<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <copyright>Copyright © 2026. 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>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>Enhancing pedestrian thermal comfort in subtropical cities: an integrated spatiotemporal analysis of tree morphology and route planning</title>
      <link>https://trid.trb.org/View/2706720</link>
      <description><![CDATA[Street trees are known to be a key element in mitigating thermal discomfort within urban canyons, yet most current research tends to optimize tree morphology or analyze route selection independently. This study utilizes ENVI-met simulations and the Weighted Outdoor Thermal Comfort Autonomy (OTCAw) index to systematically evaluate the performance of 54 tree morphologies under different street orientations. Hierarchical partitioning and interaction models were applied to identify the context-dependent contribution patterns of morphological parameters, while route-level OTCAw and dynamic physiological indicators were used to assess the combined effects of tree morphology and pedestrian route choice. Results show that Leaf Area Density, as a key parameter, provides a stable and foundational independent contribution averaging 25.8%, while geometric parameters such as Crown Height and Crown Width primarily exert their influence through joint effects. Based on these findings, this study proposes differentiated optimal tree morphologies for different orientations. At the route level, combining the optimal tree morphology with the optimal route increased OTCAw to 92.7%, exceeding all single-domain optimization scenarios. Thermophysiological evaluation further showed that the integrated strategy reduced skin temperature by up to 2.1°C and sweat production by up to 88.5% during the hottest period of the day. These findings support the combined use of orientation-specific greening design and route-level pedestrian guidance to improve heat adaptation in subtropical urban streets.]]></description>
      <pubDate>Mon, 24 Aug 2026 09:03:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/2706720</guid>
    </item>
    <item>
      <title>Spatial Analysis of Microbiological Behavior in Sub-Tropical Coastal Wetlands</title>
      <link>https://trid.trb.org/View/2703857</link>
      <description><![CDATA[This study examines the spatial interactions between microbiological indicators and environmental factors, including water flow characteristics, in the coastal wetlands of Chabahar Bay, Iran, to assess ecological risks and guide conservation strategies. The objectives are to quantify Total Coliforms (TCs) and Fecal Coliforms (FCs) at six sampling stations and identify key environmental drivers of microbial proliferation through qualitative analysis. Field sampling was conducted over three days in October 2018 at six stations along a river feeding Chabahar’s coastal wetland. Water samples were collected during low tide. In-situ measurements of temperature, pH, humidity, and electrical conductivity were recorded. Microbiological analyses quantified total and fecal coliforms using the Most Probable Number (MPN) method. Total Organic Carbon (TOC) was measured using standard laboratory procedures, and Total Organic Matter (TOM) was determined by the loss-on-ignition method. Duplicate samples ensured data reliability, and data normality was tested with the Kolmogorov-Smirnov test. Descriptive statistics, graphical methods, and matrix analysis assessed relationships between TCs, FCs, temperature, pH, EC, TOC, and TOM. TC counts peaked at S2 (1500 MPN/100 ml), exceeding Iranian Class 2 water quality standards (1500 MPN/100 ml), with FCs detected only at S2 (900 MPN/100 ml) and S3 (23 MPN/100 ml). Temperature ranged from 30.6°C (S6) to 35.9°C (S1), showing an inverse relationship with coliform levels. EC ranged from 1900 to 24,610 µS/cm, displaying a strong inverse correlation with TCs and FCs due to salinity-induced osmotic stress. TOC and TOM peaked at S3–S4 (TOC: 2.8–3.2%; TOM: 5.1–6.0%), correlating inversely with TCs and FCs, suggesting microbial competition. pH (7.71–8.06) showed no significant correlation with coliform levels. Matrix analysis confirmed a high correlation between total and fecal coliforms (p < 0.05), with temperature and pH as independent factors. Sewage inputs at S2 drive significant microbial contamination, with coarse sediments and optimal temperatures facilitating coliform proliferation, while high EC and organic matter in mangrove zones (S3–S4) reduce coliform levels through osmotic stress and microbial competition. Mangroves at S4–S5 act as effective biofilters, mitigating contamination. These findings underscore the need for targeted sewage control and mangrove conservation to protect Chabahar Bay’s wetlands from ecological risks. Future research should examine seasonal variations and additional pollutants to improve management strategies.]]></description>
      <pubDate>Wed, 20 May 2026 13:50:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2703857</guid>
    </item>
    <item>
      <title>Mechanistic and spatiotemporal evolution of alkali-pumping in newly constructed bridge pavements in subtropical environments</title>
      <link>https://trid.trb.org/View/2654764</link>
