<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3AE%2A" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>A Multicriteria Analytical Framework for Site Selection of Mobility Hubs</title><link>http://pubsindex.trb.org/view/2711633</link><description><![CDATA[Mobility hubs (MHs) have emerged as a novel concept to enhance multimodal travel. A MH provides supporting infrastructure, amenities, and services for multimodal travelers at strategic locations, facilitating seamless integration of various modes. Despite growing interest in MHs, cities and transit agencies lack an established analytical framework for selecting optimal MH locations. To address this gap, we propose a multicriteria approach to identify locations for MH development within an existing or planned transit network. Our approach consists of four steps: 1) determine key criteria and collect data, 2) compute MH index for multiple scenarios, 3) identify MHs and assign typology, and 4) determine MH sites with community engagement. Our approach differs from existing methods by using transit stop clusters (obtained using a density-based clustering algorithm) as the unit of analysis, explicitly incorporating first-/last-mile connectivity as a primary consideration, and distinguishing the typology of each hub. We demonstrate and validate the approach by conducting case studies in Gainesville, Florida, and in West Palm Beach, Florida. In both cities, we have engaged the local transportation agencies and residents, whose inputs verified the desirability of the identified MH locations and confirmed the usefulness of the proposed approach. By combing data-driven analysis with community participation, our approach offers a valuable tool for transportation planners and policymakers in MH planning and development across diverse contexts. We acknowledge several limitations of the proposed approach and emphasize the role of this method as one step in a broader, stakeholder-driven planning process.]]></description><pubDate>Fri, 05 Jun 2026 11:27:53 GMT</pubDate><guid>http://pubsindex.trb.org/view/2711633</guid></item><item><title>Optimized Laboratory Fabrication of Small-Specimen Geometry for Streamlining Dynamic Modulus and Cyclic Fatigue Testing of Asphalt Mixtures</title><link>http://pubsindex.trb.org/view/2709230</link><description><![CDATA[The asphalt community is focused on the paradigm shift in mixture design from the volumetrics to an optimization procedure based on performance testing called balanced mixture design. Streamlining performance testing to obtain index properties quickly and using a smaller quantity of materials is critical for the successful implementation. This paper aims to streamline dynamic modulus (|E*|) and cyclic fatigue testing by optimizing the number of 38 mm diameter specimens extracted from a single 150 mm diameter Superpave gyratory-compacted (SGC) specimen. The current provisional standard methods require vertical coring of four small specimens from a single SGC specimen. In this study, two sets of testing specimens were fabricated by coring four and five small specimens from each SGC specimen. The success rate in meeting target air voids, the |E*| analysis, and the cyclic fatigue results including cyclic fatigue index parameter (Sₐₚₚ) values were compared between the two sets of specimens. No significant or consistent differences were observed in performance testing results. Furthermore, innovative image analysis and microscopy techniques were used to study air voids distribution and aggregate structure within each specimen and to further validate the proposed coring pattern. Based on these findings, coring five 38 mm diameter testing specimens from one SGC sample is suggested to run |E*| and cyclic fatigue tests. This proposed modification to AASHTO TP 132 and TP 133 may save technicians’ time and allows for the optimal use of materials. The latter may become a significant saving when integrating these methods with laboratory long-term aging protocols and forensic studies.]]></description><pubDate>Tue, 02 Jun 2026 11:01:49 GMT</pubDate><guid>http://pubsindex.trb.org/view/2709230</guid></item><item><title>Mechanistic Analysis and Design Framework for Geosynthetic Stabilized Unpaved Roads</title><link>http://pubsindex.trb.org/view/2709229</link><description><![CDATA[Geosynthetics provide mechanical stabilization benefits to paved or unpaved roads through lateral restraint of unbound aggregate particles and bearing capacity improvement over weak subgrades. The current state of the art incorporating geosynthetics into paved or unpaved road design involves conducting proper elastic layered system mechanistic analysis to determine the improvement of aggregate layer stiffness for increased traffic capacity or reduction in aggregate layer thickness. This paper presents a mechanistic analysis and design pipeline for determining the required aggregate thickness via the finite element (FE) modeling approach. An advanced FE analysis tool, C-FLEX, was employed to analyze axisymmetric multilayered unpaved road structures, accounting for the nonlinear stress-dependent behavior of unbound aggregates. The modulus enhancements were quantified for 10 different geosynthetics using the latest Bender Element sensor technology in both triaxial and large-scale tests