2018 IEEE International Smart Cities Conference (ISC2), 2018
Smart mobility is an essential element in building smart cities. To realize connected and automat... more Smart mobility is an essential element in building smart cities. To realize connected and automated smart mobility as a service, the capability to efficiently estimate the travel-time reliability measures responding to various operating conditions is of critical importance. This paper presents a travel-time reliability estimation system, which is applied to determine the effects of the operational changes on the travel-time reliability. The application results to the metro freeway network in Minnesota indicate the substantial improvements in travel-time reliability after the changes were introduced, indicating the possibility of modeling the causal relationship between reliability and specific operational strategies.
Final reportPDFTech ReportMN/RC 2015-26CTS # 2012007(c) 99008 (wo) 3Ramp meteringBottlenecksVaria... more Final reportPDFTech ReportMN/RC 2015-26CTS # 2012007(c) 99008 (wo) 3Ramp meteringBottlenecksVariable speed limitsAdaptive controlHighway corridorsUnited StatesMinnesotaMinnesota. Dept. of Transportation. Research Services & LibraryKwon, EilPark, ChongmyungUniversity of Minnesota, Duluth. Department of Civil EngineeringMinnesota. Dept. of Transportation. Research Services & LibraryUS Transportation CollectionIn this study, the effectiveness of the I-35W variable advisory speed limit system on the improvement of the trafficflow was evaluated with the real traffic data. The analysis results indicate there was significant reduction in theaverage maximum deceleration and also the traffic time reliability was substantially improved during a peak hourperiod. Based on the assessment results, an enhanced version was developed to be able to reflect more effectivelythe time-variant road traffic conditions in determining the variable speed limits in real time. The coordinatedadaptive metering strategy, developed in the previous phase of this research, is also enhanced and implemented inthe field in this research. The field test results of the new metering system with the 100 NB corridor indicatesubstantial improvements in both the mainline and ramp traffic performance compared with those from the oldstratified algorithm
An on-line decision support system is developed for an adaptive management of freeway networks. T... more An on-line decision support system is developed for an adaptive management of freeway networks. The system has been specifically designed to support the zone-based ramp metering control currently being operated by the Minnesota Department of Transportation. The key components of the system include the on-line prediction and parallel simulation modules that can be used for real time evaluation of alternative management and operational strategies with predicted traffic conditions. The prediction module, adopting an adaptive approach with filtering, predicts freeway traffic demand at each ramp and capacities of given bottlenecks, which are of critical importance for the zone-based metering operations. Further, the on-line simulation module employs a distributed computing architecture and uses the interprocess communication procedures available under the Windows NT operating system. For the covering abstract see IRRD E102946.
An adaptive procedure is presented to estimate the time-variant capacity at consecutive weaving a... more An adaptive procedure is presented to estimate the time-variant capacity at consecutive weaving areas in real time. The proposed procedure uses the volume/occupancy data commonly available from single loop detectors and estimates the maximum total volume that can enter a given freeway weaving segment through time. The behavior at several weaving sites with consecutive weaving segments were analyzed, using loop and video data as well as visual observation. The online identification process with a Kalman Filter reduces estimation errors by continuously updating the parameters of the underlying models with the most recently measured data. The test results with real data show that the proposed procedure can estimate the upper limit values of the mainline flow approaching given weaving segments with reasonable accuracy. This procedure addresses the effects of entrance ramp flows, which can be controlled through ramp metering, on the maximum possible mainline volume approaching weave area...
This paper presents an automatic process to determine the normal condition regain time (NCRT) usi... more This paper presents an automatic process to determine the normal condition regain time (NCRT) using the traffic flow data a given snow event. To reflect the different traffic flow behavior during the day and night time periods, two types of the normal conditions are defined for each detector station. The normal condition for the day time is defined with the average speed-density patterns, while the time-dependent average speed patterns are used for representing the night time periods. In particular, the speed-density functions for the speed recovery and reduction periods were calibrated separately for a given location to address the well-known traffic hysteresis phenomenon. The resulting NCRT estimation process determines the NCRT as the time when the snow day speed recovers to the target level of the normal recovery speed at the corresponding density level for the day time periods. The application results with the snow routes in Twin Cities, Minnesota, show the promising possibilit...
