Active Research Projects

Projects as Principal Investigator

 

	Evaluation of Road Ripples on North Carolina Roadways North Carolina Department of Transportation, 2026-2028 Abstract: Road ripples are an emerging form of asphalt pavement distress observed on North Carolina roadways that are not well defined in existing distress manuals and lack standardized diagnostic or treatment approaches. These washboard-like surface undulations, sometimes accompanied by shallow cracking, can reduce ride quality and may indicate underlying structural, material, or drainage concerns. Preliminary evidence suggests road ripples may result from interactions among residual moisture in asphalt mixtures, trapped moisture within pavement layers, environmental conditions, weak layer bonding, and construction practices. However, their causes and impacts have not been systematically evaluated in North Carolina. This project will establish a foundational understanding of road ripple distress through literature review, field evaluations, laboratory testing, and performance analysis. The research will document the extent and severity of road ripples, evaluate potential causative mechanisms, and assess their implications for pavement performance and service life.
	Guidelines for Storage of Asphalt Mixture and Performance Test Specimens National Cooperative Highway Research Program, 2026-2028 Abstract: The shift toward balanced mix design (BMD) has revealed critical inconsistencies in the storage practices for asphalt mixtures and compacted specimens, leading to variability in performance test results. Current practices lack standardized protocols, as identified in NCHRP Synthesis 552, resulting in discrepancies across laboratories due to differing storage times, temperatures, and conditions. This research aims to develop standardized guidelines for the storage of asphalt mixtures and specimens to improve the reliability and consistency of test outcomes. Phase I will involve a comprehensive review of current domestic and international practices to identify key storage factors influencing asphalt performance. Phase II will implement an experimental plan to assess the impact of these factors, with the goal of drafting storage protocols for potential adoption by AASHTO. In Phase III, the guidelines will be refined and accompanied by materials to aid adoption, including stakeholder impact analyses and implementation resources. The project will result in a set of guidelines for consistent storage practices across laboratories, enhancing the comparability of asphalt performance data and supporting the durability and quality aims of BMD approaches in asphalt engineering.
	Enhancing Pavement Surface Macrotexture Measurement Quality Federal Highway Administration, 2025-2027 Abstract: This project aims to improve the quality and consistency of pavement surface macrotexture measurements collected at highway speeds. Macrotexture affects roadway safety by influencing tire-pavement friction, splash and spray, and vehicle control. Common metrics such as Mean Profile Depth (MPD) and Root Mean Square Depth (RMSD) are widely used but vary significantly due to differences in devices, data processing, and filtering, reducing their reliability in pavement management. The work will focus on three activities: (1) assembling a comprehensive database of texture profiles from past and upcoming collections, including the 2025 Surface Properties Rodeo; (2) evaluating and recommending best practices for filtering, anomaly correction, and metric computation; and (3) developing a quality system that standardizes equipment specifications, operational procedures, and processing algorithms. The result will be harmonized protocols that ensure accurate, repeatable, device-independent measurements and support broader use of macrotexture data to improve agency decisions and roadway safety.
	Microsurfacing Mix Design Evaluation North Carolina Department of Transportation, 2025-2027 Abstract: Microsurfacing is increasingly used in North Carolina as a pavement preservation treatment, offering a service life extension of 7 to 9 years while enhancing surface texture and friction. However, the current North Carolina Department of Transportation (NCDOT) microsurfacing mix design relies on guidelines from the International Slurry Surfacing Association (ISSA), which do not account for state-specific aggregate specifications, performance concerns, or functional requirements. This research aims to develop a North Carolina-specific microsurfacing mix design by evaluating stockpile gradations, mix performance sensitivity, and surface preparation effects on texture and friction. The study will refine NCDOT special provisions and provide recommendations for optimized microsurfacing application. The anticipated outcomes include improved pavement longevity, enhanced skid resistance, and cost-effective implementation, aligning with NCDOT’s strategic goals to preserve roadway infrastructure and improve surface performance. The findings will support the broader adoption of microsurfacing as a durable, high-performing pavement preservation technique in North Carolina.
	Pavement Performance Impacts Predicted by Climate Change Models in Arizona, Phase 2 Arizona Department of Transportation, 2023-2025 Abstract: General circulation models (GCM) for the global climate, have predicted wide ranging changes over the next several decades. Some of these changes relate to roadways and pavement infrastructure. As outlined by the Arizona DOT’s Asset Management, Extreme Weather, and Proxy Indicators Pilot Project report, pavement impacts from future extreme events and climate patterns are expected to include decreased lifespan due to extreme heat and extreme cold as well as changes in the specific patterns of each (e.g., freeze/thaw cycling and heat waves). In this project, the NCSU research team is working with GCMs in Arizona to; provide insights and analysis to identify relevant pavement related climate stressors, identify the weather related risks to these pavements, quantify the impacts to specific assets, and assess which assets are at critical risk. This work will also be of value to other agencies outside Arizona by providing tangible examples that they can replicate with respect to analysis and interpretation for each step in this framework.

