Rapid transit systems in India include metro, monorail and light rail networks. The first was the Kolkata Metro in 1984. Delhi Metro, which began operations in 2002, was India's first modern metro. Rapid transit systems are now under construction or planning in major cities across India to help address issues of congestion, pollution, and accidents from increasing vehicle numbers. The Delhi Metro is the largest and most extensive metro system in India, with six lines spanning 189 kilometers and 142 stations. It has helped reduce traffic and fuel consumption in Delhi significantly.