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International Journal of ITS Research
| HOME ＞ Vol. 6, No. 1 Abstracts & papers |
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| Abstracts & papers |
Reseach Papers 2007-15 This study deals with demand forecasting for the carsharing system with multi-station and flexible returning station and time. Neural network is employed as the simulation model to forecast the demand at each station at certain time period in the system. This study introduces intelligent filtering techniques as a tool to remove the noise of the data before it is fed into the simulation model. Two filtering techniques have been tested, namely outlier analysis and cluster analysis. Results show that outlier analysis is better compared to cluster analysis in enhancing the accuracy of forecasting model. This shows that proper choice of techniques is important to guarantee that the introduction of this extra procedure could improve the forecasting accuracy. Keywords: Simulation, Data Mining, Demand forecasting
2007-17 Inside tunnels, the possibility of over-reach of radiated power from the Dedicated Short Range Communications (DSRC) service zone to the out-of-service zone is high, since the waves are confined in the tunnel space. To inspect this more carefully, wideband directional channel measurements were conducted inside an arched transportation tunnel, and the gain, angle-of-arrival and delay of each propagation path were estimated from the measured data. These propagation paths reveal that paths scattered from ground and sidewalk are the dominant factors that cause the over-reach of radiated power. This then suggests that the ground and sidewalk paths together with the LoS path can be used to predict the over-reach inside a typical transportation tunnel. Keywords: DSRC, over-reach, tunnel propagation, wideband directional measurements
2007-04 A set of travel time reports from probe vehicles is a sample. The adequate sample size required to estimate mean travel time of all vehicles (population) reliably has been studied in many literatures. However, in these literatures, the population is simply assumed as normal or approximate normal. In this paper, the properties of the population are discussed. The population is divided into three stages and the properties of the population in each stage are described in qualitative analysis and the description is verified by microscopic traffic simulation model. From this, some conclusions that are important to develop probe-based estimation method are made. Keywords: Link Travel Time, Probe Vehicle, Population, Simulation
2007-03 One serious problem of continuous large-scale data collection with probe vehicle is the dilemma of balancing the cost economization and system reliability improvements. The polling frequency is found to be one of the major factors that determine the operation cost of a probe vehicle-based traffic data collection system. This paper focuses on evaluating the cost-effectiveness of a probe vehicle system at various space-based polling intervals, with the purpose of data collection on providing roadway travel time estimation at certain reliability. The proposed optimization framework concentrates on the least total operation cost through a combining consideration on the polling frequency and the required probe size, which gives a simple and valuable solution on the issue of cost-effective traffic data collection. Keywords: Cost-effectiveness, Probe vehicle system, Polling frequencies
2007-10 In recent years, there have been world-wide interests in developing intersection collision avoidance systems. In such systems, computing, sensing, and communication technologies are utilized for the implementation of advanced driver assistance systems by issuing alerts to drivers in potential hazardous situations. To assess the effectiveness of proposed safety countermeasures, it is necessary to investigate whether the countermeasures can result in favorable and desirable driver responses. For the purpose of exploring design options and implementation issues of driver assistance functions, driver reactions can best be observed through the collection of field data in a real-world setting. This paper describes a study related to the collection, utilization and interpretation of field data. In addition, a criticality index function is proposed to quantify the safety risks in specific traffic scenarios. The availability of such risk index can be used to determine the safety impact of suggested collision avoidance systems. Keywords: Driver Assistance Systems, Intersection Collision Avoidance, Safety Risk
2008-01 The number of persons injured due to Traffic Accidents in Japan has exceeded 1 million during each of the past eight years (as of 2006), and reducing the number of traffic accidents has become an urgent issue. We believe that reducing the opportunities for encountering traffic incidents, which may lead to traffic accidents, is an effective means of reducing the number of traffic accidents. Previous analysis of traffic incidents using drive recorders was conducted primarily to analyze the factors which cause traffic accidents and to analyze driver behavior. This study utilized a questionnaire investigation to collect examples of traffic incidents which occur during ordinary driving, analyzed the driver behavior and driver mental and physical states immediately before encountering the traffic incident, and identified driver characteristics which make traffic incidents more likely. We also conducted a comparison with the regression analysis results from previous research concerning daytime subjective sleepiness ・a factor that is likely to lead to serious accidents. Based on these results, we propose a direction for further research concerning physiological signal-driven driving support systems that detect driver physiological signals in order to prevent traffic accidents. Keywords: Driver Monitoring, Mental and Physical States, Physiological Signals, Regression Analysis
2008-11 This study focuses on the possibility that providing the information on short-term trend of traffic condition (trend information) with exiting travel time information might affect the decision-makings of travelers and lead to the enhancement in traffic control by information provision. As an initial step to confirm the effectiveness of trend information, this study conducts the in-laboratory experiment to obtain a kind of panel data of route choices under the provision of information. In this study the parameters of Mixed Logit Model are estimated in order to statistically analyze the influences of trend information upon decision-makings of respondents considering the accuracy of information. The basic findings obtained in this study are as follows. 1)There is a strong possibility that the trend information may significantly affect the decision-makings on route choices of respondents. 2)The influence of information upon the decision-makings of respondents may depend upon the accuracy of both travel time information and trend one. 3)Judging from the estimated parameters of standard deviation of travel time information, there must be the heterogeneity in the sensitivity toward the travel time information among the respondents. Keywords: route choice behavior, travel time information, trend information, in-laboratory experiment |
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