• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.138-149
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• 2016

The study reviewed the effects of the variable speed limit under adverse weather conditions by using a driving simulator. The study assumed that the display of the reduced speed limit without any change of the weather condition and the display of the same speed limit under the change of the weather conditions violate the expectancy of drivers, so it brings the negative effects on the safety. The study regards drivers conformance as the index of the degree of the compliance of driver expectancy, and utilizes the cumulative probability density within the certain range of the speed including displayed speed limit as the quantitative measure of effectiveness. The study reviewed this assumptions by using a driving simulator. As the results, the cases assumed to violate the expectancy of drivers showed the negative effects on the driving behaviour of driver relatively.

• Journal of Korean Society of Transportation
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• v.20 no.6
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• pp.69-80
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• 2002

차로변경이 발생하는 두 가지 상황 즉, 강제 차로 변경과 선택적 차로 변경 중, 선택적 차로변경 상황에서 운전자가 수락 가능한 간격을 발견했을 때, 차로별 속도 차가 차로 변경 의사결정에 미치는 영향을 모사할 수 있는 모형식을 추정하였다. 즉, 선택적 차로 변경은 운전자의 차로 변경 여부에 대한 상황판단과 함께 목적 차로의 간격 수락여부에 대한 의사결정으로 이루어지는데, 본 논문에서는 목적 차로에 수락 가능한 간격이 존재할 경우 차로별 속도차가 운전자의 의사결정에 어떤 영향을 미치는지에 대해 분석하였다. 이를 위해, 운전자 의 의사결정에 영향을 미칠 수 있는 다른 요소 즉, 중차량, 기하구조, 및 합·분류의 영향을 최소화하는 지점을 선택하여 표본조사를 실시하였으며, 보다 설명력 있는 모형식을 얻기 위해 상관분석 등을 수행하여 불필요하다고 생각되는 변수는 제외시켰다. 또한, 운전자의 희망속도와 주행 속도 차에 의한 영향을 반영하기 위해 현 차로 속도를 부가적인 변수로 추가하였으며, 계수추정은 통계패키지인 SAS를 이용하였는데, 자료분석에 있어, 속도차 구간에 따라 다른 간격수락 특성을 보여 차로별 속도차를 0∼2.0m/s구간과 2∼11.52m/s구간으로 나누어 분석을 수행하였다. 분석결과 속도차 0∼2.0m/s구간에서는 속도차가 증가할수록 차로 변경률이 높아졌으나, 2∼11.52m/s구간에서는 오히려 차로 변경률이 낮아지는 것으로 나타났는데, 이는 속도 차의 증감에 대해 운전자로 하여금 차로 변경을 유도하는 요소와 함께 저항하게 하는 요소가 있다는 것을 알 수 있었다. 분석결과. 2.0m/s 이상의 속도차에서 차로변경에 대한 저항이 상대적으로 크게 작용한다는 것을 알 수 있었으며, 도로 설계시 이를 반영하여 도로기하구조 및 안전성 등을 향상시킬 수 있을 것으로 보인다.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.95-105
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• 2004

The fundamental diagram is a important element in a variety of transportation studies. While various shapes of the fundamental diagram have been proposed and numerous debates on the best-fit fundamental diagram have been made, the reason why the fundamental diagram has many different shapes has not been well explained. This study introduces time sap as a key parameter to understand drivers' behavioral differences at different locations and traffic conditions, then relate to the shape of the fundamental diagram. From the freeway event detector data, it is shown that time gap follows a certain probabilistic distribution and its mean value varies along locations. It also turns out that drivers take different time gaps for different travel speeds. Three different types of time gap-speed diagrams are identified and matched to Greenberg, reversed-lambda, and inverted-V types of fundamental diagrams, respectively. This study explains the characteristics of fundamental diagrams using time gap as a microscopic variable and describes drivers' behavioral characteristics according to traffic and geometric conditions.

