With the legalization of recreational marijuana emerging next week, how should we react to the potential problems that the legalization brings along, especially for driving?

We have conducted a simulation experiment with CTV Vancouver to measure change in driving behavior. With our brand new prototype modeling and Virtual Reality, we have a medical marijuana user in our “City of Richmond” map and did a performance comparison before and after the usage of cannabis.

We have designed a seven-minute virtual course within our City of Richmond map for this experiment. Our testee, Chris Gibson, mentioned that marijuana will not impact his ability to drive. He then proceeded to the experiment and drove on the designated route on our simulators.

There were two parts of the experiment — before and after using marijuana. To accurately measure the “before and after” performance, several key driving factors were measured such as:

  • Reaction Time
  • Safe Driving Awareness
  • Speed Maintenance
  • Space Margin
  • Vehicle Handling Skill

Our system allows multiple drivers on one map, so we also purposely inserted some unexpected scenarios to test the driver’s reaction and maneuvering skills. Here are some of the unexpected objects or scenarios that the testee would encounter:

  • Construction merge road sign
  • Reckless driver brake-checking testee
  • Excessive speeding driver
  • Driver blowing through stop sign and block testee
  • Driver changing lane and cut off testee

Our virtual driving instructor explaining the result of the experiment

We found in the experiment that, after the consumption of marijuana, the testee could still be able to maintain a stable driving position and vehicle control. In one scenario, however, when the leading car suddenly stopped under traffic light, testee had different driving style compared to before taking marijuana. Testee changed his driving style and he decided to lane change without shoulder-checking and sped off. Testee may have experienced emotional changes which influenced his judgment on driving. 

We also found that after the usage of marijuana, testee was not able to concentrate and control his speed as well as before the consumption. His speed during the second section fluctuates a lot between 35km/h – 65km/h. In this situation, testee will not be able to pass normal class 5/7 road test while road test requires testee to maintain speed around 50km/h in normal city highway with 5km/h of adjustment.

We need more scientific studies to confirm what and how marijuana affects us on driving. With the legalization next week, there is still have a lot of unknown about how we should regulate marijuana for all drivers. Driving is an important part of our daily life; without clear regulations and guidelines, legalization of marijuana could potentially bring more trouble for both smokers and non-smokers.