Ite Journal-institute of Transportation Engineers, 1998
A macroscopic simulation tool was developed to evaluate the traffic operations of the High Occupa... more A macroscopic simulation tool was developed to evaluate the traffic operations of the High Occupancy Vehicle (HOV) lanes in a freeway network. The continuum modeling approach employed in this research divides a given freeway section into 100-ft (30-m) increments and estimates the macroscopic traffic parameters, such as flow, speed, and density every second by using the numerical scheme specifically designed to solve time-dependent, compressible flows containing strong shocks. Using the built-in graphical user interface, the user can build a given freeway section on the computer screen using a mouse. The output information can be analyzed with the graphic functions or stored in a spreadsheet file format that can be imported by common spreadsheet software.
This report summarizes the final results of the enhancement and validation of the control-emulati... more This report summarizes the final results of the enhancement and validation of the control-emulation method in the real freeway environment. A computer-based control-emulation method that can evaluate various automatic rate-selection strategies was developed by this research team in the previous phase of this research. Software was developed that operationalizes this method for field applications. A method was developed and tested to determine the best metering thresholds for a given section of a freeway, under normal weather conditions, using the control-emulation method and the downhill simplex optimization procedure. The method finds the optimal thresholds for each ramp in a given section of the freeway by considering the system-wide traffic conditions. An independent procedure to determine the initial thresholds that can be used to initialize the optimization process was also developed. A preliminary study for developing an on-line predictor for freeway exit demand was performed ...
This paper develops an automatic procedure to estimate the speed recovery time for a given snow e... more This paper develops an automatic procedure to estimate the speed recovery time for a given snow event using archived traffic flow data commonly available from the in-pavement loop detectors on the field. The proposed procedure uses a two-stage process to accurately identify the speed changing points in a speed-time space with a set of smoothed and quantized 5-min traffic data. The sample test results of the new procedure with the past snow event data show a promising possibility of developing a traffic data based performance assessment system for winter snow operations.
In this study, the effectiveness of the Interstate-35W variable advisory speed limit system on th... more In this study, the effectiveness of the Interstate-35W variable advisory speed limit system on the improvement of the traffic flow was evaluated with the real traffic data. The analysis results indicate there was significant reduction in the average maximum deceleration and also the traffic time reliability was substantially improved during a peak hour period. Based on the assessment results, an enhanced version was developed to be able to reflect more effectively the time-variant road traffic conditions in determining the variable speed limits in real time. The coordinated adaptive metering strategy, developed in the previous phase of this research, is also enhanced and implemented in the field in this research. The field test results of the new metering system with the Highway 100 northbound corridor indicate substantial improvements in both the mainline and ramp traffic performance compared with those from the old stratified algorithm.
A method is developed for evaluating traffic-responsive ramp metering strategies and improving fr... more A method is developed for evaluating traffic-responsive ramp metering strategies and improving freeway performance. The method emulates real-time metering and rigorously traces the interactions between automatic rate-selection metering strategies and freeway performance through time. Given a demand pattern and freeway geometrics, it provides assessment of metering strategies that change continuously at very short time intervals. Further, it explicitly treats time delays that can be caused by hardware or introduced by the traffic engineer. The method was tested with real data in emulating volume and occupancy thresholds, rate tables and automatic rate-selection control strategies on I35W in Minneapolis. The tests indicated errors in the range from 5 to 12%. The method was also tested in assessing and selecting ramp control strategies based on freeway performance measures such as total freeway volume and delay. Evaluation results were in the expected direction, and indicated the ability to distinguish small performance differences across strategies. The report is organized as follows: Chapter 1 is an Introduction. The second chapter describes the traffic-responsive metering algorithms currently operating in the U.S. and other countries. Chapter 3 reviews advanced concepts for hierarchical, optimal freeway control presented in the literature. Chapter 4 develops a control-emulation method to evaluate automatic rate selection strategies and Chapter 5 contains test results and application examples. Finally, Chapter 6 contains discussion and conclusions regarding future research directions.
