Chennai suburbs, Kanyakumari-Trivandrum and Trichy-Tanjore routes have good local train networks, where they are necessary and used extensively. Otherwise, the bulk of rail passengers in TN is pretty much restricted to District HQs and pilgrim centers. Villages in interior TN mostly have a stagnant population and thankfully not many depend on railways say, for a visit to their adjacent villages and hence a few passenger trains/MEMUs get the job done.
Same is the case I have noticed in Karnataka as well.
But traffic towards Bangalore and Chennai where the majority of the...
more... state's floating population is based out of, is always saturated.
Kerala routes have been congestion-prone for some time now, hence local passengers have become dependent on Intercity and Long-distance trains as well. End to end passengers are few and Intercity trains there work like patched-up MEMUs.