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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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    <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>Determinants and deterrents of urban cycling : evidence from Europe</title>
      <link>https://trid.trb.org/View/2666531</link>
      <description><![CDATA[Urban cycling contributes to climate-neutral and resilient mobility, and its uptake hinges on a blend of behavioural, environmental, and infrastructural forces. This licentiate thesis brings together evidence from three empirical studies conducted in Braga, Istanbul, and Tallinn (papers A and B), as well as Paris and Barcelona (paper C) to identify and quantify drivers of cycling and to translate findings into insights that matter for policy. The first paper shows that a GPS-verified, gamified reward scheme, involving roughly 1,500 participants increased weekday cycling. The second paper applied mixed ordinal probit models to six months of data from the same reward scheme and finds that higher wind speeds and private-car ownership reduce weekly cycling, whereas public-transport use boosts it. The third paper employs ARIMAX time-series models of bicycle counts and identifies a pandemic step change, accounting for about 35,000 added bicycle trips per week in Paris and 26,000 trip per week in Barcelona. It also finds the added effects of infrastructure initiatives and lockdown stringency. The three studies highlight three overarching drivers of cycling: behavioral incentives, environmental conditions, and rapid-built infrastructure. These factors contribute to explaining when, where, and for whom cycling gains materialize. This thesis contributes with robust multi-city evidence, suggesting that targeted rewards, wind-protected lane design, car-access management, and transit integration can speed up modal shifts. It provides guidance to sustain and grow urban cycling across diverse city contexts, aligned with European climate goals.]]></description>
      <pubDate>Thu, 05 Feb 2026 08:33:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2666531</guid>
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    <item>
      <title>Lösningar för snabbare utveckling av skogsbilvägar i Sverige</title>
      <link>https://trid.trb.org/View/2534317</link>
      <description><![CDATA[]]></description>
      <pubDate>Fri, 04 Apr 2025 15:16:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2534317</guid>
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    <item>
      <title>Koll på kostnaderna : kartläggning av Trafikverkets digitala infrastruktur för kostnadskontroll</title>
      <link>https://trid.trb.org/View/2534188</link>
      <description><![CDATA[The Swedish infrastructure manager Trafikverket has repeatedly received criticism for lacking the necessary conditions to monitor the agency's output, outcomes, and costs. These shortcomings limit both the Parliament's and the Government's ability to make well-informed decisions regarding Trafikverket and the national transport infrastructure, as well as the agency's internal management and operational development. To address these issues, Trafikverket has initiated several large and costly development projects for new IT systems and improved information management. This report aims to provide an updated description and assessment of Trafikverket's digital infrastructure for central monitoring of cost control in its construction and maintenance operations. The survey is based on interviews with managers and project leaders for a selection of prioritized IT systems, governing documents and observations of the systems. The survey was conducted by VTI on behalf of Transport Analysis. We find that Trafikverket is undertaking several initiatives that could lead to significant improvements in central monitoring of operations and cost control. Of particular importance are two new IT systems that gather information on completed work and payments, increased use of data warehouses for storing and accessing information from various systems, and efforts to harmonize the terminology structure into a common information model. However, we find that these initiatives, like several others identified in the survey, are delayed and have faced difficulties in the implementation phase. Compiling information across multiple investment projects or maintenance contracts remains difficult and resource-demanding. We find that significant effort is required from Trafikverket's internal governance to complete ongoing improvement initiatives and integrate them into a well-functioning whole.]]></description>
      <pubDate>Fri, 04 Apr 2025 15:14:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2534188</guid>
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    <item>
