• Title/Summary/Keyword: microscopic simulation model

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Comparison Study of O/D Estimation Methods for Building a Large-Sized Microscopic Traffic Simulation Network: Cases of Gravity Model and QUEEENSOD Method (대규모 미시교통시뮬레이션모형 구축을 위한 O/D 추정 방법 성능 비교 - 중력모형과 QUEENSOD 방법을 중심으로 -)

  • Yoon, Jung Eun;Lee, Cheol Ki;Lee, Hwan Pil;Kim, Kyung Hyun;Park, Wonil;Yun, Ilsoo
    • International Journal of Highway Engineering
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    • v.18 no.2
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    • pp.91-101
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    • 2016
  • PURPOSES : The aim of this study was to compare the performance of the QUEENSOD method and the gravity model in estimating Origin-Destination (O/D) tables for a large-sized microscopic traffic simulation network. METHODS : In this study, an expressway network was simulated using the microscopic traffic simulation model, VISSIM. The gravity model and QUEENSOD method were used to estimate the O/D pairs between internal and between external zones. RESULTS: After obtaining estimations of the O/D table by using both the gravity model and the QUEENSOD method, the value of the root mean square error (RMSE) for O/D pairs between internal zones were compared. For the gravity model and the QUEENSOD method, the RMSE obtained were 386.0 and 241.2, respectively. The O/D tables estimated using both methods were then entered into the VISSIM networks and calibrated with measured travel time. The resulting estimated travel times were then compared. For the gravity model and the QUEENSOD method, the estimated travel times showed 1.16% and 0.45% deviation from the surveyed travel time, respectively. CONCLUSIONS : In building a large-sized microscopic traffic simulation network, an O/D matrix is essential in order to produce reliable analysis results. When link counts from diverse ITS facilities are available, the QUEENSOD method outperforms the gravity model.

Modeling time-dependent behavior of hard sandstone using the DEM method

  • Guo, Wen-Bin;Hu, Bo;Cheng, Jian-Long;Wang, Bei-Fang
    • Geomechanics and Engineering
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    • v.20 no.6
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    • pp.517-525
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    • 2020
  • The long-term stability of rock engineering is significantly affected by the time-dependent deformation behavior of rock, which is an important mechanical property of rock for engineering design. Although the hard rocks show small creep deformation, it cannot be ignored under high-stress condition during deep excavation. The inner mechanism of creep is complicated, therefore, it is necessary to investigate the relationship between microscopic creep mechanism and the macro creep behavior of rock. Microscopic numerical modeling of sandstone creep was performed in the investigation. A numerical sandstone sample was generated and Parallel Bond contact and Burger's contact model were assigned to the contacts between particles in DEM simulation. Sensitivity analysis of the microscopic creep parameters was conducted to explore how microscopic parameters affect the macroscopic creep deformation. The results show that the microscopic creep parameters have linear correlations with the corresponding macroscopic creep parameters, whereas the friction coefficient shows power function with peak strength and Young's modulus, respectively. Moreover, the microscopic parameters were calibrated. The creep modeling curve is in good agreement with the verification test result. Finally, the creep curves under one-step loading and multi-step loading were compared. This investigation can act as a helpful reference for modeling rock creep behavior from a microscopic mechanism perspective.

A Microscopic Traffic Simulation Model for Urban Network Performance Evaluation (도시 가로망시설 운영효율평가를 위한 모의실험 모형개발)

  • 하동익;오영태;정준하
    • Journal of Korean Society of Transportation
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    • v.13 no.1
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    • pp.185-203
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    • 1995
  • The purpose of this paper is to develop a microscopic traffic simulation model which is able to both analyze and the evaluate signlaized urban network and to verify its usefulness in comparison with the other model which has alfeady been released. This simulation model adopts the General Motor's 5th model for car-following and introduces an unique lanechanging rule using acceptable gap. It analyzes single and dual-ring signal phases and generates detector information . So it could be applied to dynamic route guidance systems as wel as real time signal control systems. The results derived from Netsim and the observed data from the real network have been used to test the validit of the proposed model. The result of the test has shown that there are no significant differences between the NETSIM model and the proposed model in estimating travel speed and stopped delay. In optimum offset estimatin , it has shown the same results with NETSIM. the measure of effectiveness , however, derived from this model is slightly better than that of the real network situation. This may be due to the fact that the proposed model does not take into account side frictions from interferences and obstacles.

