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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>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Investigation of Interface between Asphalt Core and Gravel Transition Zone in Embankment Dams</title>
      <link>https://trid.trb.org/View/1531572</link>
      <description><![CDATA[The asphalt core is located between the upstream and downstream transition zones that are simultaneously placed and compacted in the central part of the embankment dam to form a strong interlocking asphalt core–gravel transition zone (AC-GTZ) interface. The asphalt core usually settles a little more than the transition zones during dam construction, and AC-GTZ interface shear displacements develop. Shear tests were conducted in the laboratory to investigate the interface behavior. Test results show that the AC-GTZ interface was gradually deformed up to a shear displacement of 60 mm, but the properties of the asphalt surface layer did not deteriorate. The integrity of the asphalt core would be better maintained if a sliding layer is placed between the core and the transition zone.]]></description>
      <pubDate>Mon, 17 Sep 2018 17:19:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/1531572</guid>
    </item>
    <item>
      <title>Corrective Countermeasure for Track Transition Zones in Railways: Adjustable Fastener</title>
      <link>https://trid.trb.org/View/1514224</link>
      <description><![CDATA[Transition zones in railway tracks are the locations with considerable variation in the vertical stiffness of supporting structures. Typically, they are located near engineering structures, such as bridges, culverts, tunnels and level crossings. In such locations, the variation of the vertical stiffness and the differential track settlement result in amplification of the dynamic forces acting on the track. This amplification contributes to the degradation process of ballast and subgrade, ultimately resulting in the increase of maintenance costs. The paper studies a corrective countermeasure that can mitigate the track degradation in transition zones when differential settlement appears. The countermeasure is the adjustable rail fastener and its working principle is to eliminate the gap under hanging sleepers by adjusting the shims (height of the fastener). The adjustable fasteners are first tested on three transition zones, wherein the adjusted heights of fasteners (accumulated voiding) are recorded after the 2-month and 5-month operation. The test results show the adjustable fasteners are effective to mitigate the track degradation in the transition zones. The effect of the adjustable fasteners on the dynamic behaviour of transition zones is analysed using the FE method. The results show that the adjustable fasteners are effective to reduce the amplification of wheel forces, achieve a better stress distribution in ballast, and decrease the normal stresses in rails in transition zones. Parametric studies are also performed to study the applicability of the adjustable fasteners.]]></description>
      <pubDate>Thu, 19 Jul 2018 14:44:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1514224</guid>
    </item>
    <item>
      <title>Numerical Simulations to Improve the Use of Under Sleeper Pads at Transition Zones to Railway Bridges</title>
      <link>https://trid.trb.org/View/1506048</link>
      <description><![CDATA[Transition zones to bridges and other structures are critical locations in railway tracks that frequently evidence poor long-term performance. Under sleeper pads (USPs) are reported to reduce ballast degradation and control the vertical stiffness of the track, which suggests that USPs can contribute to mitigating the frequent negative effects associated with transitions zones. Aiming at understanding in greater depth the influence of USPs on the dynamic behaviour of transition zones and at improving the design of such railway structures, the authors have developed an extensive experimental and numerical study. 3-D FEM models using state-of-the-art numerical approaches were successfully calibrated and validated using experimental measurements. Simulations supported previous findings, highlighting the potential benefit of USPs and pointing to the need to careful designing of the resilient properties of USPs and their arrangement along transition zones, so as to avoid introducing abrupt variations in track vertical stiffness.]]></description>
      <pubDate>Tue, 29 May 2018 16:04:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1506048</guid>
    </item>
    <item>
      <title>Field study using additional rails and an approach slab as a transition zone from slab track to the ballasted track</title>
      <link>https://trid.trb.org/View/1508160</link>
