MANILA — The Philippines has embarked on a massive undertaking to transform public transportation in greater Manila under President Rodrigo Duterte’s infrastructure push and his desire to ease the capital’s notorious traffic congestion as part of his legacy.

The centerpiece of the plan is the country’s first subway line, modeled on Tokyo’s complex web of underground services. Along with a commuter rail service project and work to update a problem-stricken existing railway line, the public transit project will cost 1.17 trillion Philippine pesos ($22.4 billion) in total, funded in part by loans from Japan, with many Japanese players taking part in the efforts.

It has been a long time coming. “When we announced that we are doing the subway, many sectors did not believe it,” Department of Transportation Secretary Arthur Tugade said at the groundbreaking ceremony at the end of last month in northern Manila. More than four decades had passed since the idea was first floated, with financing challenges frustrating the effort several times.

The subway will stretch south from the northern residential town of Quezon City, linking newly developed cities and the airport, extending some 30 km. After it is fully opened in 2025, the system is expected to transport 370,000 riders a day in the first year. The system is expected to connect with two existing light rail lines, likely developing into a network of railways in the future.

The Japanese government is giving full backing to the project. Last March, it signed an agreement with the Philippine government for some 104.5 billion yen ($936 million) in loans for the first phase of the project, which covers a stretch that goes through three train stations to be built in the north. The design and construction work was given to a four-member consortium of Japanese contractors Shimizu, Fujita and Takenaka Civil Engineering & Construction, and a Filipino company.

Corporate Japan is helping to train personnel. Tokyo Metro, one of the two operators of the Japanese capital’s vast subway network, will teach conductors safe and punctual operating skills at a training center to be built adjacent to a railway depot. The center will also take on conductors from the metropolitan rail system, said an official at Tokyo Metro.

The training program, the first of its kind in the country, comes at the request of Secretary Tugade, who was impressed by Tokyo Metro’s training center during his visit to Japan in August 2017.

Greater Manila has roughly the same area as the 23 wards of Tokyo, but the Philippine capital has a larger population of a little more than 12 million compared with Tokyo’s 9.2 million people — and the inflow continues. With more drivers on the road, traffic keeps worsening, with one estimate blaming congestion for 2.4 billion pesos of economic loss a day.

Duterte’s predecessors had worked to improve the railway system, but the effort got a significant boost after the Duterte government decided to tap official development assistance from foreign countries. Its needs also matched Japan’s drive to boost infrastructure exports.

Duterte reiterated his commitment to the project, claiming last month that he fulfilled all of his campaign promises except easing traffic. He apparently wants to leave his legacy in this area before his term is up in 2022.

Japan is also a key partner in another undertaking, a North-South commuter railway project. Sumitomo Mitsui Construction began working on a 38 km section in the north out of the roughly 150 km service last month. Loans from the Japanese government will cover about 40% of the 748 billion-peso project, with service set to fully open in 2025.

This section was to be developed by a Chinese contractor. But after facing a corruption scandal and other setbacks, the project was abandoned.

Now areas surrounding the envisioned commuter rail line are expected to be developed. Ayala, the biggest property developer in the Philippines, has been acquiring land near where train stations will be built, said a source.

According to the source, Ayala will model its project after the urban development that Japanese railway operator Tokyu did along its railroad lines.

Japanese companies will also help update the aging Manila Metro Rail Transit System’s Line 3 that connects Quezon City with the business center, Makati. The MRT Line 3 was built by Japanese companies Sumitomo and Mitsubishi Heavy Industries, with the line becoming fully operational in 2000. The two companies took care of maintenance until 2012 when the Philippine government gave the job to a local company for cost-cutting purposes, then to a South Korean company in 2016. The line started having breakdowns and derailing incidents frequently because of poor management, and ridership tumbled.

The Philippine government asked Japan for help, and the two inked an agreement last November for yen loans to finance updates to Line 3.

The work was outsourced to Sumitomo and Mitsubishi Heavy Industries again, which began working on upgrading locomotives, railroads and elevated tracks. The work is expected to be completed in 2022.

In the most recent example of Japanese companies’ involvement in Manila area development, Marubeni announced on Thursday that it has received an order from the Philippine Department of Transportation for a railway extension in the capital.

The Japanese major trading house received the nearly 6.9 billion yen ($61 million) order in late February for the joint project with Philippine builder D.M. Consunji to extend the existing LRT-2 line in Metro Manila. Construction is to be completed by summer 2020.

The 13.8-km LRT-2 runs east to west across Metro Manila. The 4-km extension will ease congestion in the area and reduce carbon dioxide emissions. Two new stations will be added to the existing 11.

Marubeni will contribute traffic signals, networks and transformer units. D.M. Consunji will be responsible for the tracks. The order does not include construction of train stations and high-level roads, which were ordered separately.