A method is developed for evaluating traffic-responsive ramp metering strategies and improving fr... more A method is developed for evaluating traffic-responsive ramp metering strategies and improving freeway performance. The method emulates real-time metering and rigorously traces the interactions between automatic rate-selection metering strategies and freeway performance through time. Given a demand pattern and freeway geometrics, it provides assessment of metering strategies that change continuously at very short time intervals. Further, it explicitly treats time delays that can be caused by hardware or introduced by the traffic engineer.Center for Transportation Studie
This paper summarizes the current status of the live intersection laboratory being developed in M... more This paper summarizes the current status of the live intersection laboratory being developed in Minneapolis, Minnesota, by the University of Minnesota in consultation with the City of Minneapolis, the Minnesota Department of Transportation ITS program, called Guidestar, and private industry. The laboratory intersection, located at Franklin and Lyndale Avenues in downtown Minneapolis, Minnesota, currently exhibits frequent congestion and delay during peak hours. Further, the location and distance of the intersection from the adjacent intersections make it possible to operate it as an isolated intersection, but it can be easily incorporated into coordinated network control. In addition, the incident rate at the intersection proper is relatively high, and this can provide valuable data for future development of intersection incident detection strategies.
A method is developed for evaluating traffic-responsive ramp metering strategies and improving fr... more A method is developed for evaluating traffic-responsive ramp metering strategies and improving freeway performance in intelligent vehicle-highway systems operations. The method emulates real-time metering, as currently practiced in the United States and Canada, and traces the interactions between automatic rate-selection metering strategies and freeway performance through time. The method can facilitate traffic management by aiding in the design of new traffic-responsive ramp strategies, and in the evaluation of existing real-time control systems and selection of the best metering schemes. The method was tested successfully in emulating volume and occupancy thresholds, rate tables, and automatic rate-selection control strategies, and in assessing and selecting ramp strategies based on freeway performance measures (such as total volume and delay) on I-35W in Minneapolis.
2018 IEEE International Smart Cities Conference (ISC2), 2018
Smart mobility is an essential element in building smart cities. To realize connected and automat... more Smart mobility is an essential element in building smart cities. To realize connected and automated smart mobility as a service, the capability to efficiently estimate the travel-time reliability measures responding to various operating conditions is of critical importance. This paper presents a travel-time reliability estimation system, which is applied to determine the effects of the operational changes on the travel-time reliability. The application results to the metro freeway network in Minnesota indicate the substantial improvements in travel-time reliability after the changes were introduced, indicating the possibility of modeling the causal relationship between reliability and specific operational strategies.
Final reportPDFTech ReportMN/RC 2015-26CTS # 2012007(c) 99008 (wo) 3Ramp meteringBottlenecksVaria... more Final reportPDFTech ReportMN/RC 2015-26CTS # 2012007(c) 99008 (wo) 3Ramp meteringBottlenecksVariable speed limitsAdaptive controlHighway corridorsUnited StatesMinnesotaMinnesota. Dept. of Transportation. Research Services & LibraryKwon, EilPark, ChongmyungUniversity of Minnesota, Duluth. Department of Civil EngineeringMinnesota. Dept. of Transportation. Research Services & LibraryUS Transportation CollectionIn this study, the effectiveness of the I-35W variable advisory speed limit system on the improvement of the trafficflow was evaluated with the real traffic data. The analysis results indicate there was significant reduction in theaverage maximum deceleration and also the traffic time reliability was substantially improved during a peak hourperiod. Based on the assessment results, an enhanced version was developed to be able to reflect more effectivelythe time-variant road traffic conditions in determining the variable speed limits in real time. The coordinatedadaptive metering strategy, developed in the previous phase of this research, is also enhanced and implemented inthe field in this research. The field test results of the new metering system with the 100 NB corridor indicatesubstantial improvements in both the mainline and ramp traffic performance compared with those from the oldstratified algorithm
An on-line decision support system is developed for an adaptive management of freeway networks. T... more An on-line decision support system is developed for an adaptive management of freeway networks. The system has been specifically designed to support the zone-based ramp metering control currently being operated by the Minnesota Department of Transportation. The key components of the system include the on-line prediction and parallel simulation modules that can be used for real time evaluation of alternative management and operational strategies with predicted traffic conditions. The prediction module, adopting an adaptive approach with filtering, predicts freeway traffic demand at each ramp and capacities of given bottlenecks, which are of critical importance for the zone-based metering operations. Further, the on-line simulation module employs a distributed computing architecture and uses the interprocess communication procedures available under the Windows NT operating system. For the covering abstract see IRRD E102946.
