Delhi-Mumbai Expressway under construction near Bharuch, Gujarat. (@sahil11p/Twitter) The countryâs longest 1350-km expressway between Mumbai and Delhi that will reduce the commute time between the two metros to 12 hours is set to be completed by January 2023. The project spans across the states of Haryana, Rajasthan, Madhya Pradesh, Gujarat and Maharashtra and is being constructed at a cost of Rs 90,000 crore. The expressway has eight lanes currently but it has enough space left on both sides to be expanded to 12 lanes. As many as two million trees and shrubs will be planted on the entire stretch and it will be watered through drip irrigation.