which is in turn connected to Coimbatore. The centenary old Pamban Bridge over sea connecting Rameswaram in Pamban island to the mainland is an engineering marvel. It is one of the oldest cantilever bridges still in operation, the double-leaf bascule bridge section can be raised to let boats and small ships pass through the Palk Strait in the Indian Ocean. The government of Tamil Nadu created a Special Purpose Vehicle (SPV) for implementing the Chennai Metro Rail Project. This SPV named as "Chennai Metro Rail Limited" was incorporated on 3 December 2007 under the Companies Act. It has now been converted into a joint venture of the governments of India and of Tamil Nadu with equal equity holding. Chennai has a well-established suburban railway network and is constructing a Chennai Metro with phase1 operational since July 2015. Major railway junctions (four and above lines) in the state are Chennai, Coimbatore, Katpadi, Madurai, Salem, Erode, Dindigul, Karur, Nagercoil, Tiruchirapalli, and Tirunelveli. Chennai Central, Chennai Egmore, Coimbatore Junction, Tiruchirappalli Junction, Madurai Junction, Salem Junction and Katpadi Junction are upgraded to A1 grade level. Loco sheds are located at Erode, Arakkonam, Royapuram in Chennai and Tondaiyarpet in Chennai, Ponmalai (GOC) in Tiruchirappalli as Diesel Loco Shed. The loco shed at Erode is a huge composite electric and diesel Loco shed. MRTS which covers from Chennai Beach to Velachery, and metro rails also running from Washermenpet to Airport metro station and Central metro station to St.Thomas Mount metro station. Airports Tamil Nadu has three international airports, namely Chennai International Airport, Coimbatore International Airport, Tiruchirappalli International Airport. Madurai Airport is the only customs airport in the state. Salem Airport, Tuticorin Airport and Vellore Airport are the domestic airports. Chennai International Airport is a major international airport and aviation hub in South Asia. Besides civilian airports, the state has three air bases of the Indian Air Force namely Sulur Air Force Station, Thanjavur Air Force Station and Tambaram Air Force Station and two naval air stations INS Rajali and INS Parundu of Indian Navy. Neyveli Airport is being renovated since 2019 to start the service from mid 2020. Seaports Tamil Nadu has three major seaports located at Chennai, Ennore and Thoothukkudi, as well as seven other minor ports including Cuddalore and Nagapattinam. Chennai Port is an artificial harbour situated on the Coromandel Coast and is the second principal port in the country for handling containers. Ennore