Let it be u see Central is more congested during morning hrs due to passing through train. Central is not via station its a terminal. Because this it loose its terminal status. They have to provide water to passing through trains. Loco change tooks time and also affects suburban traffic. U see in mumbai they constructed a bye pass station panvel which is very useful trains coming form south will pass through without touching CST / BANDRA / CENTRAL etc... likewise chennai can do Chengalpattu / ajj is not a distance now a days. From there to city suburban / city buses are available so they can plan to avoid passing through trains in central / egmore.
Benefits....
1....
more... cleanliness will be there.
2. Water save
3. Loco Save
4. Will not affect suburban traffic.
5. start more trains by compensating this passing through