They already have those in some Tokyo stations; off the top of my head, I think Roppongi it-chome and other Namboku line stations have them, among others. But the article mentions that it's very expensive, and that's why they're trying other things before installing platform fences in every station. There are thousands of train platforms in the Tokyo area, so installing fences at all of them is going to take an extensive amount of time and money. I don't think the blue lights are going to work, but hey, it's cheaper.Edit: Yeah, in fact, here's a pic of the station I mentioned that I dug up on Wikipedia,http://en.wikipedia.org/wiki/File:Roppongi_1chome- ...