Standing inside a carriage of the country's first mass rapid transit system, just three months after its inauguration, Indonesian President Joko "Jokowi" Widodo could not stop smiling Tuesday to see a lot of passengers in the train during the off-peak hours.

With one hand holding a straphanger, he patiently served requests from passengers to take selfies with him.

He chatted with some of them about their ride in the 15.7-kilometer Phase 1 of the North-South Line that allows city residents to travel faster between South Jakarta and Central Jakarta while easing choked road traffic.

"Infrastructure is very important. It is important for transportation, particularly for Jakarta and its surrounding areas," Jokowi told Kyodo News in an interview at the State Palace after riding the train from the Lebak Bulus MRT Station in South Jakarta to Bundaran Hotel Indonesia MRT Station in Central Jakarta.

Inaugurated just a month before the April 17 legislative and presidential elections, the MRT line was then seen as one of would-be victory factors for Jokowi, who in 2012, as then Jakarta governor, revived the plan to build the rapid transit urban line that had been stalled for three decades.

"We want Jakarta to have a world-class transportation system," Jokowi said.

More than 10 million people live in Jakarta itself, while the greater metropolitan area is home to three times that number. With an average of nearly 15,500 residents per square kilometer, Jakarta is also one of the region's most crowded cities.

Currently, it takes two to three hours by bus in each direction at rush hour to travel that 15.7-km stretch, gridlock that costs the metropolitan city up to 65 trillion rupiah ($4.6 billion) a year, according to a government estimate.

The MRT cuts the travel to just 30 minutes, and in air-conditioned cars. Less congestion then is expected the years to come.

Many believe the project, which is partly financed by a 125 billion yen ($1.29 billion) soft loan from the Japan International Cooperation Agency for the first phase, will improve the lives of Jakartans.

A modern public transport system operating in the city is expected by many to change the habits, the attitude and the culture of the people in various ways, shifting passengers from private cars to public transportation.

In a chat with PT Mass Rapid Transit Jakarta William Sabandar on the Tuesday ride, Jokowi expressed happiness to know that the ridership target of about 85,000 passengers a day has been achieved.

[NurPhoto/Kyodo]

(File Photo shows a rail yard of Ratangga, Indonesia's first mass rapid transit, in Jakarta.)

Taking a look at Phase 1's success, Jokowi reiterated in the interview that an 8-km Phase 2 of the North-South Line from Bundaran Hotel Indonesia Station to Kota Station in West Jakarta will be soon constructed, while the 32-km East-West line is still under feasibility study.

"If these ones are (also) completed, the traffic congestion in Jakarta can be reduced a lot," the president said, reiterating that cooperation with Japan will continue to develop the MRT within the coming decade with a total of 230 km of routes to be built.

Jokowi stressed, however, that despite the ongoing bilateral cooperation to develop the MRT, the greater "use of local content and transfer of technology from this cooperation" are among the conditions Japan has to meet.

"The most important thing is that the national interest of Indonesia will not be hurt," he said, adding after the construction in Jakarta is completed, other cities in Indonesia, such as the West Java provincial capital of Bandung and the East Java provincial capital of Surabaya, may follow.

Still focusing on infrastructure development for his second term in office starting Oct. 20, Jokowi eyes the immediate construction of a 725-km medium-speed railway line between Jakarta and Surabaya.

"It's still under the process of feasibility study, which may be completed this year, and the construction may start next year but we expect earlier -- the earlier, the better," said the president, who was reelected on April 17.

"The ball now is not in (the court of) Indonesia. The ball is now in (the court of) Japan," he added, laughing.

Last year, a "political decision" was made by the government that only Indonesian and Japanese companies will participate in the tender to build the railway network.

Indonesia has been intensively approaching Japan over the railway network in an apparent effort to ease the latter's disappointment at losing to China in 2015 in bidding to construct a high-speed railway between Jakarta and Bandung.

When rising to power in 2014, Jokowi promised infrastructure projects, including air and seaports, as well as toll roads, worth some $340 billion. Prices of basic commodities and fuel are expensive in some regions in the archipelago due to the lack of connectivity among its 17,000 islands.

(Rudy Madanir and Sepsha Dewi Restianingsih contributed to this story from Jakarta)