The construction and rail industry are anti-anything, no way in hell are they going to allow folk work who've had a spliff at the weekend.... See what bills they draft in,if you have a perscription and your drug checked and have CBD,THC or CBC in your system you should be covered,this isn't about a spliff at the weekend,sativex is an oral for example,its going to have stringent regulations.
For it to have any benefits I'm guessing the dosage will have to be on spliff levels.....