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    <title>Transport Research International Documentation (TRID)</title>
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    <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>
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      <title>Transport Research International Documentation (TRID)</title>
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      <title>Hydraulic Loading for Bridges Founded on Rock</title>
      <link>https://trid.trb.org/View/2225903</link>
      <description><![CDATA[Instantaneous stream power is defined as the product of shear stress and stream velocity representing the scouring condition. Hydraulic loading conditions are being expressed in terms of stream power which can be accumulated over the life of a bridge structure. The prediction of scour in erodible rock must consider the hydraulic loading imposed over many years over all the flood events over those years. This is true whether or not a threshold condition must be exceeded before the rock in the streambed is exposed to erosive forces. Long-term observations of scour in erodible rock combined with a history of hydraulic loading (expressed as stream power) provide a valuable index of the relative erodibility of the particular rock formation. An index, herein described as the Scour Number Kₛ, is defined as the amount of scour observed over a period of time divided by the cumulative hydraulic load over the same period. Given a future cumulative hydraulic loading, the Scour Number can be used to estimate the future scour associated with that loading, for the particular rock formation. Probability weighted flood frequency captures the range of flow conditions and is converted to average annual scour.]]></description>
      <pubDate>Tue, 17 Dec 2024 17:09:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/2225903</guid>
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    <item>
      <title>Time-Dependent Scour Depth under Bridge-Submerged Flow</title>
      <link>https://trid.trb.org/View/2225850</link>
      <description><![CDATA[Current practice for determining the scour depth at a bridge crossing is based on the equilibrium scour depth of a design flood (e.g., 50-year, 100-year, and 500-year flood events), which is unnecessarily larger than a real maximum scour depth during a bridge life span since the peak flow period of a flood event is often much shorter than the corresponding scour equilibrium time. The objective of this study was to present a design method for time-dependent scour depth under bridge-submerged flow. To this end, a series of flume experiments on scour depth under bridge-submerged flow were conducted to collect scour data at different times. A semi-empirical model for estimating time-dependent scour depth was then presented based on the mass conservation of sediment, which agrees very well with the collected data. The proposed method can appropriately reduce the design depth of bridge scour according to design flow and a peak flow period, which can translate into significant savings in the construction of bridge foundations.]]></description>
      <pubDate>Tue, 17 Dec 2024 17:09:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2225850</guid>
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      <title>Optimized Bridge Maintenance Strategies: A System Reliability–Based Approach to Enhancing Road Network Performance</title>
      <link>https://trid.trb.org/View/2319735</link>
      <description><![CDATA[Though road authorities have well-defined inspection protocols for evaluating bridge serviceability, gaps remain in understanding optimal timing and the impact of maintenance strategies on an individual bridge and its subsystems and, consequently, on the holistic performance of a road network. This paper proposes an innovative model based on system reliability principles that develops optimized bridge maintenance strategies aimed at enhancing the overall reliability of a bridge-dominated road network by considering the quantified impact of bridge component deterioration. Using the first-order second-moment method, the authors initially determine the reliability index for each bridge based on condition ratings derived from routine inspections as outlined in the bridge inspection manual. Advanced optimization algorithms then formulate the optimal maintenance strategies for the bridge structures. Finally, the authors gauge the system reliability of the network using Ditlevsen bounds approximation, considering the impact of maintenance actions on varied bridge structural components. The developed model was implemented on a typical bridge-dominated road network in Chongqing, China. The results demonstrate the model has the capacity to quantify the impact of diverse bridge maintenance strategies on the total road network, offering valuable insights for decision makers to design effective, efficient maintenance strategies aimed at extending the lifespan of bridge-dominated road networks.]]></description>
      <pubDate>Fri, 26 Jan 2024 10:02:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2319735</guid>
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    <item>
      <title>Brake Pad Wear Prediction Using Finite Element Techniques</title>
      <link>https://trid.trb.org/View/1847295</link>
