The transport ministry announced a mid- to long-term execution plan for a project on an integrated development of urban underground rail lines.

The announcement comes as a special law on underground rail lines, in which the ground rail lines will be placed underground by means other than state funding, is set to take effect on January 31.

According to the roadmap put forth on Monday, the cost of underground rail lines will be obtained through profits from higher-up development initiatives, and those that lack profitability will proceed in consideration of local government support and ripple effect on the regional economy.

The project will be enforced and managed by a new affiliate of the Korea National Railway, while the plan specified reference to the creation of an artificial ground on the upper part of the rail infrastructure in the project.

The ministry said it intends to announce details of the first-phase of the underground rail development following further consultation with local governments.

It had previously planned to announce details of the first-phase development by the year's end.