Jeong Y.,Korea Road Traffic Authority |
Kim Y.,University of Seoul
KSCE Journal of Civil Engineering | Year: 2014
This research proposes a new tram progression model, TRAMBAND, which is a passive tram signal priority strategy. TRAMBAND was formulated based on the MAXBAND model, which is a traditional arterial signal optimization model to maximize bandwidth. A tram that leaves a station during an appointed green time can arrive at subsequence station without experiencing intersection delays and stops by using the tram bandwidth. In order to guarantee a desired green time for other road users and minor streets, the TRAMBAND model determines the traffic signal timings for tram passive priority using only a left-turn phase sequence and offset. This strategy also maximizes the general vehicles bandwidth in the context of the fixed tram bandwidth in a median tram rail. The tram dwell-time and its variability influence the efficiency of the passive priority. In this study, the stop time at station is divided by the dwell-time and waiting time. The tram has to wait at station during the waiting time after the dwell-time; however, the waiting time is used as slack time to absorb the dwell-time variability and to maximize the general vehicle bandwidth. The case study is based on nine signalized intersections and a micro-simulator VISSIM, wherein it demonstrates that the proposed tram priority model, TRAMBAND, is capable of computing signal timings so as to avoid intersection delays and stops of tram and maintain the general vehicle bandwidth. © 2014 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.
Kim K.S.,Sungkyunkwan University |
Myeong M.H.,Korea Road Traffic Authority
Accident Analysis and Prevention | Year: 2011
Upon conviction for particular traffic offenses, drivers can have their licenses revoked. Drivers who receive license revocation have an opportunity to apply for a sentence reduction, and some of those who apply receive a reduced sanction - license suspension. There may be differences between drivers whose license was revoked as originally sentenced and drivers who received the reduced sanction of license suspension with regard to traffic violations and crashes after driving privileges are restored. This study verified the differences during the follow-up periods of 6, 12, and 18 months using analysis of covariance and the t-test with stratified samples based on the police profiles of approximately 154,000 drivers in South Korea. The study found that drivers in the group whose license had been suspended committed traffic violations and caused traffic crashes less often for all time periods than those whose license had been revoked. However, omitted factors such as the attitude of suspended drivers and exposure to traffic violations and crashes (e.g.; driving frequency after license reinstatement), are likely to affect the findings; thus, caution should be exercised when the findings are referenced for policy implications. © 2010 Elsevier Ltd All rights reserved.
Ahn G.-H.,Korea Road Traffic Authority |
Ki Y.-K.,Korea Road Traffic Authority |
Kim E.-J.,Korea Road Traffic Authority
IET Intelligent Transport Systems | Year: 2014
Travel speed is an important parameter for measuring road traffic. urban traffic information system (UTIS) was developed as a mobile detector for measuring link travel speeds in South Korea. However, UTIS incur errors, such as those caused by irregular vehicle trajectories and communication delays. This study describes an algorithm developed for estimating reliable and accurate average roadway link travel speeds using UTIS data. The algorithm estimates link travel times using a robust data-filtering procedure to identify valid observations within a sampling interval using a varying data validity window. The size of the data validity window varies as a function of the standard deviation of observations in previous intervals. A field test showed that the variance of the percent errors of link travel times was reduced when measured using the new model. Therefore it can be concluded that the proposed model significantly improves travel speed measuring accuracy. © The Institution of Engineering and Technology 2014.