Three Dalian train sets hit the Metro Rail Transit (MRT-3) rails on Monday, the Department of Transportation (DOTr) said.
The additional wagons, which were bought from China a few years ago, reduced waiting times between trains and added to public transport options in Metro Manila under the general community quarantine.
Currently, the MRT-3 has a total of 19 train sets in operation.
The government had an agreement with the supplier, CCRC Dalian Co., to make technical adjustments and modifications to all units without spending a single centavo, the DOTr said.
Third-party consultant TUV Rheinland from Germany was in charge of Reliability, Availability, Maintainability at Sustainability (RAMS) Validation testing, to ensure passenger safety.
"No Face Shield and Face Mask, No Entry" is being strictly implemented at each station, as well as one-meter social distancing between passengers inside trains. Talking and answering the phone are also prohibited in accordance to COVID-19 protocols.