<?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%3ATtkf%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>Feasibility of Stabilized Titanium Gypsum as Roadway Subgrade Material: Evaluation of Geotechnical Properties and Leachability</title><link>http://pubsindex.trb.org/view/2711990</link><description><![CDATA[Leachates from unlined titanium gypsum (TG) dumps can pose significant environmental pollution risks to surrounding soils and groundwater. Reusing open-dumped TG as construction material is effective in alleviating the risks. This study presents a systematic evaluation of the geotechnical properties and leachability of novel binder-stabilized TG used as a roadway subgrade material. The binder consisted of reactive magnesia (MgO), ground granulated blast furnace slag (GGBS), fly ash (FA), and rice husk ash (RHA). Macroscopic and microscopic tests, including unconfined compression, one-dimensional swell, batch-type leaching, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy with energy-dispersive X-ray analysis, were conducted to evaluate the strength, swelling behavior, leachability, mineralogy, and microstructure of stabilized TG. Based on the consideration of strength and leached concentrations of chloride (Cl⁻) and sulfate ions (SO₄²⁻), in TG stabilized with 10% binder (by dry weight), the reactive MgO:GGBS:FA mass ratios in the binder were optimized as 1.3:5.2:3.5. The stabilized TG cured for 7 days under standard conditions possessed an unconfined compressive strength of 3.72 MPa and zero swell strain, whereas TG had an unconfined compressive strength of 0.73 MPa and a swell strain of 7.6%. Compared with TG, the concentrations of Cl⁻ and SO₄²⁻ leached from stabilized TG cured for 28 days decreased by 54% and 61%, respectively. Microscopic test results revealed that the formation of calcium-(ferrite)-silicate-hydrate and layered double hydroxides in stabilized TG was the primary mechanism for the immobilization of Cl⁻ and SO₄²⁻. The results are useful for facilitating safe utilization of TG in roadway construction.]]></description><pubDate>Wed, 10 Jun 2026 10:47:04 GMT</pubDate><guid>http://pubsindex.trb.org/view/2711990</guid></item><item><title>Assessment of Geopolymer Synthesis Parameters for Strength of Stabilized Fat Clay Using Statistical and Machine Learning Techniques</title><link>http://pubsindex.trb.org/view/2704073</link><description><![CDATA[Calcium-based chemical stabilizers are traditionally used for the stabilization of weak subgrade soils. However, these traditional stabilizers incur significant environmental costs which make them less desirable. As a result, alternative materials based on recycled waste and industrial byproducts are becoming popular. Geopolymers (GP) are a new addition to this list that are gaining traction because of their environmental benefits. GPs improve the soil by precipitation of a polymer gel as a result of mixing an alkaline activator (activator) with an aluminosilicate source (precursor). The effectiveness of GP and the improvement in engineering performance of GP-stabilized soils is contingent on sound GP synthesis parameters. This study investigates the effectiveness of GP-based treatments in improving weak soil and evaluates the significance of various parameters in contributing to the efficacy of GP treatment. As a result, a group of eight GP mixes was designed with a range of values for controlling parameters namely water/solid, activator/precursor, Si/Al and cation/Al ratios. A fat clay was treated by the application of these GP mixes at a dosage of 10% by dry weight. Improvements in mechanical strength were evaluated through unconfined compression strength testing. This was followed by statistical inference on laboratory strength data using analysis of variance (ANOVA) and post hoc tests. Ultimately, parameter importance was quantified by the random forest (RF) regression model. The results indicated that GP-based treatments enhanced the strength of untreated soil. Additionally, GP with higher aluminosilicate content and sufficient activator performed better. Overall, this study provides insight into the relative contribution of various GP synthesis parameters to the performance of GP-stabilized subgrade soils.]]></description><pubDate>Thu, 21 May 2026 09:09:19 GMT</pubDate><guid>http://pubsindex.trb.org/view/2704073</guid></item><item><title>Transportation Engineering 2.0: A Vision for the Future Transportation Engineering Workforce</title><link>http://pubsindex.trb.org/view/2701142</link><description><![CDATA[This study sought to advance a future-ready transportation engineering (TE) workforce by investigating emerging industry-wide challenges, essential skills, and opportunities for interdisciplinary collaboration. To accomplish this, a national survey was conducted with seventy transportation engineers and managers, using open-ended questions to capture perspectives on pressing transportation challenges, critical TE workforce competencies, and the current and future integration of engineering and non-engineering disciplines. Thematic qualitative coding of survey responses was applied to identify and analyze trends. The findings underscore the importance of integrating traditional TE with fields such as computer science, big data analytics, social sciences, behavioral science, and public policy to more effectively consider human behavior, transportation system safety and resilience, and broader societal impacts. Although the need for greater interdisciplinary integration is increasingly recognized, institutional barriers and underrepresentation persist in both education and practice. To address these gaps, a two-pronged strategy is recommended: (1) embedding interdisciplinary coursework and projects within university TE curricula and (2) offering professional development opportunities that expose practitioners to emerging technologies and non-engineering perspectives. Future evidence-based research should focus on how integrating socio-technical approaches into TE education and practice can better prepare the workforce to tackle the complex challenges of a rapidly evolving industry.]]