It cost Rs 1,171 crore, took 16 long years to build and was projected to carry six lakh people a day. Chennai's Mass Rapid Transit System (MRTS) covers a distance of about 20 km and passes through (mostly as an elevated structure) some of the most congested localities in the city.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/mass-rejected-transit-system
[2] http://admin.indiaenvironmentportal.org.in/category/author/n-madhavan
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/business-today-new-delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/transport
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rail-transport
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/tamil-nadu
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/chennai-t