Delhi Metro Phase 4: Corridors proposed under the Delhi Metro's phase 4 were recently criticized by Arvind Kejriwal-led Delhi government\u2019s finance department. According to the finance department, the corridors under the phase 4 of the metro network will not carry enough commuters to qualify as a \u201chigh capacity\u201d metro system even in 2031! The department has said that the Delhi Metro phase 4 project will be a "colossal\u201d waste of money, according to an IE report. Yesterday, the Union Finance Ministry granted in-principle approval to the project. As Delhi Transport Department awaits the Delhi government's nod, the work cannot be started for the project till their approval. In order to examine the DPR (detailed project report) of Delhi Metro's phase 4 project, the department suggested that a committee including experts from various areas of railways engineering, transport planning, project and financial appraisal shall be formed. The project, which is estimated to cost around Rs 52,625 crore involves the development of six corridors measuring 104 km. As per the report, the cost per km of the project is estimated to be around Rs 481 crore. The department on examining the potential peak hour peak direction traffic (PHPDT), found that the corridors do not qualify for a high capacity metro. The report also stated that high-quality metro systems need to have a PHPDT of at least 40,000, therefore PHPDT is an important factor in deciding the choice of a transit system. According to the report, even if the threshold is reduced to 25,000 PHPDT, the majority of the corridors would still not qualify even with increased traffic in the year 2031. For example, the estimated PHPDT of the Tughlaqabad to Aerocity corridor in the year 2031 is 22,415 in one section, while the PHPDT in other sections of this corridor is 3,717 to 15,103 and the peak hour headway, which means the time between two trains proposed is as much as 8 minutes, the report stated. It further stated that even in 2031, the PHPDT for Lajpat Nagar to Saket G block corridor is 11,216. Similarly, in all sections except a small section between Surghat and Khajuri Khas in the Mukundpur-Maujpur corridor, the PHPDT is below 12,000 in 2031. Also, in Rithala to Narela corridor, in sectors within Rohini, the traffic is only in the range of 14,000 to 21,000 while all other segments have less than 15,000 PHPDT. The report also stated that the time gap between two trains from Bawana to Narela will be 32 minutes from 1 pm to 3 pm, and 24 minutes between 12 pm to 1 pm and 3 pm to 4 pm. In some corridors, even in peak hours, the headway is 8 to 10 minutes. Due to high demand, there is a high frequency of trains. The report further stated that heavy investments are made on fixed assets such as tunnels, pillars, tracks, signals, etc. Therefore, it will be a colossal waste of money to under-utilize these assets by operating few trains, the report added. Earlier this year, the Delhi Metro had written to the Delhi government seeking approval for Aerocity to Tughlaqabad corridor, Janakpuri West to RK Ashram corridor and Mukundpur to Maujpur corridor. The finance department accordingly conveyed that Mukundpur to Maujpur and Janakpuri West to RK Ashram corridors along with Inderlok to Indraprastha and Lajpat Nagar to Saket G Block corridors may be considered, while the Rithala-Bawana and Tughlaqabad to Aerocity corridors may be deferred due to negative cash flow.