The Seoul Metropolitan Government is pushing for an 8.5 trillion-won project to make urban railway available within 10 minutes of any place in the city.

The plan calls for building 10 new subterranean light rail lines in the city’s northeastern, northwestern and southwestern districts, where it takes more than 10 minutes to get to the nearest metro station.

City officials say the project is intended to transform Seoul’s mass transit system. Currently, the metro accounts for 36 percent of transit passengers in Seoul, a level much lower compared with that of other cities ― 86 percent in Tokyo, 65 percent in London and 58 percent in Paris.

The planned light rail project, when completed 10 years from now, is expected to boost the share of railway services by some 10 percentage points.

The city’s plan to put rail at the center of its mass transit system is basically a step in the right direction. Rail is more convenient, environment-friendly and economical than other means of transportation.

Yet the problem is that the city’s scheme requires a huge amount of investment that would place pressure on its already strained balance sheets. The city government’s accumulated debt has topped 26 trillion won.

To ease the pressure, the city plans to finance more than 45 percent of the project cost, or about 4 trillion won, with capital from private financial investors.

Yet it remains to be seen whether the city would be able to attract private investors, as it has decided not to provide them with any minimum revenue guarantee, an assurance that it would compensate for any shortfall in investors’ projected income with taxpayers’ money.

The project’s wisdom is also challenged as bus services in Seoul are well developed ― they are cheap, convenient and extensive. Their coverage of the areas where subway is not easily accessible is not bad for what they are.

In this regard, the multibillion-dollar light rail scheme is being seen as a pork-barrel project pushed by Mayor Park Won-soon for himself and other Democratic Party politicians who will run in next year’s local elections.

This suspicion is not groundless. The project was first proposed by former Mayor Oh Se-hoon in 2008. After his election in 2011, Park killed six of the seven lines proposed by Oh, citing their huge costs.

But he has flip-flopped on the issue. He even went further than Oh by adding three more lines to the initial plan. Park needs to be prudent in pushing the scheme. The light rail debacles in other cities, including Yongin, should serve as a lesson to him.