      <title>Examining the Effect of Binder Types on Moisture Damage Resistance of HMA Mixtures Incorporating Recycled Concrete Aggregate</title>
      <link>https://trid.trb.org/View/2464798</link>
      <description><![CDATA[Moisture damage refers to the reduction in stiffness and strength in asphalt mixtures due to moisture exposure, compounded by the mechanical stress from traffic load, leading to a condition commonly known as stripping. Moisture damage, which causes a decline in the structural integrity of asphalt pavement, is a major factor in the emergence of various types of distress such as fatigue cracking, rutting, and more. Hence, the objective of this research is to assess the impact of different binder types and treatment methods of Coarse Recycled Concrete Aggregate (CRCA) on the tensile strength and moisture resistance of Hot Mix Asphalt (HMA) of Ontario Superpave mixtures. This study employs two kinds of binders: PG 64-28 and PG 52-34. Thermal treatment method, accompanied by short mechanical treatment, were carried out to improve the CRCA properties. Two different types of binders, 0.0% and 30% CRCA, were used to conduct mix designs of asphalt mixtures. At a 30% CRCA level, the emphasis was on evaluating the impact of binder types and treatment techniques. The tensile strength and moisture sensitivity of the asphalt mixtures were assessed in relation to the binder types and treated CRCA. The study found that when compared to the typical control mix, HMA mixtures with different types of binder combined with treated CRCA showed higher tensile strength. Additionally, the laboratory analysis showed that all TSR values for mixtures containing various binder types with CRCA treatment are higher than the MTO specifications’ minimum demand value, except the control mixture containing PG 52-34. Furthermore, the outcomes demonstrated that mixes containing treated CRCA, and the PG 64-28 binder type had greater Tensile Strength Ratio (TSR) and Indirect Tensile Strength (ITS) than mixes containing the PG 52-34 binder type. These findings suggest that mixtures containing CRCA performed exceptionally well. The ANOVA analysis outcomes indicated that the type of binder has a higher impact on ITS and moisture susceptibility outcomes than treating CRCA. Furthermore, because of their negligible interaction, these parameters function independently of one another.]]></description>
      <pubDate>Wed, 08 Jan 2025 13:52:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2464798</guid>
    </item>
    <item>
      <title>Erhöhung der höchstzulässigen Gesamtlänge für Lang-Lkw durch Ausstattung mit emissionsfreien Antrieben und/oder aerodynamischen Anbauten</title>
      <link>https://trid.trb.org/View/2431334</link>
      <description><![CDATA[Das Forschungsprojekt soll wissenschaftliche Erkenntnisse zur Frage liefern, welche Herausforderungen für den Einsatz von Lang-Lkw entstehen könnten, sofern eine technische Ausstattung mit emissionsarmen Antrieben und/oder aerodynamischen Fahrzeugfronten unter der Voraussetzung erfolgt, dass die technischen Anpassungen weder eine Reduzierung der Ladelänge noch eine Änderung der technischen Vorgaben für Führerhäuser nach sich ziehen soll. Die Umsetzung dieser Voraussetzungen hätte eine Erhöhung der höchstzulässigen Gesamtlänge für Lang-Lkw zur Folge, deren Auswirkungen bisher unerforscht sind. Es soll untersucht werden, inwieweit eine Erhöhung der höchstzulässigen Gesamtlänge in Paragraf 4 Absatz 1, 2 und 3 der Ausnahme-Verordnung für den Einsatz von Lang-Lkw (LKWÜberlStVAusnV) durch verlängerte Lkw-Führerhäuser oder die Ausstattung mit emissionsfreien Antrieben (Wasserstoffspeicher hinter dem Führerhaus) möglich ist und welche neuen Anforderungen sich hieraus unter Umständen für den Einsatz von derartigen Lang-Lkw ergeben. ABSTRACT IN ENGLISH: The aim of the research project is to provide scientifical findings on the question of what challenges could arise for the use of long trucks if these are technically equipped with low-emission drives and/or aerodynamic vehicle fronts, provided that the technical adaptations do not result in a reduction in the loading length or a change in the technical specifications for driver's cabs. The implementation of these requirements would result in an increase in the maximum permissible overall length for long lorries, the effects of which have not yet been researched. It is to be investigated to what extent an increase in the maximum permissible overall length in Section 4 (1), (2) and (3) of the Exemption Ordinance for the use of long lorries (LKWÜberlStVAusnV) is possible with extended cabs or with emission-free drives (hydrogen storage behind the cab) and what new requirements may result from this for the use of such long lorries.
