That means chengalpattu was a junction even in british era
This railway map is more than 9 decades old atleast 1928 or before, reason, Madurai-Bodi railway line came into existence in 1928. South Indian Railways (S.I. Railway system as shown in map) was merged with Southern and Mahratta railway and Mysore state railway to form Southern Railway in 1951.
This map clearly shows that not much railway lines have been added since independence in Tamil Nadu except SA-NMKL-KRR-DG line and ATQ-MNM-VPT line and couple of lines.