1. Drugs & Driving: What now and what next?
Road Safety Research Office Ministry of Transportation of Ontario
CARSP Conference 2016

2. What is the situation?
2013 collision data: 64 road users killed by drivers who had used drugs

3. What is the situation?
2013 collision data: 64 road users killed by drivers who had used drugs
2013 coroner data: 39% of drivers killed tested positive for drugs*

4. What is the situation?
2013 collision data: 64 road users killed by drivers who had used drugs
2013 coroner data: 39% of drivers killed tested positive for drugs*
2014 roadside survey data: 10.5% of sampled drivers were drug-positive

5. What do we know?
There is existing technology for detecting drug presence at roadside.
Oral Fluid Screening Devices

6. What do we know?
There is existing technology for detecting drug presence at roadside.
Oral Fluid Screening Devices
There is an existing test battery for detecting impairment at roadside.
Standardized Field Sobriety Test

7. What don’t we know?
Despite having methods to test for drug presence and drug impairment, presence and impairment is not a one-to-one relationship.

8. Marijuana has impairing effects.
(per lab & simulator studies)
Attention
Reaction time
Distance perception
Speed variability
Car following
Lane positioning

9. Effect estimates of marijuana on collision risk are mixed (per epidemiology studies).
Differences in biological samples

10. Effect estimates of marijuana on collision risk are mixed (per epidemiology studies).
Differences in biological samples
Confounding factors, e.g., age, sex

11. Effect estimates of marijuana on collision risk are mixed (per epidemiology studies).
Differences in biological samples
Confounding factors, e.g., age, sex
Misclassification of exposure

12. Effect estimates of marijuana on collision risk are mixed (per epidemiology studies).
Differences in biological samples
Confounding factors, e.g., age, sex
Misclassification of exposure
Specific populations

13. What are we doing about this?
Calculating an Ontario-specific estimate of collision risk from marijuana.
Different places, different usage habits?

14. What are we doing about this?
Calculating an Ontario-specific estimate of collision risk from marijuana.
Different places, different usage habits?
Mediated by “driver profile”?
E.g., collision history, conviction history

15. HOW are we doing this?
Recall from earlier slide:
2013 coroner data: 39% of drivers killed tested positive for drugs*
2014 roadside survey data: 10.5% of sampled drivers were drug-positive

16. Update 2013 coroner data to 2014 Recall:
2013 coroner data: 39% of drivers killed tested positive for drugs*
2014 roadside survey data: 10.5% of sampled drivers were drug-positive
Update 2013 coroner data to 2014

17. Adjust for confounders, e.g., age, sex
Recall:
2013 coroner data: 39% of drivers killed tested positive for drugs*
2014 roadside survey data: 10.5% of sampled drivers were drug-positive
Update 2013 coroner data to 2014
Adjust for confounders, e.g., age, sex

18. Adjust for confounders, e.g., age, sex
Recall:
2013 coroner data: 39% of drivers killed tested positive for drugs*
2014 roadside survey data: 10.5% of sampled drivers were drug-positive
Update 2013 coroner data to 2014
Adjust for confounders, e.g., age, sex
Adjust thresholds to reflect recent usage

19. Adjust for confounders Adjust thresholds to reflect recent usage
Recall:
2013 coroner data: 39% of drivers killed tested positive for drugs*
2014 roadside survey data: 10.5% of sampled drivers were drug-positive
Update 2013 coroner data to 2014
Adjust for confounders
Adjust thresholds to reflect recent usage
Isolate the “marijuana-only” cases

20. Adjust for confounders Adjust thresholds to reflect recent usage
Recall:
2013 coroner data: 39% of drivers killed tested positive for drugs*
2014 roadside survey data: 10.5% of sampled drivers were drug-positive
Update 2013 coroner data to 2014
Adjust for confounders
Adjust thresholds to reflect recent usage
Isolate the “marijuana-only” cases
Match for time of day, day of week, etc.

21. Next Steps
Monitor literature for emerging evidence on drugs and driving, particularly cannabis and driving.
Continue with our in-house collision risk estimate, with results by year end.

22. Tracey Ma Team Lead, Special Projects Road Safety Research Office Ministry of Transportation