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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Dynamic Response of Rigid Pavement under Moving Multi-Load</title>
      <link>https://trid.trb.org/View/2283275</link>
      <description><![CDATA[The dynamic response of rigid pavement under moving multi-load is investigated. Solutions of dynamic stress and deflection of infinite plate on viscoelastic foundation subjected to moving load are obtained by means of Fourier transform. Four load patterns are discussed respectively, including single-wheel load, single-axle load, tandem-axle load and whole-vehicle load. The numerical calculations are carried out by using Fast Fourier Transform (FFT). In the numerical example, the dynamic responses obtained with the four load patterns are compared. It is found that tandem-axle load is the major cause for the maximum response of the plate. In the end, the effects of load traveling velocity, thickness and elastic modulus of the plate on the distribution of the deflection and the stress are studied.]]></description>
      <pubDate>Thu, 17 Oct 2024 09:15:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2283275</guid>
    </item>
    <item>
      <title>Axle Weight Limits for Single and Tandem Axles</title>
      <link>https://trid.trb.org/View/2194371</link>
      <description><![CDATA[Axle load limits for single axles, 89 kN (≈20  kips), and tandem axles, 151 kN (≈34  kips), are set to control potential pavement damage. These axles, at their corresponding weight limits, are considered equivalent. Because pavement layers are more complicated than a linear elastic material, using linear elastic theory would result in erroneous loading response prediction and, hence, potential pavement damage. Thus, actual tandem- and single-axle loading, along with flexible pavement structure, were modeled using an advanced finite-element model. The influences of a 1.2-m-spaced tandem axle and a single axle on flexible pavement responses were assessed qualitatively. Transfer functions from AASHTOWare were used to compute pavement distresses. Tandem and single axles were found to be inequivalent, confirming that the distresses due to the tandem axle were greater than those of the single. Load equivalency was calculated for different parameters, such as tire type, pavement material, and structure. The load equivalency was found to be dependent on various parameters. Wide-base tires (tire type) had the highest influence on the weight limits [135 kN (≈30  kips)]. Because 72% of national goods are moved on highways, accurate weight limits should be applied using an established equivalency factor.]]></description>
      <pubDate>Thu, 22 Jun 2023 09:49:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2194371</guid>
    </item>
    <item>
      <title>Multibody Dynamics Analysis of Tandem Axle Rubber Suspension Using MSC ADAMS</title>
      <link>https://trid.trb.org/View/1889465</link>
      <description><![CDATA[Tipper application has always been associated with rough roads and very high payload. This makes suspension design the most complex job as it has to cater for needs ranging from good ride at no load condition to stability of vehicle at fully loaded condition. Bogie suspension being most commonly used brings in maintenance and breakdown issues which is not desirable by the fleet owners, due to the cost and downtime associated with it. Rubber suspension has been looked upon as options due to its ability to not only provide good ride and stability but also to be almost maintenance free. Tandem axle walking beam rubber suspension is thus suitable for tipper application and has started to make its space in Indian market. Suspension design and development includes costly processes in terms of testing. FEA being the most common tool used for component design, requires inputs like forces acting on each component in various directions which is quite complex to predict. RLDA being an option to provide this input, brings with it a huge cost associated. Also RLDA cannot predict data at all locations and thus fails to cater the need. ADAMS is the tool which can provide the desired output forces to be used as input for design activity. This research work caters to the same needs and is thus a critical activity in research and development of the tandem axle walking beam rubber suspension. ADAMS modeling involves template, subsystem and assembly building of walking beam suspension, involving inclusion of all the compliances, stiffness, damping and loading. Providing all the above inputs makes the model close to accuracy. Force distribution for critical components is being predicted for longitudinal, lateral and vertical loading case.]]></description>
      <pubDate>Tue, 28 Dec 2021 09:37:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1889465</guid>
    </item>
    <item>
      <title>Estimation of Weigh-in-Motion System Accuracy from Axle Load Spectra Data</title>
