[3] The highway starting from its junction with NH-48 near Chennai connecting Chengalpattu, Tindivanam, Puducherry, Cuddalore, Chidambaram, Karaikal, Nagapattinam, Velankanni, Thiruthuraipoondi, Muthupettai, Adirampattinam, Manamelkudi, Thondi, Devipattinam, Ramanathapuram bypass, Thiruppullani, Keelakarai, Ervadi, Valinokkam, Sayalgudi, Vembar, Vaippar, Kulathur, Veppalodai, Pattina, Maruthur and terminating at its junction with NH-44 near Thoothukudi.

[3] The highway is planned to extend with a 123 kilometres (76 mi) long stretch from Thoothukudi to Kanyakumari.

In the first phase, four lane will be completed from Thoothkudi to Karaikudi covering 230.2 kilometres (143.0 mi).

Next phase of four laning will be completed from Karaikudi to Cuddalore covering 222.3 kilometres (138.1 mi).

The last phase of four laning will be completed in Cuddalore to Chennai stretch covering 204.5 kilometres (127.1 mi).