An adaptive procedure is presented to estimate the time-variant capacity at consecutive weaving a... more An adaptive procedure is presented to estimate the time-variant capacity at consecutive weaving areas in real time. The proposed procedure uses the volume/occupancy data commonly available from single loop detectors and estimates the maximum total volume that can enter a given freeway weaving segment through time. The behavior at several weaving sites with consecutive weaving segments were analyzed, using loop and video data as well as visual observation. The online identification process with a Kalman Filter reduces estimation errors by continuously updating the parameters of the underlying models with the most recently measured data. The test results with real data show that the proposed procedure can estimate the upper limit values of the mainline flow approaching given weaving segments with reasonable accuracy. This procedure addresses the effects of entrance ramp flows, which can be controlled through ramp metering, on the maximum possible mainline volume approaching weave area...
This paper presents an automatic process to determine the normal condition regain time (NCRT) usi... more This paper presents an automatic process to determine the normal condition regain time (NCRT) using the traffic flow data a given snow event. To reflect the different traffic flow behavior during the day and night time periods, two types of the normal conditions are defined for each detector station. The normal condition for the day time is defined with the average speed-density patterns, while the time-dependent average speed patterns are used for representing the night time periods. In particular, the speed-density functions for the speed recovery and reduction periods were calibrated separately for a given location to address the well-known traffic hysteresis phenomenon. The resulting NCRT estimation process determines the NCRT as the time when the snow day speed recovers to the target level of the normal recovery speed at the corresponding density level for the day time periods. The application results with the snow routes in Twin Cities, Minnesota, show the promising possibilit...
Ite Journal-institute of Transportation Engineers, 1998
A macroscopic simulation tool was developed to evaluate the traffic operations of the High Occupa... more A macroscopic simulation tool was developed to evaluate the traffic operations of the High Occupancy Vehicle (HOV) lanes in a freeway network. The continuum modeling approach employed in this research divides a given freeway section into 100-ft (30-m) increments and estimates the macroscopic traffic parameters, such as flow, speed, and density every second by using the numerical scheme specifically designed to solve time-dependent, compressible flows containing strong shocks. Using the built-in graphical user interface, the user can build a given freeway section on the computer screen using a mouse. The output information can be analyzed with the graphic functions or stored in a spreadsheet file format that can be imported by common spreadsheet software.
This report summarizes the final results of the enhancement and validation of the control-emulati... more This report summarizes the final results of the enhancement and validation of the control-emulation method in the real freeway environment. A computer-based control-emulation method that can evaluate various automatic rate-selection strategies was developed by this research team in the previous phase of this research. Software was developed that operationalizes this method for field applications. A method was developed and tested to determine the best metering thresholds for a given section of a freeway, under normal weather conditions, using the control-emulation method and the downhill simplex optimization procedure. The method finds the optimal thresholds for each ramp in a given section of the freeway by considering the system-wide traffic conditions. An independent procedure to determine the initial thresholds that can be used to initialize the optimization process was also developed. A preliminary study for developing an on-line predictor for freeway exit demand was performed ...
This paper develops an automatic procedure to estimate the speed recovery time for a given snow e... more This paper develops an automatic procedure to estimate the speed recovery time for a given snow event using archived traffic flow data commonly available from the in-pavement loop detectors on the field. The proposed procedure uses a two-stage process to accurately identify the speed changing points in a speed-time space with a set of smoothed and quantized 5-min traffic data. The sample test results of the new procedure with the past snow event data show a promising possibility of developing a traffic data based performance assessment system for winter snow operations.
