Publications

Crash Classification by Congestion Type for Highways

Song, T.-J., Kim, S., Williams, B. M., Rouphail, N. M., & List, G. F. (2020), APPLIED SCIENCES-BASEL, 10(7). https://doi.org/10.3390/app10072583

Modeling Framework for Capacity Analysis of Freeway Segments: Application to Ramp Weaves

Xu, D., Rouphail, N. M., Aghdashi, B., Ahmed, I., & Elefteriadou, L. (2020), TRANSPORTATION RESEARCH RECORD. https://doi.org/10.1177/0361198119900157

Assessing traffic-related environmental impacts based on different traffic monitoring applications

Teixeira, J., Macedo, E., Fernandes, P., Bandeira, J. M., Rouphail, N., & Coelho, M. C. (2019), 21ST EURO WORKING GROUP ON TRANSPORTATION MEETING (EWGT 2018), pp. 107–114. https://doi.org/10.1016/j.trpro.2018.12.172

Characterizing Lane Changes via Digitized Infrastructure and Low-Cost GPS

Ahmed, I., Karr, A., Rouphail, N. M., Chun, G., & Tanvir, S. (2019), TRANSPORTATION RESEARCH RECORD, 2673(8), 298–309. https://doi.org/10.1177/0361198119841277

Lane Change Rates at Freeway Weaving Sites: Trends in HCM6 and from NGSIM Trajectories

Ahmed, I., Xu, D., Rouphail, N., & Karr, A. (2019), TRANSPORTATION RESEARCH RECORD, 2673(5), 627–636. https://doi.org/10.1177/0361198119841281

Queue-Based Guidance for Signalization Consideration at Two and Three-Legged Intersections

Warchol, S., Rouphail, N. M., Vaughan, C., & Kearns, B. (2019), TRANSPORTATION RESEARCH RECORD, 2673(10), 416–426. https://doi.org/10.1177/0361198119847468

Characteristics and Temporal Stability of Recurring Bottlenecks

Ahmed, I., Rouphail, N. M., & Tanvir, S. (2018), TRANSPORTATION RESEARCH RECORD, 2672(42), 235–246. https://doi.org/10.1177/0361198118798991

Data-driven approach for identifying spatiotemporally recurrent bottlenecks

Song, T.-J., Williams, B. M., & Rouphail, N. M. (2018), IET INTELLIGENT TRANSPORT SYSTEMS, 12(8), 756–764. https://doi.org/10.1049/iet-its.2017.0284

Effect of Light Duty Vehicle Performance on a Driving Style Metric

Tanvir, S., Frey, H. C., & Rouphail, N. M. (2018), TRANSPORTATION RESEARCH RECORD, 2672(25), 67–78. https://doi.org/10.1177/0361198118796070

Reliability Assessment Tool: Development and Prototype Testing

List, G. F., Rouphail, N., Smith, R., & Williams, B. (2018), TRANSPORTATION RESEARCH RECORD, 2672(14), 29–38. https://doi.org/10.1177/0361198118798296

View all publications via NC State Libraries

Grants

Project G3: Utilization of Connectivity and Automation in Support of Transportation Agencies’ Decision Making

US Dept. of Transportation (DOT)(1/01/20 - 4/15/21)

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Project G3: Utilization of Connectivity and Automation in Support of Transportation Agencies’ Decision Making

Sponsor: US Dept. of Transportation (DOT)

Start Date: 1/01/20

End Date: 4/15/21

Abstract

This project will identify, develop, and implement a suite of simulation models and methods for use in assessing the implications of the presence of connected vehicles (CV), automatous vehicles (AV), and connected automated vehicles (CAV) in the traffic stream and in evaluating the impacts of associated applications that use these technologies. The project will build on current national and international efforts including the on-going research conducted by the Federal Highway Administration (FHWA). As such, the research will start with a comprehensive review and assessment of the literature and existing products on the subject including examining the products of the FHWA effort. Using the review and assessment as a basis, high priority CAV applications to be addressed in this project will be identified based on defined criteria and a framework and guidelines will be developed for the use of analysis, simulation, and modeling of CAV. The project will then develop procedures for calibrating and validating simulation models to ensure the proper use of these models in replicating emerging vehicle technologies and applications. The research team will also identify and develop utilities and extensions of existing models to allow the modeling of selected high priority modeling applications. The project will demonstrate the use of the project development to support agency decisions with regard to high priority CAV applications.