></description><pubDate>Mon, 11 May 2026 12:24:46 GMT</pubDate><guid>http://pubsindex.trb.org/view/2701142</guid></item><item><title>Is Induced Travel Covered in Transportation Engineering Textbooks? Not Very Well</title><link>http://pubsindex.trb.org/view/2691796</link><description><![CDATA[Induced travel is the new travel that materializes after expanding infrastructure, and accounting for it is essential for accurately describing the long-term benefits and environmental impacts of a project. However, engineers rarely account for induced travel during project planning and environmental review, perhaps owing in part to unfamiliarity with and skepticism about induced travel. This research explores whether transportation engineering textbooks introduce students to the concept of induced travel. We conducted a systematic review of seven engineering textbooks to assess whether they 1) clearly define induced travel, 2) indicate the expected magnitude of induced travel, 3) feature the concept in problem sets to be consistent with engineering’s signature pedagogy, and 4) describe the implications of induced travel for engineering practice and transportation policy. Three textbooks omitted the idea entirely, whereas the others offered only partial coverage. No single textbook included all four essential elements. Beyond this, all textbooks placed a greater emphasis on accommodating demand rather than managing it. Textbooks also offered an asymmetric portrayal of how drivers adjust to traffic conditions. Overall, the engineering textbooks reviewed here leave students unprepared to understand induced travel or its implications.]]></description><pubDate>Tue, 14 Apr 2026 10:08:40 GMT</pubDate><guid>http://pubsindex.trb.org/view/2691796</guid></item><item><title>Study of On-Site Monitoring Analysis and Protective Measures for Long-Distance Parallel Excavation and Underlying Metro Tunnels</title><link>http://pubsindex.trb.org/view/2689787</link><description><![CDATA[With the acceleration of urbanization, the development and utilization of underground space have become increasingly common, leading to growing concerns about the impact of long-distance parallel excavation of deep foundation pits on underlying subway tunnels. This paper focuses on a foundation pit project where the parallel distance between the excavation area and the subway tunnel reached 270 m, using a combination of field monitoring and numerical simulation to analyze the deformation characteristics of subway tunnels during long-distance parallel excavation. The research results indicate that, with the increase in parallel distance, both vertical and horizontal displacements of the tunnel significantly increase. Furthermore, the “hardening soil” constitutive model achieved great simulation accuracy in modeling the deformation behavior of the soil surrounding the tunnel. Subway tunnel deformation control can be approached from three aspects: offsetting the additional stress load, improving the soil stiffness, and reducing the overall additional stress load. This study provides data support for further research on the impact of such extreme conditions on subway tunnels and offers a reference for designing and constructing similar engineering projects.]]></description><pubDate>Thu, 09 Apr 2026 09:01:27 GMT</pubDate><guid>http://pubsindex.trb.org/view/2689787</guid></item><item><title>Dynamic Response of Frozen Pisha Sandstone Reconstituted Soil under Multi-Stage Cyclic Loading</title><link>http://pubsindex.trb.org/view/2685657</link><description><![CDATA[The dynamic mechanical properties of basic fill soil in seasonally frozen regions are highly sensitive to temperature. This study investigates the dynamic behavior of a widely used fill material in the Loess Plateau Pisha Sandstone (PS) regions, namely, Pisha Sandstone Reconstituted Soil (PSRS), under multi-stage cyclic loading. A series of cyclic triaxial tests were conducted on PSRS under different temperatures (0, −5, −10, −15°C), confining pressures (100, 200, 300 kPa), and loading frequencies (1, 2, 5 Hz). The results indicate that the dynamic elastic modulus (DEM) exhibits three stages of variation: an initial elastic stage (with DEM remaining stable), an elastoplastic stage (DEM gradually increasing), and a failure stage (DEM rapidly decreasing). The maximum dynamic elastic modulus (DEM[subscript max]) increases rapidly as temperature decreases. When the temperature is constant, DEM[subscript max] is positively correlated with both the confining pressure level and the vibration frequency. During the non-failure loading stage, the damping ratio at 0°C first decays rapidly and then stabilizes slowly, whereas at −5°C to −15°C, it shows a pattern of rapid initial decay followed by stabilization. During the failure loading stage, the damping ratio of all temperature groups exhibits abrupt increases, but lower temperatures significantly delay the occurrence of the critical failure point. This study established a DEM[subscript max] prediction model for frozen PSRS based on the coupled effects of temperature, confining pressure, and frequency, with R² = 0.858 and mean absolute percentage error ≤ 7.73%. This model provides a practical theoretical framework and a reliable tool for predicting PSRS stiffness, which can guide the design and stability assessment of transportation infrastructure in cold regions.]]