• Journal of Korean Society of Transportation
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• v.29 no.6
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• pp.107-116
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• 2011

In this paper, we implement an algorithm of transit signal priority control that not only maximizes service quality and efficiency of bus, but also minimizes the control delay of passenger cars using UTIS currently being deployed and operated in Seoul national capital area. For this purpose, we propose an algorithm that coordinates the strength of TSP by estimating bus demand. Typically, the higher the strength of TSP is on main street, the bigger the control delay is on the cross street. Motivated by this practical difficulty, we proposes an algorithm that coordinates TSP's strength by checking the degree of saturation of cross street. Also, we verify the possibility of field implementation via simulation analysis using CORSIM RTE based HILS (Hardware In the Loop Simulation). The result shows that travel time of bus improves about 10 percent without increasing control delay of passenger cars by TSP. We expect the result of this research to contribute to increasing the overall transit ridership in this country.

• Journal of Korean Society of Transportation
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• v.31 no.6
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• pp.67-89
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• 2013

This study is to perform empirical analysis on observational before-after studies in Naive Method, Comparison Group(CG) Method and Empirical Bayes(EB) Method, and to compare with their results and to propose ways to apply to evaluation researches. For this purpose, the evaluation of road safety audit executed on Y$\breve{o}$ng-dong freeway in 2005 and 2006 was performed. As a result, all three methods have showed improved effects due to safety treatments. The safety effectiveness of Naive method is the largest, CG Method is the second and EB method is the last. The results of Naive method are overestimated due to the trend of reducing traffic accidents and those of CG method are affected by the external casual effects of comparison group. In the EB method, as "regression to the mean" phenomenon are controlled by reference group's accident model, it's result is relatively more accurate than that of other methods. In the conduct of evaluation studies, the analysts have to understand the pros and cons of each evaluation method. And after leading the survey on accident trends of related all sites, evaluation analysis is performed to be able to minimize bias.

• Journal of Korean Society of Transportation
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• v.36 no.1
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• pp.23-37
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• 2018

In recent years, it is very difficult to construct and expand new infrastructures in a city center because of long-term low growth and lack of space due to urban overcrowding. So, there is a need to study a variety of Retrofitting techniques and urban applications that can lead to sustainable development while efficiently utilizing existing facilities. 'Retrofit' means a sustainable urban retrofitting as a directed alteration of the structures, formations and systems of existing facilities to improve energy, water and waste efficiencies. In this study, we applied a hierarchical network design technique that can reflect the structural hierarchy of a city to study how to retrofit public transportation routes in Seoul. The hierarchical network design means dividing the hierarchy according to the functions of hubs and connecting different hierarchies to form a hierarchical network. As a result of comparing the application results of various retrofitting scenarios of public transport, the differences of daily PKT and PHT by about 2.6~3.2% less than before the improvement address that the convenience of passengers is increased. Therefore, it is expected that if the route planning is established according to the proposed method, it will increase the number of passengers and the operational efficiency by the improved convenience of public transit passengers.

• Journal of Korean Society of Transportation
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• v.33 no.6
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• pp.554-563
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• 2015

This study dealt with developing an accident model for rural signalized intersections with random parameter negative binomial method. The limitation of previous count models(especially, Poisson/Negative Binomial model) is not to explain the integrated variations in terms of time and the distinctive characters a specific point/segment has. This drawback of the traditional count models results in the underestimation of the standard error(t-value inflation) of the derived coefficient and finally affects the low-reliability of the whole model. To solve this problem, this study improves the limitation of traditional count models by suggesting the use of random parameter which takes account of heterogeneity of each point/segment. Through the analyses, it was found that the increase of traffic flow and pedestrian facilities on minor streets had positive effects on the increase of traffic accidents. Left turning lanes and median on major streets reduced the number of accidents. The analysis results show that the random parameter modeling is an effective method for investigating the influence on traffic accident from road geometries. However, this study could not analyze the effects of sequential changes of driving conditions including geometries and safety facilities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.1
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• pp.81-90
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• 2018

The purpose of this study is to evaluate the effect of downward speed limit of urban arterial roads at 29 sites in Busan Metropolitan Police Agency to reduce road traffic accidents from '10 to '15. As a result of analyzing the traffic accidents occurred for 1~3 years after the decrease in the speed limit, the number of traffic accidents decreased by 3.09% and the number of injured persons decreased by 8.76%, but the number of deaths decreased by 36.73% The results of this study are as follows. The average speed reduction rate of 6.31km/h was decreased by investigating the change of the vehicle speed before and after the downward speed limit, and the change of average speed was statistically significant in most of the sections. The rate of compliance with the speed limit increased by 10.26% p, which is considered to have greatly improved overall traffic safety. A survey conducted by residents near the target area with a lower speed limit showed that 57.9% of the respondents felt the driving speed of the vehicle was lowered. However, this project was focused on vehicles with limited speed road signs and traffic safety signs, Only 25.8% of respondents said walking safety was improved. In the future, it is necessary to consider the safety of pedestrians by improving roads around roads such as road curvature and separation. In addition, there is a clear positive result in terms of decreasing the fatal accidents in the downward speed limit zone of Busan Metropolitan Subway. However, more detailed analysis is needed for the 29 accidents. Therefore, it is expected that traffic practitioners will be able to utilize it as a basis to increase the accident reduction effect by setting an appropriate speed limit based on the easy and objective grounds.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.2
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• pp.1-17
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• 2018

