Which is the apex body responsible to improve the quality of roads at the national level in India?

National Highway Authority of India (NHAI)

The National Highways Authority of India (NHAI) is an independent agency of the Government of India, accountable for the management of a network of over 50,000 km of National Highways out of 1,15,000 km in India. It is a nodal agency of the Ministry of Road Transport and Highways.