Guoyuan Wu - Academia.edu (original) (raw)

Papers by Guoyuan Wu

Path Research Report, May 1, 2010

Reports on an in-depth study of problems associated with grade crossings configured with an adapt... more Reports on an in-depth study of problems associated with grade crossings configured with an adaptive trolley signal priority (ATSP) system. The system is designed for large-scale field implementation of the ATSP System and consists of three subsystems: an onboard subsystem , a roadside control subsystem and a central control subsystem. Laboratory design testing was conducted on the proposed ATSP system prior to a preliminary field operational testing (FOT) of the system in San Diego. These tests are used to demonstrate the applicability of the FOT. The proposed system utilizes the QuicNet/4 central control system as used in the San Diego Transportation Management Center (TMC) and Type 170 controllers at the roadside. Overall performance of the proposed ATSP system was not as successful as expected. Additional issues are observed and studied as they impact the San Diego trolley and roadway operation. Identified issues are summarized and recommendations provided to further improve the system performance. An additional FOT is recommended to confirm findings and resolve newly identified issues in use of the adaptive signal priority system design. The recommendations cover six aspects: signal transition, signal progression, dwelling time prediction, arrival time prediction at stations, integration of priority decision with prediction, and the automatic vehicle location (AVL) system.

San Diego Trolley has implemented a passive priority system in the San Diego downtown area since ... more San Diego Trolley has implemented a passive priority system in the San Diego downtown area since 1990. With the changes in trolley operations as well as traffic conditions in the downtown area, the passive priority system has been observed to have various limitations. In this study, by employing GPS data collection method to obtain trolley operation data, we confirm what we observed as well as discover the potentials for system improvements from the data analysis. Incorporating the travel time predictor and the dwelling time predictor developed using the GPS data collected, an active priority system is proposed for better performance of both trolley and general auto traffic. A simulation model is constructed and calibrated to evaluate the proposed priority system. Testing results from the simulation model are presented and discussed. Future research work is also identified.

Transportation Research Record Journal of the Transportation Research Board

Reports on an in-depth study of problems associated with grade crossings configured with an adapt... more Reports on an in-depth study of problems associated with grade crossings configured with an adaptive trolley signal priority (ATSP) system. The system is designed for large-scale field implementation of the ATSP System and consists of three subsystems: an onboard subsystem , a roadside control subsystem and a central control subsystem. Laboratory design testing was conducted on the proposed ATSP system prior to a preliminary field operational testing (FOT) of the system in San Diego. These tests are used to demonstrate the applicability of a proposed FOT. The proposed system utilizes the QuicNet/4 central control system as used in the San Diego Transportation Management Center (TMC) and Type 170 controllers at the roadside. Overall performance of the proposed ATSP system was not as successful as expected. The maximum average reduction on average number of stops and average travel time is less than 15%. Additional issues are observed and studied from the perspective of trolley operation, and traffic operation, Analysis indicates methodology may be suitable as a predictive tool for trolley movement and station dwelling time. Identified issues are summarized and recommendations provided to further improve the system performance. A FOT is recommended to confirm findings and further justify use of adaptive signal priority systems to reduce congestion. The recommendations cover six aspects: signal transition, signal progression, dwelling time prediction, arrival time prediction at stations, integration of priority decision with prediction, and the automatic vehicle location (AVL) system.

Transportation Research Part D: Transport and Environment, 2011

ABSTRACT This paper investigates the environmental impacts of signal timing on vehicle emissions ... more ABSTRACT This paper investigates the environmental impacts of signal timing on vehicle emissions at a pre-timed signalized intersection. We use a two-stage approach: the first consists of developing optimization models that examine the trade-off between vehicle delays and the number of stops; and, based on the outcomes of the first stage, the second of estimating vehicle emissions using microscopic emission estimation models. A dynamic programming algorithm is developed to solve the optimization problems appearing in the first stage. A vehicle specific power approach is used to estimate the vehicle emissions near the intersection based on the results from the first stage.Highlights► The total delay increases if the reduction of the number of vehicle stops is imposed in the optimization model. ► For our specific instances, slightly reducing the number of the vehicle stops may result in the reduction of CO at the expense of slightly increasing of CO2 and HC. ► When the reduction of a large number of vehicle stops is imposed in the optimization model, all of four pollutant emissions increase due to significantly increased delay.