conducted on typical dense-graded base aggregates. They were then incorporated into base course stiffness characterization via a sublayering approach for the unpaved road comprising aggregate base placed over soft subgrade. Both the measured enhanced moduli and the the extent of geosynthetic influence zones were adequately established in the sublayering approach. Further, sensitivity analysis was conducted for different aggregate modulus models and different sublayer structures, which verified the proposed design pipeline to provide satisfactory results. The method was also compared with the Giroud and Han method, which revealed the inherent difference in the two methods, given that the design here is based on the critical pavement responses and subgrade strength, while the Giroud and Han method also incorporated the field data with performance evaluation.]]></description><pubDate>Tue, 02 Jun 2026 11:01:49 GMT</pubDate><guid>http://pubsindex.trb.org/view/2709229</guid></item><item><title>Evaluating the Safety Impact of Roadway Rightsizing in Jefferson County, Kentucky</title><link>http://pubsindex.trb.org/view/2709128</link><description><![CDATA[This research provides a safety assessment of rightsizing projects that took place in Jefferson County, Kentucky. Rightsizing has become increasingly popular as a solution for multimodal access improvements and enhancing roadway safety. A cross-sectional before–after analysis was applied to a 15-year panel dataset from 2010 to 2024 to estimate the impact of rightsizing on crash frequency. A matched control group was developed using traffic volume and segment length using nearest-neighbor approach. Negative binomial safety performance functions were estimated with untreated sites and adjusted with annual calibration factors for seasonal changes consideration. Empirical Bayes methods were applied to correct for regression-to-the-mean bias and estimate counterfactual crash frequencies. Crash modification factors (CMFs) were calculated and disaggregated by crash type (all, bicycle, pedestrian, and intersection-related) and severity level (KA, BC, O). The analysis reveals that rightsizing treatments were associated with a 32% reduction in fatal and severe injury crashes, and consistent crash reductions at intersections. However, elevated CMFs across all severity levels for bicycle crashes suggest increased risk, potentially because of higher exposure without corresponding protective infrastructure. Pedestrian findings varied by severity level. The findings highlight crash severity reduction potential for rightsizing while indicating a requirement for including facilitative infrastructure for protection of vulnerable road users. The study includes practical recommendations for transportation agencies considering rightsizing as part of a broader safety and multimodal mobility initiative.]]></description><pubDate>Tue, 02 Jun 2026 11:01:49 GMT</pubDate><guid>http://pubsindex.trb.org/view/2709128</guid></item><item><title>Comparison of Pavement Roughness Indicators from Traditional Inertial Profilers and Emerging Connected Vehicle Sensors</title><link>http://pubsindex.trb.org/view/2709233</link><description><![CDATA[This study is an evaluation of the consistency and potential of crowdsourced connected vehicle (CV) data as an alternative to traditional inertial profiler (IP) measurements for road roughness evaluation. IP data were collected from three roadway corridors, SH 21, SH 6, and FM 2818, in Bryan, Texas, which comprised a variety of pavement types and functional classifications. Lane-specific international roughness index (IRI) values were recorded using a calibrated inertial profiler and analyzed at every 10 ft. These were compared with direction level ride values collected at an average spacing of 82 ft from a third-party CV data provider. A general agreement was found between IP and CV data on asphalt and concrete surfaces, but there were substantial differences between seal coat sections, where CV ride values overestimated roughness by 80–100 in./mi. A grouping analysis was conducted to compare segments categorized by roughness level from both datasets. The results showed a moderate match in identifying the roughest segments by the CV system, compared with those identified by IP. This match rate varied by profile and improved with broader grouping sizes. Results show that CV data might have greater sensitivity to vehicle behavior (for example, braking at intersections), while IP-based systems are calibrated to record actual road roughness. This could be one of the reasons for the moderate mismatch in identifying rougher segments using the two methods. Despite these limitations, the CV system’s high frequency of measurements, especially on highways, demonstrates its potential for cost-effective, network-level pavement monitoring.]]