• International Journal of Highway Engineering
• /
• v.14 no.6
• /
• pp.183-190
• /
• 2012

PURPOSES : The fundamental diagram provides basic information necessary in the analysis of traffic flow and highway operation. When traffic flow is congested, the density-flow points in the fundamental diagram are widely scattered and move in a stochastic manner. This paper investigates the pattern of density-flow point transitions and identifies car-following behaviors underlying the density-flow transitions. METHODS : From a microscopic analysis of 722 fundamental diagrams of NGSIM data, a total of 20 transition patterns of fundamental diagrams are identified. Prominent features of the transition patterns are explained by the behavior of the leader and follower. RESULTS : It is found out that the average speed and the speed difference between the leader and the follower critically determine the density-flow transition pattern. The density-flow path is very sensitive to the values of vehicle speed and spacing especially at low speed and high density such that most fluctuations in the fundamental diagram in the congested regime is due to the noise of speed and spacing variations. CONCLUSIONS : The result of this study suggests that the average speed, the speed difference between the leader and the follower, and the random variations of speed and spacing are dominant factors that explain the transition patterns of a fundamental diagram.

• Journal of information and communication convergence engineering
• /
• v.8 no.6
• /
• pp.623-629
• /
• 2010

A geographical routing protocol is typically utilized for a route selection of VANET. Even if it is conceptually well adapted into VANET, message delivery tends to be unreliable with frequent network partitions, which mainly come from the inherent characteristics such as high mobility and irregular traffic density. In this paper, we deal with a method to enable reliable message delivery with reflecting the traffic density on routing decision. By concatenating the message delivery cost of each of inbetween junction section, $1^{st}$ and $2^{nd}$ shortest paths are initially determined. When it is not possible to deliver the message on a junction on the 1st path, we utilize two novel ideas, that is, letting the message stay on the junction to find out a new relay node, and putting a replicated copy to reach via a detour path. By using the NS-2 network simulator, our method has been examined in terms of message delivery rate and delay. It shows that our method is much efficient than the other method in the low density environment, while it brings similar results in the high density environment.

• The Korean Journal of Applied Statistics
• /
• v.23 no.6
• /
• pp.1179-1190
• /
• 2010

Management of the existing traffic network and understanding current traffic conditions is the most important and effective way to solve traffic congestion. This research investigates the status of Korea expressway through the Speed-Flow-Density diagram and finds the best suitable queueing model for each area. Dynamic structure in the queueing model enables us to reflect the structural change of the road in case of traffic congestion. To find the best model and estimate the parameters, we use the Newton-Raphson method. Finally, we examine the road efficiency in view of the optimal speed and density using the conditional distribution of speed and density of a S-F-D diagram.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.35 no.8
• /
• pp.101-109
• /
• 2019

Korea's transportation paradigm is shifting from a vehicle-oriented transportation plan to a pedestrian-friendly environment that emphasizes walking safety. However, the level of pedestrian traffic accidents in Korea is still high and serious. The purpose of this study is to investigate factors affecting the severity of pedestrians traffic accidents using the multilevel logistic regression model based on 2015-2017 pedestrian accidents data provided by the Traffic Accident Analysis System(TAAS). The main results of the multilevel logistic regression model showed that 89% of pedestrian traffic accidents in Seoul were explained by individual characteristics such as drivers and pedestrians, and 11% were explained by neighborhood environmental characteristics. The results are as follows : In the individual characteristics such as pedestrians and drivers, the older the pedestrians and the drivers, the higher the traffic accident severity. The severity of traffic accidents was high when the pedestrians were female and the drivers were male. In the case of accident types, traffic accidents were more serious in the cases of heavy vehicles, inclement weather, and occurring at intersections and crosswalks. The results of the neighborhood environmental characteristics are as follows. The intersection density and the crosswalk density tended to reduce the severity of traffic accidents. On the other hand, the traffic light density and the school zones were founded to related to the higher level of traffic accident severity. This study suggests that both individual and neighborhood environmental characteristics should be considered together to prevent and reduce the severity of pedestrian traffic accidents.

• Journal of Navigation and Port Research
• /
• v.29 no.4
• /
• pp.313-318
• /
• 2005

Usually marine traffic survey has been conducted by some methods like an ocular observation using portable RADAR, a questionnaire, etc. But these should have expended a lot of manpower and expenses. In this paper, we have developed new observation module which could capture the RADAR image using PC camera simply, and allowed as to track targets on the PC monitor directly. And it has been programmed to make a database of RADAR image, target's track and information, and analyze the marine traffic tendency in various ways like vessel number crossed over gate line, vessel's velocity distribution in gate line, traffic density distribution, etc. We have confirmed that this module could observe and analyze the marine traffic efficiently and economically through several on-the-spot experiments.

