Metro construction under phase 4 may start even before the 140-km phase 3 network is completed. Addressing the valedictory session of the fifth Urban Mobility Conference 2012 on Saturday, Union urban development
minister Kamal Nath said, “If not completely, we would like to start work on some sections through which we can connect the existing phase 1 and 2 and also the Phase 3 which is under-construction.”

Batting for Delhi Metro's expansion plans, Nath last year had asked Delhi Metro Rail Corporation (DMRC) to prepare the detailed project report for phase 4 so that benefits of phase 1 and phase 2 could be fully reaped.

Nath had assured the Union government's full support to phase 4 and said funds would not be an issue.
“When phase 4 is fully completed, Delhi will have 440 km of metro network, which will be bigger than the London underground,” he said.

Airport metro
The minister spoke about Delhi's Airport Metro Express, which has missed several deadlines for reopening fixed by his department earlier.

“The airport express line might start functioning by the end of this month or early next year, as an inspection by the Commissioner of Metro Rail Safety is expected by then,”
he said.

The minister also said that the proposed monorail will function as a “good feeder to unviable metro projects” by supplementing Metro on certain routes.