This document reports the development and implementation of an integrated Adaptive Transit Signal... more This document reports the development and implementation of an integrated Adaptive Transit Signal Priority (ATSP) and Dynamic Passenger Information (DPI) system, and extensive testing with a real-world operation setting on a 10-mile-long ATSP-enabled road segment along El Camino Real, between 42nd Avenue in San Mateo and Bayhill Road in San Bruno, and on two SamTrans (San Mateo County Transit District)

Transportation Research Record: Journal of the Transportation Research Board, 2007

The basic concept and implementation of an active priority system of light rail transit (LRT) for... more The basic concept and implementation of an active priority system of light rail transit (LRT) for highway–rail grade crossings are presented. The proposed priority system consists of four major components: train detectors, train travel and dwell time predictors, priority request generator (PRG), and traffic signal controllers. As the brain of the system, the PRG adopts a three-scheme conditional priority control strategy. Scheme I, which applies to late LRT trains, features a timing optimization model. The objective of this optimization model is to minimize intersection delays for late trains and meanwhile to minimize impacts on other traffic. Unlike existing signal priority studies, which typically focus on isolated intersections, the proposed model deals with signal timings at multiple intersections and provides an optimized green band for an incoming train. The optimized green band would start at the right time to cover the predicted train arrival time and would be wide enough to...

Transportation Research Record: Journal of the Transportation Research Board, 2012

This paper presents some fundamentals of the dynamic lane grouping (DLG) concept, the aim of whic... more This paper presents some fundamentals of the dynamic lane grouping (DLG) concept, the aim of which is to improve lane utilization under variations in traffic demand. The problem was formulated as a mathematical programming model to determine the optimal lane allocation of an isolated intersection in relation to minimizing the maximum lane flow ratio (defined as the assigned flow divided by the saturation rate). Shared lanes and user equilibrium status for lane use were also considered in the model. Numerical analyses were conducted for four cases with different numbers of lanes, saturation levels, and methods for setting signal timing (adaptive and fixed timing). The results indicated that DLG might provide significant performance improvement in reducing the maximum-flow ratio under the spatial variation in demand. The performance of DLG was also compared with real-time adaptive signal timing by means of the average delay; improvements to the average delay were also observed when th...

Journal of Transportation Engineering, 2012

ABSTRACT In urban areas, conventional transit priority systems (e.g., passive priority) present s... more ABSTRACT In urban areas, conventional transit priority systems (e.g., passive priority) present some problems, such as causing too many traffic delays and degradation of on line performance due to the lack of real-time data. The purpose of this study is to develop an on line adaptive priority strategy to optimize traffic operation at a series of consecutive grade crossings in urban areas. The proposed strategy takes into account the impact on cross-street traffic as well. A mathematical model of non linear programming with linear constraints is formulated to minimize overall passenger delays at grade crossings for light rail transit and to minimize the impact on cross-street traffic. The optimization is enabled by real-time arrival-time prediction with GPS-equipped vehicles. To exhibit the anticipatory performance of the proposed strategy, both a numerical analysis and a simulation test are conducted with trolley operation along a stretch of C Street in San Diego. Compared with current signal timings, those obtained from the proposed strategy demonstrate promising results. DOI: 10.1061/(ASCE)TE.1943-5436.0000344. (C) 2012 American Society of Civil Engineers.

arXiv (Cornell University), Aug 22, 2022

Transportation Research Board 98th Annual MeetingTransportation Research Board, 2019

Iet Intelligent Transport Systems, Oct 4, 2022

With the rapid development of the cooperative vehicle infrastructure system, eco‐approach and dep... more With the rapid development of the cooperative vehicle infrastructure system, eco‐approach and departure has been attracting increasing attention for mitigating the impact of signalized intersections, which helps improve the energy efficiency of equipped vehicles. However, existing studies have rarely considered the balance of electric bus energy consumption and traveling time. Meanwhile, the joint effect of bus stops and signalized intersections, and their interactions were not discussed widely with connected and automated electric buses (CAEBs). In this study, an integrated CAEB trajectory planning methodology with the balance of traveling time and energy consumption is proposed. A bi‐level programming model is developed to obtain the optimal trajectories of CAEBs. Numerical experiments are conducted to analyse and compare the model with two baseline models. The results demonstrate the optimal performance of the derived scheme in terms of bus energy consumption, with approximately 30–50% energy savings. Furthermore, model sensitivity analysis is conducted to quantify the impacts of the related system parameters. The findings also reveal that the entry time, conversion coefficient, and final speed have significant impacts on electric bus energy consumption along signalized arterials with bus stops.

