2013 Session: 402

• Vehicle-Class-Specific Control of Freeway Traffic
  Abstract: Active Traffic Management (ATM) aims at reducing congestion levels and the costs that are induced by it. Currently, most ATM measures disregard the vehicle classes traffic is composed off. Nevertheless, few measures proposed are indeed vehicle-class specific, such as high-occupancy and toll lanes (HOT) or truck lanes. Recently, multi-class versions of ramp meters and route guidance have been developed and analyzed in terms of traffic flow theory. However, they have never been combined or coordinated to reduce the traffic of a realistic freeway.In this paper, we develop a multi-class controller for Active Traffic Management and apply it in simulations of a freeway with heavy truck traffic. By coordinating a multi-class ramp meter and two multi-class route guidance measures in an optimal control approach, the traffic conditions are improved compared to their mixed-class counterparts. These results suggest that the costs of congestion are reduced if Active Traffic Management is applied vehicle-class specifically.
  Authors: Schreiter, Thomas; Van Lint, Hans; Hoogendoorn, Serge
  Authors: Schreiter, Thomas; Van Lint, Hans; Hoogendoorn, Serge
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-0585
• Self-Learning Adaptive Ramp Metering: Analysis of Design Parameters on a Test Case in Toronto, Canada
  Abstract: Ramp metering (RM) is the most effective dynamic traffic measure in response to growing congestion in urban freeway networks. Among the extensive RM methods, those based on optimal control theory have shown strong potential in improving freeway performance. However, these algorithms require an accurate traffic model, which limits their applicability in practice. Reinforcement learning (RL) provides the tools to achieve optimal RM control without reliance on any traffic model. In this paper a guideline for designing RM control systems based on RL is presented by testing different states representations, learning methods, action selection, and reward definitions. A microscopic simulation testbed based on a portion of Highway 401 in the city of Toronto is developed to evaluate each of the above design parameters and quantify various ramp metering control strategies. Comparing the reinforcement learning ramp metering (RLRM) algorithm with highly renowned ALINEA, shows the potential of RLRM to improve freeway traffic condition. The proposed RLRM algorithm and ALINEA reduce the total travel time by 40% and 20% with respect to the case with no RM, respectively.
  Authors: Rezaee, Kasra; Abdulhai, Baher; Abdelgawad, Hossam
  Authors: Rezaee, Kasra; Abdulhai, Baher; Abdelgawad, Hossam
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-1054
• Macroscopic Travel Time Reliability Diagrams for Freeway Networks
  Abstract: Travel time reliability is considered to be one of the key indicators of transport system performances. The knowledge on the mechanisms of travel time unreliability enables the derivation of explanatory models with which travel time reliability could be predicted and utilized in traffic management. Inspired by the Macroscopic Fundamental Diagram (MFD), describing the relationship between production (average flow completing their trips) and vehicle accumulation (average density) in a traffic network, this paper investigates a so-called Macroscopic travel time (un)Reliability Diagram (MRD), relating the travel time (un)reliability to the network accumulation. The potential of the MFD relation lies in the fact that it characterizes the state of an entire traffic network with just two (production, accumulation) or three (adding spatial variability of accumulation) state variables. Likewise, the MRD describes the network travel time reliability as a function of just one independent state variable (network accumulation). Empirical analyses are performed to investigate the variability in MFD as seen in scatters and to show the travel time (un)reliability in relation to the network accumulations. Traffic data from Dutch freeway networks are employed to facilitate the analyses. It is found with the MRD on different freeway networks that a critical travel time (un)reliability accumulation exists, below which network accumulation has little or even no impacts on travel time (un)reliability and above which the accumulation has significant impacts on travel time (un)reliability. It is also found that the critical travel time (un)reliability accumulation is in general lower than the critical MFD accumulation. These findings provides insights for the road authorities in how to make tradeoffs between the maximum production and the travel time reliability in traffic management.
  Authors: Tu, Huizhao; Li, Hao; Van Lint, Hans; Knoop, Victor L.; Sun, LiJun
  Authors: Tu, Huizhao; Li, Hao; Van Lint, Hans; Knoop, Victor L.; Sun, LiJun
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-1123
• Using Variable Speed Limits for Motorway Off-ramp Queue Protection
  Abstract: Motorway off-ramps are a significant source of traffic congestion and collisions. Heavy diverging traffic to off-ramps slows down the mainline traffic speed. When the off-ramp queue spillbacks onto the mainline, it leads to a major breakdown of the motorway capacity and a significant threat to the traffic safety. This paper proposes using Variable Speed Limits (VSL) for protection of the motorway off-ramp queue and thus to promote safety in congested diverging areas. To support timely activation of VSL in advance of queue spillover, a proactive control strategy is proposed based on a real-time off-ramp queue estimation and prediction. This process determines the estimated queue size in the near-term future, on which the decision to change speed limits is made. VSL can effectively slow down traffic as it is mandatory that drivers follow the changed speed limits. A collateral benefit of VSL is its potential effect on drivers making them more attentive to the surrounding traffic conditions, and prepared for a sudden braking of the leading car. This paper analyses and quantifies these impacts and potential benefits of VSL on traffic safety and efficiency using the microsimulation approach.
