The national highway network connecting Delhi, Mumbai, Chennai and Kolkata is called ______.

The correct answer is Option 4. 

Key Points

•  The national highway network that connects Delhi, Mumbai, Chennai, and Kolkata is commonly referred to as the Golden Quadrilateral.
• It is a system of highways that spans a total length of 5,846 kilometers (3,633 miles) and connects the four major metropolitan cities in India.
• The Golden Quadrilateral was completed in 2012 and is considered a significant infrastructure achievement for India, as it has improved transportation and connectivity across the country.

Additional Information

•  The Diamond Quadrilateral railway project is to develop high speed rail network across several metros of India.
• This quadrilateral railway network connects major metro cities in India, i.e. Delhi, Chennai, Mumbai, Ahmedabad, Kolkata Hyderabad and Chennai.
• This project is similar to Golden Quadrilateral which is roadway project of India which connects four metros by express ways, the project falls under National Highways Development Project which has supported for better road transport in India.
• In the same way to improve India’s rail infrastructure there is a need to implement High speed trains/ Bullet trains.
• On 9th June 2014, The President of India Shree Pranab Mukherjee officially announced that the government project led by Prime Minister Sri Narendra Modi will launch a diamond quadrilateral project and fulfill the demand of high speed trains.