It’s a known cultural trait - suicide by jumping. For some reason Chinese prefer to jump to death from HDB flats and onto tracks. The primary driver is to share their plight with the public. Malays do not kill themselves and Indians preference is to hang themselves in the the privacy of their homes
I do recall in old Singapore before flats became common place, ingesting poison usually weedkillers were common.
Once this trend of jumping on track sets in, you have no choice but to address it.