Transportation Research Record, Jun 15, 2023

Effective incentive strategies have played a major role in the electrification of on-road vehicle... more Effective incentive strategies have played a major role in the electrification of on-road vehicles. Similar approaches to the off-road sector will be needed to continue decarbonizing the transportation sector. Estimating cost-effectiveness with given incentive funds is crucial to successfully develop and implement financial incentive strategies. Because of the lack of cost information for electric off-road equipment, forecasting cost-effectiveness of electrifying the off-road fleet is not feasible. We developed cost projection models for major components of off-road equipment and combined them into an equipment cost simulation tool. This simulation tool was then used to estimate NO x, particulate matter, and CO2 emission-based cost-effectiveness when diesel off-road equipment is replaced with equivalent electric equipment. Use of the developed cost-effectiveness framework in developing incentive strategies was also demonstrated. Finally, a sensitivity analysis was conducted to address potential variations of the assumptions made for projecting the cost of components and the resulting cost-effectiveness estimates. The framework demonstrated in this paper will inform governmental inventive funding programs to design the most cost-effective strategies, considering equipment vocation, model year, and usage.

IEEE Transactions on Intelligent Transportation Systems, 2017

Transportation Research Board 95th Annual MeetingTransportation Research Board, 2016

It is widely accepted that eco-driving saves energy for individual vehicles. However, it is incon... more It is widely accepted that eco-driving saves energy for individual vehicles. However, it is inconclusive whether these energy savings hold up for the overall traffic stream, and over how one should eco-drive (e.g., long, slow acceleration or rapid acceleration). This paper seeks to shed light on these issues by: 1) simulating the impact of eco-driving using the real-world effects of an eco-driving technology, on a network that has been calibrated specifically for energy/emissions estimation; and 2) conducting a comprehensive search for the acceleration and deceleration behaviors that maximize energy savings. For (2), the maximum acceleration rate and deceleration rate were each limited by 10, 20, 30, 40, and 50%. By testing all of the resulting combinations of acceleration/deceleration rates, the greatest energy savings (about 4%) were found at a 10% reduction in acceleration rate and 50% reduction in deceleration rate. These results suggest that deceleration, more than acceleration, should be limited in order to maximize energy savings for the overall traffic stream under the conditions examined in this paper.

Vehicles, Aug 6, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

In recent years, various versions of the eco-approach and departure (EAD) application have been d... more In recent years, various versions of the eco-approach and departure (EAD) application have been developed and evaluated. This application utilizes signal phase and timing information to allow connected and automated vehicles (CAVs) to approach and depart from a signalized intersection in an energy-efficient manner. To date, most existing works have studied the EAD application from an ego-vehicle perspective (Ego-EAD) using vehicleto-infrastructure communication, while relatively limited research takes into account cooperation among vehicles at intersections via vehicle-to-vehicle communication. In this paper, we developed a cluster-wise cooperative EAD (Coop-EAD) application for CAVs to further reduce energy consumption compared to existing Ego-EAD applications. Instead of considering CAVs traveling through signalized intersections one at a time, our approach strategically coordinates CAVs' maneuvers to form clusters using various operating modes: initial vehicle clustering, intracluster sequence optimization, and cluster formation control. The novel Coop-EAD algorithm is applied to the cluster leader, and CAVs in the cluster follow the cluster leader to conduct EAD maneuvers. A preliminary simulation study with a given scenario shows that, compared to an Ego-EAD application, the proposed Coop-EAD application achieves 11% reduction on energy consumption, up to 18% reduction on pollutant emissions, and 50% increase on traffic throughput, respectively. Index Terms-Eco-approach and departure, connected and automated vehicles, cluster, cooperative adaptive cruise control, signalized intersection.

