Yasuhiro Nagata

Current State of Pedestrian Slip-and-Fall Accidents in Winter in Sapporo and the Characteristics of Icy Sidewalk Surfaces

Pedestrian falls in winter in Sapporo, Hokkaido (Japan), have been a serious problem that requires an urgent solution. Pedestrians who fell severely enough to require ambulance transport to hospitals in winter have numbered between 600 and 800 a year. Pedestrians are prone to falls on slippery, icy road surfaces. Icy surfaces on roads and sidewalks form by a process that differs greatly from that of icy surfaces of natural snow cover, because the ice on roads and sidewalks is created by the compaction, breakage and re-compaction of snow by the pressure of passing heavy vehicles and pedestrians. In this study, icy sidewalk surface slipperiness and weather conditions were monitored in January and February 2009. Sidewalk surface ice core samples were taken to survey the microstructural characteristics of the ice when the sidewalk surface was particularly slippery. The survey results identified the typical weather conditions that lead to the emergence of an extremely slippery sidewalk surface : intense snowfall of 10 cm or more, followed by a series of days with daytime positive temperatures without snowfall. They also proved that when the density of the sidewalk surface layer is 500 kg/ m 3 or greater and the surface temperature of the layer is -2°C or higher, the slippery, icy sidewalk surface is most likely to emerge.

Development of a Road Visibility Forecast Model on the Basis of a CCTV-Camera-Based Road Visibility Information System

This study proposes a model that forecasts visibility in winter on the basis of a CCTV-Camera-Based Road Visibility Information System (RVIS) that was developed by the authors to minimize winter hazards including traffic accidents resulting from snowstorm-induced poor visibility. The RVIS quantifies road images recorded by multiple closed-circuit television (CCTV) cameras along the roads to automatically apply the quantified information to pre-defined visibility indexes that indicate levels of road visibility. To quantify the road images, the weighed intensity of power spectrum (WIPS) is calculated such that its magnitude represents the difference in spatial frequencies. When road visibility decreases from snowstorm or fog, the contrast of road view contained in the CCTV camera image decreases. From WIPS values, the road visibility index (RVI) is calculated. The RVI is categorized into 4 ranks for greater understandability by users: Level l (≧500 m), Level 2 (200~500 m), Level 3 (100~200 m) and Level 4(<100 m). From the RVI ranks, road users can know the visibility level on the route where they are planning to drive. The objective of this study is to develop a visibility forecast model, utilizing the RVIS. To achieve the goal, we used the data of the WIPS values and RVI ranks recorded by the RVIS as well as 1-km-mesh meteorological data recorded by the Japan Weather Association. A feasibility study on the visibility forecast model was conducted during the winter of 2009-2010 at a 35-km section of National Route 40 in Hokkaido, Japan. In the study, 1-km-mesh meteorological data were used to estimate the WIPS values and RVI ranks a few hours ahead of time by employing a multiple-regression model and the Kalman filter. And, the relationship between WIPS data from road images as dependent variables and the meteorological data as independent variables was examined to compare the accuracy of WIPS estimation between the two models. As a result, the correlation coefficient for the Kalman filter indicated better fit than that for the multiple-regression model, thereby the Kalman filter was identified to be more applicable than the multiple-regression approach to create a road visibility forecast model.

Case study on Impact of Providing Traffic Information on Driver's Attitude

There have been many researches on impact of traffic information on behavioral patters of drivers.Nevertheless, these researches have merely looked at response of a driver under a hypothetical situation using a questionnaire surveys or computer simulation. Only a few research have made reference to real world data to analyze actual responses of drivers and influence on traffic flows as a result of such responses.This research, using Miki Junction of Sanyo Expressway as a specimen, studied impact of traffic information at the junction by analyzing fluctuation of traffic volume after diverging point and also using questionnaire surveys (RP survey).

Research on driver's perceptiveness and behavior to traffic information

A challenge we face in traffic information control is to identify theoptimum facility, position, type of information and means to provide information to the driver to achieve maximum efficiency and effectiveness. Secondly, we must determine the type of driver, driving behavior and the drivers reaction, and account for each type of behavior with consideration for the criteria used by the driver for decisions. This research is conducted through study and analysis of the results of a questionnaire which will provide the basis for achieving efficient traffic information provision system development.

A Study on Providing Traffic Information for Park and Bus-Ride System in Scenic Areas

In recent years they study on Transportation Demand Management not only for commuting but alsoin scenic areas. In Kanazawa city Park and Bus-Ride System is carried out in a succession of holiday begining of May.Introducing this system make modify traffic congestion and reduce travel time. We studied on providing traffic information for increasing to Park and Bus-Ride System user in scenic area, especially we paid attention to the method of providing information, type of information and the object of providing.We analized the relation between the user generic character and using this system using by cross tabulation and quantification theory II.