Sustainable Development Goals
Status
ongoing
50%
City
Aomori Prefecture
Main actors
Regional Government
Project area
Whole City/Administrative Region
Duration
Ongoing since 2006
Treating bridges as social capital
The Bridge Asset Management System is a total management system that involves treating roads as assets; objectively assessing and evaluating the condition of the structures on the road; predicting the mid-to-long-term condition of those assets; and deciding the best time, method, and place to carry out counter-measures under budgetary constraints.
City
Aomori Prefecture, Japan
Size and population development
According to the 2011 census Aomori Prefecture has a population of 1,362,820. The city covers an area of 9,645.59km2 with a population density of 135.6 people per km2.
Population composition
The population of Aomori Prefecture comprises 722,121 females and 640,699 males. Estimated population of Japanese nationality is 1,359,540.
Main functions
The Aomori Prefecture is located in the Tōhoku region of Japan and is the northern most point of the Japanese main island of Honshu. There are 10 cities in the prefecture of which Aomori City is the capital. Aomori prefecture is surrounded by the sea on three sides and the Ou Mountain Range located in the center of the prefecture divides into two, creating a topography of complicated land and marine features.
Main industries / business
Aomori Prefecture is dominated by traditional industries of farming, forestry and fishing. The Prefecture is host to the Misawa Air Base, the only combined, joint U.S. service installation in the western Pacific servicing Army, Navy and Air Force, as well as the Japan Defence Forces.
Sources for city budget
The Aomori Prefecture draws its budget for public expenditure largely from property tax, fees, operating revenues and other taxes from the cities of the prefecture and subsides from the National Government of Japan.
Political structure
Aomori Prefecture is administered by a Governor and has 8 districts and 40 municipalities. The prefectural government is made up of a decision-making body and an executive body in order to carry out the administration of the prefecture. The executive body is made up of the governor and various administrative commissions and they serve to carry out administration of the prefecture in accordance with the decisions made by the prefectural assembly. The decision-making body is the prefectural assembly, which is comprised of assembly members elected directly by the citizens of the prefecture and makes decisions regarding important basic policies of the prefecture, including approval of the budget and the enactment of ordinances. The prefectural assembly (48 seats) is made up of assembly members that are elected every 4 years from 16 electoral districts in the prefecture, in the same way that the governor is elected. The prefectural assembly convenes to hold regular sessions 4 times a year in June, September, November, and February in addition to extraordinary sessions that may be held.
Administrative structure
The governor carries out administration of the prefecture in accordance to the decisions made by the prefectural assembly and has vice governors to assist him in this task, and under them there are departments, bureaus, divisions, and offices, etc. which divide up duties and each handle specific responsibilities. In addition to this, each area of the prefecture has a local district administration office and other local agencies in order to carry out work that is closely involved with the area. In order to promote democratic public administration, various types of administrative commissions are established independently from the Governor and are composed of persons from each area that represent the prefectural citizens, and each has its own secretariat.
Website
http://www.pref.aomori.lg.jp/
The Aomori Prefectural Government manages approximately 2,300 bridges (bridges that are 2m or longer), and as many of them were constructed during the period of rapid economic growth after WW2, it is expected that the need for repair and replacement on many will come at the same time. Thus, the prefecture anticipates a possible shortage of funds for maintenance costs.
In addition, Aomori Prefecture is an extremely harsh environment for bridges:
The prefecture is situated at the northernmost point of Honshu, encompasses the Mutsu Bay in the middle, and is surrounded by sea on three sides, with the Tsugaru Strait to its north, the Pacific Ocean to its east, and the Sea of Japan to its west. It is a cold region with the heaviest snowfall in Japan. Additionally, cold, wet seasonal winds blow in from the Sea of Japan during wintertime, bringing salt from the seas, damaging concrete structures, corroding the steel materials, and causing salt damage. Furthermore, as there is heavy snowfall on the west side of the Ou Mountains, antifreeze materials employed on roads are causing further salt damage. Finally, the cold, dry air blowing in from the Pacific Coast causes the moisture in the concrete to freeze and expand, bringing significant frost damage.
In this environment, in order to maintain the road network and ensure that the citizens of the prefecture can live safely and securely, there is a need to minimise and stabilise maintenance costs by shifting over from corrective maintenance management to preventative maintenance management.
Project objectives
- Maintain a robust road network to ensure that the citizens of the prefecture live safely and securely
- Move from corrective maintenance to preventative maintenance through on-going prevention and maintenance measures
- Implement reductions in bridge maintenance and renovation costs
- Transfer this methodology of maintaining social capital to other areas in Japan
Continuity is the key to the Bridge Asset Management System, so in order to achieve this, a Total Management System was implemented. It brings together people with expertise and knowledge of bridges that is essential for bridge maintenance, IT systems that link together inspections and measures based on Bridge Asset Management, and manuals and organisations to support the system.
The IT system was developed to support all of the PDCA (plan-do-check-act) elements of the Bridge Asset Management System including:
- predictions of deterioration (from data gathered from periodic inspections)
- life cycle cost calculations,
- budget simulations
- mid-long-term budget plans
- medium-term project plans.
Deterioration predictions are calculated using a deterioration prediction model based on each aspect involved, such as the components, materials, methods, deterioration mechanisms, and environmental conditions. Moreover, if the result of an inspection does not show the state of deterioration that was predicted by the model, the prediction model automatically revises its predictions to reflect the inspection results, and to increase the accuracy of the deterioration predictions.
In addition to the deterioration prediction model being needed for life cycle cost calculations, a database has been set up detailing management standards, construction methods for counter-measures, costs, and levels of maintenance required for restorations after countermeasures have been carried out.
A maintenance and management scenario is set up for each bridge, and budgets can be adjusted by changing scenarios.
Additionally, road network management is improved by selecting maintenance and management scenarios for each bridge and reflecting it in budget simulations, mid-to-long-term budget plans, and medium-term project plans. This makes it possible to reflect both the current condition of individual bridges, while formulating feasible medium-term project plans and adhering to budget constraints.
The lead agency for the project is the Department of Land and Infrastructure/Roads Division/Bridge and Asset Promotion Group at the Aomori Prefectural Government.
Since 2006, the results of this project have seen an improvement in the management of bridge maintenance and stabilisation of maintenance management costs. In addition, the Total Management System has enabled a shift from corrective maintenance management to preventative maintenance management.
With the introduction of the Bridge Asset Management System, training of staff and system upgrades are the key challenges. The following strategies have been put in place:
- on-going training for staff
- periodic revisions and updates to manuals and documentation
- a separate project was set up to raised funds to IT development and to familiarise users with the IT system
The Bridge Asset Management System is a successful method for bridge maintenance, and the Aomori Prefectural Government is pro-actively sharing their knowledge and data with other municipalities in Japan and other cities around the world.
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