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 (UNI). The American variant is specified by the American National Standards Institute (ANSI) in T1.601. In Europe, the NT1 belongs to the network operator, so the user doesn't have direct access to the U interface. The European variant is specified by the European Telecommunications Standards Institute (ETSI) in recommendation ETR 080. The ITU-T has issued recommendations G.960 and G.961 with world-wide scope, encompassing both the European and American variants of the U interface. Like all other ISDN basic rate interfaces, the U interface carries two B (bearer) channels at 64 kbit/s and one D (data) channel at 16 kbit/s for