      <description><![CDATA[In hot and humid regions, early alkali-pumping frequently occurs in newly constructed asphalt pavement layer on cement concrete bridge deck, with surface whitening often observed even before the bridge is opened to traffic. This phenomenon severely compromises the durability and service performance of the bridge deck system. To elucidate its formation mechanism and dominant influencing factors, this study investigates a newly built cement concrete bridge deck located in a typical subtropical climate zone, where extensive surface whitening occurred even before the bridge was opened to traffic. A combination of field investigation, permeability testing, ground penetrating radar (GPR), computed tomography (CT) scanning, and X-ray analyses (XRD/XRF) was employed to systematically explore the water migration pathways and the spatiotemporal characteristics of alkali-pumping evolution. The results indicate that the early occurrence of alkali-pumping is closely related to insufficient interlayer compaction, moisture accumulation in structural depressions, and preferential infiltration through poorly drained zones such as shoulders and joints. CT analysis demonstrated the presence of interconnected pores within the asphalt layer, which serve as channels for upward moisture migration and calcium ion transport. XRD and XRF tests confirmed that the alkali-pumping products are primarily composed of calcium carbonate, originating from the free calcium components in the cement concrete decks. This study advances the theoretical understanding of alkali-pumping in cement concrete bridge decks under hot and humid environments and provides a scientific basis and technical reference for improving structural design and early-stage damage prevention.]]></description>
      <pubDate>Wed, 01 Apr 2026 11:46:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2654764</guid>
    </item>
    <item>
      <title>Active route choice to minimize pedestrian thermal discomfort in a high-density subtropical city</title>
      <link>https://trid.trb.org/View/2587459</link>
      <description><![CDATA[Overheating of cities is becoming increasingly critical due to the combined effects of urban heat islands and global climate change, impacting walkability and public health, particularly in high-density tropical or subtropical cities. While interventions such as shading and green infrastructure can mitigate street heat, their effectiveness is limited by resource constraints and the dynamic nature of urban microclimates. Most existing studies focus on streets themselves, overlooking how pedestrians actively select walking routes based on thermal comfort. This study proposes an active route bioclimatic choice framework that minimizes pedestrian heat exposure and discomfort. Using high-resolution microclimate simulation and exhaustive path generation, over 2.2 million pedestrian routes were created for 1200 origin-destination (O-D) pairs in a densely populated district of subtropical Hong Kong. A route-level thermal discomfort index, PetL, was developed by integrating Physiological Equivalent Temperature (PET) values exceeding a pre-defined discomfort threshold along each segment length. Results show that thermally-driven routes outperform shortest routes for 81 % of the O-D pairs, reducing thermal discomfort by up to 96 %. In contrast, simple shade-based routing proved unreliable, highlighting the limitations of shade as a sole criterion for pedestrian route selection. The effectiveness of thermally-driven route choice varied at different times of day, peaking in the early morning, and increased with both route length and permissible detour length, largely stabilizing at 700–800 m and 110 % of the shortest path, respectively. The approach presented in this paper can be embedded in pedestrian navigation systems to enhance walkability and reduce thermal exposure, especially for vulnerable urban populations, thereby promoting healthier, climatically adaptive, and more active urban living. A street renewal strategy is also proposed, prioritizing segments that are both thermally stressful and frequently used. The open-access dataset offers a robust foundation for future research.]]></description>
      <pubDate>Fri, 26 Sep 2025 13:39:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2587459</guid>
    </item>
    <item>
      <title>A Guide to the Structural Design of Surfaced Roads in Tropical and Sub-Tropical Regions: Integrating Climate Resilience into Road Networks</title>
      <link>https://trid.trb.org/View/2143893</link>
      <description><![CDATA[TRL's Road Note 31, first published in 1962 and revised in 1966, 1977 and 1993, takes account of advances in road materials and pavement design. This fifth edition covers new technologies, techniques and materials to make paved roads in low- and middle-income countries in tropical and subtropical regions affordable, efficient, and resilient to climate change. It is directed at highway engineers working on pavement maintenance and road design and construction, and is applicable to roads that carry up to 80 million equivalent standard axles in one direction. The design of concrete roads and strengthening overlays is covered but earth and gravel roads are not covered. (Design guidance for unpaved roads and low-volume roads can be found in Rural Road Note 01 (2020). While design of roads in urban areas is covered, some aspects of urban roads, such as curbs, subsoil drainage, and skid resistance are not covered.]]></description>