]]></description>
      <pubDate>Wed, 25 Sep 2024 05:30:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/2431334</guid>
    </item>
    <item>
      <title>Road Safety Action Plan 2022-2025 : 250 measures that 33 authorities and stakeholders intend to implement to increase road safety</title>
      <link>https://trid.trb.org/View/2388975</link>
      <description><![CDATA[Since 2018, the Swedish Transport Administration has been tasked by the Government to lead overall collaboration on road safety work. This assignment means that the Swedish Transport Administration must lead the collaboration in a way that creates a continued and increased commitment and responsibility among the relevant authorities and stakeholders to contribute to safe road traffic in which no one is killed or seriously injured. One of the activities conducted as part of this assignment is that the Swedish Transport Administration brings together authorities, organisations and stakeholders who have the opportunity to contribute to this work in a joint action plan. The purpose of the action plan is to strengthen and highlight effective measures implemented by various stakeholders to actively contribute to safe road traffic in the period 2022 to 2025. The plan will also highlight the respon-sibilities of different authorities and stakeholders in the short term, with a focus on a number of priority action areas. The plan is also a tool for the Swedish Transport Administration to be able to lead and monitor the road safety work in an effective and result-oriented manner. The action plan is the second of its kind and applies to the period 2022–2025.]]></description>
      <pubDate>Mon, 10 Jun 2024 14:04:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2388975</guid>
    </item>
    <item>
      <title>How is traffic safety affected by changes in traffic speeds following speed limit increases? An evaluation with probe vehicle data</title>
      <link>https://trid.trb.org/View/2100425</link>
      <description><![CDATA[Maximum speed limits continue to be an important policy issue. Research has consistently shown speeds to increase following speed limit increases. These increases have also generally coincided with increases in both the frequency and severity of crashes. However, research has been more limited as to the direct relationship between speed and safety. To this end, the present study evaluates the effects of increasing speed limits on the safety of rural limited access freeways while accounting for contemporaneous changes in the speed profiles of these same roadways. The speed limit increases in Michigan occurred between May 1 and June 12 of 2017, when the maximum speed limits were increased from 70 to 75 mph on approximately 600 miles of freeways. The maximum speed limits for trucks were also increased from 60 to 65 mph on all freeways state-wide at this same time. Speed data were obtained for the Michigan rural freeway network through probe vehicles. These data are merged with pertinent roadway data, as well as police-reported crash data at various levels of injury severity. The impacts of the speed limit increase on safety were evaluated by estimating random effects negative binomial models as part of a case-control before-after study design. The results show that the locations where the speed limits were increased experienced a 5% increase in crashes, while a marginal reduction in crashes was observed where speed limits did not increase. Interestingly, mean speeds were found to be negatively associated with crash frequency, while the standard deviation of speed was found to exhibit a positive relationship. Several site-specific characteristics were also found to be strong predictors of crash frequency. The results provide important insights into the nature of the relationship between speed and safety and will help to guide subsequent speed limit policy decisions.]]></description>
      <pubDate>Mon, 23 Jan 2023 12:29:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2100425</guid>
    </item>
    <item>
      <title>Utredning av mål för ökad cykling i Sverige : ett regeringsuppdrag</title>
      <link>https://trid.trb.org/View/2075213</link>
      <description><![CDATA[Today, there is no defined national target level regarding increase in bicycling in Sweden. VTI received a governmental assignment to define that. The assignment includes a definition of a target structure and suggestion of indicators as well as a system for monitoring. We have gathered information through literature studies, a workshop, a survey as well as through own analyses of data from national travel surveys. We have limited the definition of cycling to include pedal cycle with or without electric assistance. Simply speaking, the rate of bicycling should double by 2035 and, more specifically, we suggest the following targets: Overall objectives: Cycling in Sweden should increase to improve accessibility, strengthen public health, and decrease the climate and environmental impact. Intermediate target 1: The bicycle share of the total number of travellers in Sweden should increase to 20 percent by 2030 and to 26 percent by 2035, without reducing the share of pedestrians or public passenger transports. Intermediate target 2: The bicycle share of the total transport system work in Sweden should increase to 3 percent by 2035, without reducing pedestrians or public passenger transports. Milestone 1: The total share of bicycle travel in Sweden, shorter than 10 km, should increase to 30 percent by 2030 and to 45 percent by 2035, without reducing the share of pedestrians or public passenger transports. Milestone 2: The total share of bicycle travel for primary school children in Sweden should increase to 40 percent by 2030 and to 50 percent by 2035, without reducing the share of pedestrians.  