></description><pubDate>Tue, 31 Mar 2026 10:14:38 GMT</pubDate><guid>http://pubsindex.trb.org/view/2685657</guid></item><item><title>Predicting Metro Tunnel Deformation from Adjacent Excavation Using a Nonlinear Shear-Considered Model</title><link>http://pubsindex.trb.org/view/2684244</link><description><![CDATA[To more accurately predict existing shield tunnel deformation induced by adjacent excavation, this study developed a nonlinear Pasternak–Timoshenko model (NPTM). The model innovatively integrates nonlinear soil response with the tunnel’s structural shear deformation. Validation against a finite element model and two engineering cases confirmed the NPTM’s reliability. A key finding was that for wide excavations, soil nonlinearity dominated, and the deformation peak occurred at the excavation edge. Conversely, for narrow excavations, the tunnel’s structural shear behavior was more critical. Parametric analysis revealed deformation was highly sensitive to the pit–tunnel distance, d, and soil undrained shear strength, Sᵤ. Quantitatively, the benefit of increasing Sᵤ diminished significantly when Sᵤ exceeded 80 kPa. This suggests an economic threshold for ground improvement. Furthermore, deformation attenuated sharply when the pit–tunnel distance, d, exceeded 15 m. The model provides a practical, preliminary design tool for helping engineers to identify critical deformation zones and optimize protective measures.]]></description><pubDate>Thu, 26 Mar 2026 13:38:05 GMT</pubDate><guid>http://pubsindex.trb.org/view/2684244</guid></item><item><title>Propagation of Compaction Quality from Subgrade to Base Layer in Pavement Structures</title><link>http://pubsindex.trb.org/view/2646124</link><description><![CDATA[Density has long been the main quality control (QC) and acceptance (QA) indicator in pavement foundation construction; however, the nuclear density gauge (NDG) method has limitations in assessing large sections. These spot measurements are limited in depth and area and may be biased by outside factors. Deflection-based testing is a more promising alternative as the depth of influence is greater; however, it, too, is a spot test limited by the plate diameter. Intelligent compaction (IC), with an even deeper depth of influence, can cover the entire area and provide information almost in real time. An integrated approach that considers the density, deflection modulus, and IC stiffness is essential for a complete QC or QA evaluation. This paper focuses on the overall compaction of a pavement foundation by comparing NDG density and lightweight deflectometer (LWD) modulus with IC stiffness. Twelve lifts between two accelerated pavement loading test pits were analyzed in both the longitudinal and transverse paths of an IC-equipped soil compactor to show the limitations of current QA standards and how vital sublayer compaction control affects the upper lifts. NDG shows little to no variability across lifts, while LWD measurements show the opposite, consistent with IC. IC highlights that poor compaction in the subgrade or subbase layer propagates throughout the structure, leading to suboptimal compaction in the layers above, even if the density is consistent. These findings highlight the limitations in accepting density and how deflection and IC stiffness can help state highway officials ensure a more uniform product that will last longer.]]></description><pubDate>Tue, 30 Dec 2025 13:51:27 GMT</pubDate><guid>http://pubsindex.trb.org/view/2646124</guid></item><item><title>Design and Testing of Modular Expansion Joint Noise Mitigation Strategies</title><link>http://pubsindex.trb.org/view/2630562</link><description><![CDATA[This investigation focuses on the design and feasibility of noise mitigation strategies for installation in modular expansion joints (MEJs) on highway bridges. Expansion joints are necessary for effective bridge function but contribute greatly to surrounding noise pollution. The three primary sources of noise from MEJs identified include the resonance of the air within the gaps, the resonance of the beams, and the resonance of the tires. By incorporating engineered chevron support structures into the gaps of the MEJs, the research demonstrates the feasibility of significantly reducing noise emanating from MEJs. The novel chevron design flexes to expand and contract, matching the movement of the roadway but resisting vertical loading from cars driving overhead. The noise reduction treatment was applied to a westbound lane of the east MEJ on the SR 520 floating bridge across Lake Washington, connecting Seattle with the city of Medina, for a 2-month evaluation period. According to energy spectral density data collected from roadside audio recordings, this solution proved to be highly effective. At a distance of 160?ft from the joint, a noise reduction of more than 10?dB in the 500–900?Hz frequency range was recorded. Beyond 500?ft, the distinction between noise from the concrete road surface and from the MEJ diminished to the extent that it became challenging to discern when individual cars traversed the MEJ.]]