• International Journal of Highway Engineering
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• v.18 no.6
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• pp.153-160
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• 2016

OBJECTIVES : The objective of this study is to develop a traffic accident model of a roundabout based on the type of land use. METHODS : The traffic accident data from 2010 to 2014 were collected from the "traffic accident analysis system (TAAS)" data set of the Road Traffic Authority. A multiple linear regression model was utilized in this study to analyze the accidents based on the type of land use. Variables such as geometry and traffic volume were used to develop the accident models based on the type of land use. RESULTS : The main results are as follows. First, the null hypothesis that the type of land use does not affect the number of accidents is rejected. Second, four accident models based on the type of land use have been developed, which are statistically significant (high $R^2$ values). Finally, the total entering and circulating volumes, area of the central island, number of speed breakers, mean number of entry lanes, diameter of the inscribed circle, mean width of the entry lane, area of the roundabout, bus stops, and number of circulatory roadways are analyzed to see how they affect the accident for each type of land use. CONCLUSIONS : The development of the accident models based on the type of land use has revealed that the accident factors at a roundabout are different for each case. Thus, more speed breakers in commercial areas and an inscribed circle of proper diameter in commercial and residential areas are determined to be important for reducing the number of accidents. Additionally, expanding the width of the entry lanes, decreasing the area of the roundabouts in residential areas, and reducing the conflict factors such as bus stops in green spaces are determined to be important.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.115-123
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• 2011

This study was conducted to investigate the early-age behavior and performance of precast pavements constructed by replacing existing asphalt pavements for an intersection in urban bus only lanes. The monitoring items included level differences between asphalt pavement and precast panels at the beginning and ending locations of the precast pavement, level differences and joint widths between precast panels, precast panel settlement, and skid resistance of the panel surface. At a certain time after the construction, the diamond grinding method was applied and its effect was also investigated. The monitoring results showed that as time went by, the panel level, joint width, settlement, and skid resistance were not much varied. That implied the stable sustaining of external loads by the precast pavements. In addition, it was verified that employing diamond grinding could reduce the level differences between precast panels.

• International Journal of Highway Engineering
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• v.20 no.2
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• pp.75-85
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• 2018

PURPOSES : This study aimed to analyze traffic accidents at circular intersections, and discuss accident reduction strategies based on land use and vehicle type. METHODS : Traffic accident data from 2010 to 2014 were collected from the "traffic accident analysis system" (TAAS) data set of the Road Traffic Authority. To develop the accident rate model, a multiple linear regression model was used. Explanatory variables such as geometry and traffic volume were used to develop the models. RESULTS : The main results of the study are as follows. First, it was found that the null hypotheses that land use and vehicle type do not affect the accident rate should be rejected. Second, 16 accident rate models, which are statistically significant (with high $R^2$ values), were developed. Finally, the area of the central island, number of speed humps, entry lane width, circulatory roadway width, bus stops, and pedestrian crossings were analyzed to determine their effect on accidents according to the type of land use and vehicle. CONCLUSIONS : Through the developed accident rate models, it was revealed that the accident factors at circular intersections changed depending on land use and vehicle type. Thus, selecting the appropriate location of bus stops for trucks, widening entry lanes for cars, and installing splitter islands and optimal lighting for motorcycles were determined to be important for reducing the accident rate. Additionally, the evaluation showed that commercial and mixed land use had a weaker effect on accidents than residential land use.

• Journal of the Korean Society for Railway
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• v.16 no.2
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• pp.129-137
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• 2013

This study This study aims to identify sound developmental directions for transit-oriented development (TOD), which is a topic of interest in the field of urban development, and conducts an empirical analysis of station influence areas within Seoul according to the characteristics of transit types. The results suggest that there are differences among variables that influence demand for public transportation according to transit types. This means that it is necessary to identify improvement plans in developing public transport strategies for the capital region based on such differentiated influence factors and to build foundations to continue to increase demand for public transportation. Also, station influence areas should be developed into hubs by establishing appropriate bus-only lane networks as a supplementary means, rather than directly connecting subway stations with each other.

• Journal of the Korean Society of Safety
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• v.27 no.2
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• pp.111-116
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• 2012

This study deals with the traffic accidents of circular intersections in Korea. The purposes are to comparatively analyze the characteristics by operational type, and to develop the models using the data of 82 intersections. In pursuing the above, this study gives particular emphasis to modeling such the accidents as the roundabout and rotary in urban area. The main results analyzed are as follows. First, the null hypotheses that the number of accidents are the same in both the urban and rural intersections, and roundabout and rotary in urban area, were analyzed to be rejected. Second, 3 accident models were developed, which were all statistically significant. The independent variables used in the above models are the ADT, number of approach lane, bus stop, parking facilities, and others. This study could be expected to give some implications to the traffic safety policy decision-making.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.131-138
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• 2013