      <description><![CDATA[An abrupt change in the stiffness of railway tracks at the junction between slab track and ballasted track causes increased dynamic loads, asymmetric settlements, damage of track components, and, consequently, increased maintenance costs. Due to this, a transition zone is usually built at the junction between the ballasted and the ballastless tracks to reduce the aforementioned problems. One of the methods suggested as a transition zone in these areas is to use a combination of an approach slab and additional rails. This study evaluates the dynamic behavior of this type of transition zone using field tests and also compares its performance with a transition zone built only with an approach slab. Hence, in the Tehran–Karaj railway line, two types of transition zones were constructed: one including only the approach slab and the other one including additional rails and an approach slab. Then, by conducting some field tests, the dynamic behavior of the track in these two types of transition zones was examined. The results of the field measurements show that for the analyzed case study, at the combined transition zone with additional rails and an approach slab, instead of a sudden increase in rail displacements from the slab track to the ballasted track (i.e. by 53%), initially, in the first part of the transition zone (with additional rails and an approach slab), the deflections increase by an average of 31%, and then in the second part of the transition zone (with additional rails only) the deflections increase additionally by 11%.]]></description>
      <pubDate>Fri, 27 Apr 2018 12:21:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1508160</guid>
    </item>
    <item>
      <title>Dynamic behaviour of transition zones in soft soils during regular train traffic</title>
      <link>https://trid.trb.org/View/1504820</link>
      <description><![CDATA[Transition zones in railway tracks are of importance for infrastructure managers, due to the high maintenance required to maintain appropriate track geometry. To improve our understanding of the performance of transition zones, a research program was conducted in The Netherlands, in which a transition zone was extensively monitored during regular train traffic. This paper presents some of the results from the monitoring of this transition zone. The results highlight the poor performance of this transition zone compared to its expected design performance. The track was found to be hanging over the transition zone, exhibiting a rocking motion about a culvert. Track stiffness was found to reduce linearly with increasing train speed. The implications on the design of transition zones are discussed, with recommendations made.]]></description>
      <pubDate>Wed, 11 Apr 2018 11:37:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1504820</guid>
    </item>
    <item>
      <title>Modeling Progressive Settlement of a Railway Bridge Transition Zone</title>
      <link>https://trid.trb.org/View/1495795</link>
      <description><![CDATA[This paper models the progressive ballast settlement of a railway bridge transition using a three  dimensional dynamic numerical model that includes the train truck, rails, ties, ballast, subgrade, and bridge abutment. A ballast settlement model that relates tie load to ballast settlement is presented and demonstrated using an iterative procedure to evaluate bridge transition response up to 28 MGT. The results indicate transition zones attempt to reach a state of equilibrium in which the ballast settlement profile evenly distributes the wheel load to the underlying and surrounding ballast. This analysis scenario represents ideal transition zone behavior because it is assumed that the ballast is homogenous and has identical properties throughout the bridge approach. This assumption is challenged with simulations exploring heterogenous ballast conditions and the results suggest heterogenous ballast conditions may be a large contributor to differential settlement at transition zones.]]></description>
      <pubDate>Mon, 12 Mar 2018 15:02:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1495795</guid>
    </item>
    <item>
      <title>Dynamic response analysis of road-bridge transition section without slab</title>
      <link>https://trid.trb.org/View/1487677</link>
      <description><![CDATA[The objective of this research is to investigate the pavement response of road-bridge transition section without slab under impact load caused by vehicle bumping. The three-dimensional (3D) finite element models (FEM) of road-bridge transition section without slab were developed to simulate the response under impact load. The influence of different parameters (damping ratio, step height, vehicle speed as well as axle load) on the pavement response was investigated. Results indicated that an obvious increase of pavement response was observed with the step height and axle load rising. On the contrary, the rise of vehicle speed and damping ratio led to the decrease of pavement response. In addition, the pavement under impact load exhibited larger response as compared to under static load. Therefore, the phenomenon that static load was considered only in the traditional pavement structure is defective. Finally, the correction coefficients of design index for highway asphalt pavement were proposed to consider the influence of impact load.]]></description>
      <pubDate>Mon, 13 Nov 2017 16:31:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1487677</guid>
    </item>
    <item>
      <title>Experimental Assessment of the Dynamic Behaviour of the Train-track System at a Culvert Transition Zone</title>
      <link>https://trid.trb.org/View/1459681</link>
