The fences and guards have absolutely helped. When I first started the commute we had something like 12-14 deaths one year. Since those fences went up it’s dropped dramatically.
Things effective one place, are less effective in others because of "sociocultural" reasons [0], but there is some evidence to suggest denying people access to the tools to commit suicide, and reducing media coverage (social contagion/clustering) seem to help.
With that said, yes, you are right, just changing one thing doesn't do much, there needs to be a bigger picture approach that addresses many factors.
Putting up fences next to train tracks won't do much for the former, but I suspect it will reduce the frequency of the latter (which it did, in this case).
It reduced the frequency of "suicide by train". But suicides overall went up 30% from what the article states. It's more likely that the people who could no longer use this method as a spur of the moment thing just chose something else. Transportation related suicide accounts for 0.4% (or ~170 in 2012) of suicides in the US. [0] "Fall", another spur of the moment method, accounts for 6 times as much. You can only build so many fences.
As someone with a bit of experience on the topic I can tell you that when suicidal ideation reaches the tipping point you need more than a fence to stop them.
But I'm not saying "don't put up the fence". I just found GP's remark that "The fences and guards have absolutely helped" either a bit cynical or unrealistically optimistic. The only thing we can say with certainty is that it helped keep the trains going. I'm not sure it definitively saved lives. For that we need to do a lot more than build a fence...
[0] http://lostallhope.com/suicide-statistics/us-methods-suicide