In addition, we have suggested seven indicators with associated measures linked to the targets suggested above. The national travel survey could be used to monitor the targets and the annual report by the National Council of Bicycling could preferably be used for monitoring the indicators.]]></description>
      <pubDate>Fri, 02 Dec 2022 11:41:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2075213</guid>
    </item>
    <item>
      <title>Evaluation of Cracking Resistance and Permanent Deformation of Control and Fibre-modified Plant-produced Hot-mix Asphalt</title>
      <link>https://trid.trb.org/View/2071807</link>
      <description><![CDATA[The asphalt binder is a viscoelastic substance that exhibits both viscous and elastic behaviour. Asphalt binder is an effective adhesive material for use in the pavement, however it is a difficult material to understand and describe due to the wide variety of its behaviour. This research aimed to investigate the impact of polymer modification on nonrecoverable creep compliance (Jnr). Three modifiers (fly ash (FA), Styrene-Butadiene- Styrene (SBS), and fly ash-based on geopolymer (GF)) were used. Asphalt binders were tested at various temperatures, ranging from 40 to 70 °C with a 3 °C gap, and regression models were developed. The results revealed that 2% SBS modified asphalt binder exhibited elastomeric behaviour at low temperatures, whereas 4% SBS modified asphalt binder exhibited noteworthy elastomeric behaviour at various temperatures. The power-law models most effectively illustrated the correlation between temperature and nonrecoverable creep compliance (Jnr) at different stresses, 0.1 kPa and 3.2 kPa. The developed models proved to be effective for appropriately selecting the polymer type and amount suitable to minimize the Jnr. The hybrid and 4%SBS binders performed best in terms of strain recovery at high temperatures, with Jnr values of less than 0.5 being achieved at 58 °C and 3.2 kPa.]]></description>
      <pubDate>Tue, 29 Nov 2022 14:16:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2071807</guid>
    </item>
    <item>
      <title>Vikten av att följa upp kommunal upphandling av beläggningsunderhåll</title>
      <link>https://trid.trb.org/View/1948887</link>
      <description><![CDATA[To deepen the understanding of municipal procurements of pavement maintenance and renewal, information on the activities carried out in 2018 and 2019 has been collected from several municipalities. Response rate and access to the requested information is not sufficient to draw firm conclusions. One result of the collection work is therefore that there is still a lack of coherent knowledge about the municipalities' procurements of paving work. Despite this, it is possible to make preliminary recommendations based on available material, the purpose of which is to strengthen the business in the long term.  In part, the proposals are based on work that the research group has carried out over several years on analysing the Swedish Transport Administration's tendering of the same type of activities. While the Swedish Transport Administration procures many individually large pavement projects, the municipalities tender framework agreements that specify several comparatively small measures that may be called off over a multi-year agreement period. The Swedish Transport Administration's orders therefore state what, within an uncertainty interval, is to be carried out, while the municipalities describe activities that may be called off.  In addition to the uncertainty about which jobs a municipality will order, there are also differences in knowledge between the ordering municipality and the companies that submit tenders. While each of Sweden's 290 municipalities carries out a procurement every few years, some dominant contracting companies submit tenders each year for several dozen procurements in different parts of the country. This means that bidders in many cases have a better understanding of which business may be called off than the customer itself has. The company that holds the contract up for re-tendering has a particularly good understanding of the situation in the municipality.]]></description>
      <pubDate>Fri, 06 May 2022 17:07:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/1948887</guid>
    </item>
    <item>
      <title>Kontrakt för underhållsbeläggningar : analyser av produktivitet, effektivitet och kostnadsförändringar mellan avtal och slutkostnader</title>
      <link>https://trid.trb.org/View/1894973</link>