      <description><![CDATA[Brakes are the critical component, plays a significant role regards to performance of vehicle. Vehicle safety is also strongly influenced by proper braking operation, which depends on pad to disc contact interface. Pad and disc surfaces are worn out due to continuous braking events, which in turn affects the life of the brake assembly and its performance. This paper presents the brake pad wear prediction of a disc brake assembly. A new and unworn pair of brake pads are considered for the study and tested under different braking scenarios. Wear simulation procedure is formulated based on Rhee’s wear formula and wear calculation model is established based on friction and wear mechanism. The correlation between the wear behavior of a friction material tested under controlled laboratory conditions and finite element method is investigated. Based on the calculated wear, lifespan of the brake pad is also calculated. The predicted life of the pad using inertia brake dynamometer (IBD) is then correlated with the finite element analysis (FEA) results. The variation of wear during a various braking situations are studied and influence of brake pressure, rotor velocity, coefficient of friction, and temperature on the wear is analyzed. As the disc brakes are not sealed, some of the wear particles can become airborne. This paper also presents the simulation procedure to predict the number of airborne particles generated from friction materials in laboratory environments. It is demonstrated that by using the proposed methodology, it is possible to predict the brake pad wear, and the corresponding life span with an accuracy close to the test results. Therefore, this study will be beneficial to design the pad material formulation and to predict its actual life span.]]></description>
      <pubDate>Fri, 23 Jul 2021 15:26:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1847295</guid>
    </item>
    <item>
      <title>The price of precision: trade-offs between usability and validity in the World Health Organization Health Economic Assessment Tool for walking and cycling</title>
      <link>https://trid.trb.org/View/1853426</link>
      <description><![CDATA[The widely used World Health Organization (WHO) Health Economic Assessment Tool (HEAT) for walking and cycling quantifies health impacts in terms of premature deaths avoided or caused as a result of changes in active transport. This article attempts to assess the effect of incorporating ‘life-years’ as an impact measure to increase the precision of the model and assess the effect on the tool's usability. This article is a methods paper, using simulation to estimate the effect of a methodological change to the HEAT 4.2 physical activity module. The authors use the widely used WHO HEAT for walking and cycling as a case study. HEAT currently quantifies health impacts in terms of premature deaths avoided or caused as a result of changes in active transport. The authors assess the effect of incorporating “duration of life gained” as an impact measure to increase the precision of the model without substantially affecting usability or increasing data requirements. Compared with the existing tool (HEAT version 4.2), which values premature deaths avoided, estimates derived by valuing life-years gained are more sensitive to the age of the population affected by an intervention, with results for older and younger age groups being markedly different between the two methods. This is likely to improve the precision of the tool, especially where it is applied to interventions that affect age groups differentially. The life-years method requires additional background data (obtained and used in this analysis) and minimal additional user inputs; however, this may also make the tool harder to explain to users. Methodological improvements in the precision of widely used tools, such as the HEAT, may also inadvertently reduce their practical usability. It is therefore important to consider the overall impact on the tool's value to stakeholders and explore ways of mitigating potential reductions in usability.]]></description>
      <pubDate>Mon, 07 Jun 2021 09:43:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1853426</guid>
    </item>
    <item>
      <title>Main Factors to Consider for Rehabilitation on Bridges</title>
      <link>https://trid.trb.org/View/1743965</link>
      <description><![CDATA[In order to make a comparison between bridge rehabilitation methods, it is necessary to carry out inspections to ascertain the condition of the bridge, identifying the damage and detecting whether it is minor or large-scale. Once the inspection is analyzed, planning and studies of the different rehabilitation methods are carried out. The purpose of this is to determine the most suitable rehabilitation for the bridge in question. When carrying out the corresponding studies, the cost-benefit of each type of rehabilitation must be taken into account, as well as its advantages and disadvantages. This must be in accordance with the structure of the bridge, the area in which it is located, the traffic, the maintenance it will have in the future, etc., seen from a technical and economic point of view.  