Delhi has experienced rapid population growth which increased traffic congestion and pollution. To address this, the Delhi Metro Rail Corporation was established in 1995 to build a mass rapid transit system. The first section opened in 2002. It has since expanded to over 96 km of lines, carrying over a billion passengers. It uses automated trains running at speeds up to 80 km/h. The metro has been profitable without subsidies by keeping costs low and generating revenue from advertisements and property development in addition to fares. It has received international recognition for its environmentally friendly practices.