Constructing a 233-metre concrete bridge 17 metres above the ground with crush-packed local trains zipping past down below; constructing a viaduct at 7 metres above the Andheri flyover on Western Express Highway
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/how-countrys-most-expensive-elevated-metro-rail-corridor-will-be-built
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-mumbai
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/urban-transport
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/metro