That might be addressed in the bus company, transportation district (or whatever) rules, rather than the statutes. Or in the Department of Transportation rules (which may govern trucks and orther commercial traffic.) Whether that has the force of law would be another question.
I'm not on solid ground by stating this becuase I usually avoid public transportation, but the Regional Transportation District out here (commonly called RTD, which runs the bus and light rail system) seems to be a quasi-governmental organization whose service area overlaps several cities and counties.
They (RTD, here) recently started putting biiiig signs over the left hand turn signal areas of the buses warning that you must yield to the bus when pulling out with its signals on, and conclude in biiiiig-assed lettering, "It's the Law." When they started that, I wondered, "What law?" but I never researched it. If indeed that's "The Law," it seems kind of dangerous in terms of traffic rules, since the buses now have "carte blanche" to just haul ass out of a bus stop and screw you, the mere mortal behind it.
So. Maybe you ought to contact your bus outfit or commercial traffic regulatory agency directly, although I warn you in advance that whoever you contact may well lie about it so demand specific citations.
And the phrase "article or material which is likely to cause harm to others" is, once again, so vaguely worded that I wonder about its enforceability. "Likely?" If I go to the supermarket and incidentally pick up a can of Drano and a couple of those small propane tanks for my little Bernz soldering torch, or a can of lighter fluid for my Zippo along with my milk and hamburger, can I carry them home on the bus?
Or do I have to Hazmat them home by Fedex or something?
Too often I have seen "laws" which can only interpreted in terms of "Oh, you know what I mean."
Well, no. Criminal laws are supposed to be specifically written, I am told.
"Likely," indeeed.
Terry, 230RN