of Measures to Combat Aging Infrastructures” was inaugurated. In November of the same year, it came up with “the Basic Plan for Life Extension of Infrastructure” to envision future approaches directed at infrastructures of all kinds to be taken by the state, local public entities and so on. The basic plan requires the manager or the like of each individual infrastructure to draw the Action Plans for Life Extension of Infrastructure to encourage steady implementation of measures to combat all aging infrastructures nationwide.

The MLIT responded by working out a MLIT’s the Action Plans for Life Extension of Infrastructure in May 2014 ahead of all other ministers and agencies to finalize and visualize specific approaches based on the basic plan, declaring it as a maintenance guide to present a roadmap to the implementation of maintenance cycles (Figure II-2-2-2).

Figure II-2-2-1	Present Status of Aging Social Infrastructures
Among all infrastructures that have been built after the rapid-growth period of the nation's economy, including highway bridges, tunnels, rivers, sewage systems and ports and harbors, the proportion of those facilities that will reach 50 years of age or older in 20 years to come will expand at an accelerating pace. * The status of aging of facilities is not uniformly determined by when they were initially built, but it varies depending on where they are located, how they have been maintained and managed and so on. For convenience's sake, an actual age of 50 years after initial construction is used as a measure of aging.
<Percentage of social infrastructures that have been built for 50 years or longer>>
March 2013	March 2023	March 2033
Highway bridges [about 400,000 bridges Note 1 (of about 700,000 bridges having a bride length of 2 m or longer)]	Approx. 18%	Approx. 43%	Approx. 67%
Tunnels [about 10,000 tunnels Note 2]	Approx. 20%	Approx. 34%	Approx. 50%
River management facilities (such as water gates) [about 10,000 facilities Note 3]	Approx. 25%	Approx. 43%	Approx. 64%
Sewer pipes [total distance: approx. 450,000 km Note 4]	Approx. 2%	Approx. 9%	Approx. 24%
Port and harbor quays [approx. 5,000 facilities Note 5] (4.5 m deep or deeper)]	Approx. 8%	Approx. 32%	Approx. 58%
Note 1) Approximately 300,000 bridges whose year of initial construction is unknown have been excluded from percentage calculations. Note 2) Approximately 250 tunnels whose year of initial construction is unknown have been excluded from percentage calculations. Note 3) State-managed facilities only, including approximately 1,000 facilities whose year of initial construction is unknown. (Since records generally exist of those facilities that have been built within the last 50 years, those facilities whose year of initial construction is unknown have been sorted as being approximately 50 years of age or older.) Note 4) Including approximately 15,000 km of piping whose year of initial construction is unknown. (Since records generally exist of those facilities that have been built within the last 30 years, those facilities whose year of initial construction is unknown have been sorted as being approximately 30 years of age or older and their length proportionally distributed in the ratio of construction by documented number of years elapsed. Note 5) Approximately 100 quays whose year of initial construction is unknown have been excluded from percentage calculations.

Source) MLIT