• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.437-448
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• 2016

Some previous researches suggested a transit trip destination inference method by constructing trip chains with incomplete(missing destination) smart card dataset obtained on the entry fare control systems. To explore the feasibility of the transit trip destination inference method, the transit trip chains are constructed from the pre-paid smart card tagging data collected in Busan on October 2014 weekdays by tracing the card IDs, tagging times(boarding, alighting, transfer), and the trip linking distances between two consecutive transit trips in a daily sequences. Assuming that most trips in the transit trip chains are linked successively, the individual transit trip destination zones are inferred as the consecutive linking trip's origin zones. Applying the model to the complete trips with observed OD reveals that about 82% of the inferred trip destinations are the same as those of the observed trip destinations and the inference error defined as the difference in distance between the inferred and observed alighting stops is minimized when the trip linking distance is less than or equal to 0.5km. When applying the model to the incomplete trips with missing destinations, the overall destination missing rate decreases from 71.40% to 21.74% and approximately 77% of the destination missing trips are the single transit trips for which the destinations can not be inferable. In addition, the model remarkably reduces the destination missing rate of the multiple incomplete transit trips from 69.56% to 6.27%. Spearman's rank correlation and Chi-squared goodness-of-fit tests showed that the ranks for transit trips of each zone are not significantly affected by the inferred trips, but the transit trip distributions only using small complete trips are significantly different from those using complete and inferred trips. Therefore, it is concluded that the model should be applicable to derive a realistic transit trip patterns in cities with the incomplete smart card data.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.145-154
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• 2009

The main goal of this paper is to develop a methodology for increasing the reliability of truck OD matrices in Seoul Metropolitan Area. We propose a Hybrid Method made up of five processes by using Non-Traffic Assignment and Gradient Method. A Hybrid Method and Gradient Method have applied for comparison and estimation in Seoul Metropolitan Area. Mean Error and Root Mean Square Error of a Hybrid Method present lower than Gradient Method. The findings of this paper show that the new truck OD matrices created by a Hybrid Method are more reliable than the existing truck OD matrices in the Seoul Metropolitan Area.

• Journal of Korean Society of Transportation
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• v.5 no.2
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• pp.113-126
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• 1987

본 논문은 통행 기·종점 및 교통수단선택의 문제를 교통망 평형모형과 종합하여 이를 하나의 최적화 문제로 구성하는 방법 및 그의 실제응용 방법을 제시, 검토하였다. 두 가지의 행태적 특성, 즉 교통비용을 최소화하려는 사용자 평형과 통행 기·종점 및 교통수 단 등의 선택에 있어 어느 수준의 상호교류를 유지하려고 하는 엔트로피 극대화 현상이 병 애되어 최적화 문제를 형성하게 된다. 본 연구의 목적은 이의 체계적 구성과 아울러 이를 여러 도시에서 설치, 사용되고 있는 개재의 UTPS프로그램과 종합시킴으로써 개재의 대한 데이터베이스를 사용케하고 실제응용을 단순화 시키는데 있다. 개발된 모형과 방법은 시카 고 지역의 자료를 이용하여 그 타당성이 검토되었다.

• Journal of Korean Society of Transportation
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• v.24 no.6 s.92
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• pp.89-102
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• 2006

The purpose of this paper is to develop a dynamic OD estimating model to overcome the limitation of depicting teal situations in dynamic simulation models based on static OD trip. To estimate dynamic OD matrix we used the hybrid discrete choice model(called the 'Demand Simulation Model'), which combines travel departure time with travel mode and travel path. Using this Demand Simulation Model, we deduced that the traveler chooses the departure time and mode simultaneously, and then choose his/her travel path over the given situation In this paper. we developed a hybrid simulation model by joining a demand simulation model and the supply simulation model (called LiCROSIM-P) which was Previously developed. We simulated the hybrid simulation model for dependent/independent networks which have two origins and one destination. The simulation results showed that AGtt(Average gap expected travel time and simulated travel time) did not converge, but average schedule delay gap converged to a stable state in transportation network consisted of multiple origins and destinations, multiple paths, freeways and some intersections controlled by signal. We present that the hybrid simulation model can estimate dynamic OD and analyze the effectiveness by changing the attributes or the traveler and networks. Thus, the hybrid simulation model can analyze the effectiveness that reflects changing departure times, travel modes and travel paths by demand management Policy, changing network facilities, traffic information supplies. and so on.

