The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Gang-len Chang - One of the best experts on this subject based on the ideXlab platform.
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An Integrated Control Algorithm of the Advanced Merge and Speed Limit Strategies at Highway Work Zones
2020Co-Authors: Kyeong-pyo Kang, Gang-len ChangAbstract:Despite the potential effectiveness of the DLM (Dynamic Late Merge) control, its independent system without the VSL (Variable Speed Limit) control may bring about significant speed variation because of the frequently changing merge strategies under time-varying traffic conditions. Thus, to facilitate the merging maneuvers and minimize potential collisions during the DLM operation, this study has developed a system control process that can integrate the VSL with the DLM so as to maximize the total effectiveness of the Highway Work-zone operation. The proposed integrated control process has used the optimal VSL control model as a supplementary strategy of the entire DLM operation, and coordinated the sequence of variable message sign (VMS) messages generated from the DLM and VSL algorithms. From the simulation experiment, the integrated algorithm of the DLM and VSL controls has shown to respond well to time-varying traffic conditions and yielded more Work-zone throughputs than the DLM control without VSL. It has also demonstrated that the integrated control results in an increase in the average speed and a decrease in the speed variation. In particular, the VSL effect is evident as a supplementary role for the dynamic merge control under the fluctuating traffic demand patterns.
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Dynamic Late Merge Control at Highway Work Zones: Evaluation, Observations, and Suggestions
2020Co-Authors: Kyeong-pyo Kang, Gang-len ChangAbstract:The objective of this study is to evaluate the performance of a dynamic late merge (DLM) system for Highway Work-zone operations, tested by Maryland State Highway Administration. The evaluation is focused on both the operational efficiency such as the Work-zone throughputs, and the resulting safety impacts on the upstream segment of the Work zone. The evaluation results reveal that the deployed DLM system can indeed outperform the conventional merge control regarding an increase in the total Work-zone throughputs, but such a system may result in excessive traffic conflicts if not properly integrated with existing static warning signs for Work-zone operations. Some suggestions and guidelines developed from the field observations and analysis results for the DLM performance improvement are also presented in this study.
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dynamic late merge control at Highway Work zones evaluations observations and suggestions
Transportation Research Record, 2006Co-Authors: Kyeong-pyo Kang, Gang-len Chang, Jawad ParachaAbstract:The purpose of this study is to present the evaluation result of a dynamic late merge (DLM) system for Highway Work zone operations, experimented by the Maryland State Highway Administration and International Road Dynamics Inc. The evaluation focuses mainly on the operational efficiency such as the input-output analysis, Work zone throughput, volume distribution, and resulting queue length. Evaluation results reveal that a properly deployed DLM system can indeed outperform the conventional merge control with respect to the total Work zone throughputs. Such a system, however, may result in excessive traffic conflicts if not properly integrated with existing static warning signs for Work zone operations. Some suggestions and guidelines developed from field observations and analysis results for potential improvement of the DLM performance are also presented in this paper.
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A robust model for optimal time-of-day speed control at Highway Work zones
IEEE Transactions on Intelligent Transportation Systems, 2006Co-Authors: Kyeong-pyo Kang, Gang-len ChangAbstract:This paper proposes a new speed control strategy, named time-of-day speed limit (TOD SL) control, for Highway Work-zone operations. The main purposes of the TOD SL control are to overcome the difficulty in setting the optimal real-time speed limit due to the lack of detectors and to maximize the use of available data such as the historical volume data on the target Work zone. Its core logic is to divide the entire day of operations into a number of control periods and to accommodate the time-varying traffic conditions within each control period. The measure of effectiveness (MOE) selected in the TOD SL model takes into account both the operational efficiency and traffic safety. To encompass all possible traffic conditions during each control period, the control model employs traffic flow relations calibrated from historical data to estimate the speed and density data with available volume under possible traffic scenarios. The performance of the proposed TOD SL control has been evaluated with the simulation experiments and compared with the other speed control strategies based on the selected measures of effectiveness
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a robust model for optimal time of day speed control at Highway Work zones
12th World Congress on Intelligent Transport SystemsITS AmericaITS JapanERTICO, 2005Co-Authors: Kyeong-pyo Kang, Gang-len ChangAbstract:This paper proposes a new speed control strategy, called time-of-day speed limit (TOD SL) control, for Highway Work-zone operations. The main motivations of the TOD SL control are to overcome the difficulty in setting the optimal real-time speed limit due to the lack of detectors, and maximize the use of limited available data such as the historical volume data on the target Work zone. Thus, the core logics of TOD SL control are to divide the entire day of operations into a number of control periods and accommodate the time-varying traffic conditions within each control period. The measure of effectiveness (MOE) selected in the TOD SL model takes into account both the operational efficiency and traffic safety to produce the optimal speed limits during each time-of-day control period. To cover all possible traffic conditions during each control period, the control model employs precalibrated traffic flow models to estimate the speed and density data with available volume data, and design possible traffic scenarios. The performance of the proposed TOD SL control has been evaluated with the simulation experiments, and compared with the other speed control strategies based on the critical measures of effectiveness.