      <description><![CDATA[This article describes the experimental assessment of the dynamic behaviour of the train-track system at a culvert transition zone located at the Northern line of the Portuguese railway network. Based on receptance tests, the dynamic flexibility of the track along the transition was characterised. From the full track resonance frequency, a reduction of 60% was observed on the dynamic flexibility of the track on the structure in relation to the track on the embankment; The dynamic response of the track was also monitored in different sections for the passage of the Alfa Pendular trains at a speed of 220 km/h. Based on these tests, it was concluded that the displacements of the track on the structure and on the transition wedge were, respectively, 45% and 30% lower than those of the track on the embankment. Despite the significant variations of the dynamic stiffness of the track, the accelerations of the sleepers, after the application of a low-pass filter for eliminating contributions from irregularities of the track and of vehicle wheels, did not exhibit relevant variations along the transition zone. Likewise, no substantial variations were registered in terms of the dynamic loads applied by the train at the monitored track sections. Finally, synchronized measurements of the dynamic response of the track and of the inspection vehicle EM 120 were made at a speed of 100 km/h, where no significant amplifications induced by the transition were recorded for the accelerations on the axles, on the bogies and on the vehicle box.]]></description>
      <pubDate>Tue, 28 Mar 2017 17:09:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1459681</guid>
    </item>
    <item>
      <title>Under-Tie Pads to Improve Track Resiliency in Railroad Transition Zones</title>
      <link>https://trid.trb.org/View/1438321</link>
      <description><![CDATA[Under-tie pads were installed under twenty-nine (29) ties within an existing high-speed passenger bridge approach on the Northeast Corridor in an effort to alleviate reoccurring track geometry problems at this transition. Anticipated benefits of under-tie pads include: (1) a reduction in approach ballast and tie degradation by better distributing the load to the ballast, (2) increased vibration damping, and (3) reduced contact stress between the tie and individual ballast particles. After installation, the approach track geometry and behavior was measured using track geometry cars and non-invasive instrumentation, e.g., video cameras and accelerometers, to assess performance. These field measurements show stable track geometry after about one year of traffic.]]></description>
      <pubDate>Mon, 27 Mar 2017 09:32:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/1438321</guid>
    </item>
    <item>
      <title>Static and Dynamic Behavior of Transitions Between Different Railway Track Typologies</title>
      <link>https://trid.trb.org/View/1446205</link>
      <description><![CDATA[A railway track stretch comprising three different track typologies (i.e., ballasted track, asphalt slab track and concrete slab track) has been modeled using a three-dimensional Finite Elements model, which has been calibrated and validated using real acceleration records. In this model, two different analyses have been run: a static analysis to assess the stiffness evolution and a dynamic analysis to calculate the accelerations induced by the train loads along the transition zones. These analyses have been used to assess the performance of three different techniques existing in the literature to improve the structural behavior of the track in the transition areas: the variation of the stiffness of the elastomers, the implementation of additional rails and the use of resilient mats. Results have demonstrated that these techniques perform generally better in the track vertical stiffness transition between the concrete and asphalt slab tracks while the dynamic response is not significantly altered in any scenario.]]></description>
      <pubDate>Mon, 27 Feb 2017 09:39:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/1446205</guid>
    </item>
    <item>
      <title>The Influence of Train Running Direction and Track Supports Position on the Behaviour of Transition Zones</title>
      <link>https://trid.trb.org/View/1447109</link>
      <description><![CDATA[Different types of track infrastructure can be found along railway lines. Separation zones between these different types of structures are the source of a lot of problems. Transition zones on a railway line represent a gradual solution for the problems between conventional railway structure and singular structures located at different points along the line. The different nature, positioning and geometry used with the materials generate changes in the stiffness on both sides of these singular zones leading to an increase in wear and a loss of geometry, with the associated maintenance costs.  This article describes the use of mathematical modelling to represent the behaviour of these zones as a function of train running direction and track supports. Available research into transition zones has not studied these separation points where high increases in load are generated for very short periods of time.  Finite elements are used to model two types of track (conventional ballasted track and slab track), using a vehicle to dynamically simulate the behaviour in these zones as a function of train running direction and the position of track supports.  The magnitudes analysed were the vertical stresses and the vertical displacements under the sleepers and the supports in both types of structure.  The results show increased stresses at the separation zone between both structures which varied in magnitude and position depending most of track supports’ location than the train running direction.]]></description>
      <pubDate>Mon, 27 Feb 2017 09:38:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1447109</guid>
    </item>
    <item>
      <title>The influence of substrate moisture preparation on bond strength of concrete overlays and the microstructure of the OTZ</title>
      <link>https://trid.trb.org/View/1441002</link>
