Yeah, once the PVC gets going it burns pretty good (and that explains all of the black smoke).
This highlights what may become an increasing problem in the USA and throughout the world - razers.
Alfred (Michael Caine): Some just want to watch the world burn.
That term is currently so unfamiliar to our culture that it triggers the spell checker because it doesn't recognize it as a word at all.
The word "raze" or "rase" derives from Old English "scratch or incise" which derives from French rase, "to shave off, remove".
We have heard of the word in regard to "razing" (demolishing) a building or more archaically, to raze a town to the ground (which seems odd to the ear because we think of "raising up").
I once read a science fiction story in which a culture was beset by a sub-culture which spent most of its time running around destroying things that the mainstream culture built. They were known as "razers" and were hunted like animals and killed on sight.
With the lunatic leftists running things more and more, helping to create and normalize things like double-digit unemployment or "cradle-to-grave" poverty in first tier economies, we will doubtless see things like this more and more.
A psychologist once postulated that one of the basic human needs, in addition to food, water, shelter from the elements, medical treatment, is "esteem" or, "a sense that one is worthy and powerful". When people, for whatever reason, feel unworthy and powerless, they begin to feel as if they are no longer a part of Humanity - that they have been abandoned, left behind and forsaken by those who have decent jobs, property, assets, stability, families.
These disenfranchised people often feel as if they have no stake in or reason to cooperate with or further the laws, rules or goals of the rest of society. Such people will in some cases (often inspired by leftist hate propaganda against capitalism or "the rich") take drugs or drink and work themselves up into a hate frenzy - during which they do violent, destructive things (like arson).
Post-arrest interviews with people who start fires or commit great acts of destruction for no purpose other than "fun" reveal that for many such people, what they sought in their acts was to feel "powerful and important". That is understandable in a twisted way, since they spend so much of their lives feeling insignificant, powerless and minute in the scheme of the universe.
Maybe they didn't really intend to take down the bridge, but they might well have intended to start the biggest fire that they could - and in that they succeeded.
This highlights the potential for a much larger problem, since the homeless, chronically unemployed (and unemployable, mentally-ill) population of the world is so massive and if anything is increasing, not getting smaller.
Our culture will have to face up to the fact that these sort of things may become a chronic problem going forward and that not only ideological terrorists, but disenfranchised nihilists (who believe in nothing but rage) are likely to exploit opportunities to destroy on a large scale if they get the chance.
What we do about it is another thread, perhaps. But I would bet good money that the motivation behind this action will turn out to be three people who started a fire because they wanted to enjoy watching the world burn.