Kyeong-pyo Kang - One of the best experts on this subject based on the ideXlab platform.
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An Integrated Control Algorithm of the Advanced Merge and Speed Limit Strategies at Highway Work Zones
2020Co-Authors: Kyeong-pyo Kang, Gang-len ChangAbstract:Despite the potential effectiveness of the DLM (Dynamic Late Merge) control, its independent system without the VSL (Variable Speed Limit) control may bring about significant speed variation because of the frequently changing merge strategies under time-varying traffic conditions. Thus, to facilitate the merging maneuvers and minimize potential collisions during the DLM operation, this study has developed a system control process that can integrate the VSL with the DLM so as to maximize the total effectiveness of the Highway Work-zone operation. The proposed integrated control process has used the optimal VSL control model as a supplementary strategy of the entire DLM operation, and coordinated the sequence of variable message sign (VMS) messages generated from the DLM and VSL algorithms. From the simulation experiment, the integrated algorithm of the DLM and VSL controls has shown to respond well to time-varying traffic conditions and yielded more Work-zone throughputs than the DLM control without VSL. It has also demonstrated that the integrated control results in an increase in the average speed and a decrease in the speed variation. In particular, the VSL effect is evident as a supplementary role for the dynamic merge control under the fluctuating traffic demand patterns.
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Dynamic Late Merge Control at Highway Work Zones: Evaluation, Observations, and Suggestions
2020Co-Authors: Kyeong-pyo Kang, Gang-len ChangAbstract:The objective of this study is to evaluate the performance of a dynamic late merge (DLM) system for Highway Work-zone operations, tested by Maryland State Highway Administration. The evaluation is focused on both the operational efficiency such as the Work-zone throughputs, and the resulting safety impacts on the upstream segment of the Work zone. The evaluation results reveal that the deployed DLM system can indeed outperform the conventional merge control regarding an increase in the total Work-zone throughputs, but such a system may result in excessive traffic conflicts if not properly integrated with existing static warning signs for Work-zone operations. Some suggestions and guidelines developed from the field observations and analysis results for the DLM performance improvement are also presented in this study.
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dynamic late merge control at Highway Work zones evaluations observations and suggestions
Transportation Research Record, 2006Co-Authors: Kyeong-pyo Kang, Gang-len Chang, Jawad ParachaAbstract:The purpose of this study is to present the evaluation result of a dynamic late merge (DLM) system for Highway Work zone operations, experimented by the Maryland State Highway Administration and International Road Dynamics Inc. The evaluation focuses mainly on the operational efficiency such as the input-output analysis, Work zone throughput, volume distribution, and resulting queue length. Evaluation results reveal that a properly deployed DLM system can indeed outperform the conventional merge control with respect to the total Work zone throughputs. Such a system, however, may result in excessive traffic conflicts if not properly integrated with existing static warning signs for Work zone operations. Some suggestions and guidelines developed from field observations and analysis results for potential improvement of the DLM performance are also presented in this paper.
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A robust model for optimal time-of-day speed control at Highway Work zones
IEEE Transactions on Intelligent Transportation Systems, 2006Co-Authors: Kyeong-pyo Kang, Gang-len ChangAbstract:This paper proposes a new speed control strategy, named time-of-day speed limit (TOD SL) control, for Highway Work-zone operations. The main purposes of the TOD SL control are to overcome the difficulty in setting the optimal real-time speed limit due to the lack of detectors and to maximize the use of available data such as the historical volume data on the target Work zone. Its core logic is to divide the entire day of operations into a number of control periods and to accommodate the time-varying traffic conditions within each control period. The measure of effectiveness (MOE) selected in the TOD SL model takes into account both the operational efficiency and traffic safety. To encompass all possible traffic conditions during each control period, the control model employs traffic flow relations calibrated from historical data to estimate the speed and density data with available volume under possible traffic scenarios. The performance of the proposed TOD SL control has been evaluated with the simulation experiments and compared with the other speed control strategies based on the selected measures of effectiveness
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a robust model for optimal time of day speed control at Highway Work zones
12th World Congress on Intelligent Transport SystemsITS AmericaITS JapanERTICO, 2005Co-Authors: Kyeong-pyo Kang, Gang-len ChangAbstract:This paper proposes a new speed control strategy, called time-of-day speed limit (TOD SL) control, for Highway Work-zone operations. The main motivations of the TOD SL control are to overcome the difficulty in setting the optimal real-time speed limit due to the lack of detectors, and maximize the use of limited available data such as the historical volume data on the target Work zone. Thus, the core logics of TOD SL control are to divide the entire day of operations into a number of control periods and accommodate the time-varying traffic conditions within each control period. The measure of effectiveness (MOE) selected in the TOD SL model takes into account both the operational efficiency and traffic safety to produce the optimal speed limits during each time-of-day control period. To cover all possible traffic conditions during each control period, the control model employs precalibrated traffic flow models to estimate the speed and density data with available volume data, and design possible traffic scenarios. The performance of the proposed TOD SL control has been evaluated with the simulation experiments, and compared with the other speed control strategies based on the critical measures of effectiveness.
