Metro trains in Delhi have four coaches and a maximum capacity of 1,400 commuters. The frequency of trains ranges from 5 minutes during peak hours to 25 minutes on some corridors. Overcrowding is turning out to be a major problem, primarily during rush hour.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/coaches-are-overcrowded
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/down-earth
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi-metro-rail-corporation-dmrc
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/metro
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/transport
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/public-transport
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/urban-transport