## 6 Proper management and renewal of social infrastructure

(Advancing of social infrastructure deterioration)

In our country, the social infrastructure was intensively constructed during the high-growth period. These stocks are assumed to be rapidly deteriorating because 30 to 50 years have passed since they were constructed. Comparing the ratio of social infrastructure that is more than 50 years old today (FY2010) and that in 20 years, for instance, the ratio for road bridges will surge from approximately 8% to 53%. The ratio for river management facilities, such as drainage pump stations and water gates, etc., will surge from approximately 23% to 60%, the ratio for sewer lines will surge from approximately 2% to 19%, and the ratio for harbor quays will surge from approximately 5% to 53%.

Chart. 150 Ratio of infrastructure more than 50 years since construction

FY2010	FY2020	FY2030
Road bridges $ ^{*} $ Approx. 155,000 bridges (Bridges longer than 15 meters)	Approx. 8%	Approx. 26%	Approx. 53%
Drainage pumping stations, water gates, etc. $ ^{*} $ Approx. 10,000 facilities	Approx. 23%	Approx. 37%	Approx. 60%
Sewer lines $ ^{*} $ Total extension: Approx. 430,000 km (Note)	Approx. 2%	Approx. 7%	Approx. 19%
Harbor quays $ ^{*} $ Approx. 5,000 facilities	Approx. 5%	Approx. 25%	Approx. 53%

Note : Excludes Iwate prefecture, Miyagi prefecture, and Fukushima prefecture Source: MLIT

### Chart. 151 Deteriorated facilities

Examples of deteriorated river management facilities

Impeller equipment of pump facilities

Source: MLIT

Gate equipment

1980 (15 years elapsed): Cracks and rusty fluid occur in lower surface of main girder

Example of National Route 7 Kuretsubo Overpass (concrete bridge) in Yamagata Prefecture

1991 (26 years elapsed): Breaks in PC steel main girder

1991 (26 years elapsed): Newly installed 2 props to secure load bearing capacity

(Increase of maintenance, management, and renewal costs)

Taking examples of deteriorated social infrastructure, the cost of maintenance, management, and renewal is expected to increase from now on. Fig.152 shows the estimated cost (including natural disaster relief expenditure; the same shall apply hereinafter) of maintenance, management, and renewal of the social infrastructure of MLIT (roads, ports, airports, public apartment houses, sewage systems, urban parks, river improvements, and coasts) in the future based on the past investment records, etc. If the growth of the total sum of future investment after FY2010 is increased by $ \pm0\% $ compared to the previous fiscal year, and is assumed to continue at the same expenditure level for maintenance, management, and renewal, the cost for maintenance, management, and renewal will exceed the total sum of investment in FY2037. Trial calculation shows that the portion of renewal costing approximately 30 trillion yen (approximately 16% of the entire amount required) out of the total renewal cost required for 50 years from 2011 to 2060 (approximately 190 trillion yen) will not be able to accomplish.

If appropriate maintenance is not carried out due to the lack of funds for maintenance, management and renewal, malfunction of the infrastructure might affect the life of people, and also the possibility of accidents or disasters due to deterioration might become a concern. In fact, there was an accident where a bridge over the Mississippi River in Minnesota, USA, collapsed in 2007. With 13 dead and more than 100 injured, this accident was a catastrophe. Neglecting inspections and repairs, etc., of old infrastructures leads not only to trouble providing the infrastructures' primary functions, but also similar major accident like this in some cases.