Yingfeng Li - One of the best experts on this subject based on the ideXlab platform.
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Determining the Effectiveness of Temporary Traffic Control Measures in Highway Work Zones
2020Co-Authors: Yingfeng LiAbstract:Highway Work zones constitute a major safety concern for government agencies, legislatures, the Highway industry, and the traveling public. Each year, hundreds of people lose their lives and many more are injured due to vehicle crashes in Work zones on the national Highway system. Over the years, temporary traffic control (TCC) measures have been developed to improve the safety in Work zones. To improve the safety countermeasures and to identify the traffic control deficiencies in Work zones, evaluating the effectiveness of existing TTC measures based on the real crash experience is necessary. In the present study, researchers evaluated the effectiveness of several commonly used TTC methods using logistic regression technique and various chi-square statistics. The assessed TTC methods included flagger/officer, stop sign/signal, flasher, no passing zone control, and pavement center/edge lines. A total of 655 severe crashes in Kansas Highway Work zones between January 2003 and December 2004 were used for the evaluation, which included 29 fatal crashes and 626 injury crashes. The results indicated that flagger, flasher, and pavement center/edge lines were effective in reducing the probability that Work zone crashes would involve fatalities. In addition, the effectiveness of these devices in preventing some common human errors, such as “disregarded traffic control,” “inattentive driving,” “followed too closely,” and “exceeded speed limit or too fast for condition,” from causing severe crashes was also determined.
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Investigating the Human Factors Involved in Severe Crashes in Highway Work Zones
2020Co-Authors: Yingfeng LiAbstract:Highway Work zones create an inevitable disruption in regular traffic flows and result in traffic crashes with injuries or fatalities. In many of these crashes, driver errors have been reported as the most significant causal factors. Understanding the role of human factors in these Work zone crashes and then lowering the probability that they will cause crashes is critical for improving safety in Highway Work zones. In this study, the role of human factors in severe Work zone crashes involving fatalities or injuries was investigated. The objectives of the research were as follows: (1) to explore the influence of human factors on the occurrences and characteristics of fatal and injury Work zone crashes and (2) to investigate the effectiveness of Work zone temporary traffic control (TTC) devices in preventing human errors from causing severe crashes in Work zones. The severe crashes that occurred in Kansas Highway Work zones during 1992 and 2004 were studied in detail. Statistical techniques such as Pearson chi-square, likelihood ratio chi-square, and logistic regression were utilized in the investigation. Through the systematic study, the researchers discovered the major impacts of several common driver errors on severe Work zone crashes; the researchers also evaluated the effectiveness of some TTC methods in reducing these driver errors in Highway Work zones. The results of this study can provide knowledge that can facilitate the development of effective countermeasures for eliminating risky driver errors, ultimately in order to improve safety level in Work zones.
