New Delhi, January 6: The Cabinet has cleared the fourth phase of the Delhi Metro, which on completion will increase the daily rider ship by 8.5 lakh commuters, providing them better connectivity with outer parts of the city and also to the Delhi Airport.To be built at a cost of Rs 50,000 crore the 113-km network is expected to be completed within six years. The Phase-IV route will also comprise a 68 km elevated road and is focused on areas where traffic volume is expected to go up in the future Once the construction begins following approval by the union government, the DMRC will submit a monthly progress report to the Delhi Cabinet. The Metro phase IV will cover six crucial routes. These are Rithala, Bawana Narela, Janakpuri West to RK Ashram, Mukundpur to Maujpur, Inderlok to Indraprastha, Aerocity to Tughlakabad, Lajpat Nagar to Saket G-Block.