></description><pubDate>Mon, 01 Jun 2026 16:52:46 GMT</pubDate><guid>http://pubsindex.trb.org/view/2709233</guid></item><item><title>Cold-in-Place Recycling with 100% Recycled Asphalt Pavement Rejuvenated by Soybean Oil: Laboratory and Field Evaluation</title><link>http://pubsindex.trb.org/view/2709232</link><description><![CDATA[This study investigated the feasibility and performance of using soybean oil as a bio-based recycling agent in recycled asphalt pavement (RAP) for road reconstruction in cold regions. A comprehensive demonstration project was conducted on a 5-mile section of Old State Road in Clare County, Michigan, where a 100% RAP mixture modified with soybean oil was produced and placed using a conventional asphalt paver equipped with a screed. Laboratory evaluations included balanced mix design, rutting and cracking testing, and binder performance analysis. Field application processes, including mixing and compaction, were also documented and evaluated. The asphalt mixture tests included the Hamburg wheel-tracking test (HWTT) and the indirect tensile asphalt cracking test (IDEAL-CT), while the asphalt binder tests included dynamic shear rheometer (DSR), asphalt binder cracking device (ABCD), rotational viscometer (RV), linear amplitude sweep (LAS), Fourier transform infrared spectroscopy (FTIR), and CO2 emission analysis. An optimal soybean oil dosage of 1.0 wt.% (based on the total weight of the mix) significantly improved low-temperature cracking resistance and fatigue life while maintaining rutting resistance. Results showed that soybean oil improved compaction performance and exhibited a cracking temperature approximately 3.3°C lower than that of untreated RAP based on the ABCD test. Fatigue performance was also enhanced. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the chemical compatibility and interaction between soybean oil and the RAP binder. On-site application was completed smoothly without workability issues, and the final pavement met all compaction and density requirements. In summary, using soybean oil as an RAP recycling agent provides a practical and environmentally friendly solution to improve the performance of recycled asphalt mixes, especially for low-volume roads in cold climates, while supporting the sustainability of Michigan’s pavement and the growth of the soybean market.]]></description><pubDate>Mon, 01 Jun 2026 16:52:46 GMT</pubDate><guid>http://pubsindex.trb.org/view/2709232</guid></item><item><title>Evaluation of Critical Pavement Responses from Accelerated Pavement Testing on Airfield Flexible Pavements Surfaced with Hot and Warm Mix Asphalt</title><link>http://pubsindex.trb.org/view/2709231</link><description><![CDATA[Highway agencies frequently use warm mix additives as compaction aids. Lower production temperature of the warm mixes simultaneously entails the benefit of widening the paving window. Airport authorities can ensure significant fiscal savings with reduced downtime through the adoption of similar technologies in airfield paving. However, limited scientific information exists concerning the performance of these materials in airside flexible pavements. Aircraft gross weights and tire pressures have also been routinely increasing over the last few decades with the advent of new-generation aircraft. The Federal Aviation Administration (FAA) procured a sixth-generation heavy vehicle simulator, airfields (HVS-A) to investigate the performances of resilient pavement materials under simulated aircraft loading. Accordingly, six full-scale test lanes were constructed during Test Cycle 1 (TC1) at FAA’s National Airport Pavement and Materials Research Center (NAPMRC) using four different asphalt concrete (AC) mixes with two different binder grades. Each test lane was divided into three test sections. Asphalt strain gauges and pressure cells were installed in the test sections to monitor the critical pavement responses over the duration of traffic tests. Corresponding test sections were trafficked under different combinations of high tire pressure and temperature. This paper examines the tensile strains at the bottom of AC and compressive stresses on top of the subgrade in reference to the observed rutting performances in four TC1 outdoor test lanes. The respective hot and warm mixes exhibited comparable rutting performances, and the sensor observations corroborated the related findings.]]></description><pubDate>Mon, 01 Jun 2026 16:52:46 GMT</pubDate><guid>http://pubsindex.trb.org/view/2709231</guid></item><item><title>Examining the Role of the Built Environment in Cycling Injury Severity: Older Adults (60+) Versus Individuals Aged 10 to 59 in a Super-Aged City</title><link>http://pubsindex.trb.org/view/2706341</link><description><![CDATA[Cycling offers well-documented benefits, including reduced congestion and air pollution, enhanced mobility, and improved physical health. Reflecting these advantages, cycling participation has increased across all age groups in many developed countries. However, this growth has been accompanied by a rise in cycling crashes, raising significant urban safety concerns—particularly for older adults. Although numerous studies have investigated factors influencing the injury severity of cycling crashes, the built environment has consistently emerged as a key determinant. Nevertheless, limited research has specifically explored how micro-level built-environment characteristics are associated with the injury severity of bicycle crashes, especially among older adults. This study investigates the association between built-environment characteristics and the injury severity of bicycle crashes involving older adults, analyzing 10,502 crash cases in Seoul from 2018 to 2023 using a binomial logistic regression model. To capture detailed