I would agree with Dr. Kelsall. Again, six months is a very short time for a public health campaign to change attitudes and behaviours. Most previous ones on smoking, exercise, and other things, have taken a number of years to penetrate to thinking and behaviour. I don't think you'll get all that far in six months.
We've seen in the United States that recreational marijuana, even medical marijuana, has contributed to an increased use in marijuana. We have not yet seen a big effect on crashes, but I suspect there is one. It's almost inevitable. I think for road safety, this is not positive.