Rehabilitation methods are based on: - Maintain the bridge in its current condition (if its structural safety is guaranteed) - Carry out minor repairs with a small influence on the bridge life span - Perform a significant rehabilitation and/or reconstruction that generates a substantial extension of the bridge life span - Construction of a new bridge When evaluating the methods of rehabilitation it is observed that there is a factor that intervenes in an important way, this factor is the TIME. The estimated time in which the rehabilitation of the bridge will take place. The engineers in charge of the bridge should keep this in mind, since the TIME is MONEY and the longer the rehabilitation and the longer the execution period, the COST will increase substantially. This does not mean that we should opt for the least expensive rehabilitation, since it may be less expensive but many times it is not the one that has the necessary characteristics to give a favorable result. A good comparison study helps to obtain the best solution by combining: time-cost-benefit evaluating the most adequate and optimal for the bridge structure. Once the results of the study and the rehabilitation to be carried out are clear, the rehabilitation project is created. This is why carrying out the studies prior to the rehabilitation has as a result: An appropriate rehabilitation that brings benefits to the people in charge of it, to society and to the environment.]]></description>
      <pubDate>Wed, 03 Feb 2021 15:00:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1743965</guid>
    </item>
    <item>
      <title>Transportation Equity, Health, and Aging: A Novel Approach to Healthy Longevity with Benefits Across the Life Span</title>
      <link>https://trid.trb.org/View/1680002</link>
      <description><![CDATA[Recent evidence points to the negative consequences of restricted personal vehicle transportation on an individual’s independence, emotional and social well-being, and life expectancy. Ensuring that individuals have equitable access to transportation is vital to ensuring well-being across the life span. Therefore, there is a need for a balanced perspective that can appropriately weigh actual safety risks against the real health consequences of restricting mobility, and a partnership between the fields of health care and transportation could facilitate this balance. More sophisticated, individualized approaches and modeling are becoming available and could allow for “personalized prevention” that optimizes outcomes not only for older adults but also across the life span. This paper discusses: the  need to balance mobility and safety; new insights into driver behavior across the life span; understanding changes and transitions in transportation mobility throughout the life span; opportunities for collaboration between health care and transportation communities; opportunities to learn from international experience; and developing awareness and basic competencies among physicians.]]></description>
      <pubDate>Wed, 05 Feb 2020 15:20:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/1680002</guid>
    </item>
    <item>
      <title>Motor Vehicle Traffic Crashes as a Leading Cause of Death in the United States, 2015</title>
      <link>https://trid.trb.org/View/1503884</link>
      <description><![CDATA[For the seventh consecutive year, motor vehicle traffic crashes in 2015 were not among the top 10 causes of death in the United States. Motor vehicle crashes were the 13th leading cause of death overall among all causes. This continued drop in the rank of motor vehicle traffic crashes as a leading cause of death can be attributed to the 19-percent decline in traffic fatalities over the last decade. Nevertheless, despite this drop, motor vehicle traffic crashes continue to be among top 10 leading causes of death among younger age groups. When motor vehicle traffic crashes were ranked within unintentional injury deaths, they were the second leading cause of death during 2015. Among   unintentional injury deaths, motor vehicle deaths were the second leading cause for all ages. Assessing by another measure, the years of life lost (i.e., the number of years people would have lived had they not died), motor vehicle traffic crashes ranked 7th in 2015, as it has been ranked since 2010. This reflects the toll that motor vehicle traffic crashes take on the younger population.]]></description>
      <pubDate>Fri, 16 Mar 2018 09:53:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1503884</guid>
    </item>
    <item>
      <title>Microsimulation of Life Stages, Residential Mobility, and Location Choice Processes</title>
      <link>https://trid.trb.org/View/1497373</link>
