You Steve.
No need for ATP - just stick some trap-points beore the start of the single line. Messy, but effective.
If the driver had traces of wobbly-weed in his system, it's difficult to feel any sympathy for him. I'm told that blood chemistry can differentiate between active and passive intake.
My company has a policy that you MUST inform the shift manager of ANY drugs/medicines you have taken when you book on duty. They then ring Aldermarston which runs a drug register of almost all worldwide drugs. You can't drive til you get the all clear, so they like us to give them a few hours' warning.
They won't let you take Night Nurse within 48 hours of a turn, which is a shame because I find it works really well for me when I have a streaming cold. Like being coshed with a brick.
If at any time you are given a drug/alcohol test and they find something you didn't declare, you'll probably be down the road. Especially if it's a drowsy type medication.
I even had to tell them when I was on the Atkins diet, which to be honest did have some strange neurological and physiological effects.
You don't eat any carbohydrates, and I once foolishly succumbed to a bag of chips. It made me float on clouds for 10 minutes, but fortunately was on a Rest Day.
It's a funny old world.
Cheers, BW.