Research results

Prediction of Winter Road Surface Conditions
- "Winter Maintenance Support System" -

Dangerous slippery surfaces

Schematic diagram of the winter maintenance support system

Sample image of the winter maintenance support system

In cold, snowy regions, snow accumulation causes narrowing of road widths and freezing of road surfaces. There has been especially high demand for improvements in winter road surface management since the introduction of restrictions on the use of studded tires.
The Traffic Engineering Research Team is conducting research for establishment of more appropriate, efficient and effective winter road management methods that can contribute to the reduction of winter road management costs and other measures.
If the changes in winter road surface conditions can be predicted, it will be possible to make decisions in advance to conduct work in a timely and appropriate manner, and winter road surface management is expected to be more appropriate and efficient. Therefore, we developed a method for predicting road surface freezing.
We have been operating the "winter maintenance support system," which provides road surface freezing, snowfall and other weather forecast information to road administrators by displaying it on an online map, on a trial basis since FY 2005. Weather forecasts and surface freezing forecasts are provided for the following six and sixteen hours, respectively, to help in decision making with work-related operations. For example, antifreeze agents can be spread efficiently by predicting the time and location of freezing, in advance.
Information is currently provided for 100 fixed forecast points and eight linear surface forecast sections (approx. 155 ㎞ in total). In the future, we plan to continue improving the road surface temperature and condition estimation models and further upgrade the winter maintenance support system by increasing the number of target sections and points.

(Contact: Traffic Engineering Research Team, CERI)

Development of Soil Improvement Method that Suppress Impact on the Surroundings

Fig. 1 Problems of conventional soil improvement

(Left) No measures taken
(Right) Using the Column Link Method
Fig. 2 Investigation using model experiment)

Fig. 3 Characteristics of Column Link Method

Soil Improvement
When a large embankment or levee is constructed on ground that has a deep soft layer of soil, this soft layer will be compressed, causing major ground subsidence and eventually damaging houses and buildings in the surrounding area (Fig. 1 [blue]). When this type of ground has to be dealt with, soil improvement involving construction of underground cement columns, technically known as the deep mixing method, is conducted. Particularly in areas where the work site is close to houses and buildings, it is necessary to construct a large number of columns to reduce the impact on the surroundings, which is not an economical solution (Fig. 1 [red]).

Development of New Soil Improvement Method
In response to these problems, the Construction Technology Research Team worked with 13 private companies to conduct R&D on the "Column Link Method," designed to suppress the negative impact on the surrounding area while ensuring that the construction work is economically efficient. As part of this work, model experiments and structural analysis were conducted to find appropriate structures that can suppress the impact on the surrounding area (Fig. 2).

Characteristics of the Column Link Method
The Column Link Method uses construction of a structure that combines cement columns and cement walls, providing each element - such as internal piles, side walls, external piles and joint members - with a particular role. In order to demonstrate the extent to which the structure can suppress impact on the surroundings, a demonstration experiment is under way at a test section of the Kumamoto Uto Road in which soil improvement using this method has actually been performed (Fig. 3).

Future Tasks
Future tasks include analysis of the collected test data, preparation of a design and construction manual for the Column Link Method, and the production of public information regarding the method.

(Contact: Construction Technology Research Team)

Publication of Practical Handbook on Avalanches,
"Examples of Inspection and Emergency Measures for Avalanche Prone Slopes in Heavy Snowfall"

Photo-1: Bus pushed along by avalanche

Fig. 1: Example of points to focus on during patrols (overhanging snow and snowdrifts)

Photo-2: Removal of overhanging snow. Important precautions are also stated, such as "Stand in a horizontal line when removing snow", "Stay clear of areas under overhanging snow" and "Remove snow in relatively small pieces so that it does not trigger an avalanche as it falls".

Snowfall in 2006 - First Large Snowfall in the Past 20 Years
Although we have had a series of warmer winters in the past few years, the fact is that avalanche disasters occur annually.
In an avalanche that occurred at Yamanouchi Town, Shiga Plateau, Nagano Prefecture, on Feb. 6th, 2010, a bus pushed along by sliding snow hit the entrance of a hotel, injuring two hotel guests (Photo-1).
The winter of 2006 had the first large snowfall for 20 years, and many of the people concerned were unprepared.
The lesson that we learned from this is that, even if the warm winters continue, we need to use the opportunity to ensure that we can respond quickly and appropriately to emergencies by systematically reviewing patrol (inspection) procedures for dangerous avalanche locations and updating emergency preparedness programs.

Compilation of Examples of Patrol and Emergency Measures in Various Districts
"Examples of Inspection and Emergency Measures for Avalanche Prone Slopes in Heavy Snowfall" is a compilation of actual examples from Hokkaido and Hokuriku etc, organized into a practical handbook for administrative and operational personnel engaged in patrols and emergency measures (we are currently preparing a site to downloaded it, click here (Japanese Only)). The handbook was prepared by the Snow Avalanche and Landslide Research Center (in Myoko City, Niigata Prefecture) and the Snow and Ice Research Team (in Sapporo City, Hokkaido) , which engage in research on avalanches at PWRI.
[Main Content]
- Basic knowledge regarding avalanches (types of avalanche, mechanisms of occurrence, etc)
- Points to focus on when looking for signs of potential avalanche and observing snowfall conditions on slopes
(overhanging snow, snowdrifts, and cracks in snow-covered slopes, etc Fig. 1)
- Inspection and management procedures for dangerous locations (preparation of inspection charts, etc.)
- Emergency measures (manual or mechanical removal of overhanging snow, Photo-2)

Preventing Disasters caused by Avalanche
Dec. 1st to 7th of every year is Avalanche Disaster Prevention Week. Even in years without large snowfall, it can in no way be assumed that avalanches will not occur, since localized heavy snow is still possible.
Before fully entering the snowy season, active measures will be taken in various parts of the country, including patrols of locations prone to avalanches and activities encouraging residents to appreciate the danger that avalanches pose. On Dec. 3rd, during Avalanche Prevention Week, PWRI plans to hold an Avalanche Disaster Prevention Seminar in Gifu City (we will be announcing the program soon). It is our hope that the newly published handbook, together with these initiatives, will contribute to the elimination of damage caused by avalanche related disasters.

(Contact: Snow Avalanche and Landslide Research Center,
Snow and Ice Research Team, CERI)