Projects as Co-Principal Investigator

	Understanding and Quantifying Driver Behavior in Wet Weather Conditions for Hydroplaning Safety Assessment North Carolina State University, PI: Danjue Chen Abstract: Rainfall is frequent on North Carolina’s roads, and hydroplaning remains a critical safety concern. While NCDOT has developed tools to evaluate hydroplaning potential, a major gap is the lack of calibrated information on how drivers adjust speed under rainfall, particularly heavy rain. Without this behavioral component, current assessments are incomplete and may misrepresent risk. The overall objective of this project is to develop a validated behavioral model that quantifies driver speed adjustments to rainfall intensity under varying roadway and environmental conditions. The results will include (1) a controlled rainfall dataset, (2) a validated simulation framework, and (3) a calibrated behavioral model of driver speed adjustment. Together, these products will allow NCDOT to incorporate driver behavior into hydroplaning assessments, improving prediction accuracy and supporting more effective roadway design, safety planning, and mitigation strategies.
	Asset Management Action Plan for Natural Disaster Recovery Federal Highway Adminstration, PI: Engineering and Software Consultants  Abstract: This project will develop a Disaster Recovery Action Plan (DRAP) for roadway infrastructure to assist transportation agencies in systematically incorporating natural disaster impacts into asset management practices. The DRAP will synthesize literature, peer exchanges, and case studies into a practical framework that links response, recovery, and rebuilding strategies to lifecycle performance outcomes. Deliverables include guidance documents, outreach materials, and a potential web-based tool. By documenting best practices and integrating decision-support methods, the project will enhance agencies’ resilience, cost efficiency, and reliability in post-disaster contexts, ensuring infrastructure performance expectations are safeguarded through systematic, lifecycle-oriented recovery approaches.
	Improving Asphalt Mixture Testing Efficiency North Carolina Department of Transportation, PI: Cassie Castorena (NCSU) Abstract: Efficient asphalt mixture design and quality assurance (QA) procedures are critical for ensuring durable pavements. However, performance tests like the Asphalt Pavement Analyzer (APA) and Tensile Strength Ratio (TSR) test are resource-intensive, limiting their feasibility in routine QA processes. Additionally, the absence of a complementary cracking test alongside the APA may unintentionally favor rutting resistance over balanced performance. This research investigates efficient alternative tests, such as monotonic indirect tensile (IDT) loading for rutting assessment and the Boil test with Asphalt Compatibility Tester (ACT) for moisture damage evaluation. The study will compare these alternatives to existing NCDOT tests in terms of correlation, sensitivity, and precision, while also exploring implementation strategies. The findings will support the adoption of more efficient QA practices, potentially integrating a cracking test and optimizing testing resources. Ultimately, this research aims to improve asphalt mixture performance assessments while reducing testing time, labor, and costs.
	University Transportation Centers of Excellence Sustainable and Resilience Infrastructure North Carolina Department of Transportation, PI: Tim Brock (NCSU, ITRE) Abstract: Developing sustainable and resilient infrastructure systems is vital to ensure that transportation investments deliver reliable, long term mobility options for the citizens of North Carolina. The North Carolina Department of Transportation (NCDOT) has shown a deep commitment to developing sustainable and resilient infrastructure to transportation facilities and systems across the state. To better prepare for and mitigate disruptions in the transportation network, NCDOT is developing a Center of Excellence focusing on sustainable and resilient infrastructure research. The portion of the research being carried out through this multi-institutional research consortium that involves PI Underwood will: identify and document the policy and process landscape related to NCDOT policy on asset management; develop a ranking system to aid the NCDOT in choosing strategies that manage infrastructure assets for resilience considerations; develop a decision support guideline that documents and quantifies the resilience impacts from engineering and operational strategies; identify the policy implications to implementing the guide; and and identify data sources that would aid expansion of the rankings for network prioritization.
