planned Shinkansen extensions; five Shinkansen routes proposed in 1973
Refers specifically to the five Shinkansen route extensions planned under the 1973 Nationwide Shinkansen Railway Development Act. Often used in policy, construction, and regional development contexts.
Construction of the planned Shinkansen extensions requires enormous costs.
Part of the Hokkaido Shinkansen, one of the planned Shinkansen extensions, has opened.