      <description><![CDATA[The influence of substrate moisture preparation on the direct shear bond strength of composite substrate-overlay specimens was evaluated. The substrate surface was exposed to four different moisture conditions prior to overlay application. A quantitative analysis of backscattered electron images of the microstructure of the overlay transition zone (OTZ) was carried out to quantify its properties along the interface and help analyse the results of the shear bond testing. The results show that pre-wetting the substrate surface prior to application of the overlay provides no added benefit towards increasing the bond strength and may in some cases reduce bond strength significantly. The microstructural investigations confirmed that pre-saturated substrates increase the w/c ratio and the porosity in the OTZ, which was found to have a thickness of about 100 µm. The OTZ in overlays cast on dry substrate surfaces had lower porosity and an increased amount of anhydrous cement.]]></description>
      <pubDate>Sat, 14 Jan 2017 17:18:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1441002</guid>
    </item>
    <item>
      <title>Iterative Method for Predicting Uneven Settlement Caused by High-Speed Train Loads in Transition-Zone Subgrade</title>
      <link>https://trid.trb.org/View/1437953</link>
      <description><![CDATA[Uneven subgrade settlement associated with rail deflection occurs mainly in the bridge–embankment transition zones of high-speed railways. An iterative method of computation is proposed for studying such uneven settlement in these zones. A vehicle–track–subgrade model is used to investigate the vehicle–track interactions and the deviator stress field of the transition zone, and a soil cumulative plastic strain model is used to obtain the deterioration process of uneven settlement in the transition zone. Results indicate that uneven settlement caused by train loads in the transition zone tends to plateau at 40,000 repeated load applications. Subgrade settlement changes abruptly in the first measured 5 m, as well as from 25 to 30 m from the abutment; these two regions should be adequately strengthened and should receive more attention for track maintenance.]]></description>
      <pubDate>Thu, 29 Dec 2016 15:53:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1437953</guid>
    </item>
    <item>
      <title>Structural Performance and Strength Prediction of Steel-to-Concrete Box Girder Deck Transition Zone of Hybrid Steel-Concrete Cable-Stayed Bridges</title>
      <link>https://trid.trb.org/View/1413318</link>
      <description><![CDATA[Because a large longitudinal force exists in hybrid girder cable-stayed bridges due to the cable tension, its transfer mechanisms on the steel-concrete combination segment would be an important issue. In this study, experiments and theoretical analysis were conducted to characterize the longitudinal force transfer mechanisms of the steel-concrete combination segment in hybrid girder cable-stayed bridges. Five full-scale local structure specimens were designed and manufactured based on the original design of the steel-to-concrete transition zone according to a completed cable-stayed bridge in China. The specimens were subjected to monotonic loading and tested up to complete failure. The load-slip curves; stress distribution and failure modes, which varied with the thickness of the bearing plate; and the shear connector distribution were obtained. To simulate the test properly, calculation methods for predicting the shear connector capacity and corresponding load-slip curves were proposed based on the analysis and experimental results including headed studs and perfobond strip connectors. Thus, a finite-element model using a nonlinear spring to simulate the shear connectors was proposed and validated by the test. Force transfer mechanisms were analyzed, and load distributing between different components of this composite system were revealed. As a result, the load distributing mode could be used to instruct preliminary engineering design and the modeling method could be used to verify it.]]></description>
      <pubDate>Mon, 29 Aug 2016 11:14:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/1413318</guid>
    </item>
    <item>
      <title>Numerical analysis of railway transition zones in soft soil</title>
      <link>https://trid.trb.org/View/1416983</link>
      <description><![CDATA[Transition zones are constructions intended to provide smooth passage of a train, when moving from a track supported on an embankment to a track on a stiff structure, such as a bridge, tunnel or culvert. The design of transition zones is based on creating a gradual stiffness variation between the free track and the stiffer structure. In the Netherlands, the standard transition zone design consists of placing a concrete approach slab before and after the structure. In the present paper, the performance of a typical transition zone is assessed, by means of numerical analysis. After validation of the results it is shown that the presence of a concrete slab, combined with the fact that the sleepers are hanging, causes a stress redistribution towards the free end of the approach slabs. This aggravates the long-term deformation of the soil and increases the differential settlement under normal train speed. A critical train speed is identified for the transition zone.]]></description>
      <pubDate>Thu, 28 Jul 2016 10:45:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/1416983</guid>
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