An aluminum
around pennsylvania rust is a major problem, coating guardrails only helps till the coating is damaged by say someone scraping it.
road salt causaes much of the problem, i will try a magnet on some this week.
i suppose they could spot weld the guardrails to the uprights to make them more vandal resistant.
i took a bunch of scap in recently they now make a copy of your drivers license, no doubt the poilce will be called if you take in guardrails or light poles.