state and is the main hub of the city's rail network. Sydney Trains is the suburban rail service. Its tracks form part of the New South Wales railway network. It serves 175 stations across the city and had an annual ridership of 359 million passenger journeys in 2017–18. Sydney's railway was first constructed in 1854 with progressive extension to the network to serve both freight and passengers across the city, suburbs, and beyond to rural New South Wales. The main station is the Central railway station in the southern part of the CBD. In the 1850s and 1860s, the railway reached areas that are now outer suburbs of Sydney. Sydney Metro, a driverless rapid transit system separate from the suburban commuter network, commenced operation in May 2019 and will be extended into the city and down southwest by 2024 and through the inner west to Parramatta by 2030. It currently serves 13 stations. A line to serve the greater west is planned for 2026 and will include a station for the second international airport. Ferries At the time the Sydney Harbour Bridge opened in 1932, the city's ferry service was the largest in the world. Patronage declined from 37 million passengers in 1945 to 11 million in 1963 but has recovered somewhat in recent years. From its hub at Circular Quay, the ferry network extends from Manly to Parramatta. Airports Sydney Airport, officially "Sydney Kingsford-Smith Airport", is located in the inner southern suburb of Mascot with two of the runways going into Botany Bay. It services 46 international and 23 domestic destinations. As the busiest airport in Australia, it handled 37.9 million passengers in 2013 and 530,000 tonnes of freight in 2011. It has been announced that a new facility named Western Sydney Airport will be constructed at Badgerys Creek from 2016 at a cost of $2.5 billion. Bankstown Airport is Sydney's second busiest airport, and serves general aviation, charter and some scheduled cargo flights. Bankstown is also the fourth busiest airport in Australia by the number of aircraft movements. Port Botany has surpassed Port Jackson as the city's major shipping port. Cruise ship terminals are located at Sydney Cove and White Bay. Environmental issues and pollution reduction As climate change, greenhouse gas emissions and pollution have become a major issue for Australia, Sydney has in the past been criticised for its lack of focus on reducing pollution, cutting back