Mumbai's railway system is
“perhaps the most complex, densely loaded and intensively utilized system in the world” , carrying more than six million passengers a day. At peak times, the trains are so overloaded that it has been estimated that there can be 14 passengers crowded into a single square meter  (this statistic is probably based on the floor area of the carriages and ignores the fact that many of the riders will be clinging to the outside of the train). An average of around 10 people die on the system every day, either run down by trains while crossing the tracks, or as a result of falling from the roofs or open doorways of the overloaded trains.
Having time and money on my side, I avoided rush hour and rode in first class whenever I took the trains. Even so, when I didn't pay attention to the time and arrived at Chhatrapati Shivaji Terminus (CST) just as rush hour began, I was practically knocked off my feet by the wave of commuters scrambling aboard the train I was trying to leave. Even outside the station, trying to walk against the human tide pouring down to CST to catch their train was a challenge.