      <link>https://trid.trb.org/View/1856948</link>
      <description><![CDATA[Inaccurate weigh-in-motion (WIM) data may result in significant over-or under-estimation of the pavement performance period, leading to over-or under-design pavements. Therefore, the data collected at WIM systems must be accurate and consistent. The paper presents an approach to estimate WIM system accuracy based on axle load spectra attributes [normalized axle load spectra (NALS) shape factors]. This alternative approach to assess WIM system accuracy is needed to characterize temporal changes in WIM data consistency. The WIM error data collected before and after calibration were related to NALS shape factors for Class 9 vehicles. This analysis’s main objective is to determine WIM system errors based on axle loading without physically performing equipment calibration. This approach can help highway agencies select optimum timings for routine maintenance and calibration of WIM equipment without compromising its accuracy. The results show that the WIM accuracy for the tandem axle (TA) can be estimated with TA NALS shape factors with an acceptable degree of error for bending plate (BP) and quartz piezo (QP) sensors. Further, the results obtained using different statistical methods for model development and validation show reasonable goodness of fit. The use of NALS to estimate the TA WIM accuracy can save a significant amount of time and resources, which are usually spent on equipment calibrations every year.]]></description>
      <pubDate>Fri, 23 Jul 2021 15:26:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1856948</guid>
    </item>
    <item>
      <title>Linking Traffic Volume and Weight Data for Mechanistic-Empirical Pavement Design</title>
      <link>https://trid.trb.org/View/1691495</link>
      <description><![CDATA[Pavement engineers are now practicing the cluster method to categorize routes by grouping them based on the similarity of their axle load spectra (ALSs). Ideally, once clusters are formed, a classification model needs to be developed with the help of site-specific attributes to assign a new site to an appropriate cluster. Still, there is no straightforward model that can relate the clustered ALSs with the easily collectible information, such as routes’ types or traffic volume data. To this end, this study developed a new ALS database based on the routes’ functional classes, locations, and vehicle class distribution (VCD) data. In the beginning, the routes were divided into six groups on the basis of their locations and functional classes. After that, this study performed a cluster analysis to split the routes of each group into an optimum number of subgroups considering both ALSs and VCDs of those routes. Finally, the representative ALS of each subgroup was calculated by averaging the site-specific ALSs of routes belonging to that subgroup. It is found that the absolute error computed for the proposed ALS database with respect to site-specific ALSs is lower than the existing methods. The observations and findings are based on the tandem axle of the single-trailer truck, which can be applicable to other axle types.]]></description>
      <pubDate>Wed, 22 Apr 2020 12:26:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1691495</guid>
    </item>
    <item>
      <title>Bridge Damage Detection Using Vehicle Axle-Force Information</title>
      <link>https://trid.trb.org/View/1489503</link>
      <description><![CDATA[Moving Force Identification (MFI) is the process of back-calculating the applied axle force histories from bridge measurements. This paper investigates the use of an MFI algorithm to detect the presence of bridge damage by monitoring calculated vehicle applied axle forces. Bridge deflections at three points along the bridge are used as the input to the algorithm. It is found that the combination of mean calculated gross vehicle weight and mean calculated axle weight ratio for a population of similar two-axle vehicles can be combined to indicate the location and severity of damage on a bridge. The bridge is modelled as a simply supported beam and deflections at the quarter point, midpoint and three quarter point are used as the inputs to the MFI algorithm. The method is shown to work best when damage is closer to the centre of the bridge.]]></description>
      <pubDate>Thu, 30 Nov 2017 09:54:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1489503</guid>
    </item>
    <item>
      <title>Impact Assessment in the Pavement Life Cycle Due to the Overweight in the Axle Load of Commercial Vehicles</title>
      <link>https://trid.trb.org/View/1460553</link>