	Impact of Flooding on the Resilience of Pavement Systems National Cooperative Highway Research Program, PI: Applied Pavement Tech. Abstract: Transportation agencies have dealt with natural events and their consequences for decades. However, recent extreme events have been particularly catastrophic and with climate change, projections suggest that these types of events will be more prevalent and impactful in the future. When these events occur, pavements are flooded and the life of these pavements can be greatly affected. This research will address these issues and meet the following objectives: Develop a guide for state departments of transportation (DOTs), local agencies, and practitioners to help quantify the effect of flooding on pavement systems, and improve pavement system resilience during planning, design, construction, operation, and maintenance in flood-prone areas. Develop a framework for state DOTs to incorporate analyses, material characterization, and other tools to consider the effects of flooding into mechanistic-empirical pavement design.
	Use of Artificial Intelligence to Unravel Asphalt Mixture Service Life (AIMLife) The Research Foundation – Flanders, PI: David Hernando (University of Antwerp) Abstract: The construction industry accounts for 50% of raw material consumption and 35% of CO₂ emissions in the EU, highlighting the need for sustainable solutions that extend material service life. In the road sector, variations in asphalt mixture composition—whether intentional for optimization or unintentional due to production inconsistencies—directly impact performance and longevity. Understanding these composition-driven factors is critical for designing durable asphalt mixtures. AIMLife aims to develop a physics-based AI framework to analyze how asphalt mixture composition influences service life. This collaboration between the University of Antwerp and North Carolina State University employs a multiphase research approach to enhance predictive modeling and decision-making. The project’s outcomes will support optimized mixture designs for extended durability and lower environmental impact, facilitate data-driven green public procurement, and quantify the effects of production deviations on service life. By integrating advanced AI-driven analysis, AIMLife seeks to revolutionize asphalt mixture design, ultimately contributing to more sustainable and resilient road infrastructure.
	ER23-C3-3683 – PFAS Transport and Interaction with Portland Cement and Asphalt Concrete: A Field and Laboratory Study SERDP, PI: Mohammad Pour-Ghaz (NCSU) Abstract: Portland cement concrete (PCC) and asphalt concrete (AC) exposed to AFFF have become an increasing challenge and environmental liability for the department of defense (DoD). Of critical importance to the DoD is the extent to which these AFFF-impacted materials are serving as a source of PFAS release to the environment due to PFAS leaching to stormwater runoff and migration to the substrate. The extent of this leaching for existing in-place materials, removed/stockpiled debris, and potentially recycled materials are unknown. The overarching goals of this proposal are to attain insight into PFAS leaching from AFFF-impacted PCC and AC to inform the management of these materials, understand the potential transformation of PFAS during PCC and AC recycling, and develop PFAS transport models that can translate standardized leaching test data to actual field leaching data.
	Advancing Sustainability and Resilience in Pavements: FHWA Sustainable Pavement Program Cooperative Center Federal Highway Administration, PI: John Harvey (UC Davis) Abstract: The sustainable pavement program has advanced the sustainability knowledge and practices in the area of pavements. Tangible outcomes include systematic methods for lifecycle assessment of pavements and initial guidelines on environmental product declarations. With new legislation, including the infrastructure law and inflation reduction act, there are even greater motivation for developing more sustainable and resilient pavement networks. In addition, programs like the FHWA Climate Challenge, FHWA Low-Carbon grant program, and Every Day counts initiative are further increasing demands for action and guidance from the US DOT. This proposed cooperative agreement will build upon the success of the sustainable pavements program by “exploring topics related to sustainability and resilience, including, but not limited to, sustainable and resilience infrastructure, equity, life cycle cost analysis (LCCA), LCA, social LCA, vulnerability assessment, use of low-carbon materials that are suitable to use in the US public road system, and other related topics.” The cooperative agreement will also advance the development and deployment of new technologies by delivering technical documents, case studies and tech brief, marketing/implementation plans, engaging subject matter experts, developing training tools, marketing of case studies, data analysis, compilation of findings, and supporting stakeholder engagement.