National Highway 6 & Economic Corridor 1 (EC1) (commonly referred to as NH6), was a National Highway in India that has been separately designated under the new national highway numbering system. It was officially listed as running over from Surat to Kolkata. The route was also known as Asian Highway 46 (AH46) & Mumbai - Kolkata Highway and Great Eastern Highway.
NH6 ran through Gujarat, Maharashtra, Chhattisgarh, Odisha, Jharkhand and West Bengal state in India. The highway passed through the cities of Surat, Dhule, Jalgaon, Bhusaval, Khamgaon, Akola, Amravati, Nagpur, Bhandara, Gondia, Amgaon, Dongargarh, Rajnandgaon, Durg, Raipur, Mahasamund, Bargarh, Sambalpur, Kharagpur, Kolkata.
Historically, the route from Bangriposi to Gopiballavpur via Baripada was constructed before the 18th century by James Rennell Sahib in 1776. It is still known as Old Kolkata-Mumbai Road prior to 1999 period & it used to go via Kharagpur, Jhargram, Chilkigarh, Chichra, Gopiballavpur, Kandnashol, Murgabadi, near Baripada, Bhajpur Chowk in Bhanjpur, Gangraj, Kalabadia, Pathuri to Bangriposi. In 1999-2002 period, the long Baharagora-Bangriposi Highway via Jharpokharia was constructed & the traffic of Old Mumbai Road shifted on that new stretch. Then Old Mumbai Road lost it's importance & NH-6(Now NH49) became an important route.
As of 2010 notification from Ministry of Road Transport and Highways, old NH 6 has been renumbered as follows.
This route is One of the incomplete Highways of India due to presence of numerous ghat sections between Bangriposi & Sambalpur, crossing mountain & hill ranges of Odisha, Ghats Between Nagpur To Amravati Near Talegaon Village, Karanja (Ghadge), District Wardha in Maharashtra.
This highway crossed the AH47 at Dhule and Asian Highway 43 at Nagpur.
Many cities and towns in various districts in the States of Gujarat, Maharashtra, Chhattisgarh, Odisha, Jharkhand and West Bengal were connected by National Highway 6.
To shorten distance of National Highway 6, 4 lane wide Tatanagar - Rourkela Expressway is planned. This long expressway will reduce travel time Kolkata & Sambalpur. Currently Kolkata to Sambalpur by road takes 12 hours 30 mins to cover . The Tatanagar - Rourkela Expressway will increase Kolkata to Sambalpur distance to , but will reduce 1 hour 15 minute travel time.