Road network in Tamil Nadu June 2018, Tamil Nadu's road network has a total road length of . Tamil Nadu has about of highways which is designated as "National Highways" and "State Highways" on the basis of traffic intensity and connectivity. The various types of roads and their lengths are given below: Road stretches which have heavy traffic intensity of more than 30,000 Passenger Car Units (PCUs) connecting different state capitals, major ports, large industrial areas and tourist centers are designated National Highway by Government of India. In Tamil Nadu, "National Highways Wing" of Highways & Minor Ports Department was established in the year 1971
U interface U interface The U interface or U reference point is a Basic Rate Interface (BRI) in the local loop of an Integrated Services Digital Network (ISDN). It is characterized by the use of a 2-wire transmission system that connects the network termination type 1 (NT1) on the customer's premises and the line termination (LT) in the carrier's local exchange. It is not as distance sensitive as a service using an S interface or T interface. In America, the NT1 is customer premises equipment (CPE) which is purchased and maintained by the user, which makes the U interface a User–network interface