High Quality Content by WIKIPEDIA articles! Grand Southern Trunk Road or National Highway 45 is one of the busiest National Highways in Southern India with a total length of 472 km (293 mi). The highway starts from Kathipara junction in Guindy, a very busy confluence of five roads in southern Chennai and extends up to Theni. It connects Chennai to its airport and the southern suburbs. The two important Cities connected by this highway are Chennai and Trichy and the two important towns connected by this highway are Dindigul and Theni in Tamil Nadu. The highway has a 4 lane (2 lanes each direction) system between Chennai and Trichy, though a complete change to 6 lanes is being planned.The Chennai International Airport is located on this highway within the Chennai City limits.