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    <title>Transport Research International Documentation (TRID)</title>
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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>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>On the Stabilizing Effect of Weigh Stations on Truck Equivalency Factors for Pavement Design</title>
      <link>https://trid.trb.org/View/2187119</link>
      <description><![CDATA[In Costa Rica, weigh stations for trucks and commercial vehicles were reinstated in 2008. Since then, a stabilizing trend in the percentage of heavy vehicles with excess loading was observed. For pavement design purposes, this resulted in reduced variability in truck equivalency factors. These were statistically validated by processing all the weight data collected at different stations located throughout the national road network between 2008 and 2011. Using linear regressions, it was verified that given a constant noncompliance percentage, the truck equivalency factor for C2, C3, and T3-S2 vehicles tended to stabilize at 0.20, 0.66, 1.19, respectively. These results were consistent with additional power regression performed on the data. Higher weight enforcement on the T3-S3 vehicles’ tandem axle would result in a 0.17 decrease in the truck equivalency factor. The findings presented herein should aid countries that have yet to implement weigh stations, considering the benefits of exploring the evolution of truck factors if weigh stations were installed. This weigh station implementation case study exhibits the reality and development of pavement loading over time. Therefore, government authorities should be encouraged to control truck traffic with weigh stations to reduce pavement damage.]]></description>
      <pubDate>Thu, 22 Jun 2023 09:49:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2187119</guid>
    </item>
    <item>
      <title>Development of Toll Equivalency Factors for FASTag Lanes Under Mixed Traffic Conditions</title>
      <link>https://trid.trb.org/View/2078672</link>
      <description><![CDATA[The traffic conditions in India consist of a high degree of heterogeneity in vehicle categories plying on the highways without any lane-following behavior. A similar behavior is observed at the toll plazas where a dedicated lane assigned to a vehicle class is encroached by the vehicles of other categories, causing a mixed nature of the traffic in the same lane. In the present study, service headway is taken as the measure of effectiveness for studying the effect of mixed traffic conditions on traffic operations at electronic toll collection system (ETC) lanes, which are called FASTag lanes in India. Service headway is composed of processing time and the clearance time of the vehicle. Videographic data were collected at three different toll plazas located on National Highways in India to capture the variability in traffic and human behavior. The results showed that the service headway for a vehicle varies between 1.56?s and 34.40?s. The service headway-based toll equivalency factors (HTEF) are developed for converting the mixed traffic flow into a homogeneous equivalent for FASTag lanes. The results showed that the HTEF varies from 1.01 to 2.61. The results are validated spatially with data taken from a different site, and no significant difference was found between both the converted and equivalent data. Field engineers can use the developed HTEFs to estimate the traffic flow in equivalent terms based on the traffic composition. Further, the present study results can also be used to study the capacity and level of service (LOS) of FASTag lanes.]]></description>
      <pubDate>Thu, 08 Dec 2022 16:29:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2078672</guid>
    </item>
    <item>
      <title>Estimation of System delay Based Toll Equivalency Factors at Toll Plazas using Simulation</title>
      <link>https://trid.trb.org/View/2012085</link>
      <description><![CDATA[The service time and time headway of the vehicles are used to define the equivalency factor of different vehicle classes at the toll plaza. Both the service time and time headway are point measures and do not account for the system delay (time difference when a vehicle enters the queue and leaves the tollbooth) caused to the vehicle. The present study aims to quantify the system delay incurred to the vehicles at electronic toll collection (ETC) lanes under mixed traffic conditions using a microsimulation approach. Field data collected from one toll plaza located on a National Highway are used for simulation model generation. A new terminology called system delay-based toll equivalency factor (DTEF) is introduced to convert the different vehicle classes into equivalent passenger cars. The DTEF variation for different approach volumes and heavy commercial vehicle (HCV) compositions were checked at different ETC penetration levels. A total of 288 scenarios have been worked out, and simulation runs have been made for all such scenarios to obtain the DTEF values. The average DTEF value of HCV was obtained as 2.20. Further, it is found that with an increase in approach volume and HCV share in the traffic stream, the DTEF value increases. The outcome of the present study will be useful to field practitioners and engineers to determine the capacity in equivalent DTEF/hr and level of service of a toll plaza in terms of system delay.]]></description>
