National Highway 4 (NH 4) was a major National Highway before National Highway renumbering in Western and Southern India. NH 4 linked four of the 10 most populous Indian cities – Mumbai, Pune, Bangalore, and Chennai. NH 4 was in length and passed through the states of Maharashtra, Karnataka and Tamil Nadu. Route NH 4 constituted roughly 90% of the Golden Quadrilateral's Mumbai–Chennai segment. As a part of this project NH 4 has been widened from two-lane single carriageway to four-lane dual carriageway. The highway is known as Pune–Bangalore (PB) Road in some parts of Karnataka where it passes through. The Mumbai–Pune section of the highway was supplemented by the Mumbai–Pune Expressway in 2000. The NH 4 highway passes through highly populated towns and cities of Maharashtra, Karnataka, Tamil Nadu and Andhra Pradesh namely Pune, Satara, Karad, Sangli, Kolhapur, Belgaum, Dharwad, Hubli, Haveri, Ranibennur, Davanagere, Chitradurga, Tumkur, Bangalore, Kolar, Kanchipuram, and Sriperumbudur. The Bangalore-Chennai section of the highway is supplemented by the triangle of National Highways NH 7, NH 46, and returns to NH 4 at Walajapet in Vellore district. In some areas, one side of the highway is made of concrete while the other side is of tar. To overcome heavy traffic between Bangalore and Chennai the NHAI had planned to build the Bangalore–Chennai Expressway which allows vehicles to ply at a max speed 120kmph.It will start from Sriperumbudur in Tamil Nadu and terminate at Hosakote near Bangalore in Karnataka which is nearly 240 km. The NH 4 by-passed Pune from Dehu Road to Katraj. The Pune bypass has 4 lanes. There is a partial service lane which cannot be called as motorable. Now, it is being widened by two more lanes, making it a 6-lane road from Dehu Road to Katraj since it is also used by the people of Pune as the city is growing on the other side of the highway too. NH 4 now also bypasses the busy Katraj ghat in Pune by a tunnel which saves almost one hour of travel on NH 4. NH 4 bypasses Sangli at about . There are two exits for Sangli–Miraj twin cities on NH 4. Both exits form a triangle with NH 4 and Sangli is about from each exit. Peth Naka exit is used by vehicles coming from Mumbai and Pune towards Sangli. Shiroli Naka exit is used by vehicles coming from Bangalore, Hubli, Belgaum and