When it's raining, some BART stations have floors that get floody, not to mention slippery, especially by the stairs where water accumulates from the dripping rain. I saw someone slip in a muddy wet puddle today inside the station! That isn't the first time I've seen someone fall flat on their butt. This woman needed help up--she was well over her 50s. I've even slipped a couple times in the past and had to balance myself before falling.
On occasions, there are caution signs..I guess that is the least they can do to keep people safe. Sometimes, not only are not no signs, the puddles are so large and the wetness has spread so far into the stations that it is truly a serious hazard.
Those of you who work for BART will probably say...we don't have the resources, we can't keep up with the cleaning, we'll need to raise fares to keep the station floors dry...etc. There are always reasons why BART can't be better.
Until you get someone who falls, breaks their bones, is hospitalized and sues you for reparations on top of exorbitant medical bills, I know nothing will change.