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A Study on Traffic Impact Assessment Method using Microscopic Simulation Model (미시적 교통류 시뮬레이션을 활용한 교통영향평가 분석기법 개선방안)

  • Shin, Dae-Sup;Lee, Seon-Ha
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.1
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    • pp.31-37
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    • 2008
  • Traffic flow which is prescribed under previous traffic effect/access act is analyzed by traffic volume, V/C, mean speed on road and LOS on the intersection. These indexes based on analytical method can not consider stochastic characteristics of traffic flow. Moreover it is hard to analyze traffic flow visually in whole traffic effect area because only individual road and intersections are targeted. In this study, it is devised to show traffic flow analysis method within traffic effect area visually applying microscopic-simulation by car-following theory, and then based on this, effect analyze ways are studied according to space range plan, improvement measure establishment and etc. To execute this study, effect area is set up using V/C, and the change of traffic current around development area is analyzed using microscopic-simulation program.

A Study on Comparison of Improved Floor Field Model and Other Evacuation Models (개선된 Floor Field Model과 다른 피난시뮬레이션 모델의 비교 연구)

  • Nam, Hyunwoo;Kwak, Suyeong;Jun, Chulmin
    • Journal of the Korea Society for Simulation
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    • v.25 no.3
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    • pp.41-51
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    • 2016
  • In this study, we propose an improved Floor Field Model(FFM) that considers the physical characteristics of pedestrians, i.e., body size, shape, and posture. Also we analyse limits of FFM and features of improved model compared with existing evacuation simulation models. FFM is a typical microscopic pedestrian model using CA, but it does not reflect the physical characteristics of pedestrians. Because of this, FFM is difficult to modeling phenomena such as collision, friction between pedestrians. As a result, FFM calculates a very short evacuation time when compared with the other models. We performed a computational experiment to compare improved model with other models such as FFM, Simulex, Pathfinder in an actual campus building. We carried out a comparison of evacuation aspect according to the change in number of evacuees. Also we compared evacuation aspect by exit. Finally, we confirmed that improved model reflects physical phenomena which were not reflected in FFM. Especially, experimental results were very similar to the Simulex.

Evaluation of Mobility and Safety of Operating an Overlap Phase on a Shared-Left-Turn Lane Using a Microscopic Traffic Simulation Model (미시교통시뮬레이션모형을 이용한 공용 좌회전 차로의 중첩현시운영의 이동성과 안전성 평가 연구)

  • Yun, Il-Soo;Han, Eum;Woo, Seok-Cheol;Yoon, Jung-Eun;Park, Sung-Ho
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.11 no.5
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    • pp.15-26
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    • 2012
  • Government agencies including the national police agency have executed diverse efforts including continuous improvements of traffic facilities and operation methods, education, enforcements in order to improve traffic operation systems; nevertheless there have been continuous criticisms on irrationality in traffic signal and road facility operation. One of the reasons may be the lack of systematic preliminary evaluations on various alternatives. However, there was no appropriate tool to evaluate the mobility and safety of thus alternatives in a systematic way. Therefore, this study proposes the systematic use of microscopic traffic simulation models as a comprehensive evaluation tool. In addition, this study verified the potential of using a microscopic traffic simulation model using the case of operating an overlap phase on a shared-left-turn lane through a systematic way where the evaluation was conducted through data collection, building networks, calibrating microscopic simulation models, producing performance measures, evaluating mobility and safety, and so on. As a result, the operation of overlap phase on a shared-left-turn lane showed no big difference from other operation scenarios such as leading left-turn on exclusive left turn lane in terms of mobility. However the operation of overlap phase on a shared-left-turn lane decreased safety by increasing potential conflicts.

A Study on the Implementation of Microscopic Traffic Simulation Model by Using GIS (GIS를 이용한 미시적 수준의 교통모형 구현에 관한 연구)

  • Kim, Byeongsun
    • Spatial Information Research
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    • v.23 no.4
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    • pp.79-89
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    • 2015
  • This study aims to design and implement a traffic model that can simulate the traffic behavior on the microscopic level by using the GIS. In the design of the model, the vehicle in the simulation environment recognizes the GIS road centerline data as road network data reflecting number of lanes, speed limit and so on. In addition, the behavior model was designed by dividing functions into the environmental perception model, time headway distribution model, car following model, and lane changing model. The implemented model was applied to Jahamun-road of Jongno-gu district to verify the accuracy of the model. As a result, the simulation results on the Jahamun-road had no great error compared with the actual observation data. In the aspect of usability of model, it is judged that this model will be able to effectively contribute to analysis of amount of carbon emission by traffic, evaluation of traffic flow, plans for location of urban infrastructure and so on.