built-environment attributes, we applied DeepLabV3+ for semantic segmentation of Google Street View images collected from four directions at each crash location. The results indicated that higher proportions of road surfaces, obstacles, and vegetation were associated with increased injury severity among older adults (60+), whereas the presence of traffic devices reduced injury severity. Among individuals aged 10 to 59, greater building density was linked to lower injury severity. A common risk factor across both age groups was collisions with motor vehicles. These findings underscore the necessity of age-sensitive safety interventions. For older adults in particular, measures such as separating cycling paths from obstacles and increasing the installation of traffic control devices may help improve cycling safety.]]></description><pubDate>Thu, 28 May 2026 10:47:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/2706341</guid></item><item><title>Improving Pavement Sustainability and Resilience: Pavement Life Cycle Cost Analysis Case Study</title><link>http://pubsindex.trb.org/view/2706168</link><description><![CDATA[The effects of climate change and extreme weather have caused flooding and inundation of many roadways, resulting in numerous pavement failures and negatively affecting the condition and functionality of pavement networks. This has driven a growing focus on creating resilient infrastructure, including the use of rigid pavement sections in flood-prone areas. The higher cost of these solutions requires justification through performance and economic analyses. In this study, a life cycle cost analysis (LCCA) of rigid and flexible pavement designs is conducted using the North Carolina pavement design procedure to develop equivalent performance across alternatives. Initial and long-term costs were evaluated using deterministic and probabilistic methods. Findings suggest that optimized jointed plain concrete pavement can be a cost-effective alternative in widened lane configurations without shoulder drains. Unbonded concrete overlays also proved to be competitive when rigid pavement pricing remained stable. The high variability in rigid pavement pricing remains a concern. Probabilistic LCCA results revealed that including shoulder drains significantly influences cost-effectiveness. Rigid pavements with high truck traffic volume are required to have shoulder drainage in accordance with the agency's pavement design guidance. In this study, the LCCAs for the rigid pavement alternatives were analyzed with and without shoulder drainage to determine its impact on the cost-effectiveness of rigid pavement. Full-depth asphalt was the most economical option in over 80% of cases when shoulder drains were included, whereas rigid alternatives became more competitive when drains were excluded. Results underscore the need for a balanced approach in pavement design requirements and competitive bidding environments to enhance sustainability, resilience, and cost-effectiveness in pavement investments.]]></description><pubDate>Wed, 27 May 2026 13:06:57 GMT</pubDate><guid>http://pubsindex.trb.org/view/2706168</guid></item><item><title>Coastal Flooding on Transportation Infrastructures: Systematic Review of Patterns, Impacts, and Methodologies</title><link>http://pubsindex.trb.org/view/2706089</link><description><![CDATA[Critical transportation infrastructure—central to societal well being and economic activity—is facing increasingly severe risks from coastal flooding intensified by climate change and sea-level rise. Although the vulnerability of low-lying transportation networks is widely recognized, existing research on their complex and often systemic failure mechanisms remains fragmented across disparate disciplines, highlighting the need for a systematic synthesis to guide resilient decision-making. To address this gap, this study conducts a systematic literature review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, synthesizing findings from 83 peer-reviewed articles published between 2000 and 2025. Results reveal a clear evolution in the field, shifting from isolated single-hazard assessments toward more comprehensive evaluations of compound coastal events. However, three major deficiencies are identified. First, aligning with the Intergovernmental Panel on Climate Change Sixth Assessment Report hazard typology, the review identified a widespread omission of preconditioned events, specifically vertical land motion and subsidence. Second, a methodological disconnect exists between hydraulic modeling approaches and structural engineering analyses, limiting integrated risk characterization. Third, the literature exhibits strong model skew, with approximately 70% of studies exclusively targeting roadway systems, thereby overlooking cascading, system-level disruptions across critical intermodal nodes such as ports and railways. These findings underscore the need for next-generation modeling frameworks that integrate nonclimatic drivers, capture multimodal interdependencies, and support probabilistic, forward-looking, evidence-based adaptation strategies for coastal transportation resilience.]]