      <pubDate>Thu, 17 Nov 2022 10:15:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2012085</guid>
    </item>
    <item>
      <title>Research of multi-axles effects on the flexible pavement based on the viscoelastic continuum damage model</title>
      <link>https://trid.trb.org/View/2047392</link>
      <description><![CDATA[Damages caused by the multi-axles load on the pavement are more complex, due to the interaction between axles. To investigate influences of the multi-axles load on the bottom-up crack of the flexible pavement, the equivalent factor (EF) that represents damage ratios of multi-axles to single-axle based on the viscoelastic continuum damage model was proposed. Through the finite element method, influences of temperature, pavement thickness, and axle configuration on the EF were analyzed. Results suggest that the asphalt mixture with smaller m-value is more likely to have smaller EF. With the increase of temperature and asphalt layer thickness, EF of dual-axles load increases but EF of triple-axles load decreases. Besides, the wheelbase is the only factor of the axle configuration that has remarkable impacts on the EF. Making the distance between the maximum compressive and tensile stress close to the wheelbase can reduce the damage of multi-axle load.]]></description>
      <pubDate>Wed, 16 Nov 2022 11:36:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2047392</guid>
    </item>
    <item>
      <title>Simulation of autonomous truck for minimizing asphalt pavement distresses</title>
      <link>https://trid.trb.org/View/1941694</link>
      <description><![CDATA[The improvement of the pavement performance by different means is essential for the smooth movement of autonomous trucks (ATs). This study focuses on minimising the pavement distress by controlling vehicular loading distribution pattern (wander), traffic distribution on lanes (lane sharing) of a road, and limiting the running duration of AT to low-temperature time only. Mechanistic-Empirical Pavement Design Software, AASHTOWare, was incorporated in this research to analyze and then minimise the generation of asphalt pavement distress from autonomous truck loading. Different loading distribution patterns and traffic distribution of autonomous trucks were devised in AASHTOWare using the load equivalency factor (LEF) and lane distribution factors. Using multilayer elastic theory, LEFs were calculated for fatigue cracking and rutting separately. The acquired performances clearly showed significant improvement in pavement distress for a small increase of standard deviation of wheel wander and uniform distribution of traffic loading and for equally distributed ATs on the road lanes. In addition, an attempt has been made to optimise pavement distress in putting all ATs in a low-temperature duration of a day. Placing all ATs in a certain period of a day is beneficial for reducing asphalt pavement distresses and can bring a fruitful solution to prevent the early deterioration of the pavements.]]></description>
      <pubDate>Thu, 28 Apr 2022 09:39:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1941694</guid>
    </item>
    <item>
      <title>An intelligent optimization method for highway route selection based on comprehensive weight and TOPSIS</title>
      <link>https://trid.trb.org/View/1924005</link>
      <description><![CDATA[In order to accurately analyze and evaluate multi-index and multi-route traffic schemes for comparison and selection, the authors introduce herein a comprehensive weight and an intelligent selection algorithm for traffic scheme optimization to improve upon the shortcomings of common qualitative and quantitative analysis methods. Firstly, the authors establish an evaluation index system of transportation by traffic scheme considering the factors of technology, ecological environment, social environment, and economy, based on the whole life cycle. Secondly, the comprehensive weight based on subjective and objective factors is constructed. Finally, the authors establish an optimization method for transportation schemes by using the comprehensive weight and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) model. The results show that the evaluation index system based on the whole life cycle is more comprehensive and accurate. The comprehensive weight vector avoids the defects of single weight methods and makes full use of subjective data and expert opinions. The comprehensive weight vector is introduced into the decision-maker’s preference coefficient, so that analysts can determine the scheme according to the subjective and objective information and to the required accuracy. This method uses a large number of evaluation groups to evaluate the scheme, and the evaluation results show greater objectivity and efficiency.]]></description>
      <pubDate>Fri, 18 Mar 2022 12:17:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1924005</guid>
    </item>
    <item>
      <title>Developing Mixed Traffic Equivalency Factors to Estimate Saturation Flow at Urban Signalized Intersections</title>
