• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.109-120
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• 2010

This study aims to develop mathematical models for estimating saturation flow rates at the stop line of signalized intersection due to Workzones in the vicinity, since the saturation flow rate is the most critical parameter in capacity analysis for signalized intersections. It was found by reference review that saturation flow rates are sensitively influenced by the location of Workzone, the number of lanes, cycle length and effective green time. Extensive microscopic simulation runs were also performed and compared to the those of mathematical models for model verification. Mathematical models were developed based on traffic flow theory and dualizing them by the location of workzones. And then each result produced by changing important parameter values was carefully examined and analyzed. Small but consistent differences in saturation flow rate values between mathematical models and simulations exist. However, the pattern of changes in saturation flow rates depending on each variable was similar.

• Journal of Korean Society of Transportation
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• v.29 no.5
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• pp.121-138
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• 2011

More affordable and available cutting-edge technologies (e.g., wireless vehicle communication) are regarded as a possible alternative to the fixed infrastructure-based traffic information system requiring the expensive infrastructure investments and mostly implemented in the uninterrupted freeway network with limited spatial system expansion. This paper develops an advanced decentralized traveler information System (ATIS) using vehicle-to-vehicle (V2V) communication system whose performance (drivers' travel time savings) are enhanced by three complementary functions (autonomous automatic incident detection algorithm, reliable sample size function, and driver behavior model) and evaluates it in the typical $6{\times}6$ urban grid network with non-recurrent traffic state (traffic incident) with the varying key parameters (traffic flow, communication radio range, and penetration ratio), employing the off-the-shelf microscopic simulation model (VISSIM) under the ideal vehicle communication environment. Simulation outputs indicate that as the three key parameters are increased more participating vehicles are involved for traffic data propagation in the less communication groups at the faster data dissemination speed. Also, participating vehicles saved their travel time by dynamically updating the up-to-date traffic states and searching for the new route. Focusing on the travel time difference of (instant) re-routing vehicles, lower traffic flow cases saved more time than higher traffic flow ones. This is because a relatively small number of vehicles in 300vph case re-route during the most system-efficient time period (the early time of the traffic incident) but more vehicles in 514vph case re-route during less system-efficient time period, even after the incident is resolved. Also, normally re-routings on the network-entering links saved more travel time than any other places inside the network except the case where the direct effect of traffic incident triggers vehicle re-routings during the effective incident time period and the location and direction of the incident link determines the spatial distribution of re-routing vehicles.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.3
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• pp.9-23
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• 2015

A lane change maneuver which has a high driver cognitive workload and skills sometimes leads to severe traffic accidents. In this study, the Advanced Lane Change Assist System (ALCAS) was developed to assist with the automatic lane changes in merging sections which is mainly based on an automatic control algorithm for detecting an available gap, determining the Optimal Lane Change Start Point (OLCSP) in various traffic conditions, and positioning the merging vehicle at the OLCSP safely by longitudinal automatic controlling. The analysis of lane change behavior and modeling of fundamental lane change feature were performed for determining the default parameters and the boundary conditions of the algorithm. The algorithm was composed of six steps with closed-loop. In order to confirm the algorithm performance, numerical scenario tests were performed in various surrounding vehicles conditions. Moreover, feasibility of the developed system was verified in microscopic traffic simulation(VISSIM 5.3 version). The results showed that merging vehicles using the system had a tendency to find the OLCSP readily and precisely, so improved merging performance was observed when the system was applied. The system is also effective even during increases in vehicle volume of the mainline.

• Journal of Korean Society of Transportation
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• v.29 no.4
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• pp.7-15
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• 2011

Emerged in early 1990s, so called 'Quick service' industry that provides faster delivery of small parcels than regular mail service accelerated use of motorcycles. As the economic grows, use of large bicycles (more than 250CC displacement) for leisure purpose has also rapidly increased. Traffic crash data clearly shows the increasing trend in motorcycle crashes. The ratio of motorcycle involved crashes out of total has increased from 5.7% in 2005 to 8.3% in 2008, and similar trend can be found in fatalities ratio as well. In this study, we assess the level of risk when motorcycles operate on motorways by analyzing traffic rule violation ratio, lane change behaviour, driving speed behaviors of motorcycles in Uninterrupted Traffic Flow Facilities and using PC-CRASH simulation we also calculate car shock impulses occurred when an accident happens. Analysis result shows that the motorcycle is different from the car in terms of lane change timing and average speed, and also shows motorcycle drivers tends to conduct more improper driving behavior particularly when traffic is congested. The results from this study could be usefully applied when the law enforcement agent decides whether bicycles shall be allowed to use motorways. The result could be also utilized as fundamental information for further study of bicycles' driving behavior.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.867-878
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• 2018