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Determining the drivers’ acceptance of EFTCD in Highway Work zones
Accident Analysis & Prevention, 2010Co-Authors: Yingfeng LiAbstract:Traffic safety is a major concern in the temporary one-lane, two-way Highway Work zones due to the increasing of construction and maintenance operations. To prevent rear-end crashes and to mitigate the severity of these crashes caused by the inattentive driving, the utilization of the Emergency Flasher Traffic Control Device (EFTCD) was under consideration by government agencies, in addition to existing temporary traffic control devices installed in the one-lane, two-way Highway Work zones. The EFTCD was a newly proposed traffic warning device implemented through the use of vehicles' hazard warning flashers. The primary objective of the research project was to investigate the drivers' acceptance of the proposed EFTCD by measuring the mean speed changes of vehicles with and without EFTCD and by evaluating the drivers' opinions of the EFTCD using the survey method. Field experimental results revealed that the EFTCD effectively reduced the mean vehicle speeds in the upstream of two Work zones. A slow speed is more likely to reduce the severity of a crash in Work zones. In addition, survey results indicated that 60% of the drivers thought the EFTCD signified a need for speed reduction and 82% of drivers recommended the implementation of the EFTCD in one-lane, two-way Work zones. These results provide the necessary scientific justifications for the government agencies to decide if the EFTCD should be implemented in the one-lane, two-way Highway Work zones to prevent rear-end crashes and to mitigate the severity of these crashes. Language: en
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Highway Work zone risk factors and their impact on crash severity
Journal of Transportation Engineering-asce, 2009Co-Authors: Yingfeng LiAbstract:Numerous factors may contribute to high-severity crashes in Highway Work zones. Identifying these factors and then alleviating their impact is a challenging task that traffic engineers and researchers have to confront. In this study, the Work zone risk factors that could increase the probability of causing fatalities when severe crashes occur were examined using a comprehensive approach. The researchers first identified the significant risk factors based on a screening process that incorporates both statistical analyses and empirical research findings. They then systematically investigated these factors using logistic regression and frequency analysis techniques. The severe crashes including the fatal crashes between 1998 and 2004 and injury crashes between 2003 and 2004 in Kansas Highway Work zones were used in the study. The assessed risk factors included variables describing driver characteristics, environmental conditions, crash road conditions, and other crash information. The results of this study will help traffic engineers to understand these risk factors and how the factors could increase the likelihood of having fatalities when a severe crash occurs in a Work zone. Consequently, effective safety countermeasures may be designed at the Work zone planning and installation stages to prevent safety deficiencies.
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effectiveness of temporary traffic control measures in Highway Work zones
Safety Science, 2009Co-Authors: Yingfeng LiAbstract:In the United States, hundreds of people lose their lives each year and many more are injured due to vehicle crashes in the Work zones. Over the years, temporary traffic control (TCC) measures have been developed and deployed in Work zones. To continuously improve the safety, there is a need to identify the traffic control deficiencies in Work zones by evaluating the effectiveness of existing TTC measures based on the real crash cases. In this study, researchers evaluated the effectiveness of several commonly used TTC methods using logistic regression techniques and various significance test methods including likelihood ratio test, score test, and Wald test. These TTC methods included flagger/officer, stop sign/signal, flasher, no passing zone control, and pavement center/edge lines. A total of 655 severe crashes in Kansas Highway Work zones between January 2003 and December 2004 were used for the evaluation, which included 29 fatal crashes and 626 injury crashes. Results indicated that flagger, flasher, and pavement center/edge lines were effective in reducing the probability of causing fatalities when severe crashes occurred. In addition, using these devices could prevent some common human errors, such as "disregarded traffic control", "inattentive driving", "followed too closely", and "exceeded speed limit or too fast for condition", from causing severe crashes. Language: en
Zongzhi Li - One of the best experts on this subject based on the ideXlab platform.
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Highway Work zone safety audits for safety improvements
Engineering Construction and Architectural Management, 2010Co-Authors: Zongzhi LiAbstract:Purpose – The paper aims to review current practices of road safety audits worldwide, investigate the perceptions of experts on Highway Work zone safety in the USA and issues of adopting Work zone safety audits in the country, and propose a frameWork for developing guidelines for implementing Work zone safety audits for safety improvements.Design/methodology/approach – The paper was conducted by reviewing the existing literature of road safety audits and administering four‐week questionnaire surveys of experts on Highway Work zone safety in the USA.Findings – Road safety audits have been successfully adopted worldwide to maximize safety of the roadway environment for Highway users. The questionnaire surveys have clarified leading causes of Work zone safety problems and effective countermeasures, types of projects suitable for auditing and audit frequencies, audit team composition and funding sources, audit tasks and tools, and project staff safety training audits. A similar procedure for road safety audit...
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Highway Work Zone Safety Audits at the Construction Stage
2009Co-Authors: Jonathan Shi, Zongzhi Li, Mark SnyderAbstract:The nation’s Highways are in need of extensive maintenance and reconstruction Work. High traffic demand requires state and local transportation agencies to consider practical strategies for minimizing a Work zone’s impacts on the traveling public and construction Workers. Work zone safety audit is a proactive tool to serve the purpose. This paper presents the guidelines for Highway Work zone safety audits at the construction stage. After a brief description of the key features of Work zone safety audit, an eight-step audit process is presented. Then, the article focuses on the five key audit tasks which are performed in the audit process including pre-audit reviews, audit meetings, audit field inspections, audit analyses and audit recommendations. Finally, a case study is introduced to show the proposed guidelines.