      <description><![CDATA[This  paper  presents  the  microsimulation  results  of  life-stage  transitions,  residential mobility,  and  location  choice  processes  within  a  life-oriented  agent-based  integrated  Transport Land  Use  and  Energy  (iTLE)  modeling  system.  Multi-domain  interactions  and  feedbacks  are established during the estimation and simulation of the decision processes within the iTLE. The simulation runs at a yearly time-step from 2007-2021 for Halifax, Canada. The simulation results are  validated  with  the  2011  Census  information.  The  results  suggest  that  the  iTLE  generates reasonably  satisfactory  population  estimates.  For  example,  around  37%  of  the  DAs  show  a difference in the number of households of less than ±50, and 52% of the DAs show an APE value of less than 30%. The predicted results regarding the spatio-temporal evolution of Halifax suggests an  increase  of  around  14%  population  in  2021  compared  to  2007.  Younger  population  residing closer to the CBD are predicted to be more frequent movers than older population residing farther away  from the CBD. Higher  proportions of the  households are predicted within 25km from the CBD over the years. Proportion of households in these high density neighborhoods are predicted to increase from 68% in 2007 to 71% in 2021. A higher density of single person households are predicted in the urban core in 2021. Density is predicted to be more variable and skewed towards suburban neighborhoods as household composition changes through marriage and child birth.]]></description>
      <pubDate>Thu, 22 Feb 2018 09:17:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/1497373</guid>
    </item>
    <item>
      <title>Relationship Between Lifespan and Mechanical Performance of Railway Ballast Aggregate</title>
      <link>https://trid.trb.org/View/1465341</link>
      <description><![CDATA[As lifespan is the main criterion for the selection of aggregate for ballast and for planning the maintenance of railroad, it is important to define the relationship between the particle load resistant characteristics and the ballast‘s lifetime in structure. Assessment of the quality of the ballast particles under dynamic and static loading should reflect both the toughness and hardness, and these can be identified with the values of Los Angeles Abrasion and microDeval Abrasion. In order to predict the amount of loads, expressed in cumulated tonnes, the model formerly developed by Canadian Pacific Railroads was adapted. A number of different aggregate mixtures were tested in the laboratory including dolomite and granite rocks. The results were used to assess the gross tonnage possible to transport during the lifetime of ballast until repair or reconstruction should be done. The outcome of this study is the possibility to classify the requirements for aggregates‘ Los Angeles abrasion and micro-Deval abrasion values attributing them to designed traffic volumes.]]></description>
      <pubDate>Fri, 28 Apr 2017 16:50:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1465341</guid>
    </item>
    <item>
      <title>Predicting the evolution of social networks with life cycle events</title>
      <link>https://trid.trb.org/View/1370160</link>
      <description><![CDATA[This paper presents a model of social network evolution, to predict and simulate changes in social networks induced by lifecycle events. We argue that social networks change with lifecycle events, and we extend a model of friendship selection to incorporate these dynamics of personal social networks. The model uses theories of homophily and reciprocity and is formulated in a random utility maximization framework to predict the formation of social ties between individuals in the population. It is then extended to predict the evolution of social networks in response to life cycle events. The model is estimated using attribute data of a national sample and an event-based retrospective dataset collected in 2009 and 2011 respectively. Findings suggest that homophily has a strong effect on the formation of new ties. However, heterophily also plays a role in maintaining existing ties. Although the motivation of this research stems from incorporating social network dynamics in large-scale travel behaviour micro-simulation models, the research can be used in a variety of fields for similar purposes.]]></description>
      <pubDate>Fri, 23 Oct 2015 09:46:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1370160</guid>
    </item>
    <item>
      <title>Extended Performance of Media Filter Drains: New Media</title>
      <link>https://trid.trb.org/View/1363532</link>
      <description><![CDATA[There are numerous linear best management practices used by many state departments of transportation (DOTs) for highway runoff treatment. An example of one type is a media filter drain (MFD) which is a trench filled with aggregate and three active ingredients: dolomite, gypsum, and perlite (MFDs are also called Ecology embankments or bioslopes). Initial research on MFDs predicted that their life spans were at least 10 years. Recent studies indicate that for dissolved zinc and copper metal removal, the life span may exceed 20 years. The dissolved concentrations of these metals are of issue as higher concentrations in receiving waters can impact many aquatic species, particularly some cold water fish such as salmon. This study extended the life further in laboratory tests for MFDs made with media with slightly higher amounts of active ingredients. Zinc and copper removal remained high. However, some possible channeling was suspected with slightly lower removal rates after long periods without moisture.]]></description>
      <pubDate>Mon, 24 Aug 2015 14:11:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1363532</guid>
    </item>
    <item>
      <title>Mobility Socialization in Work Trip Biographies: 
Work Trips Over the Life Course of two Generations</title>
      <link>https://trid.trb.org/View/1337450</link>
