Everyone Agrees that the Local Trains are the lifeline of Mumbai. In fact the growth of Mumbai can be singularly attributed to the amazingly awesome Railway system.
No other city had such a widespread network, which at its greatest length was 126 kms, till Delhi got the Metro.

What the sad part was the criminal negligence that successive Govts subjected the Mumbai Railway to.
First the coaches. Till 2015, most of the Mumbai network, ran on local trains, that were designed in the 1950s. Even today, they haven't been completely eliminated.

Also, the story of the AC local train is so sad that it is funny.
The first proposal for an Ac train, was made in 2002.
The approval came thru in 2013.
The first train was delivered in 2016.
And the first time it ran for the public was in 2017.
It took a total of 15 years.

It took 15 years for us to manufacture and run an AC train, based on the same technology, running on the same track.
15 years.