      <description><![CDATA[Commercial vehicles may have different wheel and axle set ups, usually presenting single or dual wheels, and single-axle or dual or triple tandem-axles. In pavement design, requests caused by these various set ups of wheels and axles are converted into the request of the standard axle, loading 8.17 ton-force, which together make up the Number “N”. Due to mechanical manufacture of axles and wheels, and to ensure that the pavements will not receive excessive point loads that might lead to its rupture, there are set weight limits for axle set ups. In Brazil, the legislation on dimensions and weights of vehicles is Resolution n.º 12, dated February 6, 1998, CONTRAN – National Traffic Council. Despite being established by laws, not all roads are properly monitored to assure these limits are being respected, such as free access roads, roads with insufficient weighing scales for proper control or urban roads. Although overweight axles may cause damage to vehicles, as well as high operation and maintenance costs, depending on the profile of the conductors, it may be more common to disrespect these limits, which shortens the life cycle of pavements. This article aims to analyse and compare the effect on the life cycle of the pavement when requested by single axle with single wheels, and single-axles, dual and triple tandem-axles with dual wheels, when the axles have 20%, 35%, 50% and 70% overload Brazilian legal values, according to the equivalences axles for AASHTO and USACE methods.]]></description>
      <pubDate>Tue, 28 Mar 2017 11:39:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1460553</guid>
    </item>
    <item>
      <title>Development of Functional Class-Based Axle Load Spectra for Mechanistic-Empirical Pavement Design</title>
      <link>https://trid.trb.org/View/1439596</link>
      <description><![CDATA[Axle load spectra (ALS) are one of the primary inputs for mechanistic empirical (ME) pavement design. The current practice for the development of ALS is either arithmetic average method or cluster analysis. The average method does not consider the variability of route type. On the other hand, in cluster analysis, there is no easy way to select the appropriate clustered input values for an unknown route. To this end, this study developed the ALS based on the functional classes of the routes. Traffic data of 666 Long-Term Pavement Performance (LTPP) sites were used to generate these ALS in order to provide data support for the ME pavement design and analysis. This study found that the peak percent frequency of loaded tandem axles of Class 9 (single-trailer) trucks increases with an increment of the percent of single-trailer trucks. Therefore, the ALS of some functional groups were subdivided into three groups based on the percent of single-trailer trucks. The developed ALS show that most of the rural interstates experience significantly higher volume of loaded single-trailer trucks than the other routes. Other routes experience lower to moderate volume of loaded single-trailer trucks.]]></description>
      <pubDate>Mon, 20 Feb 2017 16:44:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/1439596</guid>
    </item>
    <item>
      <title>Design and Execution of the Unbonded Overlay Experiment at the NAPTF</title>
      <link>https://trid.trb.org/View/1428198</link>
      <description><![CDATA[The Innovative Pavement Research Foundation (IPRF) executed a contract for the development of a Roadmap document to lay out the plan for the investigation of unbonded concrete airfield overlays. The scope of work also included the design an execution of the first phase of the experiment described by the Roadmap. This paper presents the development of the Roadmap document, and execution of the first phase of the research. The Roadmap document focused on the development of a research approach which could be accomplished in manageable portions of research activity. It deals with identification of the performance related parameters, and structuring of these into functional research project increments. Three phases of work were identified within the Roadmap to address all the issues relevant to unbonded overlay performance. The first phase of research was designed to address a limited number of the factors identified in the Roadmap, including existing pavement condition, the influence of matched and mismatched joints, and the relative thickness of underlying and overlay slabs. The paper discusses the first phase experiment design and construction. It was necessary to factor construction and instrumentation elements into the experiment design, as well as physical limitations of the loading facility. All phases of the research are to be conducted using the accelerated loading equipment at the National Airfield Pavement Test Facility (NAPTF). The paper also discusses the first phase loading plan developed and executed at the Facility. Loading was conducted for both tandem and tridem gears on parallel pavement tracks. Response data was collected at multiple load levels, but primary load repetitions were conducted at a single load level. Finally, the paper discusses the distresses which resulted from the loading. Distress types, identified mechanisms, and implications of certain distresses are also addressed.]]></description>