      <description><![CDATA[Every year, the Swedish Transport Administration carries out paving work to maintain an acceptable standard on longer road sections for almost SEK 3 billion. The report summarizes the results of three analyses made of this type of procurement. Both the project cost in the contract between the Swedish Transport Administration and a contractor and the final invoiced cost are treated. The purpose is to identify opportunities to further develop the business's productivity and efficiency. Each percentage point cost savings can free up significant funds to order more maintenance or to transfer to other, more urgent purposes. The first sub-study points to opportunities to streamline the applications of hot coatings. Analysis of the cost of 293 such contracts show that there are strong reasons to consider making the contracts larger than today. The more square meters of asphalt in each contract, the lower the cost per square meter. The second sub-study tries to explain why the final cost is on average 14 percent higher than the cost in the contracts signed, while the third study reports a productivity analysis of the same contracts. Even though several hundred pavement contracts were tendered during the pertinent period, only 91 observations have been available for analysis. The explanation is that it is not possible to link the activities procured with the result of the assignments. This applies to both the costs of the business and the actual amount of work, which may differ from the orders placed.  The final review of the report has also identified shortcomings in the matching between contract and final cost, which means that it is not possible to report any policy conclusions. However, the analyses illustrate how follow-ups can be carried out to deepen the understanding of, among other things, cost deviations.]]></description>
      <pubDate>Wed, 01 Dec 2021 14:50:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1894973</guid>
    </item>
    <item>
      <title>Impact of Cement or Asphaltenes on Low-temperature Performance of Asphalt Emulsion Stabilized Base Courses</title>
      <link>https://trid.trb.org/View/1887390</link>
      <description><![CDATA[A pavement’s structure gradually deteriorates due to repeated traffic load and environmental effects. These effects lead to distresses such as permanent deformation, fatigue cracking and thermal cracking. Granular base course stabilization using asphalt emulsion is one the most popular techniques to enhance the layer performance in order to achieve sufficient bearing capacity and resistance to pavement distresses. The major drawbacks of asphalt emulsion-stabilized base course, though, are its low early strength, long curing time, and low resistance to permanent deformation and moisture damage. To address these drawbacks, the asphalt emulsion-stabilized layer is usually modified with cement, which can improve its early strength and performance properties. However, using the cement makes the treated base course more prone to shrinkage cracking. Asphaltenes is a waste material derived from Alberta oil-sands with no significant use in the pavement industry. Asphaltenes is one of the polar fractions of asphalt binder, and its addition to asphalt binder has been found to have a considerable effect in increasing stiffness. In this context, the present study compares the impact of cement versus asphaltenes on the asphalt emulsion-stabilized base performance properties. For this purpose, different concentrations of cement and asphaltenes (1% and 2% per weight of total mixture) are added to asphalt mixtures, and the mechanical properties of the mixtures, including the low-temperature performance, are evaluated. It is concluded that both asphaltenes and cement are effective in improving a mixture’s strength and rutting resistance. However, cement-modified mixtures are found to be more prone to low-temperature cracking than are asphaltenes-modified mixtures.]]></description>
      <pubDate>Fri, 22 Oct 2021 15:20:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1887390</guid>
    </item>
    <item>
      <title>Ermüdungsfestigkeit von Konsolträgern an Stahlverbundbrücken und Überprüfung der Schädigungshypothese an Stahlbetonplatten unter Zug und Querkraftbeanspruchung</title>
      <link>https://trid.trb.org/View/1872998</link>
      <description><![CDATA[Brücken mit Stahlverbund-Hohlkasten und Konsolträgern bieten beim Neubau von Großbrücken beträchtliche Vorteile. Für eine schnelle Umsetzung werden für die Fahrbahnplatten häufig Konstruktionen mit Teilfertigteilen und Ortbetonergänzung gewählt, welche die Verkehrslasten planmäßig in Längsrichtung abtragen. Zur Sicherstellung von robusten und dauerhaften Konstruktionen sind aufgrund fehlender normativer Regelungen für diese Bauweise bestimmte Festlegungen des BMVI zu beachten. Mit den geplanten Untersuchungen sollen Teile dieser Regelungen überprüft und wissenschaftlich abgesichert werden. Im Fokus steht dabei die Ermüdungsfestigkeit längszugbelasteter Stahlbetonplatten von Verbundbrücken unter Berücksichtigung des Querkraftabtrags. Mithilfe von statischen Referenz- und dynamischen Mehrstufen-Versuchen soll überprüft werden, ob die Schädigungshypothese nach Palmgren-Miner auch für gerissene Stahlbetonplatten gültig ist. Einen weiteren Untersuchungsbereich bilden