      <pubDate>Thu, 18 May 2023 17:08:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2143893</guid>
    </item>
    <item>
      <title>Effects of urban tree planting on thermal comfort and air quality in the street canyon in a subtropical climate</title>
      <link>https://trid.trb.org/View/2121646</link>
      <description><![CDATA[Planting trees is considered to relieve the thermal load. However, trees may "pollute" the air quality. Tree net effects should receive more attention, but only a few studies have simultaneously addressed thermal comfort and air quality. By computational fluid dynamics (CFD) simulations, the authors created an evaluation model of trees and investigated the overall effects of tree planting inside street canyons. They considered the following four parameters by comparing seven common tree species in Hong Kong (subtropical climate): three tree morphological indicators (leaf area index (LAI), tree height (Hₜᵣₑₑ), and crown spread (Scrown)) and tree planting density (Pₜᵣₑₑ). The results demonstrated that under a high ambient wind speed, higher trees with a lower near-ground leaf area density are better options, which more greatly reduces the physiological equivalent temperature (PET) by up to 1.1 K but causes the least pollutant accumulation. Bigger-crown trees on the windward side are advocated, while smaller ones are suitable for the leeward side. In such a way, there was at least a 0.7 K decrease in PET on the tree-planted side while maintaining better air quality. Thermal comfort can be improved by increasing LAI or Pₜᵣₑₑ, but a higher LAI or Pₜᵣₑₑ causes a greater accumulation of pollutants. Increasing Pₜᵣₑₑ can cause a 1.1 K reduction in PET, while the effect of changing LAI is relatively limited. When the length of a street is reduced, varying tree factors have a comparable effect. As canyon depth increases, the effect of trees is limited.]]></description>
      <pubDate>Mon, 24 Apr 2023 16:19:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/2121646</guid>
    </item>
    <item>
      <title>Highway performance prediction model of International Roughness Index based on panel data analysis in subtropical monsoon climate</title>
      <link>https://trid.trb.org/View/2095254</link>
      <description><![CDATA[Pavement performance prediction is the crucial basis for decision-making of Pavement Management Systems (PMS). Pavement roughness is not only related to safety and comfort but also a vital index to evaluate highway performance. Therefore, it is of great significance to develop a prediction model for pavement roughness. The International Roughness Index (IRI) is the most commonly used index to represent pavement roughness in the worldwide. Many deterministic models based on time series data have been developed, but there are still few researches based on panel data to study IRI. This paper aims to investigate the rich information of panel data and develop a prediction model of IRI for semi-rigid asphalt pavements in subtropical monsoon climate. With the data from the PMS of Guizhou Province, the data matrix was built from 2017 to 2020. For the independent variables, the internal and external factors affecting IRI were considered, including climate, road age, traffic, and pavement structure. The random-effects model was employed for panel data analysis and the obtained model yielded a coefficient of determination (R²) value of 0.8858. This model can be applied to the highways which are designed, constructed, and qualified under the same standard and are located in the subtropical monsoon climate region. The predicted values in 2021 were compared with the measured values of highways in Guizhou Province. The average error is 12.7%. It shows that the model has better prediction accuracy and generalization performance with good robustness to the interference of geographic region and climate.]]></description>
      <pubDate>Wed, 22 Feb 2023 09:57:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2095254</guid>
    </item>
    <item>
      <title>Public Transport Choice Behavior Model of Short Trip under the Subtropical Climate</title>
      <link>https://trid.trb.org/View/1997884</link>
      <description><![CDATA[Short trip, including joint mode of long trip, plays an important role in daily traveling. As the modes of public transit, there is a competitive relation among public bicycle, bus, and mass transit in short trip. When choosing the public transit mode, the effect of weather on comfort and conveniences is an important consideration besides time and monetary cost. But fewer utility model researches focus on this aspect. This paper firstly investigates the choice behavior of short trip in a subtropical city, Guangzhou, and gets the choice results influenced by time, money, and weather. Secondly, temperature and precipitation are selected and analyzed as sensitive weather factors. The impact mechanism shows that the selection probability of public bicycle reaches the peak at a temperature range of 18~23 °C. Then, synthesize time cost, monetary cost, and comfort level influenced by weather and build the public transit choice behavior model of short trip. Finally, this paper applies the model to a case study.]]></description>
