The over 4.2 km-long Grey Line of the Delhi Metro, which will connect urban village area of Najafgarh to the rapid transit network for the first time, will be opened for passengers from Friday evening, officials said.

The corridor consists of three stations — Dwarka (interchange with Blue Line), Nangli and Najafgarh.

"The Dwarka-Najafgarh corridor of Delhi Metro will be formally flagged off today by Minister of State (Independent) for Housing & Urban Affairs Hardeep Singh Puri and Delhi Chief Minister Arvind Kejriwal," a senior DMRC official said.

The flagging-off ceremony is slated to take place at Metro Bhawan at 11 am and passenger services on the section shall commence from 5 pm, said Anuj Dayal, the executive director, corporate communication of the DMRC.

With the opening of this section, the Delhi Metro network will expand to 377 km with 274 stations, including the Noida-Greater Noida Aqua Line.

"The Grey Line is a standard-gauge section and out of the 4.295 km, 2.57 km is elevated and 1.5 km underground. With the opening of this section, the Dwarka metro station is all set to emerge as an interchange facility that will connect the sub-city with the locality of Najafgarh," Dayal had earlier said.

Commissioner of Metro Rail Safety (CMRS) Janak Kumar Garg had accorded the mandatory approval for starting passenger operations after inspecting the corridor for safety on Wednesday.

Dayal said a peak hour frequency of 7 minutes and 30 seconds shall be maintained on this stretch.

The total travel time on this section shall be 6 minutes and 20 seconds and three trains shall ply on this section and a fourth train has been planned, he said, adding that at present, the DMRC runs 376 trains, spanning 2,206 coaches and 4,778 trips per day.

Trial runs on the section had begun in July.

The Delhi Metro Rail Corporation had earlier said the corridor is being extended by another 1.18 km till Dhansa Stand, which is slated for completion by December 2020.

An 80 metre passageway connects the old Dwarka station of the Dwarka Sector 21 — Noida Electronic City/ Vaishali corridor or the Blue Line with the new station on the Grey Line, which has come up as part of the extension to Najafgarh.

There will be concourse to concourse connectivity through the paid area.

After the Dwarka Sector 21 station, now Dwarka will become the second interchange facility in the Dwarka sub-city.

Overall, the metro will have 28 interchange facilities after its opening, Dayal said.