  Authors: Lee, Jinwoo (Brian); Qian, Gongbin; Chung, Edward; Miska, Marc Philipp
  Authors: Lee, Jinwoo (Brian); Qian, Gongbin; Chung, Edward; Miska, Marc Philipp
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-1165
• Forecasting Freeway Dynamic Travel Times by Constructing Trip Trajectories
  Abstract: The paper develops a novel approach to construct vehicle trajectories using real-time and historical traffic data to predict dynamic travel times. The approach combines real-time and historical data within a particle filter framework to dynamically predict future traffic state maps. The predicted travel trajectory is then constructed using the velocity spatiotemporal map. Based on the nature of particle filters, the variance of each speed grid traversed during the trip can be calculated and then used to compute the travel time variance. The proposed approach is tested using simulated data along a section of I-66. The prediction results demonstrate that the proposed method produces a prediction error half that of the other state-of-the-art methods with a mean absolute deviation of 1.30 minutes and a mean absolute percentage error of 6%.
  Authors: Chen, Hao; Rakha, Hesham
  Authors: Chen, Hao; Rakha, Hesham
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-2128
• Reliability Benefits of Active Traffic Management: Managed-Lanes Case on French Urban Motorway
  Abstract: Traffic management aims to ensure a high quality of service for a maximum of users, by decreasing congestion and increasing safety. However, uncertainty regarding travel time (TT) decreases the quality of service and leads end-users to modify their plans regardless of the average TT. Indicators describing TT reliability are being developed and should be used in the future both for the optimization and for the assessment of active traffic management operation. This paper describes a managed lane experience on a motorway weaving section in France - Hard Shoulder Running (HSR) operation at rush hours. The paper describes the data measurement and the missing data replacement process. It focuses, however, on TT reliability indicators and on their use for reliability assessment on the basis of an observational before/after study. It provides some discussions on the advantages and drawbacks of reliability indicators under different traffic conditions. Indeed, the before/after study reports not only the effect of HSR but also of a speed limit campaign (SLC) which affected the free flow travel time. The study particularly shows the difference between using buffer times or buffer indexes. The paper also discusses the difficulty of interpreting the skew of TT distribution for travel reliability.
  Authors: Bhouri, Neila; Aron, Maurice
  Authors: Bhouri, Neila; Aron, Maurice
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-2531
• Particle Filter-Based Strategy for Online Calibration and Parameter Estimation of Motorway Traffic Model
  Abstract: This paper deals with a particle Bayesian filter framework for real-time motorway traffic state and online model parameters estimation, which can be useful for highway network monitoring and proactive traffic management and control applications. Due to the high nonlinearity of the traffic dynamics, Monte Carlo Bayesian approach is applied in combination with the transmission cell first order macroscopic traffic model. The implementation of this methodology demonstrates its ability to estimate, in real-time, the motorway traffic conditions together with the online estimation of model parameters. The validation is based on both simulated and real-world data.
  Authors: Sau, Jacques; El Faouzi, Nour-Eddin; Billot, Romain; Canaud, Matthieu
  Authors: Sau, Jacques; El Faouzi, Nour-Eddin; Billot, Romain; Canaud, Matthieu
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-2797
• Effect of Active Traffic Management on Travel Time Reliability: Case Study of I-5 in Seattle, Washington
  Abstract: The purpose of this study is to determine the impact that the installation of an Active Traffic Management (ATM) system has had on the travel time reliability of a seven-mile length of the I-5 corridor in Seattle, WA. The travel time reliability measures of planning time index and buffer index were used to evaluate the effectiveness of the I-5 ATM system. Using data collected from loop detectors along the highway segment, the travel time reliability of the northbound route was calculated for the period before and after the implementation of the ATM system in August 2010. Separate reliability indexes were calculated for each day of the week for each of the 19 detector locations along the route. The results of the study find an increase in the travel time reliability of the corridor after ATM system implementation. The system results in a higher level of travel time reliability during off-peak periods compared to the corridor without ATM.