      <link>https://trid.trb.org/View/1866650</link>
      <description><![CDATA[This study proposes a time occupancy approach to estimate passenger car units (PCUs) at urban signalized intersections with different interaction levels between vehicles under saturated green time conditions. The study shows a variation in PCUs with varied traffic and geometric conditions. Traffic data have been collected through videography techniques at signalized intersections in three metropolitan cities in India. Traffic flow discharge and clearance time of different vehicular categories have been extracted from the video during the saturated green time. The observed ranges of dynamic PCU values for two-wheelers, three-wheelers, big cars, light commercial vehicles, and heavy vehicles are 0.12 to 0.32, 0.45 to 0.80, 1.40 to 1.80, 1.60 to 2.20, and 3.50 to 6.50, respectively. Regression-based PCU models have been developed for each vehicle category to address the variation of individual vehicle PCUs with traffic compositions and flow rates. The model analysis shows that traffic compositions and flow rates are significantly affecting the PCU values. The PCU is a complex parameter requiring several field attributes. Therefore, to overcome the complexity of estimating PCUs, a concept of flow equivalency factor (FEF) has been proposed based on the estimated PCUs. The FEF can directly convert the mixed motorized vehicular flow into an equivalent standard passenger car flow without actually making use of different vehicles’ PCU factors. All the developed models have been validated for field conditions and results are found promising with field data. The developed approach can be used effectively for developing countries with a mixed traffic stream.]]></description>
      <pubDate>Wed, 21 Jul 2021 16:51:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1866650</guid>
    </item>
    <item>
      <title>Novel Framework for the Quantification of Pavement Damages in the Overload Corridors</title>
      <link>https://trid.trb.org/View/1716659</link>
      <description><![CDATA[Recent traffic trends and permit issuance show significant mobility demands in the energy sectors across the nation. The increase in the axle loads and frequency of operations of over-weight (OW) trucks resulted in severe damage to transportation infrastructures. Traditionally, the damage imparted by OW vehicles has been quantified by means of the equivalent axle load factors (EALFs) concept. However, because of the nature of assumptions in the development of damage equivalency factors, the field distresses substantially deviate from the prediction models. Therefore, this study aimed to bridge this gap by developing a mechanistic framework to determine damage equivalency factors tailored toward the specific characteristics of OW vehicles operating in the OW corridors, while considering the environmental conditions and the unique features of transportation facilities in the network. To achieve this objective, initially, the authors devised a plan to collect traffic information using portable weigh-in-motion devices at two intervals for 10 representative sites in the energy corridors of Eagle Ford Shale region. Subsequently, a series of nondestructive tests were conducted in the field to determine the material properties of the pavement layers for further numerical simulations. This information was further incorporated into a 3D finite element system to calculate critical input parameters in the modified damage factor models. The proposed mechanistic approach confirmed that the modified damage factors were substantially higher compared with traditional industry-standard values. Further investigation of environmental factors and pavement profiles in this study underscored the significance of these components for accurate assessment of the damage equivalency factors.]]></description>
      <pubDate>Mon, 06 Jul 2020 16:55:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1716659</guid>
    </item>
    <item>
      <title>The pavements cost due to traffic overloads</title>
      <link>https://trid.trb.org/View/1655268</link>
      <description><![CDATA[The traffic on roads is characterised by a large number of different vehicle types; these vehicles are considered in the pavement design by converting their effects through the use of truck factors. The truck factors transform the damage applied by the various axle types and loads to a standard axle. However, there is a considerable number of vehicles that travel with axle loads above the maximum legal limit. These axles/vehicles cause significant damage to the pavements, which increases the pavement construction and rehabilitation cost. This paper investigates the impact of overloaded vehicles using a vehicle weight database by examining the truck factors for different vehicle categories. The study concluded that overloaded vehicles increase pavement damage and life cycle costs by about 30% compared to the cost of the same vehicles with legal loads.]]></description>
      <pubDate>Mon, 21 Oct 2019 16:55:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/1655268</guid>
    </item>
    <item>