      <pubDate>Mon, 31 Oct 2016 16:58:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1428198</guid>
    </item>
    <item>
      <title>Replacement of FAARFIELD Tandem Factors With Cumulative Damage Factor Methodology</title>
      <link>https://trid.trb.org/View/1427116</link>
      <description><![CDATA[The United States Federal Aviation Administration (FAA) adopted FAA Rigid and Flexible Iterative Elastic Layered Design (FAARFIELD) as its standard thickness design procedure for airport pavements in September 2009. FAARFIELD includes a layered elastic analysis routine for flexible pavement design and a three-dimensional finite element structural analysis routine for rigid pavement design. The current FAARFIELD design procedure for flexible pavements accounts for the effect of aircraft gears in tandem as part of the pass-to-coverage (P/C) ratio computation. The result is a two-part P/C ratio consisting of a wander-related factor multiplied by a tandem factor. The tandem factor is computed as a straight-line interpolation between the number of wheels in tandem (for shallow structures) and unity (for deep structures). The objective of this report is to accompany the source code implementation of replacing the current method using a tandem factor with an alternative calculation, in which the cumulative damage factor (CDF) due to wheels in tandem is computed based on the subgrade linear elastic strain response. The report contains a comparison of CDFs for flexible pavements under tandem axle gear loads (two dual-gear and three dual-gear configurations), as computed by the current method (FAARFIELD Version 1.4) and by the new method. The report also contains a comparison of CDF computed by the new method with the CDF computed for multiple wheel sets in tandem using the Alizé-Aircraft program, which was developed by the Institut français des sciences et technologies des transports, de l'aménagement et des réseaux - French Institute of Science and Technology for Transport, Spatial Planning, Development and Networks (IFSTTAR) and the French Directorate General for Civil Aviation (DGAC).]]></description>
      <pubDate>Tue, 25 Oct 2016 15:09:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1427116</guid>
    </item>
    <item>
      <title>Statistical Analysis of Axle Load Distributions in India</title>
      <link>https://trid.trb.org/View/1412413</link>
      <description><![CDATA[In this investigation, the axle load data for a particular stretch of National Highway (NH-58) in India was collected and statistical analysis was carried out. A lognormal and Weibull distribution was found to fit the single axles whereas lognormal mixed distribution was found to fit the tandem axles. Analysis of the data revealed considerable amount of overloading. When front and rear single axles were considered, unimodal distribution was found to fit the data. When only the tandem rear axles were considered, two or more peaks were observed, the first peak signified the mean of axle loads below the legal limit and the other peaks signified the means of axle loads exceeding the legal limit. Using the moment statistics, the load spectra factor was calculated for various axle types. The sensitivity of overloading in the calculation of equivalent single axle load was quantified using the vehicle damage factor and truck factors.]]></description>
      <pubDate>Tue, 28 Jun 2016 16:22:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1412413</guid>
    </item>
    <item>
      <title>Numerical comparison of flexible pavement dynamic response under different axles</title>
      <link>https://trid.trb.org/View/1398570</link>
      <description><![CDATA[A three-dimensional finite element model was utilised to examine the flexible pavement dynamic response under single, tandem and tridem axles at different speeds. Using two different hot-mix asphalt (HMA) layer thicknesses, 15.2 and 25.4 cm, the dynamic effects of moving axles were investigated on critical responses. These responses include the tensile strain at the bottom of asphalt layer, compressive strain on the top of subgrade and tensile and compressive strain on the surface layer. In this study, the HMA layer and other layers were characterised as linear viscoelastic and elastic material, respectively. Since this research focuses specifically on the time and dynamic effects, considering the transient dynamic loading and inertia forces, implicit dynamic analysis was done. The important findings are as follows: (1) Strains induced by tridem axles could be greater than tandem axles or even equal at different speeds. (2) It cannot be stated that axles always induce greater critical response value to road systems at lower speed because at higher speed they can also induce greater critical response value in pavements than that at lower speed. (3) Changing trend and changing rate of strains with speed are strongly affected by pavement thickness. In general, the effects of different axle configurations are strongly affected by moving speed and surface layer thickness.]]></description>