• Journal of Korean Society of Transportation
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• v.27 no.1
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• pp.143-155
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• 2009

A dynamic traffic assignment (DTA) has recently been implemented in many practical projects. The core of dynamic model is the inclusion of time scale. If excluding the time dimension from a DTA model, the framework of a DTA model is similar to that of static model. Similar to static model, with given exogenous travel demand, a DTA model loads vehicles on the network and finds an optimal solution satisfying a pre-defined route choice rule. In most DTA models, the departure pattern of given travel demand is predefined and assumed as a fixed pattern, although the departure pattern of driver is changeable depending on a network traffic condition. Especially, for morning peak commute where most drivers have their preferred arrival time, the departure time, therefore, should be modeled as an endogenous variable. In this paper, the authors point out some shortcomings of current DTA model and propose an alternative approach which could overcome the shortcomings of current DTA model. The authors substitute a traditional definition for time-dependent OD table by a new definition in which the time-dependent OD table is defined as arrival time-based one. In addition, the authors develop a new DTA model which is capable of finding an equilibrium departure pattern without the use of schedule delay functions. Three types of objective function for a new DTA framework are proposed, and the solution algorithms for the three objective functions are also explained.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.335-336
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• 2008

최근 ITS(Intelligent Transportation Systems)의 보급으로 개인의 기-종점 간 통행시간에 많은 비용절감을 가져왔다. 지금까지의 주요 최단경로알고리즘은 네트워크의 기-종점(Origin-Destination) 거리 간 최단 통행시간을 고려하여 연구되어 왔다. 하지만, 최근 대두되는 고유가 시대의 진입과 더불어 환경에 대한 인식이 높아짐에 따라 기-종점 간 통행시간만을 고려하던 기존의 방법들에서 벗어나 추가적인 요인들의 고려 필요성이 증대되고 있다. 따라서 본 연구에서는 지리정보시스템을 이용한 환경오염을 최소화하는 친환경 최단경로 탐색방법 개발을 제안하고자 한다. 이를 위하여 3D 좌표정보 도로를 활용하여, 도로구배 조건에 따른 배출가스의 증감율을 환경오염편익으로 구분하고, 이를 사회적비용으로 환산하여, 경로탐색의 추가적인 요소로 반영하였다.

• Journal of Korean Society of Transportation
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• v.19 no.1
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• pp.89-99
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• 2001

The conventional studies on equilibrium network design problem(ENDP) with fixed travel demand models assume that the future OD travel demand might not be changed even if the structure and the capacity of the network are improved. But this fixed demand assumption may loose its validity in the long-range network design because OD travel demand actually shifts with the network service level. Thus, it is desirable to involve the variable travel demand which is determined endogenously in the model in the optimal network design. In this paper a hi-level model formulation and solution procedure for ENDP with variable travel demand are presented. Firstly It is considered how to measure the net user benefits to be derived from the improved in link capacities, and the equilibrium network design problem considered here is to maximize the increase of net user benefit which results from a set of lift capacity enhancements within the budget constraints, while the OD travel demands and link travel times are obtained by solving the lower level network equilibrium problem with variable demand. And secondly sensitivity analysis is carried out to find the links to which the network equilibrium flow pattern is the most sensitive. Finally numerical example with simple network is carried out to test the validity of the model.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.5
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• pp.53-63
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• 2008

In this paper, we propose the regional travel time measurement algorithm using the sequence pattern matching to the type of vehicles between the origin of the region and the end of the region, that could be able to overcome the limit of conventional method such as Probe Car Method or AVI Method by License Plate Recognition. This algorithm recognizes the vehicles as a sequence group with a definite length, and measures the regional travel time by searching the sequence of the origin which is the most highly similar to the sequence of the end. According to the assumption of similarity cost function, there are proposed three types of algorithm, and it will be able to estimate the average travel time that is the most adequate to the information providing period by eliminating the abnormal value caused by inflow and outflow of vehicles. In the result of computer simulation by the length of region, the number of passing cars, the length of sequence, and the average maximum error rate are measured within 3.46%, which means that this algorithm is verified for its superior performance.

• Journal of Korean Society of Transportation
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• v.31 no.3
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• pp.45-54
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• 2013

Korea Expressway Corporation has been utilizing vehicles equipped with dedicated short range communication (DSRC) based on-board equipment (OBE) for collecting path travel times. A path based method (PBM) estimates the path travel time using probe vehicles traveling whole links on the path, so it is not always possible to obtain sufficient samples for calculating path travel time in the DSRC system. Having this problem in utilizing DSRC for travel time information, this study attempted to estimate path travel time with the help of a link based method (LBM) and examined whether the LBM can be used for obtaining reliable path travel times. Some comparisons were made and identified that the MAPE difference between the LBM and the PBM estimates are less than 3%, signaling that LBM can be used as a proxy for PBM in case of sparse sample conditions. Some limitations and a future research agenda have also been proposed.

• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.7-17
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• 1999

The expressway network includes a total of about 1,899 km in our country The only 1,016 km of that is being managed by the closed Toll Collection System(TCS) which is composed of 74 tollgates. We obtain inter-tollgate O-D matrices from that system everyday. But, they are not traffic-zonal O-D matrices. So they have not been used for the expressway traffic analysis and the traffic demand estimation despite of their accuracy. If we could estimate the traffic-zonal O-D matrices from TCS O-D ones, we could perform expressway traffic analysis more efficiently. Moreover we could obtain more precise expressway O-D matrices and traffic-zonal O/D ones by this approach than by the conventional ones. In this paper. we proposed the model estimating traffic-zonal O/D matrices from TCS O-D ones. The assigned volumes with the estimated traffic-zonal O-D matrices produced the only 17.9% error all over the TCS expressway section when compared to the real traffic volumes. So, the proposed model enables for us to estimate more accurate O/D matrics than any other existing methods.