The Golden Quadrilateral is a national highway network connecting several major industrial, agricultural and cultural centres of India. It forms a quadrilateral with all the four major metro cities of India forming the vertices, viz., Delhi (north), Kolkata (east), Mumbai (west) and Chennai (south). Other major cities connected by this network include Ahmedabad, Bengaluru, Balasore, Bhadrak, Bhubaneswar, Cuttack, Berhampur, Durgapur, Faridabad, Guntur, Gurugram, Jaipur, Kanpur, Pune, Kolhapur, Surat, Vijayawada, Eluru, Ajmer, Visakhapatnam, Bodhgaya, Varanasi, Prayagraj, Agra, Mathura, Dhanbad, Gandhinagar, Udaipur, and Vadodara. The main objective of these super highways is to reduce the travel time between the major cities of India, running roughly along the perimeter of the country. The North–South corridor linking Srinagar and Kanyakumari, and East–West corridor linking Silchar (Assam) and Porbandar (Gujarat) are additional projects. These highway projects are implemented by the National Highway Authority Of India (NHAI). At 5,846 kilometres (3,633 mi), it is the largest highway project in India and the fifth longest in the world. It is the first phase of the National Highways Development Project (NHDP), and consists of two, four, and six-lane express highways, built at a cost of ₹600 billion (US$7.5 billion). The project was planned in 1999, launched in 2001, and was completed in 7 January 2012.