      <pubDate>Sat, 09 Apr 2016 15:45:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/1398570</guid>
    </item>
    <item>
      <title>Laboratory Measurements of Vortex- and Wake-induced Vibrations of a Tandem Arrangement of Two Flexible Risers</title>
      <link>https://trid.trb.org/View/1396394</link>
      <description><![CDATA[The dynamic response of two flexible model risers in tandem arrangement immersed in a stepped current was analyzed. The risers, with an external diameter of 20 mm and a total length of 6200 mm, had an aspect ratio of 310. They were hinged to the support structure at the center-to-center distances away 3-12 times the external diameter. The top 1200 mm was exposed to a uniform current at a speed which was up to 0.9 m/s (the Reynolds number was 18000) and the rest in still water. The dynamic responses, which were obtained through the Fiber Bragg Grating strain gauges mounted on the surface, were analyzed by studying the cross-flow amplitudes and modal weights. The cross-flow vibration were observed up to the third mode, and the modal transformation from the second mode to the third mode was clearly observed. The experiment confirmed that the typical vortex-induced vibration (VIV) had occurred on the up-stream riser. But for the down-stream riser, the main excitation mechanism was wake-induced vibration (WIV). The modal transformation of WIV was more complex than that of VIV, which might be helpful for other researchers to study the interference effect.]]></description>
      <pubDate>Mon, 29 Feb 2016 16:58:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1396394</guid>
    </item>
    <item>
      <title>Impact of Different Loading Patterns with Short Duration on the Permanent Strain of Asphalt Mixture</title>
      <link>https://trid.trb.org/View/1378506</link>
      <description><![CDATA[The suggested procedure for measuring the permanent deformation of asphalt concrete mixtures in the standard laboratory tests are based on using a single-hump loading. This loading type can only simulate the single-axle load, whereas pavements are subjected to single, tandem, and tridem axles at different speeds. On the other hand, the behavior of asphalt mixtures is affected by the loading pulse duration as a function of moving speed. Therefore, the laboratory investigation of permanent deformation is more logical under similar loading conditions. Accordingly, in this study, the effect of the type and duration of loading on the permanent strain of asphalt mixture have been examined at three stress levels. To investigate, the unconfined cyclic creep test was performed on asphalt specimens and, finally, the impacts of each variable on the permanent strain were evaluated, as discussed here in detail. Based on the findings of this research, it is concluded that for various loading patterns, the permanent deformation caused by the tridem axles can be greater than that caused by single and tandem axles, and under tandem axles it can be greater than that under single axles; the effects are dependent on the loading duration indeed. Also, this study showed that the impact of pulse duration on the changing trend of permanent strain is dependent on loading pattern and stress level.]]></description>
      <pubDate>Wed, 30 Dec 2015 09:02:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/1378506</guid>
    </item>
    <item>
      <title>Improvement of Axle Load Spectra Characterization by a Mixture of Three Distributions</title>
      <link>https://trid.trb.org/View/1366434</link>
      <description><![CDATA[Traffic is one of the most important variables used in pavement design methods. There are currently two methods for characterizing wheel load repetitions: equivalent single axle load (ESAL) and load spectra, which is a more precise characterization of traffic but relies on the same input data used to calculate ESALs. Although the load spectra are described using a bimodal mixture distribution, samples taken in Colombia indicate that the load spectra exhibit an intermediate region that can be modelled with an additional distribution. This research proposes the use of a mixture of three distributions: two log-normal distributions for the description of the peaks and a normal distribution for the intermediate region, finding a closed statistical solution for the formal evaluation of its properties, and deduces the expression of the nth moment that facilitates obtaining important features of the proposed distribution. In a case of application in two geographic regions of Colombia, with more than 53,000 tandem and tridem observed axles, it was found that the proposed model effectively improves the characterization of the load spectra.]]></description>
      <pubDate>Fri, 28 Aug 2015 13:56:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1366434</guid>
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