Dear friend, Mumbai Suburban Railways are one of the best in the world, if evaluated in totality
(1) over 75 lacs paxs on very small network, which is very highly worked, stretched to limits
(2) Very high frequency of suburban trains trains, once every 4 minute (peak time), however efforts are on to lower it to 3 minutes.
(3) A large number of...
more... long distance express trains also share the network
(4) Mumbai port trust freight traffic is also accommodated.
(5) this network held head high with pride when it was giving decent revenue surpluses, a unique feat in the world where govt invariably subsidise intra city rail travel. The extremes of polpulist steps (no fare rise for 10 yrs) caused the profit making suburban system into a loss making one. Even a modest and digestible increment of 5% per annum in fares during that period, could have avoided the current mess.
(6) Earlier Japanese experts visiting to study and suggest improvements, were astonished to see how such diversity and volume of traffic is handled with given technology and network.
So any improvement is very difficult in the present network. Augmentation through new tracks etc. is also extremely difficult, because at Mumbai land/space comes at extremely high premium.