The living lab is a user-participatory innovation space where users can solve problems by themselves. Living Lab members are able to participate in all aspects of product development from technology conception. In this study, to prevent pedestrian accidents, auto-image sensing signal system was developed in Jeonju City, using the Living Lab method. In addition, we measured effectiveness of the auto-image sensing signal system with respect to pedestrian waiting time, pedestrian and driver signal violation, and pedestrian jaywalking. It was also compared the measures before installation, after installation and after applying Living Lab method. As a result, all of the three measures of effectiveness appeared to be more effective after Living Lab than after installation. Overall, this study is very significant in that it is the first case where the living lab is applied in transportation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.57-66
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• 2012

This study intended to evaluate the operational performance change from the introduction of the bus signal priority system using the field data. To complete the objective, travel time and volume data were collected from the before and after study, then the distribution of individual vehicle's travel time and the difference of travel time and traffic volume were compared respectively. Analysis results showed that no significant volume change was observed from both passenger vehicle and bus for the major and cross streets. It was identified that the quality of travel time distributions of passenger vehicle and bus was improved after introducing the bus signal priority system. In terms of average speed, passenger car in a major direction increased by 6.5% and bus increased by 10.5% in general. Statistical tests showed that those speed differences were statistically significant at the 95% of confidence level. The results of this paper will be a good source for further research in the area of bus signal priority control.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.125-132
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• 2017

The development project of Busan New Port aims to be Logistics Hub Port but there are too many things to deal with ; enlargement of harbour, interport competition, modernization of harbour loading equipment and so on. At present, 23 berths of North and South container quay are in operation and 22 berths will be constructed on west and south-side by 2020. Namely, Busan New Port will operate 45 berths in 2020. When it comes to port distripark, a large-scale of Port distripark project is underway, such as Ung-Dong district 1,2 phase, West container 1,2phase, North distripark and so on. This study is to deduce traffic system problem of Busan New Port which is caused by the development project through predicting traffic need considering the development project. According to study, there are three main problems of traffic system : 1. traffic congestion caused on main crossroad, connecting second harbour back road. 2. It has been predicted that South-North road and traffic capacity of New Port road would lack compared to traffic volume-to-be-increased. Moreover, the detour volume of traffic is caused because New Port's 1st avenue and route 2 were not connected directly. Thus, this study suggests three kinds of improvement plan for smoother traffic flow. 1st. Operate roundabout on major intersection, for example, second harbour back road, west container wharf's subway corridors(South to North), and permit only right turn on sub-intersection. 2nd. Extend New Port road(North container's port road) by utilizing side walk and median. 3rd. Install exit ramp which utilizes Route 2 connecting New Port's 1st avenue and local road 1042. The method we used to analyze the effect of improvement is Vissim of Mircro Simulation Package.

• Journal of Korean Society of Transportation
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• v.30 no.1
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• pp.103-112
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• 2012

This research introduces a trip generation model reflecting time-series effects derived from a panel analysis with the data collected from the national household trip surveys conducted in 1996, 2002 and 2006. The existing methods are unable to reflect time-series effects from the change of socioeconomic conditions because the parameters applied to the model were basically from the base year of study - the parameter values were unchanged. This study proposes a new trip generation model developed through a panel analysis performed with the data collected from the last three national household trip surveys. From the results, it was found that the number of school trips increases and that the number of shopping trips decreases as time passes. The results showed that there are time-series effects affecting in trip generation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.3
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• pp.20-33
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• 2021

Modern society is steadily implementing policies to encourage public transportation to cope with the growing traffic demand on limited roads. The expectation is rising for transit signal priority to ensure the speed of buses as the installation of the bus rapid transit(BRT) expands nationwide to secure the competitiveness of buses. On the other hand, the form of BRT stops without considering some aspects of bus operation may increase the number of stops on the bus, thereby reducing the effectiveness of bus signal priority applications. This study suggests the type of bus stop to increase the operation efficiency of buses by analyzing the bus signal priority effect according to the BRT station type using Hannuri-daero, Sejong. The bus signal priority is used to maximize the two-way bandwidth of passenger cars and buses. As a result of the application, the effectiveness of the bus signal priority at the stop causing the double stop of the bus was reduced drastically, and the efficiency of the bus signal priority was increased significantly after improvement. These results are expected to be used as basic data in the form of proper bus stops considering the aspects of traffic operation when designing BRT stops in new towns in the future.