- Life Sciences
- Information and Communication
- Nanotechnology / Materials
- Manufacturing Technology
- Human and Social Sciences
- Tourism / Community development
- Arctic Research
- Social Infrastructure
- Open Facilities
Social Infrastructure: 6
A Study on Pro-beam Roadway Lighting in Urban Areas
To prevent night-time accidents involving pedestrians at intersections in urban areas, we are developing a Pro-beam road lighting system that works with headlights to help drivers quickly detect pedestrians crossing the street. Pro-beam is a lighting system whereby the light distribution of the lamps is directed in the travelling direction of the vehicles.
We have summarized the requirements and functions of pro-beam road lighting to design specific light distribution of Pro-beam lighting to increase the visibility of pedestrians crossing the road through optical simulation and visibility evaluation experiments. Using the prototype light fixture, we have evaluated drivers’ visibility of pedestrians who are standing still and measured the time until drivers detect pedestrians at intersections using video images. As a result, we have confirmed that the Pro-beam lighting system provides higher visibility of the entire road space, including the oncoming lane, and helps drivers quickly detect pedestrians crossing the road not only from the right but also from the left. We are now working on the design and development of a light fixture for practical use as a road light by developing the prototype light fixture.
Consolidated Compact City Planning
Methodology for urban consolidation in an era of a declining population
Our laboratory is the first in Japan to propose and implement the concept of a consolidated compact city, which is a top-priority issue for cities in the age of a declining population. In Yubari, a city where the population is rapidly shrinking, we have proposed the concept of a consolidated compact city, implementing a project to consolidate the urban area in collaboration with the city and local residents.
This is the first attempt in Japan to implement a consolidated compact city project. In Yubari, we are promoting reorganization into an urban area of an appropriate size through downsizing, while creating a system of relocation and settlement to form local communities, and reduce the maintenance and management costs of urban infrastructure facilities. In the course of creating a compact city, we promote consolidation of the urban area for the first 10 years while maintaining local communities, and then consolidate local communities into a central urban hub over the next 10 years. This allows residents to continue living in Yubari at ease, even while the consolidation process is under way. In cooperation with Yubari City, we have already completed the relocation and consolidation of residents in the Mayachi district of Yubari.
Our efforts have been published in research papers and the mass media, and we have received many inquiries from cities facing similar issues.
New Ground Injection Material Using Calcium Phosphate
Ground-solidifying calcium phosphate compound, a major component of the teeth and bones of living organisms in nature, is an innovative low environmental impact injection material.
Focusing on calcium phosphate compounds (CPC) as a new cementing material for geotechnical grouting, we have investigated the optimum conditions for the precipitation of CPC and the solidification of sand by CPC, newly discovering two possibilities for their use: chemical grout and biogrout.
To develop a new grout with low environmental load, we focused on minerals produced by living organisms in nature (biominerals), especially CPC, a major component of teeth and bones, and investigated the optimum conditions for CPC precipitation. We also conducted uniaxial compression tests on sand specimens solidified with CPC. In the CPC precipitation test, we have found that the precipitation volume tends to increase as the pH increases from weakly acidic to near neutral. This causes the uniaxial compressive strength of the CPC-solidified sand specimens to reach about 90 kPa, which is within the target range of 50 to 100 kPa for uniaxial compressive strength of sandy soil to prevent liquefaction. Electron microscopy of the specimens showed whisker-like CPC crystals (Fig. 1). These results indicate two possibilities of their usage: chemical grout using self-hardening property and biogrout using pH-dependent precipitation volume.
Prediction Model for Transport properties in Hardened Cement
Prediction of transport properties of cement-based materials
Concrete is widely used for infrastructure, and its longevity is essential for the construction of a sustainable society. To realize this, appropriate performance prediction technology is indispensable. In this study, we predicted the transport properties of hardened cement paste (HCP), which is a main component of concrete.
The transport properties of porous materials such as concrete does not only depend on the porosity, but also on the spatial distribution of each phase. Therefore, the transport properties of HCP, which is a main component of concrete, was predicted. Figure 1 shows a cross section of HCP observed using a backscattered electron image, showing the distribution of each phase. We extracted each phase, calculated the autocorrelation function, and based on the results, distributed each phase in three-dimensional space to construct the three-dimensional spatial image model shown in Fig. 2. Figure 3 shows a comparison of the results of the diffusion coefficient calculated by the finite difference method and the measured values. The estimated and measured values agreed well with each other, even for different samples, indicating that the diffusion coefficients of hardened cement can be predicted using this model.
Reorganization of Public Facilities in an Era of a 30% Population Decline
Grand design of “Machi no Seitai” and living areas
In Hokkaido, it is expected that more than a hundred villages will disappear in the near future. “Machi no Seitai” is an attempt to optimize the size of local cities in a broad sense, in view of the era of a 30% population decline, while focusing on the reorganization of public buildings that remain unused or underutilized in local regions.
The town of Kamishihoro in Kato-gun, Hokkaido, like other municipalities in Hokkaido, is facing a rapid population decline: from 10,309 in 1965 to about half that number in 2010. It is estimated that the population will decline to 3,222 by 2040. In 2012, taking this situation into consideration, the city established 10 themes for the creation of a city with a population of 5,000; and the first of these was to create a grand design for the layout of public facilities.
The reorganization of public facilities in urban municipalities is generally implemented to ease financial pressures by controlling the number of facilities. However, Kamishihoro Town has different challenges and objectives. We are exploring the question of that kind of affluent lifestyle that can be achieved in a small town with a population below 10,000, and the role of public facilities to this end.
Ultimate Behavior Analysis of Seismically-Isolated Structures
To prepare for a mega earthquake
Our laboratory is developing advanced analysis techniques for seismic isolation systems, and can predict the ultimate behavior of seismically-isolated buildings in the event of a mega earthquake, and propose various countermeasures to prepare for a mega earthquake.
In a seismically-isolated building, the seismic isolators deform softly during an earthquake, greatly reduce response acceleration in the superstructure and improve the seismic safety. On the other hand, ultimate events such as collisions with retaining walls and buckling or rupture of the seismic isolation bearings may occur for the ground motions exceeding design level caused by a mega earthquake such as the Nankai Trough Mega Earthquake. By using analysis technologies to precisely predict the ultimate behavior of seismically-isolated buildings, it is possible to foresee the occurrence of ultimate events and to consider countermeasures to suppress their occurrence.