• Journal of Korean Society of Transportation
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• v.33 no.4
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• pp.405-416
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• 2015

This paper developed a method analyze drivers' response characteristics using spectral analysis with car following data. Cross-correlation function and cross spectrum are produced by Fourier transform from speed fluctuations of leading vehicle and following vehicle during the designated time ${\tau}$. Based on the analysis data, a process to calculate the reaction time and stimulus-adaption index of following vehicle was developed and 170 cases of field data was applied. It was reported average of 0.654 and 2.091 seconds of stimulus-adaption index and reaction time respectively. In conclusion, the developed indexes might contribute to enhance vehicle control of autonomous vehicle more efficient and safer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.879-885
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• 2018

The highway weaving section is a point where there is a conflict caused by entry and exit vehicles. In order to minimize the impact on the main line, an accumulation line should be installed. The design speed of the collecting part is 50 km/h, but the actual driver does not have proper deceleration according to the design speed. In this study, considering the driving behaviors, the design specification, and the driver 's viewing angle, the appropriate separation distance for safe entry and exit of collecting, connecting, and collecting roads was examined. As a result of the analysis, it is found that a distance of 60m is required from the point where the merging starts. The results of this study are expected to contribute to the improvement of driver safety due to the conflict between entry and exit vehicles when applied to the weaving section where collecting roads are installed.

• Journal of Korean Society of Transportation
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• v.22 no.2 s.73
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• pp.103-108
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• 2004

The motivation of this study comes from the problem recognition that the headway of passing vehicle in signalized intersections can not be merely determined by departing sequence. Traffic speed and headway data of passing vehicles in signalized intersection have been obtained by using magnetic detectors(NC 97) and detecting program, and the data was analyzed. Without special treatment, the model established on passing behavior of vehicles was meaningless from statistical view point. Hence, special treatments such as filtering (upper 85% offensive driver driven vehicle's) and log scaling of data were carried on. With this new data, meaningful model (where coefficient of determination is 0.91) was established. This model explained the fact that vehicle headway in signalized intersection is affected by speed and headway of previous vehicle and speed of itself.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.137-144
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• 2004

The real-time traffic information is considered to be the system to alleviate traffic congestion. An effective traffic information will help drivers make efficient travel decision, and network performance will be improved. To make efficient strategy of providing information, the analyst should quantify reduced congestion by the media traffic informations. Many other route diversion models considered only media-informations as information sources and ignored the impact of on-site informations such as visible delays and average speeds, which affect drivers' route diversion decision in practice. In those models, the effect of on-site informations could be treated to be the effect of media informations, and the effects of media informations would be over-estimated. The proposed model including the impact of on-site information can estimate the effect of media-informations. The results are expected to be applied to the analysis of traffic management policy such as ITS.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.147-159
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• 2023

In order to make autonomous vehicles more trustworthy, it is necessary to focus on the users of autonomous vehicles. By evaluating the preferences for driving behaviors of autonomous vehicles, we aim to identify driving behaviors that increase the acceptance of users in autonomous vehicles. We implemented two driving behaviors, aggressive and cautious, in a driving simulator and allowed users to experience them. Biometric data was collected during the ride, and pre- and post-riding surveys were conducted. Subjects were categorized into two groups based on their driving habits and analyzed against the collected biometric data. Both aggressive and cautious driving subjects preferred the cautious driving behavior of autonomous vehicles.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.63-75
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• 2018

A Service Area plays an important role in preventing accidents in advance by creating a space for long distance drivers or drowsy drivers to rest. Therefore, proper positioning of the expressway service area is essential, and it is important to analyze accurate demand forecasting and user travel behavior. Thus, this study analysis travel behavior and developed odel of the probability of using the service area by using the DSRC data collected by the RSE on the highway. According to the analysis, the usage behavior of highway service areas was most frequently when travel time was 90 minutes or more on weekdays and 70 minutes or more on weekends. The utilization rate of the service area estimated from the probability model of use of the rest area in this study was 1 % to 2 % error. The results of this study are meaningful in analyzing the behavior of the use of rest areas using the structured data and can be used as a differentiated strategy for selecting the location of rest areas and enhancing the service level of users.

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.111-120
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• 2007

More accurate vehicle trajectory data are now readily available through Differential Global Positioning Systems (DGPS). A variety of research opportunities emerge with utilization of such high resolution traffic data. A novel approach of this study is to explore drivers' responsive behavior to variable message signs (VMS) by using individual vehicle trajectories extracted from in-vehicle DGPS data. Responsive characteristics of drivers traveling on urban freeways, which can be represented by speeds and acceleration rates, under the provision of real-time traffic information through VMS are statistically investigated. In addition to conducting an ANOVA test, probability density functions of acceleration rates were estimated. The findings of this study can be used to understand the impact of drivers' workload when providing VMS messages on traffic flow patterns. Furthermore, results can be important fundamentals to assist in conducting more realistic traffic simulations.