Real-time numbers of BART trains

Is there a listing/website where you can find out the numbers of BART trains which are on the move in real-time ?

Because if you forget an item you might want to know which train it was on.

You can see these numbers for SF busses and trains, for example,... Online on the Muni website.

Another reason could be if a friend calls you and says I'm boarding at West Oakland,.now you can clearly see online which train they're on and when are they going to arrive

Edit: kinda resolved see here see here