Transportation Research Board 94th Annual MeetingTransportation Research Board, 2015

Research on lane changing behavior has been active for decades due to its significant impact on t... more Research on lane changing behavior has been active for decades due to its significant impact on traffic operations. Most of the existing studies focuses on generic weaving sections (e.g., on-ramps), and very few of them have investigated the lane changing behavior along high-occupancy vehicle (HOV) facilities, especially in the context of comparison between different types of HOV lane configurations. In this study, the authors collected unique aerial photo data from the same roadway segment (SR-60 in Moreno Valley, California) before and after a conversion of the HOV lane configuration. Using a Kalman Filter smoothing algorithm, the raw data have been well cleaned before any lane-changing statistics were extracted. Results from extensive statistical analyses provide more in-depth insights into the impacts of HOV lane configuration on the lane changing behavior. Results from this study are consistent with the findings in previous research. The data and their analysis in this study would be useful not only for the design of HOV lanes or managed lanes, but also for the calibration of related simulation models.

Transportation Research Board 92nd Annual MeetingTransportation Research Board, 2013

There has been significant interest in plug-in hybrid electric vehicles (PHEVs) as a means to dec... more There has been significant interest in plug-in hybrid electric vehicles (PHEVs) as a means to decrease dependence on imported oil and to reduce greenhouse gases as well as other pollutant emissions. One of the critical considerations in PHEV development is the design of its energy-management strategy, which determines how energy in a hybrid powertrain should be produced and utilized as a function of various vehicle parameters. In this paper, we propose an intelligent energy-management strategy for PHEVs. At the trip level, the strategy takes into account a priori knowledge of vehicle location, roadway characteristics, and real-time traffic conditions on the travel route from intelligent transportation system technologies in generating a synthesized velocity trajectory for the trip. The synthesized velocity trajectory is then used to determine battery's charge-depleting control that is formulated as a mixed-integer linear programming problem to minimize the total trip fuel consumption. The strategy can be extended to optimize vehicle fuel consumption at the tour level if a preplanned travel itinerary for the tour and the information about available battery recharging opportunities at intermediate stops along the tour are available. The effectiveness of the proposed strategy, both for the trip-and tour-based controls, was evaluated against the existing binary-mode energy-management strategy using real-world trip/tour examples in southern California. The evaluation results show that the fuel savings of the proposed strategy over the binary-mode strategy are around 10%-15%.

Path Research Report, May 1, 2010

Reports on an in-depth study of problems associated with grade crossings configured with an adapt... more Reports on an in-depth study of problems associated with grade crossings configured with an adaptive trolley signal priority (ATSP) system. The system is designed for large-scale field implementation of the ATSP System and consists of three subsystems: an onboard subsystem , a roadside control subsystem and a central control subsystem. Laboratory design testing was conducted on the proposed ATSP system prior to a preliminary field operational testing (FOT) of the system in San Diego. These tests are used to demonstrate the applicability of the FOT. The proposed system utilizes the QuicNet/4 central control system as used in the San Diego Transportation Management Center (TMC) and Type 170 controllers at the roadside. Overall performance of the proposed ATSP system was not as successful as expected. Additional issues are observed and studied as they impact the San Diego trolley and roadway operation. Identified issues are summarized and recommendations provided to further improve the system performance. An additional FOT is recommended to confirm findings and resolve newly identified issues in use of the adaptive signal priority system design. The recommendations cover six aspects: signal transition, signal progression, dwelling time prediction, arrival time prediction at stations, integration of priority decision with prediction, and the automatic vehicle location (AVL) system.

San Diego Trolley has implemented a passive priority system in the San Diego downtown area since ... more San Diego Trolley has implemented a passive priority system in the San Diego downtown area since 1990. With the changes in trolley operations as well as traffic conditions in the downtown area, the passive priority system has been observed to have various limitations. In this study, by employing GPS data collection method to obtain trolley operation data, we confirm what we observed as well as discover the potentials for system improvements from the data analysis. Incorporating the travel time predictor and the dwelling time predictor developed using the GPS data collected, an active priority system is proposed for better performance of both trolley and general auto traffic. A simulation model is constructed and calibrated to evaluate the proposed priority system. Testing results from the simulation model are presented and discussed. Future research work is also identified.