></description><pubDate>Wed, 27 May 2026 13:06:57 GMT</pubDate><guid>http://pubsindex.trb.org/view/2706089</guid></item><item><title>Traffic Object Detection Across Diverse Environmental Conditions: Comparative Performance Evaluation of Computer-Vision Models</title><link>http://pubsindex.trb.org/view/2706173</link><description><![CDATA[This paper introduces a novel evaluation framework for systematically assessing the performance of computer-vision models in traffic-surveillance and autonomous-vehicle applications under varying environmental conditions. The framework integrates synthetic-data generation with structured experiments to analyze model performance across different weather and lighting scenarios, addressing the lack of controlled datasets for true apple-to-apple comparisons. The results obtained based on synthetic and real-world video data reveal key trade-offs between detection accuracy, inference time, and environmental resilience across different model categories. One-stage models, such as YOLO, exhibit high inference speed but suffer significant performance degradation in adverse weather, whereas RetinaNet and SSD demonstrate greater robustness. Two-stage models, particularly Faster R-CNN, provide higher accuracy and stability but require longer inference times. Diffusion-based models fail in surveillance-camera views, highlighting training limitations. Also, illumination changes affect detection performance less than rain and snow, likely because of better representation of lighting variations in training datasets. This work is among the first to systematically quantify performance degradation under controlled environmental conditions, providing valuable insights for real-world deployments in intelligent transportation systems.]]></description><pubDate>Wed, 27 May 2026 10:48:02 GMT</pubDate><guid>http://pubsindex.trb.org/view/2706173</guid></item><item><title>Digitalization of Maritime Transportation Disputes: Legal Harmonization and Procedural Gains through Online Dispute Resolution</title><link>http://pubsindex.trb.org/view/2706171</link><description><![CDATA[The maritime sector faces increasing pressure to modernize dispute resolution systems as digitalization exposes known gaps in enforceability, procedural consistency, contractual comprehension, and cross-border risk, while also introducing uncertainties linked to emerging technological and legal challenges. This study evaluates the functionality of current maritime resolution systems and the limited uptake of the Rotterdam Rules—despite their objective to provide legal certainty and uniformity for multimodal carriage since 2009—highlighting their relevance to digital processes. It situates online dispute resolution (ODR) within maritime law by examining doctrinal compatibility with admiralty jurisprudence and established arbitration frameworks, including high-court interpretations of party autonomy, fairness, and evidence standards. The research adopts an institutional–organizational perspective to position the proposed political-institutional paradigm within broader public, private, and compliance-governance structures that guide system integrity and mitigate risks of noncompliance and embedded bias. It clarifies jurisdictional limits and liability transitions along end-to-end transport chains to support structured, platform-ready ODR pathways for multimodal disputes. The analysis also notes that existing treaty frameworks do not preclude the use of electronic processes, offering interpretive space for digital adjudication. The model emphasizes coordinated standard-setting by the International Maritime Organization, the Baltic and International Maritime Council, and the United Nations Commission on International Trade Law to ensure neutral, legally harmonized, and technically reliable ODR protocols. In line with cooperative principles reflected in instruments such as the Law of the Sea Convention, this study affirms ODR as a complementary and forward-looking mechanism. Analysis of 194 maritime cases shows ODR can yield nonarbitrary, efficient, and cost-effective outcomes, complementing the gradual evolution of instruments such as the Rotterdam Rules.]]></description><pubDate>Wed, 27 May 2026 10:48:02 GMT</pubDate><guid>http://pubsindex.trb.org/view/2706171</guid></item><item><title>Transit Network Design and Frequency Setting Model Driven by Interchange Stations and Improved NSGA-II Algorithm</title><link>http://pubsindex.trb.org/view/2706169</link><description><![CDATA[The core of the transit network design and frequency setting problem lies in balancing passenger travel efficiency and operator operating costs. However, existing methods generally rely on physical distance to measure site relevance, which makes it difficult to reflect the actual connections between passenger flows. At the same time, existing algorithms are inefficient and produce poor-quality solutions when dealing with multiobjective strong constraint optimization in networks, making it difficult to effectively coordinate the optimization of complex decision variables such as route paths, station attributes, and interchange relationships. To this end, we propose a collaborative optimization framework that integrates graph representation learning and improved multiobjective evolutionary algorithms from the perspective of interchange stations. First, improved graph convolutional networks are used to deeply mine network topology and passenger flow