Optimum Chycle Time and Delay Caracteristics in Signalized Street Networks (계통교통신호체계에서의 지체특성과 최적신호주기에 관한 연구)

  • 이광훈
    • Journal of Korean Society of Transportation
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    • v.10 no.3
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    • pp.7-20
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    • 1992
  • The common cycle time for the linded signals is usually determined for the critical intersecion, just because the cpacity of a signalized intersection depends on the cycle time. This may not be optimal since the interactions between the flow and the spatial structure of the route or the area are disregarded in this case. It is common to separate the total delay incurred at signals into two parts, a deterministic or uniform delay and a stochastic or random delay. The deterministic delays and the stochastic delays on the artery particularly related to signal cycle time. For this purpose a microscopic simulation technique is used to evaluate deterministic delays, and a macroscopic simulation technique based on the principles of Markov chains is used to evaluate stochastic delays with over flow queue. As a result of investigating the relations between deterministic delays and cycle time in the various circumstances of spacing of signals and traffic volume. As for stochastic delays the resalts of comparisons of the macroscopic simulation and Newell's approximation with the microscopic simulation indicate that the former is valid for the degree of saturation less than 0.95 and the latter is for that above 0.95. Newell's argument that the total stochastic delay on an arterial is dominated by that at or caused by critical intersection is certified by the simulation experiments. The comprehensive analyses of the values of optimal cycle time with various conditions lead to a model. The cycle time determined by this model shows to be approximately 70% of that calculated by Webster's.

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Safety Assessment of Signalized Intersection Using SSAM : A Case of Actuated Signal Control (SSAM을 이용한 신호교차로 안전성 평가(감응식 교통제어 도입사례를 중심으로))

  • Yun, Il-Soo;Lee, Choul-Ki;Choi, Jin-Hyung;Ko, Se-Jin
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.10 no.6
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    • pp.1-14
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    • 2011
  • The surrogate safety assessment model which was developed based on the conflict theory by FHWA in the US is software to analyze traffic conflicts using the individual vehicle trajectory data from a microscopic traffic simulation model. This study aims at assessing the safety of different signal control strategies, including pre-time and actuated signal control, using the SSAM. To this end, this study effort has developed a microscopic traffic simulation model using VISSIM through a field study, and then produced the surrogate measures, including TTC, PET, DR, MaxS and DeltaS, and the numbers of conflicts, including rear-end, right angle and lane-changing conflicts. The assessment results indicated that the actuated signal control may produce more conflicts in terms of rear-end conflicts. The use of SSAM in the safety assessments for diverse traffic alternatives in a safe and fast way may contribute to the improvement of safety in the roadway transportation.

Microscopic Evacuation Simulation in Large-scale Buildings using EgresSIM (EgresSIM을 이용한 대형건축물의 미시적 대피시뮬레이션)

  • Kwak, Suyeong;Nam, Hyunwoo;Jun, Chulmin
    • Journal of the Korea Society for Simulation
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    • v.25 no.1
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    • pp.53-61
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    • 2016
  • This paper introduces 'EgresSIM', which is microscopic evacuation simulation software. EgresSIM developed in this paper is a three-dimensional (3D) pedestrian evacuation simulator based on the improved model advanced from the floor field model(FFM), a microscopic pedestrian model. This software can simulate large size buildings that consist of a number of floors, stairs, rooms, and exit doors. Moreover, this software can arrange several hundreds or thousands of pedestrians in indoor space and check their movements through the 3D viewer in real time, as well as produce detailed results about evacuation situations such as which paths are employed by individual pedestrians, how long does it takes to evacuate, and how many evacuees are gathered at each of the exit doors. Building data needed in the simulation are constructed as XML files according to pre-defined indoor data models and information of simulation results is also created as XML log files. A moving pattern of pedestrians can be represented in many ways by adjusting the sensitivity parameters of two walk models supported by EgresSIM. Thus, evacuation simulation can be done based on many assumptions of situations such as movement to the nearest exit door or blackout after outage.