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NCDOT University Transportation Center of Excellence on Mobility and Congestion

NC Department of Transportation(2/01/20 - 7/31/22)

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NCDOT University Transportation Center of Excellence on Mobility and Congestion

Sponsor: NC Department of Transportation

Start Date: 2/01/20

End Date: 7/31/22

Abstract

The NCDOT is launching a bold and forward-looking effort to establish multi-university transportation centers of excellence to provide broad-based, multidisciplinary research into the applications and impacts of cutting edge technologies and emergent, disruptive trends. The projects included in our center proposal were custom-built to address the research areas spelled out in the request for proposals for the desired Mobility and Congestion center. The three themes are as follows: • Theme #1: Big Data and Data-Driven Transportation Management and Decision Support • Theme #2: Active Transportation Management/Integrated Corridor Management • Theme #3: Transit and Mobility as a Service

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Traffic Analysis Tools: Assessment, Comparison and Validation Study

NC Department of Transportation(8/01/19 - 1/31/22)

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Traffic Analysis Tools: Assessment, Comparison and Validation Study

Sponsor: NC Department of Transportation

Start Date: 8/01/19

End Date: 1/31/22

Abstract

Traffic Analysis Tools-Assessment, Comparison, and Validation Study 2019-2021

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Reconciling Travel Time Saving Estimates in the SPOT Process

NC Department of Transportation(7/01/19 - 3/31/21)

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Reconciling Travel Time Saving Estimates in the SPOT Process

Sponsor: NC Department of Transportation

Start Date: 7/01/19

End Date: 3/31/21

Abstract

As stated in its mission statement, the strategic prioritization process declares that “Projects are evaluated based on their merit through an analysis of the existing and future conditions, the benefits the project is expected to provide, the project’s multi-modal characteristics and how the project fits in with local priorities”. Considering that nearly 3 billion dollars annually of NC taxpayer dollars are at stake in the State Transportation Improvement Program (STIP) Prioritization process of ranking highway projects for funding, travel time savings (TTS) constitute a key input into the projects' benefit cost analyses. Yet, estimates of those savings for various competing projects are derived from models that are completely different in scales, both spatially and temporally, including a low-resolution statewide travel demand model, a highly detailed microsimulation model and a manual calculation based on very limited data. The method of reconciling those estimates across projects has varied from no adjustments in some past Prioritization rounds, to prioritizing based on the relative number of project requests (e.g. corridor vs. intersection improvements) as was done in Prioritization 5.0. This research is intended to study, and propose alternative reconciliation methods for TTS estimates that can improve and make the ranking process more transparent, robust and replicable.

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STRIDE -Assessing and Addressing Deficiencies in the HCM Weaving Segment Analyses

US Dept. of Transportation (DOT)(8/01/18 - 8/31/20)

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STRIDE -Assessing and Addressing Deficiencies in the HCM Weaving Segment Analyses

Sponsor: US Dept. of Transportation (DOT)

Start Date: 8/01/18

End Date: 8/31/20

Abstract

The Highway Capacity Manual (HCM) is one of the most widely used references in transportation engineering, both for planning and operational analyses. The 6th edition of the HCM offers a wide spectrum of analyses ranging from freeway segments to facility travel time reliability. With the recent emphasis from Federal Highway Administration (FHWA) on the adoption of reliability performance measures for funding prioritization purposes and mitigating congestion, a new era for the usage of macroscopic models is emerging. HCM travel time reliability analysis is based on modeling a set of representative days with varying operational conditions. Weaving segments are often critical components of freeway facilities, as they can act as bottlenecks. Any bias or errors within this procedure can significantly impact facility-wide or reliability analyses, and in the process significantly brings question into the validity of the entire facility methodology. Researchers at NC State University have been advised of this issue when evaluating the implementation of the HCM6 freeway facility method in the FREEVAL software. NCHRP 03-75 developed the most recent weave analysis method found in HCM. It used real-world data and developed analytical models to assess several weave segments configurations by estimating speeds, capacities and Level of Service (LOS). The developed model was adopted in the 2010 HCM and is included in the 6th edition. In recent years, practitioners have found several cases where this method is not able to model or show sensitivity to certain important parameters under certain operating conditions. For example, the non-weaving vehicles’ speeds are not sensitive to the weave short length (which is the distance between two gore points in the weave segment). Also, the non-weaving speed is not sensitive to all lane changes within the segment. These deficiencies have led to questioning the validity of the HCM’s weave segments analysis. Furthermore, these deficiencies have gradually led to wide-spreading concerns with facility-wide or travel time reliability analyses that by default incorporate weaving segment analyses.