  Authors: DeGaspari, Michael; Jin, Jing; Wall, William Jared; Walton, C. Michael
  Authors: DeGaspari, Michael; Jin, Jing; Wall, William Jared; Walton, C. Michael
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-3004
• Proactive Optimal Variable Speed Limit Control for Recurrent Congested Freeway Bottlenecks
  Abstract: The study presents two models for proactive VSL control on recurrently congested freeway segments. The proposed basic model uses embedded traffic flow relations to predict the evolution of congestion pattern over the projected time horizon and computes the optimal speed limit. To contend with the difficulty in capturing driver responses to VSL control, this study also proposes an advanced model that further adopts Kalman Filter to enhance the accuracy of traffic state prediction. Both models have been investigated with different traffic conditions and different control objectives. Our extensive simulation analysis with a VISSIM simulator, calibrated with field data from our previous VSL demonstration site, has revealed that both proactive VSL control models can significantly reduce the travel time and number of stops over the recurrent bottleneck locations, and the one with minimizing speed variance as its control objective clearly outperforms other models, with respect to several selected MOEs.
  Authors: Yang, Xianfeng; Lu, Yang (Carl); Chang, Gang-Len
  Authors: Yang, Xianfeng; Lu, Yang (Carl); Chang, Gang-Len
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-3139
• Simulation-Based Scenario-Driven Integrated Corridor Management Strategy Analysis
  Abstract: U.S. Department of Transportation (USDOT) affirmed the initiative of Integrated Corridor Management (ICM) to mitigate traffic congestion on urban corridor networks by systematically leveraging and diverging the traffic to better utilize available capacities of parallel arterials. ICM strategies would be of utmost importance when traffic incidents happened along freeways that may cause significant delays. By effectively diverging upcoming traffic to the adjacent arterials via variable message signs and real-time traveler information system, e.g. mobile devices, the impact of incidents can be alleviated. To fully understand the effectiveness of ICM strategies, a framework needs to be developed to model, simulate, and analyze the ICM operations under different scenarios. In this study, a VISSIM simulation model is developed and calibrated based on the field-collected video and sensor data for the Seattle South of Downtown (SoDo) area, which is selected by USDOT to evaluate the applicability and robustness of ICM strategies as one of the pioneer sites for ICM studies. The analysis aims to quantify the network-wide ICM performance, by empirically diverging traffic to the adjacent arterials in response to incident management for freeway operations. Multiple scenarios were built in the simulation model to account for different diversion rates, as well as recurrent and non-recurrent congestion situations. As expected, with more traffic diverted into the arterials, the arterial's performance degrades while the improvements in terms of travel time and delay for the freeway become marginal. By quantitatively analyzing the delay, throughput, and travel time of freeway segments and arterial network, the trade-off in the overall system performance is carefully studied and understood. The research findings set up a solid foundation for ICM strategy development and traffic system operation optimization.
  Authors: Liu, Xiaoyue (Cathy); Zhang, Guohui; Kwan, Carmen; Wang, Yinhai; Kemper, Brian
  Authors: Liu, Xiaoyue (Cathy); Zhang, Guohui; Kwan, Carmen; Wang, Yinhai; Kemper, Brian
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-3432
• Innovative Coordinated Ramp Metering Control Strategy for Freeway Congestion Mitigation
  Abstract: This paper describes a coordinated ramp metering algorithm for systematically mitigating freeway congestion. A preemptive hierarchical control scheme with a three-priority-layer structure is employed in this algorithm. Ramp metering is formulated as a multi-objective optimization problem to enhance system performance. These optimization objectives include promptly tackling freeway congestion, sufficiently utilizing on-ramp storage capacities, and preventing on-ramp vehicles from overflowing to local streets, balancing on-ramp vehicle equity, and maximizing traffic throughputs for the entire system. Instead of relying heavily on accurate estimates of freeway traffic flow evolvement, this new approach models ramp meter control as a linear program and uses real-time traffic sensor measurements for minimizing the indeterminate impacts from the mainstream flow capacities. VISSIM-based simulation experiments are performed to examine its practicality and effectiveness using geometric and traffic demand data from one real-world freeway segment. The simulation test results show that the proposed ramp metering approach performed well in optimizing overall freeway system operations under various traffic conditions. The system-wide optimal control performance can be achieved to quickly mitigate freeway congestion, prevent traffic from overflowing to local streets, and maximize overall traffic throughputs. The proposed ramp metering approach can dynamically assemble relevant ramp meters to work together and effectively coordinate the individual meter rates to leverage their response strengths for minimizing time to clear the congestion. This study demonstrates that utilization of existing freeway infrastructure can be optimized through the proposed algorithm.
