The Democratic Party of Japan-led government may announce as early as next week plans to construct three more bullet-train segments, DPJ members said.
The sections are between Kanazawa, Ishikawa Prefecture, and Tsuruga, Fukui Prefecture, on the Hokuriku Shinkansen Line; Hakodate and Sapporo on the Hokkaido Shinkansen Line; and Isahaya and Nagasaki in Nagasaki Prefecture on the Kyushu Shinkansen Line's Nagasaki branch, for which planning dates back to 1973.
Actual construction is expected to start in early 2012 or later.
DPJ policy chief Seiji Maehara endorsed the start of the three sections at a meeting of the DPJ's policy research committee, the lawmakers said Thrusday.
The Land, Infrastructure, Transport and Tourism Ministry estimates construction will cost about ¥3 trillion, half of which will be covered by the rent paid by Japan Railways group companies for existing bullet train facilities.
The other half will be covered with state funds and contributions from local governments along the lines.
Construction is expected to last from 15 to 25 years, with the Hokkaido Shinkansen Line expected to be the last to start service.
The Hokkaido Shinkansen Line will link Sapporo with Aomori. Work has already begun between Aomori and Hakodate.
The Hokuriku Shinkansen Line is designed to link Tokyo and Osaka via Nagano, Toyama and Kanazawa on the Sea of Japan coast. Services on the Tokyo-Nagano section have already started.
The Kyushu Shinkansen Line's Nagasaki route aims to link Fukuoka and Nagasaki by branching out from Shin-Tosu Station in Saga Prefecture. The line's main track linking Hakata Station in Fukuoka with Kagoshima started full service on March 12.