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Predicting Lane Change Intensity within Urban Interchange Influence Areas

NC Department of Transportation(8/01/18 - 10/31/20)

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Predicting Lane Change Intensity within Urban Interchange Influence Areas

Sponsor: NC Department of Transportation

Start Date: 8/01/18

End Date: 10/31/20

Abstract

This research is intended to assist NCDOT in improving mobility and safety performance at urban interchange influence areas (IIA's) in North Carolina, to remedy the excessive levels of discretionary lane changes occurring at those locations. The research will predict how driver lane changing behavior is impacted by local traffic, by control and by site conditions. A second objective will be to ascertain whether changes in signing, markings or other traveler information near the IIA can induce fewer discretionary lane changes and thus reduce unnecessary traffic turbulence near interchanges. Currently NCDOT has no means to track lane changing behavior. This research will take advantage of an existing (and continuously expanding) NC State high resolution second by second trip database which uses an in-vehicle OBD-II unit (called i2d) in the Triangle Region. Supplemented with controlled experiments and other data sources the research will produce predictions of lane changing behavior at the vehicle scale, based on present IIA geometrics, the prevailing traffic states and any implemented lane-discipline-inducing treatments. To achieve these objectives, we are proposing to develop a statistical model to predict lane change intensity in urban interchange influence areas. Lane changes will be characterized as mandatory or discretionary. Our i2d data can inform us which type of lane change it is, based on knowledge of the trip origin and destination. Initially, however we will assume that all lane changes are discretionary except when it is known that the vehicle is either entering or exiting the IAA. Thus our predictor variable will be the expected discretionary lane change intensity per vehicle mile in the IIA.

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Impacts of Autonomous Vehicle Technology on Transportation Systems

NC Department of Transportation(8/01/18 - 7/31/21)

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Impacts of Autonomous Vehicle Technology on Transportation Systems

Sponsor: NC Department of Transportation

Start Date: 8/01/18

End Date: 7/31/21

Abstract

Autonomous vehicle (AV) technology is expected to fundamentally change transportation systems. The Transportation Planning Branch at NCDOT, which is responsible for the state’s long-range transportation plan, needs state-of-the-art information and predictions on AV technology and its potential impacts on transport to be better prepared for the upcoming changes and maximize the social benefits that this technology will enable. The Transportation Systems group faculty (Drs. Bardaka, List, Rouphail, and Williams) and Dr. Frey (Environmental Engineering) in the Department of Civil, Construction, and Environmental Engineering at NCSU as well as Dr. Cummings, the Director of the Humans and Autonomy Laboratory at Duke University will work together to leverage existing research in the area of AV technology to evaluate impacts and provide policy and future research recommendations to NCDOT. The study will include a comprehensive literature review on AV technology and its impact on transportation demand, capacity, mobility, traffic safety, emissions, energy use, and land use. The results of previous research will be analyzed and case studies for North Carolina will be developed. The study will also provide recommendations to NCDOT regarding changes in policies and regulations, future test plans and test infrastructure, and research priorities in the area of AV technology. As part of this study, the researchers will work closely with the Transportation Planning Branch to provide guidance on how existing models (such as the statewide demand model) could be adapted to account for the presence of AVs.

