• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.5
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• pp.11-20
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• 2014

Due to the importance of vehicle detector which plays an essential role in generating real-life traffic information, maintaining detector data quality is preeminent in advanced traffic management and information systems (ATMIS). To this end, agencies periodically conduct performance tests on detectors. Detector evaluation is generally performed by comparing baseline data with corresponding detector data. Here, two important things need to be addressed; one is errors (or uncertainties) included in baseline data and the other is the confidence interval concept to represent evaluation results of sample data to corresponding ones of population. To resolve these problems, a new detector evaluation scheme is introduced and the scheme is applied to individual level detector evaluations of loop, video image, and radar detectors. The purpose of individual level evaluation is to eliminate the balancing (or cancelling-out) effects of over- and under-counts. As a consequence, the proposed scheme is proven to be effectively applied to real-world detector evaluations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.67-75
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• 2011

This paper presents a new test technique for evaluating performance of vehicle detectors with interval estimation, not the conventional point estimation, for presenting statistical confidence interval. The methodology is categorized into three parts; sampling plan, analysis on the characteristic of evaluation indices, and the expression of evaluation results. Even though many statistical sampling plans exist, stratified random sampling is regarded as the most appropriate one, considering the detector performance characteristics that varies with traffic, illumination, and meteorological conditions. No magic bullet exists for evaluation index for detector evaluation, hence the characteristics of evaluation indices were thoroughly analyzed and a reasonable process for choosing the best evaluation index is proposed. Finally, the methodology to express the result of detector evaluation for the entire evaluation period and individual analysis interval is represented, respectively. To overcome the existing drawbacks in point estimation, interval estimation by which statistical confidence interval can be represented is introduced for enhancing statistical reliability of traffic detector evaluation. This research can make vehicle detector scheme improve one step forward.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.2
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• pp.34-44
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• 2007

Many urban cities deployed ITS technologies to improve the efficiency of traffic operation and management including a real-time franc control system (i.e., COSMOS). The system adopted loop detector system to collect traffic information such as volume, occupancy time, degree of saturation, and queue length. This paper investigated the applicability of detector information within COSMOS to represent the congestion level of the links. Initially, link travel times obtained from the field study were related with each of detector information. Results showed that queue length was highly correlated with link travel time, and direct link travel time estimation using the spot speed data produced high estimation error rates. From this analysis, a procedure was proposed to estimate congestion level of the links using both degree of saturation and queue length information.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.5
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• pp.22-35
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• 2013

With the increase in image detectors, concerns about the reliability of traffic information are increasing. In this paper, we propose a method to generate reliable traffic volume using analysis of the point detector data as a representative value. Therefore, targeting expressway, we analyzed the difference in traffic volume collected by loop and image detector, and verified statistically using t-test, and finally analyzed the error rate compare to the real traffic volume. Analysis revealed that there was a statistically difference the traffic date collected by the loop detector and the image detector, in the same period, the same time, respectively. In addition, the difference between the actual traffic volume and traffic that have been collected in a loop detector was the lowest Therefore, creating a traffic volume of representative value, we proposed a method to use loop detector than the average traffic volume collected by each detector. It shows that it is more important to use one high-quality data rather than various low-quality data to produce a representative value.

• Journal of Korean Society of Transportation
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• v.24 no.1 s.87
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• pp.73-84
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• 2006

This study was carried out to set up the logic to determine lengths of the homogeneous sections effectively in order to provide dynamic travel time on real time base for the application of the model. First, considering real time traffic pattern fluctuation, lengths of the homogeneous sections for each time period and the final homogeneous sections were determined. In order to determine lengths of the homogeneous sections according to traffic condition, the cluster analysis was used based on real time data. In order to verify the homogeneous section the case with detectors in all links and the case with detectors in homogeneous section for each time period are used. As the results of verification, each cases showed similar estimation results. The results of this study are expected to be used for National Highway traffic management and the system to Provide a traffic information in the future. According to this study, when the homogeneous section decision model are used to the ITS project for National Highway, operation cost is expected to be cut by effectively establishing point detectors.

