The total area of the Union Ter­rit­ory of Delhi is 148,639 ha, out of this 44,777 ha. had been earlier included in urb­an­is­able lim­its pre­scribed in the plan. This area as per 1981 census accom­mod­ated 54.5 lac urban pop­u­la­tion.
The bal­ance urban pop­u­la­tion resided in 17 set­tle­ments declared as towns in the 1981 census and Najafgarh & Narela. To accom­mod­ate the 122 lac pop­u­la­tion, a two pronged strategy was recommended:

• Increase the pop­u­la­tion hold­ing capa­city of the exist­ing urb­an­is­able lim­its i.e. Delhi Urban Area (DUA) — 1981. By this way the pop­u­la­tion hold­ing capa­city could be increased to about 82 lacs.
• Exten­sion of present urban lim­its to the extent neces­sary i.e. Delhi Urban Area (DUA) — 2001.

Stud­ies revealed that in-order to accom­mod­ate the bal­ance 40 lac pop­u­la­tion an exten­sion of DUA — 1981 to the tune of approx­im­ately 18,000 — 24,000 ha. was required. This would form DUA-2001 i.e. the pro­posed urban extension.

The exten­sion plan to accom­mod­ate Delhi’s chan­ging require­ments named as “Urban Exten­sion Plan”. This plan was entailed devel­op­ment of three sub-cities namely:

• Rohini
• Dwarka
• Narela

See the details in the respect­ive pages.