Transportation Research Record Journal of the Transportation Research Board

Reports on an in-depth study of problems associated with grade crossings configured with an adapt... more Reports on an in-depth study of problems associated with grade crossings configured with an adaptive trolley signal priority (ATSP) system. The system is designed for large-scale field implementation of the ATSP System and consists of three subsystems: an onboard subsystem , a roadside control subsystem and a central control subsystem. Laboratory design testing was conducted on the proposed ATSP system prior to a preliminary field operational testing (FOT) of the system in San Diego. These tests are used to demonstrate the applicability of a proposed FOT. The proposed system utilizes the QuicNet/4 central control system as used in the San Diego Transportation Management Center (TMC) and Type 170 controllers at the roadside. Overall performance of the proposed ATSP system was not as successful as expected. The maximum average reduction on average number of stops and average travel time is less than 15%. Additional issues are observed and studied from the perspective of trolley operation, and traffic operation, Analysis indicates methodology may be suitable as a predictive tool for trolley movement and station dwelling time. Identified issues are summarized and recommendations provided to further improve the system performance. A FOT is recommended to confirm findings and further justify use of adaptive signal priority systems to reduce congestion. The recommendations cover six aspects: signal transition, signal progression, dwelling time prediction, arrival time prediction at stations, integration of priority decision with prediction, and the automatic vehicle location (AVL) system.

Transportation Research Part D: Transport and Environment, 2011

ABSTRACT This paper investigates the environmental impacts of signal timing on vehicle emissions ... more ABSTRACT This paper investigates the environmental impacts of signal timing on vehicle emissions at a pre-timed signalized intersection. We use a two-stage approach: the first consists of developing optimization models that examine the trade-off between vehicle delays and the number of stops; and, based on the outcomes of the first stage, the second of estimating vehicle emissions using microscopic emission estimation models. A dynamic programming algorithm is developed to solve the optimization problems appearing in the first stage. A vehicle specific power approach is used to estimate the vehicle emissions near the intersection based on the results from the first stage.Highlights► The total delay increases if the reduction of the number of vehicle stops is imposed in the optimization model. ► For our specific instances, slightly reducing the number of the vehicle stops may result in the reduction of CO at the expense of slightly increasing of CO2 and HC. ► When the reduction of a large number of vehicle stops is imposed in the optimization model, all of four pollutant emissions increase due to significantly increased delay.

This document reports the development and implementation of an integrated Adaptive Transit Signal... more This document reports the development and implementation of an integrated Adaptive Transit Signal Priority (ATSP) and Dynamic Passenger Information (DPI) system, and extensive testing with a real-world operation setting on a 10-mile-long ATSP-enabled road segment along El Camino Real, between 42nd Avenue in San Mateo and Bayhill Road in San Bruno, and on two SamTrans (San Mateo County Transit District)

Transportation Research Record: Journal of the Transportation Research Board, 2007

The basic concept and implementation of an active priority system of light rail transit (LRT) for... more The basic concept and implementation of an active priority system of light rail transit (LRT) for highway–rail grade crossings are presented. The proposed priority system consists of four major components: train detectors, train travel and dwell time predictors, priority request generator (PRG), and traffic signal controllers. As the brain of the system, the PRG adopts a three-scheme conditional priority control strategy. Scheme I, which applies to late LRT trains, features a timing optimization model. The objective of this optimization model is to minimize intersection delays for late trains and meanwhile to minimize impacts on other traffic. Unlike existing signal priority studies, which typically focus on isolated intersections, the proposed model deals with signal timings at multiple intersections and provides an optimized green band for an incoming train. The optimized green band would start at the right time to cover the predicted train arrival time and would be wide enough to...

Transportation Research Record: Journal of the Transportation Research Board, 2012

This paper presents some fundamentals of the dynamic lane grouping (DLG) concept, the aim of whic... more This paper presents some fundamentals of the dynamic lane grouping (DLG) concept, the aim of which is to improve lane utilization under variations in traffic demand. The problem was formulated as a mathematical programming model to determine the optimal lane allocation of an isolated intersection in relation to minimizing the maximum lane flow ratio (defined as the assigned flow divided by the saturation rate). Shared lanes and user equilibrium status for lane use were also considered in the model. Numerical analyses were conducted for four cases with different numbers of lanes, saturation levels, and methods for setting signal timing (adaptive and fixed timing). The results indicated that DLG might provide significant performance improvement in reducing the maximum-flow ratio under the spatial variation in demand. The performance of DLG was also compared with real-time adaptive signal timing by means of the average delay; improvements to the average delay were also observed when th...