• Proceedings of the KOR-KST Conference
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• 1998.10a
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• pp.21-30
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• 1998

본 연구는 기존 구간 속도 예측기법의 고찰을 통하여 검지기에서 올라오는 교통제어변수를 이용하여 구간 속도 예측모형을 연구하는데 목적이 있다. 이를 위한 교통 제어변수로는 연속류 제어에서 통상적으로 사용되는 교통량, 점유율, 밀도, 속도 등을 사용한다. 공간적 범위로는 서울 올림픽대로의 17개의 영상 검지기 중 #3과 #16검지기에서 올라오는 속도, 점유율, 교통량 자료를 토대로 1998년 6월 11일 오전 7시부터 11시까지의 4시간동안 예측을 실시하며 Historical Traffic Pattern과 시험차량, 자동차 번호판 조사를 통한 구간 실측조사 자료를 토대로 예측을 위한 자료를 구축한다. 기존의 예측기법인 시계열 분석, 신경망 이론, 평활법과 칼만필터링을 고찰하였고, 가장 좋은 예측력을 보여주는 기법은 칼만필터링 모형이었다. 이를 토대로 Case Study를 통해 여러 구간의 다주기 예측을 통해 단기간(short-term)의 구간 속도를 예측하고 각 해당 검지기별 실측자료를 통해 비교분석을 실시하였다. 결과적으로 도출된 칼만필터링 모형의 다주기 예측을 통한 구간 통행속도의 예측이 기존의 구간 통행속도 산출 방법보다 더 나은 예측력을 보여주고 있다.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.19-30
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• 2006

This study deals with the optimized detector location considering the traffic characteristics in National Highway. Although there ave many construction works for ITS in National Highway, there is not specific criteria for detector location which can effect the accuracy of traffic information. This study. therefore. aims to Provide the optimized detector location criteria which can represent the traffic characteristics of National Highway. It collects traffic factors of study area by GPS Probe-car and defector, and Presents the optimized detector location by the correlation analysis between spot-speed and link-travel-time. The main results of this study are as followings ; First, the correlation between the spot-speed and link-travel-time Presents the opposite bell shape of the graph (U-type owe) which is increased it?on the upstream then, declined through some unspecified Point of the link. Second, the optimized detector location usually distributes around midstream of link, even though it does not have a consistency. Third, therefore, the optimized detector location generally should be located between $55{\sim}60%$ of total link length. Forth. high level of vertical slope is one of the most important factors of detector location, so it should be excluded for determination of optimized detector location. Finally, expecting that the results of this study would improve the accuracy of travel time estimation and forecasting.

• Information and Communications Magazine
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• v.21 no.5
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• pp.70-79
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• 2004

최적 경로 서비스를 제공하기 위해서는 구간 통행속도, 구간 통행시간, 회전 정보, 혼잡도 등과 같은 교통정보가 필요하다. 또한, 고객에게 신뢰성 있는 최적 경로를 제공하기 위해서는 실시간 교통정보 수집은 반드시 필요하며, 이러한 실시간 교통정보 수집 방법들에 대한 고찰과 검토가 선행되어야 한다. 기존의 교통정보 수집방법을 살펴보면 지점검지 방식의 경우, 수집되는 정보가 검지기 설치 지점의 지점속도(Spot Speed)이므로 해당 링크를 주행한 통행속도(통행시간)의 대표값으로 채택하기에는 다소 무리가 있으며 구간검지 방식의 경우, 일반적으로 급격한 교통류 변동에 따른 대기행렬 검지가 늦다는 단점이 있다.(중략)

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.1 no.1
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• pp.41-51
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• 2002

As Advanced Traveler Information System(ATIS) is the kernel of the Intelligent Transportation System, it is very important how to manage data from traffic information collectors on a road and have at borough grip of the travel time's change quickly and exactly for doing its part. Link travel time can be obtained by two method. One is measured by area detection systems and the other is estimated by point detection systems. Measured travel time by area detection systems has the limitation for real time information because it Is calculated by the probe which has already passed through the link. Estimated travel time by point detection systems is calculated by the data on the same time of each. section, this is, it use the characteristic of the various cars of each section to estimate travel time. For this reason, it has the difference with real travel time. In this study, Artificial Neural Networks is used for estimating link travel time concerned about the relationship with vehicle detector data and link travel time. The method of estimating link travel time are classified according to the kind of input data and the Absolute value of error between the estimated and the real are distributed within 5$\~$15minute over 90 percent with the result of testing the method using the vehicle detector data and AVI data of Namsan Tunnel $\#$1. It also reduces Time lag of the information offered time and draws late delay generation and dissolution.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.1 s.12
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• pp.13-26
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• 2007

A VDS data in the domestic has been used within limits to real time information such as congestion management, incident management, and route guidance service. On the other hand, a VDS data in the foreign countries had been used to various objectives such as transportation policy assessment, transportation construction evaluation, franc safety improvement, and etc. The scope and method of the study is the VDS data which was installed in the uninterrupted flow such as the freeway and the interrupted flow in a diversion route of the leeway. It has investigated and analyzed the VDS as our subject to study, study objective and study methodology for each study generally classified as 1) data collection 2) data processing 3) data store and 4) data quality section. This study has investigated and analyzed the various literatures in domestic and foreign countries regarding the VDS data. And It drew the development direction of the study which is about VDS data in domestic from now.