Chung Y.,Korea Transport Institute
Accident Analysis and Prevention | Year: 2010
Since duration prediction is one of the most important steps in an accident management process, there have been several approaches developed for modeling accident duration. This paper presents a model for the purpose of accident duration prediction based on accurately recorded and large accident dataset from the Korean Freeway Systems. To develop the duration prediction model, this study utilizes the log-logistic accelerated failure time (AFT) metric model and a 2-year accident duration dataset from 2006 to 2007. Specifically, the 2006 dataset is utilized to develop the prediction model and then, the 2007 dataset was employed to test the temporal transferability of the 2006 model. Although the duration prediction model has limitations such as large prediction error due to the individual differences of the accident treatment teams in terms of clearing similar accidents, the results from the 2006 model yielded a reasonable prediction based on the mean absolute percentage error (MAPE) scale. Additionally, the results of the statistical test for temporal transferability indicated that the estimated parameters in the duration prediction model are stable over time. Thus, this temporal stability suggests that the model may have potential to be used as a basis for making rational diversion and dispatching decisions in the event of an accident. Ultimately, such information will beneficially help in mitigating traffic congestion due to accidents. © 2009 Elsevier Ltd. All rights reserved.
Jang W.,Korea Transport Institute
Transportation Research Record | Year: 2010
Automatic fare collection systems using smart card technology have become popular because they provide an efficient and cost-saving alternative to the manual fare collection method. In 2004, the City of Seoul, South Korea, introduced a smart card-based transit fare scheme, which was a distance-based, integrated fare collection and calculation system. Over the years, the system was extended twice and now can provide detailed information about public transit use in the region. This information includes each trip's boarding and alighting times and locations, as well as the connected trip chains with transfers. This paper examines possibilities for using such data for transportation planning application. First, a process to generate a travel time map is presented. For this, more than 100 million trip data are used to estimate travel times among stops. It is also demonstrated that transfer data can be readily obtainable because the on- and off-boarding information reside in the data set. Although transfers are considered to be important information for public transit planning, it has not been easy to collect such information. This study illustrates that transfer data can be used to locate the critical transfer points that need improvement. It is also demonstrated that a simple data query can quickly identify these locations. In addition, transfer trip patterns between two zones are analyzed, which provides meaningful information about passengers' transfer location choice.
Chung Y.,Korea Transport Institute |
Yoon B.-J.,Incheon National University
KSCE Journal of Civil Engineering | Year: 2012
Data on the duration of traffic accidents have been collected by using a manual recoding method based on the statement of freeway patrol officers or eyewitness. Accordingly, the data may include cost and safety problems due to the difficulty of observing an accident from its occurrence to its clearance. To reduce these problems, this study proposes an analytical method to estimate accident duration based on the archived speed profile. The proposed method is demonstrated by a case study using data on approximately 6,200 accidents that occurred on freeways in Orange County, California, in 2001. In addition, a statistical analysis based on the Accelerated Failure Time (AFT) metric survival models was performed to identify the relationship between estimated accident duration and its causal factors. The analysis results were consistent with the theoretical expectation and prior studies. Ultimately, the proposed method will contribute to reducing observation burdens when collecting data on accident duration. © 2012 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.
Chung Y.,Korea Transport Institute
Transportation Research Record | Year: 2011
The objectives of this study are twofold: to quantify nonrecurrent congestion delay caused by traffic accidents that occur on freeways and to analyze the causal factors by different types of accidents. Unlike previous studies, this study proposes an analytical procedure to estimate congestion impact by using the difference between speed reduced by a traffic accident and accident-free normal flow speed. The proposed method is demonstrated by a case study using accident data derived from 27 freeways in South Korea in 2008. Ultimately, the method can develop a performance measure for evaluating transportation policies and planning level analyses associated with the design of transportation systems and preparation of operating plans for safety, as well as for quantitatively evaluating deployed transportation projects or technologies. Moreover, the results from statistical analyses can potentially be useful in making strategic plans and formulating mitigation measures for reducing nonrecurrent congestion delay caused by accidents on the South Korean freeway system.
Han S.,Korea Transport Institute
International Journal of Injury Control and Safety Promotion | Year: 2016
Road infrastructures are usually developed and maintained by governments or public sectors. There is no competitor in the market of their jurisdiction. This monopolic feature discourages road authorities from improving the level of safety with proactive motivation. This study suggests how to apply a principle of competition for roads, in particular by means of performance evaluation. It first discusses why road infrastructure has been slow in safety oriented development and management in respect of its business model. Then it suggests some practical ways of how to promote road safety between road authorities, particularly by evaluating safety performance of road infrastructure. These are summarized as decision of safety performance indicators, classification of spatial boundaries, data collection, evaluation, and reporting. Some consideration points are also discussed to make safety performance evaluation on road infrastructure lead to better road safety management. © 2014 Taylor & Francis.