Journal of Transportation Engineering, 2012

ABSTRACT In urban areas, conventional transit priority systems (e.g., passive priority) present s... more ABSTRACT In urban areas, conventional transit priority systems (e.g., passive priority) present some problems, such as causing too many traffic delays and degradation of on line performance due to the lack of real-time data. The purpose of this study is to develop an on line adaptive priority strategy to optimize traffic operation at a series of consecutive grade crossings in urban areas. The proposed strategy takes into account the impact on cross-street traffic as well. A mathematical model of non linear programming with linear constraints is formulated to minimize overall passenger delays at grade crossings for light rail transit and to minimize the impact on cross-street traffic. The optimization is enabled by real-time arrival-time prediction with GPS-equipped vehicles. To exhibit the anticipatory performance of the proposed strategy, both a numerical analysis and a simulation test are conducted with trolley operation along a stretch of C Street in San Diego. Compared with current signal timings, those obtained from the proposed strategy demonstrate promising results. DOI: 10.1061/(ASCE)TE.1943-5436.0000344. (C) 2012 American Society of Civil Engineers.

arXiv (Cornell University), Aug 22, 2022

Transportation Research Board 98th Annual MeetingTransportation Research Board, 2019

Iet Intelligent Transport Systems, Oct 4, 2022

With the rapid development of the cooperative vehicle infrastructure system, eco‐approach and dep... more With the rapid development of the cooperative vehicle infrastructure system, eco‐approach and departure has been attracting increasing attention for mitigating the impact of signalized intersections, which helps improve the energy efficiency of equipped vehicles. However, existing studies have rarely considered the balance of electric bus energy consumption and traveling time. Meanwhile, the joint effect of bus stops and signalized intersections, and their interactions were not discussed widely with connected and automated electric buses (CAEBs). In this study, an integrated CAEB trajectory planning methodology with the balance of traveling time and energy consumption is proposed. A bi‐level programming model is developed to obtain the optimal trajectories of CAEBs. Numerical experiments are conducted to analyse and compare the model with two baseline models. The results demonstrate the optimal performance of the derived scheme in terms of bus energy consumption, with approximately 30–50% energy savings. Furthermore, model sensitivity analysis is conducted to quantify the impacts of the related system parameters. The findings also reveal that the entry time, conversion coefficient, and final speed have significant impacts on electric bus energy consumption along signalized arterials with bus stops.

Transportation Research Record, Jun 15, 2023

Effective incentive strategies have played a major role in the electrification of on-road vehicle... more Effective incentive strategies have played a major role in the electrification of on-road vehicles. Similar approaches to the off-road sector will be needed to continue decarbonizing the transportation sector. Estimating cost-effectiveness with given incentive funds is crucial to successfully develop and implement financial incentive strategies. Because of the lack of cost information for electric off-road equipment, forecasting cost-effectiveness of electrifying the off-road fleet is not feasible. We developed cost projection models for major components of off-road equipment and combined them into an equipment cost simulation tool. This simulation tool was then used to estimate NO x, particulate matter, and CO2 emission-based cost-effectiveness when diesel off-road equipment is replaced with equivalent electric equipment. Use of the developed cost-effectiveness framework in developing incentive strategies was also demonstrated. Finally, a sensitivity analysis was conducted to address potential variations of the assumptions made for projecting the cost of components and the resulting cost-effectiveness estimates. The framework demonstrated in this paper will inform governmental inventive funding programs to design the most cost-effective strategies, considering equipment vocation, model year, and usage.

IEEE Transactions on Intelligent Transportation Systems, 2017

Transportation Research Board 95th Annual MeetingTransportation Research Board, 2016

It is widely accepted that eco-driving saves energy for individual vehicles. However, it is incon... more It is widely accepted that eco-driving saves energy for individual vehicles. However, it is inconclusive whether these energy savings hold up for the overall traffic stream, and over how one should eco-drive (e.g., long, slow acceleration or rapid acceleration). This paper seeks to shed light on these issues by: 1) simulating the impact of eco-driving using the real-world effects of an eco-driving technology, on a network that has been calibrated specifically for energy/emissions estimation; and 2) conducting a comprehensive search for the acceleration and deceleration behaviors that maximize energy savings. For (2), the maximum acceleration rate and deceleration rate were each limited by 10, 20, 30, 40, and 50%. By testing all of the resulting combinations of acceleration/deceleration rates, the greatest energy savings (about 4%) were found at a 10% reduction in acceleration rate and 50% reduction in deceleration rate. These results suggest that deceleration, more than acceleration, should be limited in order to maximize energy savings for the overall traffic stream under the conditions examined in this paper.

