What is ‘Golden Quadrilateral’? Give one advantage of it.

The golden quadrilateral is an important national highway network of India. It connects the major centres of India and the four metros- Delhi, Mumbai, Chennai and Kolkata. It is maintained by the National Highway Authority of India. It was completed in 2012. It is the largest highway project undertaken in India. The construction of this has reduced the time, distance and cost of travelling between the mega cities.