die Anschlüsse der Konsolträger an die Haupträgerstege des Hohlkastens, verbunden mit dem Ziel, diese Anschlüsse hinsichtlich Fertigung und ausreichender sicherer Ermüdungsfestigkeit zu optimieren. Außerdem sollen mithilfe von Bauwerksmonitoring an aktuell ausgeführten Bauwerken die vorgenannten Untersuchungen ergänzt werden. (A) ABSTRACT IN ENGLISH: Bridges with steel composite box girders and bracket girders offer considerable advantages in the new construction of large bridges. For a quick implementation, constructions with precast elements and in-situ concrete supplementation are often chosen for the deck slabs, which transfer the traffic loads according to plan in the longitudinal direction. In order to ensure robust and durable constructions, certain regulations of the Federal Ministry of Transport and Digital Infrastructure have to be observed due to the lack of normative regulations for this construction method. With the planned investigations, parts of these regulations are to be examined and scientifically validated. The focus is on the fatigue strength of reinforced concrete slabs of composite bridges subjected to longitudinal tensile loads, taking shear force transfer into account. With the help of static reference and dynamic multi-stage tests, it is to be checked whether the damage hypothesis according to Palmgren-Miner is also valid for cracked reinforced concrete slabs. A further area of investigation is the connections of the bracket girders to the main girder webs of the box girder, with the aim of optimising these connections with regard to fabrication and sufficient safe fatigue strength. In addition, the aforementioned investigations are to be supplemented with the help of structural monitoring on currently executed structures. (A)]]></description>
      <pubDate>Wed, 27 Oct 2021 07:51:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/1872998</guid>
    </item>
    <item>
      <title>Investigating the Freeze-Thaw Damage in Asphalt Concrete Using Imaging Techniques</title>
      <link>https://trid.trb.org/View/1754895</link>
      <description><![CDATA[In cold regions, asphalt concrete (AC) pavements experience freeze-thaw (F-T) cycles. F-T cycles can cause damage and disintegration of AC mixtures, which cause significant operational problems and a reduction in the service life of AC pavements. The evolution of the internal structure of an AC mix due to exposure to F-T cycles should be explored to have a better understanding of the mechanism of F-T damage in the mix. In this study, different AC specimens were evaluated before and after F-T cycles using two techniques: indirect tension test (IDT) to evaluate strength deterioration of specimens, and imaging techniques to capture changes in the internal structure of specimens. Three imaging techniques were used in this project: digital camera, stereomicroscope, and X-ray computer tomography (CT) scan system. Each technique has its potentials to show the internal damage details. AC specimens have been assessed at different levels of F-T cycles. 2D and 3D images for the internal structure of the specimens were collected and analyzed at 0, 15, 30 and 45 F-T cycles. The captured images will be analyzed to quantify the F-T damage according to adhesion failure (%), cohesion failure (%), broken aggregate (%), and the total length of microcracks (mm). The results from image analysis will be correlated to IDT results.]]></description>
      <pubDate>Tue, 01 Dec 2020 13:58:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1754895</guid>
    </item>
    <item>
      <title>Railway concrete arch bridge over Kalix River at Långforsen : dynamic properties and load-carrying capacity</title>
      <link>https://trid.trb.org/View/1737809</link>
      <description><![CDATA[The concrete arch bridge over Kalix River at Långforsen was built in 1960 and has a mid-span of 89,5 m and a height of 13,7 m. The bridge owner, Trafikverket, wanted to increase its allowable axle load from 225 to 300 kN. Field tests were carried out under service condition and with ambient vibrations. The test results were used to update and validate Finite Element Models. At last, the refined models were used to check the possibility to increase the axle load.   According to earlier assessments, most parts of the bridge is capable of carrying an axle load of 330 kN. The only critical sections are located in the beams carrying the rail on top of the arch in the section where the beams are united with the arch. Here the stresses in the longitudinal bottom reinforcement are slightly too high.   These sections have been studied in a FEM model for different loads and results show maximum strains of about 50·10 -6 corresponding to stresses of only about 10 MPa in the reinforcement in the critical sections. Live load vertical deflections of the crown of the arch is of the order of only ± 6 mm. Dynamic studies have also been made showing that fatigue is no issue. Altogether the studies show that the bridge is able to carry an increased axle load of 300 kN without problems.]]></description>
      <pubDate>Tue, 08 Sep 2020 14:37:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1737809</guid>
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