Huge network of metro

The network of metro is also a great work. It consists of six lines with a total length of 189.63 kilometers  with 142 stations, of which 35 are underground, five are at-grade, and the remainder are elevated. All stations have escalators, elevators, and tactile tiles to guide the visually impaired from station entrances to trains. It has a combination of elevated, at-grade, and underground lines for all different routes according to the need and space. 

Delhi metro began operation in 2002(24 December 2002) and is being built and maintained by Delhi Metro Rail Corporation. Besides construction and operation of Delhi metro, D.M.R.C is also involved in the planning and implementation of metro rail, monorail and high-speed rail projects in India and providing consultancy services to other metro projects in the country as well as abroad.

Planning for the metro started in 1984, when the Delhi Development Authority and the Urban Arts Commission came up with a proposal for developing a multi-modal transport system for the city. The Government of India and the Government of Delhi jointly set up the Delhi Metro Rail Corporation (DMRC) registered on 3 May 1995 under the Companies Act, 1956. Construction started in 1998, and the first section, on the Red Line, opened in 2002, followed by the Yellow Line in 2004, the Blue Line in 2005, its branch line in 2009, the Green and Violet Lines in 2010, and the Delhi Airport Metro Express in 2011. 

 Metro was planned to be built in phases spread over around 20 years as with each phase having a target of five years. Phase I (65 km) and Phase II (125 km) were completed in 2006 and 2011, respectively, and Phase III and Phase IV are scheduled for completion in 2016 and 2021, respectively. Work on Phase III has already started while planning for Phase IV has begun. Ex-chief of D.M.R.C hinted that by the time Phase IV is completed, the city will need Phase V to cope with rising population and transport needs. Work for construction of phase IV might start before completion of phase III. 
So a lot of more stations and areas are soon going to be covered. Surely metro is going to reach each and every part of Delhi-NCR in upcoming future.

For more information you can also view the page 

http://www.indiamike.com/india/delhi-f19/delhi-metro-phase-3-by-2016-and-phase-4-by-2021-a-t191158/

map of phase I and II

MAP OF ALL 4 PHASES PLANNED BY 2021