In this study, the effectiveness of the Interstate-35W variable advisory speed limit system on th... more In this study, the effectiveness of the Interstate-35W variable advisory speed limit system on the improvement of the traffic flow was evaluated with the real traffic data. The analysis results indicate there was significant reduction in the average maximum deceleration and also the traffic time reliability was substantially improved during a peak hour period. Based on the assessment results, an enhanced version was developed to be able to reflect more effectively the time-variant road traffic conditions in determining the variable speed limits in real time. The coordinated adaptive metering strategy, developed in the previous phase of this research, is also enhanced and implemented in the field in this research. The field test results of the new metering system with the Highway 100 northbound corridor indicate substantial improvements in both the mainline and ramp traffic performance compared with those from the old stratified algorithm.
A method is developed for evaluating traffic-responsive ramp metering strategies and improving fr... more A method is developed for evaluating traffic-responsive ramp metering strategies and improving freeway performance. The method emulates real-time metering and rigorously traces the interactions between automatic rate-selection metering strategies and freeway performance through time. Given a demand pattern and freeway geometrics, it provides assessment of metering strategies that change continuously at very short time intervals. Further, it explicitly treats time delays that can be caused by hardware or introduced by the traffic engineer. The method was tested with real data in emulating volume and occupancy thresholds, rate tables and automatic rate-selection control strategies on I35W in Minneapolis. The tests indicated errors in the range from 5 to 12%. The method was also tested in assessing and selecting ramp control strategies based on freeway performance measures such as total freeway volume and delay. Evaluation results were in the expected direction, and indicated the ability to distinguish small performance differences across strategies. The report is organized as follows: Chapter 1 is an Introduction. The second chapter describes the traffic-responsive metering algorithms currently operating in the U.S. and other countries. Chapter 3 reviews advanced concepts for hierarchical, optimal freeway control presented in the literature. Chapter 4 develops a control-emulation method to evaluate automatic rate selection strategies and Chapter 5 contains test results and application examples. Finally, Chapter 6 contains discussion and conclusions regarding future research directions.
A method is developed for evaluating traffic-responsive ramp metering strategies and improving fr... more A method is developed for evaluating traffic-responsive ramp metering strategies and improving freeway performance. The method emulates real-time metering and rigorously traces the interactions between automatic rate-selection metering strategies and freeway performance through time. Given a demand pattern and freeway geometrics, it provides assessment of metering strategies that change continuously at very short time intervals. Further, it explicitly treats time delays that can be caused by hardware or introduced by the traffic engineer.Center for Transportation Studie
This paper summarizes the current status of the live intersection laboratory being developed in M... more This paper summarizes the current status of the live intersection laboratory being developed in Minneapolis, Minnesota, by the University of Minnesota in consultation with the City of Minneapolis, the Minnesota Department of Transportation ITS program, called Guidestar, and private industry. The laboratory intersection, located at Franklin and Lyndale Avenues in downtown Minneapolis, Minnesota, currently exhibits frequent congestion and delay during peak hours. Further, the location and distance of the intersection from the adjacent intersections make it possible to operate it as an isolated intersection, but it can be easily incorporated into coordinated network control. In addition, the incident rate at the intersection proper is relatively high, and this can provide valuable data for future development of intersection incident detection strategies.
A method is developed for evaluating traffic-responsive ramp metering strategies and improving fr... more A method is developed for evaluating traffic-responsive ramp metering strategies and improving freeway performance in intelligent vehicle-highway systems operations. The method emulates real-time metering, as currently practiced in the United States and Canada, and traces the interactions between automatic rate-selection metering strategies and freeway performance through time. The method can facilitate traffic management by aiding in the design of new traffic-responsive ramp strategies, and in the evaluation of existing real-time control systems and selection of the best metering schemes. The method was tested successfully in emulating volume and occupancy thresholds, rate tables, and automatic rate-selection control strategies, and in assessing and selecting ramp strategies based on freeway performance measures (such as total volume and delay) on I-35W in Minneapolis.
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