  Authors: Zhang, Guohui; Wang, Yinhai
  Authors: Zhang, Guohui; Wang, Yinhai
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-3517
• Simulation-Based Evaluations of Real-Time Variable Speed Limit for Recurring Freeway Traffic Congestion
  Abstract: Freeway sections with lane tapers are likely to experience recurring congestion due to disruption to traffic caused by merging maneuvers. These merging maneuvers tend to create shock wave effects that cause long delays and slow traffic. This paper examines the performance of variable speed limits (VSL) as a promising mitigation treatment for freeway recurring traffic congestion. To do this an interstate highway section was selected that suffers from recurring traffic congestion caused by lane drop and lane merging in Northern Virginia. The first effort endeavored to model the 5 mile section in VISSIM and calibrate it using INRIX speed data and historical traffic counts from VDOT. Calibration efforts involved adjusting parameters embedded in VISSIM’s car following and lane changing models that led to an acceptable model performance within a selected confidence interval. A VSL algorithm developed by California PATH and programmed in AIMSUN was adopted in VISSIM to be used for determining optimum speed adjustments at three specific locations along the freeway section. Finally the VSL algorithm was applied to that section for a certain period of performance (i.e., 2 pm to 8 pm) in several VISSIM runs. These VISSIM runs used different compliance percentages. Findings show that for certain compliance rates, reductions in travel time were significant, resulting in up to 12% of network-wide total travel time savings.
  Authors: Lee, Joyoung; Dailey, Daniel J.; Bared, Joe G.; Park, Byungkyu (Brian)
  Authors: Lee, Joyoung; Dailey, Daniel J.; Bared, Joe G.; Park, Byungkyu (Brian)
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-4329
• Deterministic Framework and Methodology for Evaluating Travel Time Reliability on Freeway Facilities
  Abstract: This paper presented a methodology for incorporating freeway reliability analysis in the Highway Capacity Manual based on the Strategic Highway Research Program project L08. The methodology uses a scenario-based approach, where each scenario represents a unique combination of traffic demands and facility (segment) capacities. Demand impacts consider variability in time-of-day day-of-week and month-of-year differences, while capacity impacts quantify impacts of various non-recurring congestion sources like weather, incidents, work zones, and special events. The method combines three key components through a data repository, a freeway scenario generator (FSG), and a computational software engine, FREEVAL-RL. The FSG determines the number of scenarios for the reliability analysis based on the facility-specific combination of demand, incident, and weather events. For each scenario, it produces a set of inputs and adjustment factors that are passed on to the FREEVAL-RL engine, along with each scenario’s probability. The engine is capable of batch-processing many scenarios and estimates the reliability distribution for the facility that describes operations across the entire reliability reporting period. The method is illustrated using a real-world case study at an Interstate in North Carolina. The FSG for that facility resulted in 2,508 scenarios, which are processed in FREEVAL-RL. The resulting travel time distribution is presented and sensitivity analysis are presented to explore contributing effects of weather and incidents on the overall reliability of the facility.
  Authors: Schroeder, Bastian J.; Rouphail, Nagui M.; Aghdashi, Seyedbehzad
  Authors: Schroeder, Bastian J.; Rouphail, Nagui M.; Aghdashi, Seyedbehzad
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-4683
• Performance Evaluation of Ramp Metering Algorithms Combined with Variable Speed Limits for Auckland Motorway
  Abstract: Ramp Metering (RM) and Variable Speed Limits (VSL) are two important Intelligent Transportation System (ITS) tools that aim to improve performance of freeway systems. The former is widely used all around the world to regulate on-ramp traffic while the latter is still emerging as a supplementary tool to improve performance of RM. VSL controllers are located at immediate downstream location from the on-ramps to create some space for on-ramp traffic to merge. This paper investigates efficiency and equity of ALINEA and HERO (HEuristic Ramp metering coOrdination) RM algorithms in combination with VSL for a critical bottleneck section of Auckland Motorway using AIMSUN micro-simulation. ALINEA is the most prominent local RM algorithm while HERO is a rule-based coordinated RM algorithm, which is a simple and transparent strategy requiring no external disturbance prediction and at the same time, it can achieve efficiency close to that of complex optimal control. Total travel time and total travel distance were used to measure efficiency while Gini coefficient was used to measure equity of the freeway system. Results show that a combination of these tools has potential to improve efficiency however it can deteriorate equity of the freeway system.