• International Journal of Highway Engineering
• /
• v.16 no.4
• /
• pp.119-126
• /
• 2014

PURPOSES: Used in transportation planning and traffic engineering, almost traffic simulation tools have input variable values optimized by overseas traffic flow attribution because they are almost developed in overseas country. Thus, model calibration appropriated for internal traffic flow attribution is needed to improve reliability of simulation method. METHODS : In this study, the traffic flow model calibration is based on expressways. For model calibration, it needs to define each expressway link according to attribution, thus it is classified by design speed, geometric conditions and number of lanes. And modified greenshield model is used as traffic flow model. RESULTS : The result of the traffic model calibration indicates that internal congested density is lower than overseas. And the result of analysis according to the link attribution indicates that the more design speed and number of lanes increase, the lower the minimum speed, the higher the congested density. CONCLUSIONS: In the traffic simulation tool developed in overseas, the traffic flow is different as design speed and number of lanes, but road segment don't affect traffic flow. Therefore, these results need to apply reasonably to internal traffic simulation method.

• Korean Journal of Environment and Ecology
• /
• v.28 no.5
• /
• pp.516-522
• /
• 2014

This study was conducted to investigate the impact of the anthropogenic factors affecting distribution of the Red-crowned Crane and White-naped Crane wintering in Cheorwon, Korea. Especially, it was investigated that the impact power and its range of the anthropogenic effect to the feeding flock density in cranes due to the paved road, residential area, military facilities and greenhouse density. The Red-crowned Crane and the White-naped Crane showed the similar preference and sensitivity against anthropogenic factors, because correlation of feeding flock density of the Red-crowned Crane and White-naped Crane was similar in the same site. The feeding flock density of the cranes near the residential area was lower than that of area far from the area, and tended to increase within 2.5 km distance. The increasing tendencies of feeding flock density from military facilities and high traffic volume road were similar, but the density in military facilities increased within 0.8 km, and the density from high traffic volume road increased within 2 km. This results suggested that military facilities and the road with high traffic volume made significant influence on foraging densities to the certain range. As the distance from the road with low traffic volume increased, feeding flock density tended to decrease. The area near the low traffic volume road had high feeding flock density because remaining rice grains were preserved by intermittent disturbances in that area. If the density of greenhouse is lower than $40/km^2$, feeding flock density in the low greenhouses density area was higher than high greenhouses density area. However, there was no difference in the feeding flock density if the density of the green houses is higher than $40/km^2$.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.2
• /
• pp.153-160
• /
• 2017

It may be reasonable to consider density per unit area over time rather than analyze traffic volume, which is simply the traffic volume per unit of time, in assessing the maritime traffic congestion of a certain area. This study contributes to the standardization of maritime traffic congestion assessment methods for the maritime traffic safety diagnosis institute while seeking a new method to minimize evaluation error due to converted traffic volume per ship tonnage level. To solve this problem, a method to evaluate maritime traffic congestion by comparing the area occupied by a vessel with the area of its route using vessel identification data from the Automatic Identification System (AIS) has been proposed. In this new model, it is possible to use actual data due to the development of information and communication technology, reducing conversion error while allowing for the evaluation of maritime traffic congestion by route.

• Journal of Korean Society of Transportation
• /
• v.29 no.6
• /
• pp.39-56
• /
• 2011

This study proposed a traffic accident prediction model developed based on administrative districts of Seoul. The model was to find the relationship between accident rates and the representative land usage of the districts (development density) - the higher the development density (building floor area) is, the higher the traffic accident rate is. The findings showed that traffic accident statistics differ from (1) residential building floor area, (2) commercial building floor area and (3) business building floor area.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.4D
• /
• pp.469-476
• /
• 2008

Recently, TOD gains popularity as a traffic solution measure of high density urban regeneration projects. The purpose of this study is to investigate traffic impacts of high density TOD projects, and to identify the issues to be resolved. For a case study, it chooses Gangnamgucheong station in Gangnam area served by two subway lines, and designates 400m radius from the station as a site for high-density development. The MOEs chosen for this study is traffic volume, time, distance, speed, and mode share. The SECOM model is adopted for traffic simulation. The analysis results show that high-density TOD is an effective tool for traffic improvement even with only one station area being implemented. It is found that the traffic volume increases near the station in nature where high-density development occurs, but it declines overall in the rest of Gangam area. The total travel time and distance of passenger vehicles decline, meaning that the traffic condition becomes better than before. With regulation on parking supply, the improvement becomes more vivid. In terms of the changes of traffic speed, both alternatives show 4.1% increase in speed, but the difference between alternatives is not quite noticeable because of the induced vehicle demand driven to the streets with improved traffic condition. The mode share changes occur for the benefit of subway ridership, because the study station is equipped with two subway line services. When mixed with parking supply restriction, the impact becomes clearer.