      <title>Stream equivalency factor for mixed traffic at urban signalized intersections</title>
      <link>https://trid.trb.org/View/1581205</link>
      <description><![CDATA[At signalized intersections, the variability in vehicle types necessitates converting mixed traffic flow into equivalent passenger car flow with the help of passenger car units (PCU). This study proposes a technique to estimate saturation flow by converting mixed traffic flow from vehicles per hour to PCU per hour by estimating the PCU values using time occupancy method during the saturated green time with different level of traffic interaction. Traffic discharge and clearance time have been extracted from the video of collected data. Regression based stream equivalency models are developed for quick and easy estimation of saturation flow.]]></description>
      <pubDate>Mon, 29 Apr 2019 21:14:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1581205</guid>
    </item>
    <item>
      <title>Concept of Flow Equivalency Factor under Heterogeneous Traffic Condition for Urban Arterial Midblock</title>
      <link>https://trid.trb.org/View/1438897</link>
      <description><![CDATA[Representation of flow in terms of vehicles/hr is not justifiable due to wide range of static and dynamic characteristics of vehicles in the traffic stream under mixed flow. The dynamic characteristics of the stream may vary based on the traffic composition and type of interaction with roadway and traffic. Under prevailing roadway and traffic conditions static equivalency factor results in to unrealistic conversion of flow in equivalent terms. Hence it is a need of an hour to have vehicle equivalent factors which take care of the fluctuations in stream speed and the speed of the individual vehicles at any point of time. Present study is focused on developing concept for flow equivalency factor for heterogeneous traffic. Mixed traffic is converted into passenger car unit named as Dynamic Car Unit (DCU) by modified homogenisation coefficient method dynamically, and optimized to a single value of DCU for each vehicle type in the stream. The concept of flow equivalency is also developed to simplify the conversion of flow from veh/hr to DCU/hr. The research outcomes are helpful for traffic and transport planners of cities in evaluating performance of vital movement channels like arterial roads under given or expected roadway and traffic environment.]]></description>
      <pubDate>Tue, 28 Mar 2017 11:38:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/1438897</guid>
    </item>
    <item>
      <title>Estimating the marginal costs of bridge damage due to overweight vehicles using a modified equivalent-vehicle methodology and in-service data on life-cycle costs and usage</title>
      <link>https://trid.trb.org/View/1440975</link>
      <description><![CDATA[Civil infrastructure managers have a profound interest in knowing the costs of infrastructure degradation caused by user operations that exceed statutory limits; that way, they are better informed to establish or revise policies related to permit fee structures for such extra-legal operations. In the specific context of vehicle weight permitting for highway bridges, past determinations have typically relied largely on bridge damage simulation using theoretical relationships between the loading and failure modes. Unlike the theory-based simulations, empirical data analysis uses observed field data and therefore are expected to yield more intuitive insights about the actual relationship between in-service loading patterns and their damage (and the cost of repair thereof). A few past studies have used such empirical approaches with some success but have generally been stymied by practical considerations including the lack of adequate translational relationships between the vehicles operating on the road and the vehicle classes typically considered in load analysis. Also, the overweight (OW) cost differences across different bridges attributes (material type, design type, functional class, and age) remain to be investigated. In a bid to overcome these limitations, this paper uses observed in-service data for vehicle loads and the life-cycle costs associated with bridge deterioration repair. The proposed methodology includes a technique that correlates American Association of State Highway and Transportation Officials (AASHTO) design vehicles to Federal Highway Administration (FHWA) vehicle classes, estimates the total life-cycle cost of bridge upkeep, and allocates this cost to each user group (vehicle class) based on the axle configuration and usage frequency (vehicle-miles travelled) of that class. For each vehicle class, the marginal cost of bridge damage is determined on the basis of the incremental cost responsibility (as a result of adding that vehicle class to the traffic stream) and the typical traffic volume of that vehicle class, and were found to range from $0.01 to as much as $36.35 per ft. length per pass of bridge, depending on OW class, and bridge functional class, material type, and age. The paper quantifies the extent to which bridge damage cost due to an overweight truck is influenced by the attributes of the truck and the bridge. The results can be of help to agencies seeking to formulate, update, or evaluate current or future OW permitting policies from the perspective of highway bridge damage among other impacts. This effort is considered timely in the current era when several highway agencies are considering relaxation of their OW permitting policies as a part of efforts to project a business-friendly image in a bid to spur economic development in their states.]]></description>