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STRIDE-Project I. Freeway Management for Optimal Reliability

US Dept. of Transportation (DOT)(1/19/17 - 11/30/19)

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STRIDE-Project I. Freeway Management for Optimal Reliability

Sponsor: US Dept. of Transportation (DOT)

Start Date: 1/19/17

End Date: 11/30/19

Abstract

This project will develop tools for analyzing and optimizing system reliability on freeways. These tools include analytical and simulation frameworks for the optimization and near real-time performance forecast of active traffic management (ATM) systems. The proposed traffic congestion mitigation toolbox will include local and/or system-wide adaptive ramp metering, integrated rampmetering and variable speed limit control, hard shoulder running, speed harmonization, dynamic pricing of express lanes, optimized traffic diversions and efficient incident response and management. ATM deployment is a means to meet specific reliability goals below a desirable agency specified threshold. This two-year project will develop a methodological framework, a novel integrative process of system modeling, and will select and optimize appropriate strategies from the ATM toolbox to meet reliability goals. We will also test the validity of the proposed approach using data from a minimum of three freeway facilities in the Southeast region at both rural and urban locations.

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STRIDE-Project F. Integrated Implementation of Innovative Intersection Designs

US Dept. of Transportation (DOT)(5/16/17 - 11/15/19)

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STRIDE-Project F. Integrated Implementation of Innovative Intersection Designs

Sponsor: US Dept. of Transportation (DOT)

Start Date: 5/16/17

End Date: 11/15/19

Abstract

Alternative intersections and interchanges (AII) such as the Restricted Crossing U-Turn (RCUT), can increase safety and capacity, thereby reducing congestion for both vehicular and non-vehicular traffic. Often, RCUTs provide extended capacity for an existing intersection, typically for intersections which are under consideration for grade separation due to capacity constraints. Limited construction funding can often delay costly bridge projects for years. Consequently, AII designs can be useful in many cases because the intersection strategy provides the opportunity to extend the service life of intersections experiencing problems that will not likely be resolved otherwise in the foreseeable future. While many agencies recognize the operational and safety benefits of RCUT designs, the comparative evaluations undertaken during the selection process often have a very narrow scope. For example, in evaluating the effectiveness of RCUT intersections, studies typically model only vehicular operations. However, the implementation of RCUT intersections may significantly impact other users of other modes, such as pedestrians and bicyclists. In addition, RCUT designs may have broader level impacts on the corridor if operations are improved at one intersection and not at other upstream and downstream intersections. Accordingly, this proposed project will explore system level integration alternatives related to RCUT designs and will provide guidance for their use to optimize operations and to extend the useful life of facilities. In addition, the research team will explore the multimodal impacts of this intersection design to look at ways to improve operations for all users.

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Characterizing the Determinants of Vehicle Traffic Emissions Exposure: Measurement and Modeling of Land-Use, Traffic, Emissions, Transformation and Transport

US Environmental Protection Agency (EPA)(1/01/17 - 5/31/19)

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Characterizing the Determinants of Vehicle Traffic Emissions Exposure: Measurement and Modeling of Land-Use, Traffic, Emissions, Transformation and Transport

Sponsor: US Environmental Protection Agency (EPA)

Start Date: 1/01/17

End Date: 5/31/19

Abstract

Our proposal will determine the most important variables that explain spatial and temporal variance of near road traffic-related pollutant concentrations: We will explore the relative influence of traffic activity, the built environment (roadways and other built structures), and environmental (e.g. temperature, wind and background concentrations) factors on multi-pollutant transport, differential evolution and how all of these influence human exposure. We will also demonstrate novel surrogates of near-road traffic-related pollution: We will develop data and modeling approaches to quantify exposure concentrations of multiple pollutants emitted from vehicles or formed as secondary pollutants in the near-roadway microenvironment: fine particulate matter (PM), ultrafine particles (UPF), semi-volatile organic compounds (SVOCs), nitrogen dioxide, and carbon monoxide. The role of individual pollutants and mixtures of pollutants, and whether some pollutants are good surrogates for others, will be assessed. We will improve inputs for exposure models for traffic-related health: We will explore the implications of our measurement findings by applying them in spatial and temporal analysis of the relationship between human exposure (or surrogates for human exposure) and adverse effects, including evaluation of mixtures of pollutants and other proxies for exposure

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