Actually lots of immigrants in chennai are settled in south chennai areas like GST Road , OMR and ECR Road than other parts of chennai. These areas are superfast emerging with IT and industrial hubs. Tambaram is nearest station for them. Actually every south bound train fills only at TBM. MS to TBM will almost be empty. Now the city has streched till Guduvancheri(GST Road)/Kelambakkam(OMR Road)/Kovalam(ECR Road) in the southern direction.
P.S: I am resident of southern chennai.