      <pubDate>Mon, 30 Jan 2023 10:27:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1997884</guid>
    </item>
    <item>
      <title>Short and Long-Term Field Performances and Optimal Timing of Chip Seal in Hot and Humid Climates</title>
      <link>https://trid.trb.org/View/1677513</link>
      <description><![CDATA[Chip seal is a preventive maintenance technique typically applied on relatively low traffic roads to reduce pavement deterioration rate and to defer the need for costly rehabilitation activities. This study aims to address the common challenges with chip seal application in hot and humid climates such as Louisiana to ensure the maximum benefits are achieved. Specifically, this study evaluated the short and long-term field performances and optimal timing of chip seal by analyzing the cracking, roughness, and overall pavement conditions of 47 flexible and composite pavement sections in Louisiana. Furthermore, potential moisture damage in asphalt concrete after chip seal application was assessed. Results indicated that chip seal extended pavement service life by 4–17 years based on the pre-treatment pavement conditions and pavement type (flexible or composite). Based on the cost benefit analysis, it is recommended to use alternating cycles of asphalt overlay and chip seal on low volume roads (less than 5,300 vehicles per day) with chip seal applied when the pavement condition index (PCI) of the pavement drops to a value between 70 and 74. In this case, significant monetary savings could be achieved when compared with adding chip seals at different time periods (outside the recommended range of PCI between 70 and 74). Results also showed that the application of chip seal does not seem to contribute to moisture damage. Instead, shallow groundwater conditions present in the State seem to contribute to moisture damage in asphalt pavements owing to moisture entrapment underneath the asphalt layer.]]></description>
      <pubDate>Thu, 16 Jan 2020 10:42:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1677513</guid>
    </item>
    <item>
      <title>The influence of weather conditions on adult transit ridership in the sub-tropics</title>
      <link>https://trid.trb.org/View/1627482</link>
      <description><![CDATA[This paper investigates the influence of local weather conditions on adult transit ridership across three transit modes. Drawing on smart card data and half hourly weather station records for a 12 month period, analysis reveals that weather imposes an effect on adult transit ridership and that its influence varies by mode. Ferry ridership is found to be more sensitive to changes in weather compared to either bus or train ridership. Findings also reveal that weather’s influence on ridership varies across the course of a day. During morning and evening peak hours, weather is shown to exert a weaker effect than other periods throughout the day. The authors argue that their findings are important in their capacity to contribute to a new evidence base with the potential to inform the (re)design of more weather-resilient transit systems by shedding new light on the weather–transit ridership relationship.]]></description>
      <pubDate>Wed, 05 Jun 2019 14:20:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1627482</guid>
    </item>
    <item>
      <title>To travel or not to travel: ‘Weather’ is the question. Modelling the effect of local weather conditions on bus ridership</title>
      <link>https://trid.trb.org/View/1500886</link>
      <description><![CDATA[While the influence of weather on public transport performance and ridership has been the topic for some research, the real-time response of transit usage to variations in weather conditions is yet to be fully understood. This paper redresses this gap by modelling the effect that local weather conditions exert on hourly bus ridership in sub-tropical Brisbane, Australia. Drawing on a transit smart card data set and detailed weather measurements, a suite of time-series regression models are computed to capture the concurrent and lagged effects that weather conditions exert on bus ridership. The authors' findings highlight that changes in particularly temperature and rainfall were found to induce significant hour-to-hour changes in bus ridership, with such effects varying markedly across both a 24?h period and the transit network. These results are important for public transport service operations in their capacity to inform timely responses to real-time changes in passengers’ travel demand induced by the onset of particular weather conditions.]]></description>
      <pubDate>Tue, 20 Feb 2018 09:31:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1500886</guid>
    </item>
    <item>
      <title>Evaluating Walkability Through GIS Spatial Analysis in South Florida</title>
      <link>https://trid.trb.org/View/1495222</link>