      <pubDate>Wed, 15 Feb 2017 17:03:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/1440975</guid>
    </item>
    <item>
      <title>Determination of Load Equivalency Factors by Statistical Analysis Of Weigh-In-Motion Data</title>
      <link>https://trid.trb.org/View/1445581</link>
      <description><![CDATA[The load equivalency factors for pavement design currently in use by the Hungarian standard have been developed using Weigh-in-Motion data obtained during the first few years of operations after installing some 30 measuring sites in Hungary in 1996. In the past years, and currently, data is collected mainly at the border crossings of the country, however the data is used only for law enforcement purposes, and no comprehensive statistical analyses have been done. To develop actual load equivalency factors for the use in pavement design, data of one year was collected and statistical methods were applied. An algorithm was used to help managing the multimodal distribution of axle loads in mathematical perspectives. Monte-Carlo methods were applied to determine the factors for each heavy vehicle type and eventually for each vehicle class used by the current Hungarian pavement design manual. The calculated factors are considerably different from the current ones, indicating that the pavement design may lead to a false result. Furthermore, there are three vehicle types suggested to be incorporated into the standard due to their high occurrence.]]></description>
      <pubDate>Wed, 25 Jan 2017 15:08:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1445581</guid>
    </item>
    <item>
      <title>Equivalency Factor Using Optimization for Indian Mixed Traffic Condition</title>
      <link>https://trid.trb.org/View/1359520</link>
      <description><![CDATA[The term Equivalency Factor as PCE was introduced in 1965 by HCM. And after that, considerable research effort has been carried toward to estimate PCE value. The present empirical study is to determine the dynamic equivalency factor for mix traffic condition in Indian context. For that car as reference vehicle is considered this termed as Dynamic Car Unit (DCU). Speed and Volume studies during the peak hour are carried out and based on the observed data dynamic car unit using modified homogenization coefficient approach is calculated. The wide ranges of DCU values for different location are observed based on the side friction, composition, wide ranging traffic characteristics and lane width. To have the unique value of the DCU optimization method is used. Based on the optimization final values of the DCU are frizzed which will be utilised to present the traffic stream volume in terms of equivalent passenger cars.]]></description>
      <pubDate>Wed, 01 Jul 2015 08:54:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1359520</guid>
    </item>
    <item>
      <title>Determination of Motorcycle Passenger Car Equivalence for Uninterrupted Flow in an Urban Road of Medellin, Colombia</title>
      <link>https://trid.trb.org/View/1289778</link>
      <description><![CDATA[Motorcycle ridership has increased globally. Its high presence in traffic accidents has led to its study from the safety perspective. Its role in traffic congestion and road performance is, nevertheless, less known. Studies made in the latter aspect have shown divergent results, without leading to a general consensus. In Colombia, the annual rate of motorcycle ownership increase (15%) is the highest in South America, and to the year 2009 motorcycles already represented 45% of the national motorized fleet. The lack of knowledge of the effects of motorcycles on road performance and congestion leads to inaccuracies in road network planning and design in countries with high ridership of these vehicles. This work studies motorcycles impact in traffic congestion by determining its Passenger Car Equivalence (PCEm) in an urban road of three lanes, zero slope, uninterrupted flow and 3,2 m lane width. It was found that PCEm decreases as passenger cars density increases due to an increase in motorcycle filtering. During stable flow, the average PCEm was 0,29, whereas unstable flow showed an average PCEm of 0,05. Average PCEm observed for all regimes was 0,16. According to this, it is concluded that traditional PCEm used in Colombia (PCEm = 0,5) is not accurate and overestimates motorcycles impact on traffic. It is also concluded that the impact of motorcycles on congestion, for the observed traffic compositions, is negligible when filtering. Thus, from the traffic perspective, motorcycles can be beneficial to society for they, in certain conditions, allow people to dodge congestion and keep moving.]]></description>
      <pubDate>Wed, 26 Mar 2014 11:27:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1289778</guid>
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