  Authors: Li, Duo; Ranjitkar, Prakash
  Authors: Li, Duo; Ranjitkar, Prakash
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-4995
• Synthesizing Route Travel Time Distributions from Segment Travel Time Distributions
  Abstract: This paper examines the distributions of travel times for individual vehicles and segments with a clear focus on how to use this information to synthesize route travel time probability density functions (PDFs). The data derive from field studies conducted at various urban and rural settings throughout the United States as part of the SHRP-2 project L02 titled Establishing Monitoring Programs for Mobility and Travel Time Reliability. Four findings are highlighted. The first is that careful filtering is required to extract the travel times from the raw data because it is actually trip times that are observed not travel times – i.e., the movement of vehicles between locations. The second is that there is little variation in individual driver travel times under given operating conditions. This is an important and pleasing finding given that an assumption of driver consistency serves as basis for traffic simulation models. The third is that significant correlations exist between the travel times for adjacent segments, especially when the distances are short. The fourth is that the concept of comonotonicity, or perfect positive dependence, could be assumed when generating route travel time PDFs from segment PDFs. Bluetooth data on I-5 in Sacramento was used to further explore these ideas. Although intuition supports the notion that additivity of percentiles should hold under “Uncongested” to “Moderate congested” conditions, the results suggest that even under highly congested conditions the method seems to work very well.
  Authors: Isukapati, Isaac K.; List, George F.; Williams, Billy M.; Karr, Alan F.
  Authors: Isukapati, Isaac K.; List, George F.; Williams, Billy M.; Karr, Alan F.
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-4691
  Practice-Ready: Yes
• A Kalman Filter-Based Queue Estimation Algorithm Using Time Occupancies for Motorway On-ramps
  Abstract: The primary objective of this study is to develop a robust queue estimation algorithm for motorway on-ramps. Real-time queue information is the most vital input for a dynamic queue management on metered on-ramps. Accurate and reliable queue information enables an adaptive management of the ramp queue size and thus minimises the adverse impacts of queue flush while increasing the benefit of ramp metering for the mainline stream. The proposed algorithm is developed based on the Kalman filter framework. The fundamental conservation model is used to estimate the system state (queue size) with the flow-in and flow-out measurements. This projection results are updated with the measurement equation using the time occupancies from mid-link and link-entrance loop detectors. This study also proposes a novel single point correction method. This method resets the estimated system state to eliminate the counting errors that accumulate over time. In the performance evaluation, the proposed algorithm demonstrated accurate and reliable performances and consistently outperformed the benchmarked Single Occupancy Kalman filter (SOKF) method. The improvements over SOKF are 62% and 63% in average in terms of the estimation accuracy (MAE) and reliability (RMSE), respectively. The benefit of the innovative concepts of the algorithm is well justified by the improved estimation performance in congested ramp traffic conditions where long queues may significantly compromise the benchmark algorithm¡¯s performance.
  Authors: Lee, Jinwoo (Brian); Jiang, Rui; Chung, Edward
  Authors: Lee, Jinwoo (Brian); Jiang, Rui; Chung, Edward
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-3616
  Practice-Ready: Yes
• Self-Learning Adaptive Ramp Metering: Analysis of Design Parameters on a Test Case in Toronto, Canada
  Authors: Rezaee, Kasra
  Authors: Rezaee, Kasra
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-1054
• Reliability Benefits of Active Traffic Management: Managed-Lanes Case on French Urban Motorway
  Authors: Bhouri, Neila
  Authors: Bhouri, Neila
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-2531
• Effect of Active Traffic Management on Travel Time Reliability: Case Study of I-5 in Seattle, Washington
  Authors: Jin, Jing
  Authors: Jin, Jing
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-3004
• Proactive Optimal Variable Speed Limit Control for Recurrent Congested Freeway Bottlenecks
  Authors: Yang, Xianfeng
  Authors: Yang, Xianfeng
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-3139
• Simulation-Based Scenario-Driven Integrated Corridor Management Strategy Analysis
  Authors: Liu, Xiaoyue Cathy
  Authors: Liu, Xiaoyue Cathy
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-3432
• Synthesizing Route Travel Time Distributions from Segment Travel Time Distributions
  Authors: List, George
  Authors: List, George
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-4691
• Performance Evaluation of Ramp Metering Algorithms Combined with Variable Speed Limits for Auckland Motorway
  Authors: Ranjitkar, Prakash
  Authors: Ranjitkar, Prakash
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-4995
• Vehicle-Class-Specific Control of Freeway Traffic
  Authors: Schreiter, Thomas
  Authors: Schreiter, Thomas
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-0585
• Simulation-Based Evaluations of Real-Time Variable Speed Limit for Recurring Freeway Traffic Congestion
  Authors: Lee, Joyoung
  Authors: Lee, Joyoung
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 402
  Paper Number: 13-4329