></description><pubDate>Tue, 02 Dec 2025 09:53:44 GMT</pubDate><guid>http://pubsindex.trb.org/view/2630562</guid></item><item><title>Development of Geotechnical Asset Management for Embankments and Slopes (GAMES)</title><link>http://pubsindex.trb.org/view/2628302</link><description><![CDATA[Geotechnical asset management (GAM) systems are a critical element of transportation asset management plans. Geotechnical assets include walls, slopes, embankments, subgrades, and other features. A fully developed GAM system enables tracking of the condition of individual assets over time and the condition of each asset class as a whole. A GAM system can facilitate selection of appropriate corrective actions to optimize improvement measures and maintain and increase the value of the asset class. The objectives of this research were to develop a Geotechnical Asset Management tool for Embankments and Slopes (GAMES) in consultation with the Kansas Department of Transportation (KDOT) and to begin populating the tool with existing data. An inspection sheet was developed for use in assessing KDOT embankment slopes and cut slopes and computing a score for each based on the evaluation of nine criteria and weighted factors. Weights for the factors were developed using the analytical hierarchy process, for which 30 experts from North America were contacted as part of a systematic survey to rank the nine criteria. The overall rating accounts for safety/mobility risks. Twenty slopes were surveyed in cooperation with KDOT using the GAMES tool, and the results were found to accurately reflect the relative condition of the slopes.]]></description><pubDate>Tue, 25 Nov 2025 08:51:44 GMT</pubDate><guid>http://pubsindex.trb.org/view/2628302</guid></item><item><title>Bridge Construction Practices Using Incremental Launching</title><link>http://pubsindex.trb.org/view/2613661</link><description><![CDATA[Bridge construction over deep valleys, water crossings with steep slopes, or environmentally protected regions can offer many challenges. The incremental launching method (ILM) for bridge construction may offer advantages over conventional construction, including creating minimal disturbance to surroundings, providing a more concentrated work area for superstructure assembly, and possibly increased worker safety given the improved erection environment. The ILM involves assembly of the bridge superstructure on one side of an obstacle to be crossed, and then movement (or launching) of the superstructure longitudinally into its final position. Despite potential advantages for certain situations, the use of the ILM for bridge construction has been very limited in the United States. The objective of the work summarized in this report was to provide bridge owners, designers, and contractors with information about the ILM, including applications, limitations and benefits. To clarify the ILM procedure and the current state of practice, a comprehensive literature search and survey were conducted. Recommendations pertaining to best practices for planning, design, and construction activities, as well as applications and limitations for the ILM are also provided. Case studies are presented, which provide specific ILM bridge project information. The use of the ILM for bridge construction will never be the most efficient way to construct every single bridge. However, it is thought that a wider understanding of the applicability and potential benefits would allow potential owners, designers, and contractors to make well-informed decisions as to its use for their upcoming projects.]]></description><pubDate>Sat, 01 Nov 2025 18:26:25 GMT</pubDate><guid>http://pubsindex.trb.org/view/2613661</guid></item><item><title>Mechanical Analysis of Subgrades under Different Moisture Conditions</title><link>http://pubsindex.trb.org/view/2613379</link><description><![CDATA[Currently, Costa Rica’s pavement design is typically carried out using methodologies from the AASHTO or through AASHTOWare Pavement ME. However, sometimes the pavement structure designs are not optimal because these methodologies do not fully adapt to climatic conditions, material properties, and local calibration factors. Some pavement structures fail prematurely because of inadequate designs, often resulting from omission or miscalculation of certain factors in the initial design phase. Environmental effects, such as precipitation and groundwater levels, and traffic loads are among the most challenging to quantify yet most destructive factors affecting pavement structures. Increased moisture content in subgrades affects their mechanical properties and structural contribution to the pavement. Given Costa Rica’s climatic conditions, which favor critical moisture in subgrades from a structural standpoint, modeling the moisture impact on material properties allows one to quantify its influence on pavement performance. Therefore, incorporating unsaturated soil mechanics into pavement design and analysis enables the creation of structures that account for varying subgrades moisture conditions throughout the year. This approach acknowledges that soils are not constantly at 100% saturation. To obtain this moisture variation, soil-water characteristic curves were obtained for each soil and, with this information, the resilient modulus (RM) test was performed using different water contents and suctions. This report proposes a calibrated model for local conditions that predicts RM of soils under varying moisture conditions. The inclusion of this model in Costa Rica’s mechanistic-empirical design guide is suggested.]]