Sundaresan A Krishnamurthy - One of the best experts on this subject based on the ideXlab platform.
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STEADY-BURN LIGHTS IN Highway Work ZONES: FURTHER RESULTS OF STUDY IN OHIO
Transportation Research Record, 1992Co-Authors: Prahlad D Pant, X H Huang, Sundaresan A KrishnamurthyAbstract:Examined in this paper is the effect of steady-burn lights on driver behavior in divided and undivided Highways with horizontal and vertical curves; and with and without external lighting, entrance and exit ramps, tapered sections of lane closures, and median crossovers. The study was based on an examination of the driving behavior of a sample of driver subjects who were asked to drive an instrumented automobile in several Highway Work zones during the day, during the night when steady-burn lights were placed on drums, and during the night when steady-burn lights were removed. The effect of steady-burn lights on the lane-changing behavior of motorists in advance of the tapered sections was determined by recording traffic volume at three to four locations in each travel lane before the taper. The results showed that steady-burn lights had little effect, if any, on driver behavior in Highway Work zones. It appears that the high-intensity sheeting on drums and the flashing arrow panel had a powerful effect on drivers, thus leaving the steady-burn lights without any practical value in the Work zones. It is concluded that steady-burn lights are not required for traffic control when drums with high intensity sheeting and flashing arrow panel are used as channelizing devices in these Highway facilities.
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Evaluation of steady burn lights for traffic control in Highway Work zones
1992Co-Authors: P.d. Pant, X H Huang, Sundaresan A KrishnamurthyAbstract:This study has examined the effectiveness of Type C steady burn lights on drums with Type G high intensity reflective sheeting in typical Ohio Work zones on divided and undivided Highways including curved, lighted, unlighted and tapered sections, ramps and median crossovers. The Work zones had advance warning signs and flashing arrow panel in the beginning of taper as required by ODOT specifications. The study examined the behavior of driver subjects who drove an instrumented car in several Work zones during daytime, nighttime with steady burn lights on drums, and night time when the lights were absent, but not necessarily in that order. The measures of effectiveness included speed, lateral placement, acceleration noise, weaving, traffic conflict, lane change behavior, and driver preference. The results showed that steady burn lights on drums with high intensity reflective sheeting have little or no effect on driver behavior in Highway Work zones. It is recommended that the use of steady burn lights on drums with high intensity reflective sheeting be discontinued in the future.
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EVALUATION OF STEADY BURN LIGHTS FOR TRAFFIC CONTROL IN Highway Work ZONES. PHASE 2
1992Co-Authors: P.d. Pant, X H Huang, Sundaresan A KrishnamurthyAbstract:The study has examined the effectiveness of Type C steady burn lights on drums with Type G high intensity reflective sheeting in typical Ohio Work zones on divided and undivided Highways including curved, lighted, unlighted and tapered sections, ramps and median crossovers. The Work zones had advance warning signs and flashing arrow panel in the beginning of taper as required by ODOT specifications. The study examined the behavior of driver subjects who drove an instrumented car in several Work zones during daytime, nighttime with steady burn lights on drums, and nighttime when the lights were absent, but not necessarily in that order. The measures of effectiveness included speed, lateral placement, acceleration noise, weaving, traffic conflict, lane change behavior, and driver preference. The results showed that steady burn light on drums with high intensity reflective sheeting have little or no effect on driver behavior in Highway Work zones. It is recommended that the use of steady burn lights on drums with high intensity reflective sheeting be discontinued in the future.
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EVALUATION OF STEADY BURN LIGHTS FOR TRAFFIC CONTROL IN Highway Work ZONES, PHASE II. FINAL REPORT
1992Co-Authors: P.d. Pant, X H Huang, Sundaresan A KrishnamurthyAbstract:This study has examined the effectiveness of Type C steady burn lights on drums with Type G high intensity reflective sheeting in typical Ohio Work zones on divided and undivided Highways including curved, lighted, unlighted and tapered sections, ramps and median crossovers. The Work zones had advance warning signs and flashing arrow panel in the beginning of taper as required by ODOT specifications. The study examined the behavior of driver subjects who drove an instrumented car in several Work zones during daytime, nighttime with steady burn lights on drums, and nighttime when the lights were absent, but not necessarily in that order. The measures of effectiveness included speed, lateral placement, acceleration noise, weaving, traffic conflict, lane change behavior, and driver preference. The results showed that steady burn lights on drums with high intensity reflective sheeting have little or no effect on driver behavior in Highway Work zones. It is recommended that the use of steady burn lights on drums with high intensity reflective sheeting be discontinued in the future.