allocation information. Through third-order neighborhood aggregation, high-order feature vectors of nodes are learned, overcoming the limitations of traditional physical distance measurements. Second, a three-layer multipopulation chromosome coding mechanism (route path, station attributes, interchange relationship) and customized genetic operators (chromosome-to-chromosome/intrachromosome crossover, perturbation strategy) based on NSGA-II were designed to effectively handle complex decision variables and construct a mathematical model containing seven types of constraints, including network topology connectivity, passenger flow allocation rules, and operational coordination. Finally, experiments on the Mandl benchmark network showed that this method achieved a minimum total travel time of 199,825.65 min, a maximum direct rate of 98.89%, and a minimum average travel time of 12.76 min on a network with six lines. The proposed method eliminates secondary and higher interchanges and unmet demand in all scenarios, with a single interchange rate controlled between 1.11% and 4.41%. By adjusting the interchange penalty coefficient through sensitive parameters, the Pareto equilibrium between operator costs and passenger travel time is significantly optimized. Compared with existing methods, we show significant advantages in solution efficiency and plan quality, providing a reference for transit network optimization.]]></description><pubDate>Wed, 27 May 2026 10:48:02 GMT</pubDate><guid>http://pubsindex.trb.org/view/2706169</guid></item><item><title>Managing Highway Stormwater Quality: Driving Progress</title><link>http://pubsindex.trb.org/view/2706309</link><description><![CDATA[Our roads are both a source of and a conveyance system for pollutants to bodies of water via stormwater runoff. This report focuses on engineering and infrastructure strategies to support state departments of transportation (DOT) decision-making regarding stormwater management approaches to comply with regulations. Administered by the U.S. Environmental Protection Agency (EPA), state permitting authorities identify each water body that does not meet a water quality standard due to pollutants. Updated modeling options that account for different land uses can better enable state DOT decision makers. Acknowledging the difference in pollutants that originate from highways (such as tire and brake wear contaminants) and pollutants that do not but are conveyed to water bodies (such as nutrients and bacteria from adjacent land) may improve source control. The report also identifies areas for collaboration between state DOTs, EPA, and Federal Highway Administration officials along with state environmental authorities. These partnerships could result in improved design, construction, and maintenance procedures and guidance. Participation in alternative watershed-scale approaches for managing highway stormwater may also result in practical and desirable outcomes.]]></description><pubDate>Tue, 26 May 2026 13:17:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/2706309</guid></item><item><title>Balancing Thickness and Quality: Economic Design Framework for Flexible Pavement Foundations in Minnesota</title><link>http://pubsindex.trb.org/view/2705415</link><description><![CDATA[In Minnesota, pavement designers have traditionally favored premium Class 5/6 base aggregates directly beneath asphalt or concrete surface layers, while relegating lower-quality materials to thicker subbase layers or excluding them entirely. With the limited supply of high-quality aggregates and the steady increase in transportation costs posing restrictions for pavement construction and maintenance, local agencies are increasingly exploring the use of lower-quality, locally available materials in pavement foundation layers. This study evaluated the effects of both material quality and layer thickness requirements of base and subbase on flexible pavement performance and the associated cost, with the objective to develop an optimal design framework for statewide use, particularly in areas where locally sourced high-quality aggregates are limited. To this end, resilient modulus and strength characteristics were studied to classify Minnesota aggregate sources into high-, medium-, and low-quality levels, which were then incorporated into MnPAVE mechanistic pavement analyses for multiple traffic loads, asphalt thicknesses, subgrade stiffnesses, and Minnesota climate zones. In parallel, cost–benefit analyses were conducted to identify the most economical quality–thickness combinations of unbound aggregate base and subbase using historical bid-price data available from Minnesota Department of Transportation (DOT). An iterative procedure developed for a design framework in this research effort determines the optimal base and subbase thicknesses each aggregate quality level is required to satisfy fatigue- and rutting-life criteria for conventional flexible pavements. The resulting guidance enables local agencies to use regional materials more efficiently when high-quality aggregate materials are in short supply, while delivering sustainable and cost-optimized pavements across the state.]]></description><pubDate>Tue, 26 May 2026 09:44:22 GMT</pubDate><guid>http://pubsindex.trb.org/view/2705415</guid></item></channel></rss>