      <description><![CDATA[The life course approach is becoming increasingly recognized in travel behavior studies. Related empirical research analyzes key events and mobility experiences over the life course of individuals. In addition to these personal experiences, social context and socialization through family members play an important role in this respect. This paper applies the model of the productive processing of reality developed by Hurrelmann (1988) to mobility socialization and presents preliminary empirical results. The empirical work is based on a retrospective survey conducted annually between 2007 and 2012 at TU Dortmund University (Germany). The work trip mobility in the life course of in individual is analyzed in relation to the work trip mobility of their parents and partners through multivariate analyses. In addition, socio-demographic characteristics and the preference for a long-term place of residence are considered. The findings indicate a positive association between the work trip mobility of the younger generation and their parents´ work trip mobility. The work trip mobility of women is in addition positively associated with their partners´ mobility. These results indicate the relevance of socialization effects in work trip biographies.]]></description>
      <pubDate>Mon, 16 Mar 2015 11:35:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1337450</guid>
    </item>
    <item>
      <title>A biographical approach to studying individual change and continuity in walking and cycling over the life course</title>
      <link>https://trid.trb.org/View/1324987</link>
      <description><![CDATA[Most research studies seeking to understand walking and cycling behaviours have used cross-sectional data to explain inter-individual differences at a particular point in time. Investigations of individual walking and cycling over time are limited, despite the fact that insights on this could be valuable for informing policies to support life-long walking and cycling. The lack of existing longitudinal data, difficulties associated with its collection and skepticism towards retrospective methods as a means to reconstruct past behavioural developments have all contributed to this deficit in knowledge. This issue is heightened when the time frame extends to longer term periods, or the life course in its entirety. This paper proposes and details a retrospective qualitative methodology that was used to study individual change and stability in walking and cycling within a life course framework. Biographical interviews supported by a life history calendar were developed and conducted with two adult birth cohorts. Interpretive, visual biographies were produced from the interview materials. Analysis focused on identifying the occurrence, context and timing of behavioural change and stability over the life course. Typologies of behavioural development were generated to resolve common and distinct behavioural patterns over the life course. Whilst the validity of reconstructed biographies of walking and cycling cannot be proven, this is an approach which offers credible and confirmable insights on how these behaviours increase, diminish, persist, cease, are restored or adapted through the life course, and how behavioural trajectories of walking and cycling may be evolving through historical time.]]></description>
      <pubDate>Tue, 21 Oct 2014 14:11:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1324987</guid>
    </item>
    <item>
      <title>A Novel Method to Enable Trade-offs across the Whole Product Life of an Aircraft using Value Driven Design</title>
      <link>https://trid.trb.org/View/1246373</link>
      <description><![CDATA[The increasing need to understand complex products and systems with long life spans, presents a significant challenge to designers who increasingly require a broader understanding of the operational aspects of the system. This demands an evolution in current design practice, as designers are often constrained to provide a subsystem solution without full knowledge of the global system operation. Recently there has been a push to consider value centric approaches which should facilitate better or more rapid convergence to design solutions with predictable completion schedules. Value Driven Design is one such approach, in which value is used as the system top level objective function. This provides a broader view of the system and enables all sub-systems and components to be designed with a view to the effect on project value. It also has the capacity to include value expressions for more qualitative aspects, such as environmental impact. However, application of the method to date has been restricted to comparing value in a programme where the lifespan is fixed and known a priori. This paper takes a novel view of value driven design through the surplus value objective function, and shows how it can be used to identify key sensitivities to guide designers in design trade-off decisions. By considering a new time based approach it can be used to identify optimum programme life-span and hence allow trade-offs over the whole product life.]]></description>
      <pubDate>Mon, 15 Apr 2013 13:14:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/1246373</guid>
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