PURPOSES : The intents of the study are to identify the accident factors and to demonstrate the potentials of tobit model as a tool to study the number of accidents on arterial roads segments. METHODS : This paper uses a tobit regression as a methodology to analyze the factors affecting the number of accidents. In pursuing the above goal, this study gives particular attentions to analyzing the data of 2,446 accidents (1,610 in major arterial roads and 836 in minor arterial roads) occurred on arterial roads in 2007 to 2010. RESULTS : First, 3 accident models which were classified by total arterial roads, major arterial roads and minor arterial roads, and were all statistically significant were developed. Second, the exclusive right-turn lane as common variable, and the number of accident, traffic volume, number of lanes, link length, rate of median, number of entrances, number of pedestrian crossings, number of curves, number of bus stops and exclusive left-turn as specific variables of the models were selected. Finally, the paired sample t-test could not be rejected the null hypotheses of three types of models. CONCLUSIONS : Using data from vehicle accidents on arterial roads, the estimation results show that many factors related to roadway geometrics and traffic characteristics significantly affect to the number of accidents.

• International Journal of Automotive Technology
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• v.6 no.2
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• pp.141-148
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• 2005

In order to reduce the time and costs of improving the performance of vehicle suspensions, the techniques for optimizing damping and air spring characteristic were proposed. A full vehicle model for a bus is constructed with a car body, front and rear suspension linkages, air springs, dampers, tires, and a steering system. An air spring and a damper are modeled with nonlinear characteristics using experimental data and a curve fitting technique. The objective function for ride quality is WRMS (Weighted RMS) of the power spectral density of the vertical acceleration at the driver's seat, middle seat and rear seat. The objective function for handling performance is the RMS (Root Mean Squares) of the roll angle, roll rate, yaw rate, and lateral acceleration at the center of gravity of a body during a lane change. The design variables are determined by damping coefficients, damping exponents and curve fitting parameters of air spring characteristic curves. The Taguchi method is used in order to investigate sensitivity of design variables. Since ride and handling performances are mutually conflicting characteristics, the validity of the developed optimum design procedure is demonstrated by comparing the trends of ride and handling performance indices with respect to the ratio of weighting factors. The global criterion method is proposed to obtain the solution of multi-objective optimization problem.

• Journal of Korean Society of Transportation
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• v.32 no.4
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• pp.315-326
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• 2014

This paper analyzes and compares the pedestrian characteristics of 5 urban communities with 2012 Seoul floating population survey data. First of all, differences in total pedestrian volumes and time distribution of the volumes are compared across the 5 urban communities and the effects of pedestrian road properties are investigated. Then, we conduct a regression analysis to find factors influencing pedestrian volume according to the type of urban community and day of week. As results, the urban community had the greatest volume and the volume increased significantly at lunch time. Center bus lane, bus stop, and crosswalk lead to more trips in the urban community, while opposite patterns occurred in the other communities. Less slopes and commercial region areas caused more trips in all communities. Regression analysis results showed that a variety of variables including demographic indices, land use type and pedestrian road properties differently affect pedestrian volumes in individual urban communities. The research can be used as basic data to establish polices for pedestrian environment improvement.

• Journal of Korean Society of Transportation
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• v.27 no.3
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• pp.29-38
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• 2009

In Korea, large.scale housing complexes and residential areas began to appear in urban regions through urban plan projects from the 1970s. In addition, with the increase in the percentage of apartments in developed areas, road traffic noise at roadside apartments was raised as a new problem. Furthermore, since the late 1980s, apartments, which had been no taller than 15 stories, have grown higher to 20-30 stories and recently 40.story or higher apartments are being constructed, and as a result, residences are growing denser and road traffic noise is increasing in urban areas. Thus, the present study made a noise map using variables 'traffic volume' and 'mean spot speed' among factors influencing roadside apartments, and examined the noise reduction efficiency of the variables. According to the results, traffic volume and speed limit were found to have an effect on a limited space, and the median bus lane system was found to have a slight effect on the roadside.

• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.510-522
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• 2016

In studies involving public transport, social welfare improvement is simply explained by the increase in public transport demand. However, the increase in the demand for public transport is mostly observed by the change in the frequency of public transport service, and in-vehicle crowding in public transport has not been an object of concern. This study examines and tries to reveal the cause of the changes of the social welfare and in-vehicle crowding of the changing public transport from imposing congestion pricing. We observe that congestion pricing increases in-vehicle crowding in public transport. This predictable phenomenon is more exacerbated in case of not operating bus-only lane. It should be noted that in-vehicle crowding is more increased in suburban, but in First-best toll system it tends to get worse less than it in other congestion pricing systems. We identify that the change of in-vehicle crowding is affected by the change of proximity of the housing to workplace, the number of commuting trips, and unpredictable distortion effect of the congestion charge.