></description><pubDate>Mon, 27 Oct 2025 16:42:54 GMT</pubDate><guid>http://pubsindex.trb.org/view/2613379</guid></item><item><title>Training Low-Volume Road Engineers in Developing Regions</title><link>http://pubsindex.trb.org/view/2593747</link><description><![CDATA[For the past three decades, low-volume roads best engineering and management practices training has been conducted in numerous developing countries, particularly in Latin America. The training has been primarily sponsored by the U.S. Department of Agriculture (USDA) Forest Service’s Office of International Programs and the U.S. Agency for International Development (USAID), with occasional support from local agencies, the World Bank, and various universities and nongovernmental organizations (NGOs). Initially developed beginning around 1995 in Guatemala, Forest Service-USAID courses have been delivered in nearly every country in Central and South America, as well as in Georgia, Haiti, Morocco, Nepal, Sudan, Uganda, and Ukraine - countries where the U.S. government has long had logging, social, or technical development programs. Rural roads courses, which typically last three to five days, have included classroom instruction and at least one field day to examine local road issues, review good and bad practice, and discuss engineering and environmental solutions such as water-quality protection and wildlife crossings. Training programs highlighted in this article include: (1) logging-road training program in Bolivia; (2) reduced impact logging program and Amazon roads manual in Brazil; (3) rural-roads training in Costa Rica; and (4) World Bank training in India and China.]]></description><pubDate>Tue, 07 Oct 2025 13:15:21 GMT</pubDate><guid>http://pubsindex.trb.org/view/2593747</guid></item><item><title>International Challenges for Low-Volume Roads Management</title><link>http://pubsindex.trb.org/view/2593743</link><description><![CDATA[Low-volume roads (LVRs) are a critical component of transportation infrastructure, particularly in developing countries where they connect rural communities to urban centers, schools, health care facilities, markets, and workplaces. These roads—typically unpaved and carrying low traffic volumes—play an essential role in delivering agricultural products and raw materials for consumption or further processing, enhancing accessibility and security, promoting local development and tourism, and serving as evacuation and emergency supply routes during natural disasters. However, managing LVRs presents significant challenges that can impact their effectiveness and sustainability. TR News 355 focuses on international LVRs and offers an overview of road use, technological innovations in their construction, maintenance and safety considerations, impacts of weather events, and training of the engineers who plan, design, build, and manage LVRs.]]></description><pubDate>Tue, 07 Oct 2025 13:15:21 GMT</pubDate><guid>http://pubsindex.trb.org/view/2593743</guid></item><item><title>Evaluation of the Risk Zoning of Collapse Disasters Based on Expert Systems</title><link>http://pubsindex.trb.org/view/2569601</link><description><![CDATA[Collapse hazards are the main type of geologic hazard along highway transportation routes. To determine the focus and order of prevention and control measures for road-bearing collapse disasters in Henan province, China, based on the results of the existing comprehensive risk survey of natural disasters, the collected data were flexibly utilized, the index system method was adopted, and geographic information system software (ArcGIS) was utilized for risk evaluation based on the intensity and sensitivity indices of road-bearing collapse disasters in the area. Moreover, based on the intensity index and sensitivity index, an evaluation model for the comprehensive risk index of collapse disasters was constructed via the index system method. This model was applied to assess the risk zoning of collapse disasters affecting highway hazard-bearing bodies in the Luoyang area. The rationality and reliability of the evaluation model were verified through typical cases of collapse disasters in Luoyang city. The study results revealed that the comprehensive risk index of road-bearing collapse disasters in this region ranges from 39.66 to 83.20, and the risk zoning results coincide well with the distribution of risk points. The risk of collapse disasters was differentiated through diagrams, and the corresponding risk zones were determined, and this could provide technical guidance for risk management of road-bearing collapse disasters in Henan Province, as well as disaster prevention and mitigation.]]></description><pubDate>Tue, 01 Jul 2025 13:55:57 GMT</pubDate><guid>http://pubsindex.trb.org/view/2569601</guid></item></channel></rss>