Vehicles, Aug 6, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

In recent years, various versions of the eco-approach and departure (EAD) application have been d... more In recent years, various versions of the eco-approach and departure (EAD) application have been developed and evaluated. This application utilizes signal phase and timing information to allow connected and automated vehicles (CAVs) to approach and depart from a signalized intersection in an energy-efficient manner. To date, most existing works have studied the EAD application from an ego-vehicle perspective (Ego-EAD) using vehicleto-infrastructure communication, while relatively limited research takes into account cooperation among vehicles at intersections via vehicle-to-vehicle communication. In this paper, we developed a cluster-wise cooperative EAD (Coop-EAD) application for CAVs to further reduce energy consumption compared to existing Ego-EAD applications. Instead of considering CAVs traveling through signalized intersections one at a time, our approach strategically coordinates CAVs' maneuvers to form clusters using various operating modes: initial vehicle clustering, intracluster sequence optimization, and cluster formation control. The novel Coop-EAD algorithm is applied to the cluster leader, and CAVs in the cluster follow the cluster leader to conduct EAD maneuvers. A preliminary simulation study with a given scenario shows that, compared to an Ego-EAD application, the proposed Coop-EAD application achieves 11% reduction on energy consumption, up to 18% reduction on pollutant emissions, and 50% increase on traffic throughput, respectively. Index Terms-Eco-approach and departure, connected and automated vehicles, cluster, cooperative adaptive cruise control, signalized intersection.

Transportation Research Board 94th Annual MeetingTransportation Research Board, 2015

Research on lane changing behavior has been active for decades due to its significant impact on t... more Research on lane changing behavior has been active for decades due to its significant impact on traffic operations. Most of the existing studies focuses on generic weaving sections (e.g., on-ramps), and very few of them have investigated the lane changing behavior along high-occupancy vehicle (HOV) facilities, especially in the context of comparison between different types of HOV lane configurations. In this study, the authors collected unique aerial photo data from the same roadway segment (SR-60 in Moreno Valley, California) before and after a conversion of the HOV lane configuration. Using a Kalman Filter smoothing algorithm, the raw data have been well cleaned before any lane-changing statistics were extracted. Results from extensive statistical analyses provide more in-depth insights into the impacts of HOV lane configuration on the lane changing behavior. Results from this study are consistent with the findings in previous research. The data and their analysis in this study would be useful not only for the design of HOV lanes or managed lanes, but also for the calibration of related simulation models.

Transportation Research Board 92nd Annual MeetingTransportation Research Board, 2013

There has been significant interest in plug-in hybrid electric vehicles (PHEVs) as a means to dec... more There has been significant interest in plug-in hybrid electric vehicles (PHEVs) as a means to decrease dependence on imported oil and to reduce greenhouse gases as well as other pollutant emissions. One of the critical considerations in PHEV development is the design of its energy-management strategy, which determines how energy in a hybrid powertrain should be produced and utilized as a function of various vehicle parameters. In this paper, we propose an intelligent energy-management strategy for PHEVs. At the trip level, the strategy takes into account a priori knowledge of vehicle location, roadway characteristics, and real-time traffic conditions on the travel route from intelligent transportation system technologies in generating a synthesized velocity trajectory for the trip. The synthesized velocity trajectory is then used to determine battery's charge-depleting control that is formulated as a mixed-integer linear programming problem to minimize the total trip fuel consumption. The strategy can be extended to optimize vehicle fuel consumption at the tour level if a preplanned travel itinerary for the tour and the information about available battery recharging opportunities at intermediate stops along the tour are available. The effectiveness of the proposed strategy, both for the trip-and tour-based controls, was evaluated against the existing binary-mode energy-management strategy using real-world trip/tour examples in southern California. The evaluation results show that the fuel savings of the proposed strategy over the binary-mode strategy are around 10%-15%.