The Golden Quadrilateral Project (GQ) (Phase 1) connecting the metro cities of Delhi-Mumbai-Chennai-Kolkata-Delhi, with a total length of 5,846 km is part of the ambitious National Highway Development Project (NHDP) launched during the Vajpayee regime. The NHDP project includes North-South and East-West corridors (Phase II) connecting Srinagar (Jammu & Kashmir) to Kanyakumar (Tamil Nadu) (including Kochi to Salem spur0 and Slichar (Assam) to Porbandar (Gujarat). Total length is about 7,300 km.
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The NHDP is the largest highway project ever undertaken in the country. Under this project being implemented by National Highways Authority of India (NHAI), about 14,279 km length of National Highways is proposed to be upgraded to four to six lanes at a total estimated cost of Rs. 64,639 crores (in two phase).