As the era of AVs (Automated Vehicles) comes to a close, many researches related to AVs have been conducted. Up until now, research on traffic flow impact of AVs has been the main topic, and research on traffic management for AVs is still in beginning stage. This study analyzed the effect of Dynamic Merge Control (DMC) in manual vehicle (MV) and AV environment at work zone. Dynamic Late Merge (DLM) and DLM with Dynamic Early Merge (DEM) are compared by simulation. Simulation results showed that DLM improves travel time and work zone throughput compared to no merge control case in both MV and AV environment. In the case of additional operation of DEM, the improvement effect was not observed in MV environment, but it was improved in AV environment. As a result, DMC operation in AV environment was as effective as the improvement in transition from MV to AV environment. Therefore congestion reduction at freeway work zone by DMC will be possible in future AV environment, and the improvement of DMC can be suggested.

• Journal of Korean Society of Transportation
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• v.32 no.3
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• pp.280-292
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• 2014

A tram has been the focus of a new public transportation that can solve a traffic jam, decreasing of public transit usage and environmental problem in recent years. This study aims to develop a signal optimization model for considering the traffic signal progression of tram and vehicles, when they are operated simultaneously in the same signalized intersections. This research developed the KS-SIGNAL-Tram model to obtain a minimum tram bandwidth and to minimize a vehicle's delay to perform a tram passive signal priority, it is based on the KS-SIGNAL model and is added to the properties of a tram and it's system. We conducted a micro simulation test to evaluate the KS-SIGNAL-Tram model, it showed that the developed optimization model is effective to prevent a tram's stop on intersection, to reduce a tram's travel time and vehicle's delay.

• Journal of Navigation and Port Research
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• v.29 no.10 s.106
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• pp.833-838
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• 2005

This paper is to investigate the minimum safe distance between T/S Hanbada and a group of vessels participating in the event hosted by M broadcasting station who asked T/S Hanbada to keep a distance from $100m{\sim}500m$. The minimum safe distance was assessed by using ES Model which evaluates quantitatively the difficulty of shiphandling, and the simulation of marine traffic flow. As a result the minimum safe distance of T/S Hanbada moving at a speed of 2 knots turns out about 260m and is compared with the actual value.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.5-10
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• 2005

T.S. HANBADA will navigate to maintain the adequate distance between own ship and other ships safely for about 17 hours on the about 2 kts. On the above situation, M broadcasting station requires to maintain the distance from 100m to 500m between ships. This paper aims to calculate the minimum safe distance between ships, the distance is assessed by using ES Model which is a quantitative model for evaluating the difficulty of shiphandling. After marine traffic flow simulation, minimum safe distance for HANBADA on the 2kts is about 260m based ES value. On this paper, the result was compared about its distance to the actual navigating distance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.627-635
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• 2014

Currently the highest speed limit on the road traffic congestion or because you can not cope with climate change to cause a traffic accident may be a factor. According to the Road Traffic Act as well as 20% to 50% in case of inclement weather, but the driver must slow speed left to the judgment of the difficulties, and to slow the vehicle and the relative velocity between the vehicle does not run longer be a big influence on the environment and safety. Thus, variable speed control for drivers on the road, specify the appropriate maximum speed limit in bad weather It keeps motorists slowed the run rate to prevent accidents or reduce the severity of accident damage is expected to be possible. The purpose of this study is the frequent traffic accidents Continuous Busan (City Freeway) around the variable speed control in the appropriate sections so that it can be done by analyzing the characteristics of traffic accidents were the severity of the accident. Highway and urban environment, the geometry of the structure because it has a lot of Curved planar point compared to wet and dry road surfaces by simulated rain wet had bom the more the speed the greater the risk of an accident was the result. Based on these results, the primary section, first urban highway tunnel, near the lamp, near Toll Plaza, near binary Outlet after considering various factors such as speed reduction is needed in the first period by conducting awareness and recognize the need for the participation of the driver and the future city installation and operation of highways in all sectors is expected to be expanded.

• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.1-8
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• 2006

Recently, many ships such as VLCCs, dangerous cargo ships, high speed ferry boats are visiting Yeosu, Gwangyang harbor. The traffic volume of the year 2003 has increased as many as 2.5 times of 1988. However there is no suitable ships' routeing system which takes account of today's traffic situations in this area This study aims at the settling of hazardous factors to mitigate the danger to vessels in Yeosu${\cdot}$Gwangyang bay and to secure the safety of maritime environment.