      <description><![CDATA[Walkable communities are healthier communities, due to the physical activity of residents. Because a community’s built form has a strong influence over its walkability, many planners and public officials hope to improve walkability through zoning and infrastructure changes. However, communities that differ in factors such as geography and climate can require different solutions when planning for increased walkability. Most walkability studies in planning literature use temperate zones in the West and Northeast of the U.S. to determine which built environment factors promote higher rates of walking activity. The objective of this study was to identify variables that influence walkability in a sub-tropical climate. Four communities in South Florida were selected as case studies: two traditional neighborhoods with high Walk Scores and two modern neighborhoods with low Walk Scores. GIS spatial analysis was conducted through four perspectives: land use, built environment, transportation infrastructure, and urban tree canopy. Land use mix, building density, short block lengths in grid-like networks, and transit access were found to have the greatest effects on walkability in South Florida. These variables help reduce the walking distance between destinations, possibly mitigating the heat’s effect on pedestrian thermal comfort. While urban tree canopy and the presence of shade trees was theorized to increase walkability, no association was found. Research has applicability in other sub-tropical/tropical communities that are affected by sprawl and seek to improve walkability.]]></description>
      <pubDate>Mon, 22 Jan 2018 10:49:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1495222</guid>
    </item>
    <item>
      <title>The Effects of Heat Transfer on Flexible Pavement and Temperature Prediction Model in Taiwan</title>
      <link>https://trid.trb.org/View/1289713</link>
      <description><![CDATA[This study was to establish a suitable prediction model of pavement temperature to accommodate warmer subtropical climate and thicker pavement in Taiwan. Three typical pavement structures of freeway were constructed and instrumented to collect temperature measurements. Results showed that the peak temperature of AC layer occurred between 12:00 to 14:00, while that of BTB layer happened after 17:00. Outgoing radiation, convection energy, and conduction energy were found also influential to the pavement temperature. Two sinusoidal functions were fitted based on the representative monthly temperature measurements and validated for AC and BTB layers. It enables field engineers of highway agencies to assess FWD data conveniently and accurately by incorporating two proposed models with in-situ ambient and pavement surface temperature measurements.]]></description>
      <pubDate>Thu, 20 Mar 2014 13:39:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1289713</guid>
    </item>
    <item>
      <title>Technology Solutions for Sustainable Urban Community Design in Subtropical Taiwan</title>
      <link>https://trid.trb.org/View/898444</link>
      <description><![CDATA[This paper describes how subtropical Taiwan has to import 99% of the required energy. With limited usable land and intensified urban development, the living quality is less than desirable because of air pollution, over heating, and lack of green outdoor spaces. Aiming at sustainable urban development, the Taiwan government recognizes that appropriate technologies have to be identified and developed to better cope with the challenges. It is found that the community is an appropriate context in which to explore sustainable development issues. The criteria to approach the issues are self-sufficiency, short-distance, and sharing to deal with energy/resources conservation, a healthy environment, and the aging population. For self-sufficiency, the core concept is to consume less commercial energy and recycle/reuse waste and water. For short distances, the main idea is to reduce the transportation frequency of people/goods and to promote zero-emission mobility. For sharing, the goal is to promote virtual and physical interpersonal interaction.]]></description>
      <pubDate>Wed, 12 Aug 2009 12:47:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/898444</guid>
    </item>
    <item>
      <title>FULL FACTORIAL OPTIMIZATION OF CONCRETE MIX DESIGN FOR HOT CLIMATES</title>
      <link>https://trid.trb.org/View/714626</link>
      <description><![CDATA[This paper presents the results of a statistical analysis aimed to optimize a concrete mix design for hot climates.  A full factorial experiment with 3 X 4 X 4 X 3 treatment combinations (432) samples of 48 mixes at three levels of temperature was used.  The influences of the water/cement ratio (0.4, 0.5, and 0.6), coarse aggregate/total aggregate ratio (0.55, 0.6, 0.65, and 0.7), total aggregate/cement ratio (3, 4, 5 and 6), and temperature (24, 38 and 52 deg C) on compressive strength were characterized and analyzed using polynomial regression. Mathematical polynomials were developed for concrete strength as a function of temperature and mix proportion. Based on the statistical analysis, recommendations are provided on the optimum concrete mix for different temperatures as well as the mix that is least sensitive to temperature variations.]]></description>
      <pubDate>Sun, 02 Dec 2001 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/714626</guid>
    </item>
  </channel>
</rss>