alcohol problem, but it still remains one of the largest causes of fatalities and crashes. 30% of total fatalites are due to alcohol.

11. Alcohol Crashes… time of day, day of week

12. Alcohol Crashes… crash type, age
~50% of alc crashes are single vehicle crashes . And 8% of these were hit and run, 8% involved peds and 2% involved bicyclists.
Also, 10% of motorcycle fatalities and serious injuries

13. Drugs
The data do not indicate whether the observed increases are the result of increased testing or of increased drug use.

14. Drugs… by age group

15. Unrestrained

16. Commercial Motor Vehicles

17. Motorcycle
Exhibit Variation from year to year and 2013 have highest # of motorcycle fatalities. Previous analyses have suggested that not wearing a helmet tends to increase fatality risk much more than serious injury risk. Since the helmet law was modified in April 2012, the fatality numbers are consistent with this trend.

18. Motorcycle.. Seasonal variation
Motrcycle fatalities peak in summer months (july)

19. Pedestrian
2015 has 52% increase in pedestrian fatalities relative to 2006 – highest in the last ten years

20. Bicyclists
Highest in 2013

21. Young Drivers
15-24yrs

22. Senior Drivers
65+
2014 had fewest senior driver related fatalities

23. Rear-End
There were only 2 rear end crashes in this type of crashes results in very few fatalities and usually more injuries. However, serious injuries due to rear-end crashes is also going down.

24. Single Motor Vehicle
2011 was lowest .. And 2014 had highest # of single vehicle crashes.

25. Others
Crash cause not evident – last category. Although the cause of the crashes is not very clear from the analysis, the fatalities have decreased by 34% in This reduction could mean that these crashes have been accounted in the above categories or due to the fact that the overall number of crashes has decreased.

26. Cumulative Stacked Plot for Total Crashes
10% of Michigan crashes due to deer ; highest percentage of crashes caused by young drivers years of age, then senior drivers and winter crashes.
Accounnted reasons or causes for 80% of crashes

27. Cumulative Stacked Plot for Fatalities
The stacked bar graph compares contributions of different crash types to fatalities over the last ten years. Deer and winter weather crashes contribute to 10% of all crashes. Although there are educational campaigns and enforcements in place, this number depends primarily on seasonal variation and exposure. Focusing on the next big problem area, it is evident that alcohol fatalities remain at 25% of the total fatalities. The proportion of drug related crashes in the overall picture are steadily increasing. Pedestrian and bicycle crashes are increasing over the years and seem to be an area of major concern.
Young drivers fatalities have reduced compared to elderly driver fatalities overall trend is increasing.
Motorcycle fatalities are increasing since the helmet repeal law in truck related fatalities decreasing compared to 2006.

28. Removing Deer & Winter Weather
Deer and winter removed , patterns are more clearer- alc & drugs 40% of total fatalties. Peds and bikes and elderly drivers are increasing.

29. Cumulative Stacked Plot for Serious Injuries
A injuries separately – pattern shifts towards higher young drivers 24 and younger, drivers 65 and older and alcohol related crashes.

30. Summary 10% of Michigan crashes are due to deer.
Winter weather crashes and fatalities are variable.
Highest proportion of crashes (~40%) are due to young drivers and senior drivers.
Around 35% of Michigan fatalities are alcohol related.
Drugs related fatalities and pedestrian fatalities are increasing.

31. THANK YOU prabhans@umich.edu
Contact Information:
Prabha Narayanaswamy
University of Michigan Transportation Research Institute