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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Updated Austroads road deterioration models</title>
      <link>https://trid.trb.org/View/2404171</link>
      <description><![CDATA[This paper presents how the existing Austroads road deterioration (RD) models were updated to improve their explanatory power based on all the available data from the Austroads long-term pavement performance (LTPP) sites and long-term pavement performance maintenance (LTPPM) sites collected from 1994 to 2018. Additional data was sourced from the road agencies using time series datasets collected by the traffic speed deflectometer (TSD) from 2014 to 2018. Supplementary experimental data was also used that was derived from the accelerated load facility (ALF) specifically aimed at determining the quantitative impact of surface treatments on deterioration. The updated RD single algorithm-based models were derived from a mechanistic-empirical deterministic approach using multi-variate non-linear (MVNLR) regression analyses. The updated RD models include only statistically significant independent variables. These models are applicable to thin surfaced unbound granular base flexible pavements undergoing gradual deterioration. The thin surfaces include both sprayed seals and thin asphalt surfaces. The models can predict the impact of increased heavy vehicle loads and the varying climate conditions observed in Australia. The paper outlines the future approach to RD modelling based on future extensive datasets available from the annual TSD network monitoring of each state/territory jurisdiction. These datasets will allow the development of separate RD models regionally based within each jurisdiction. The study was managed in conjunction with the technical support of an Austroads Project Working Group (PWG) sourced from industry and the road agencies. In addition, the Australian Road Research Board (ARRB) of the National Transport Research Organisation (NTRO) sought expert advice from acknowledged experts in industry and academia. These updated RD models can be included in a typical pavement management system (PMS) used by state and local road agencies.]]></description>
      <pubDate>Thu, 18 Jul 2024 10:48:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2404171</guid>
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    <item>
      <title>A new crumb rubber technology: experiences since 2010</title>
      <link>https://trid.trb.org/View/1404855</link>
      <description><![CDATA[The development of a New Crumb Rubber Technology (NCRT) has proven to provide the South African Roads industry with a bitumen rubber technology which reduces the risk to suppliers, contractors and to the client. Flexibility in manufacturing and supply makes bitumen rubber much more readily available to a larger client base due to the removal of the limited shelf-life associated with conventional bitumen rubber. In the past, smaller quantities of bitumen rubber could not be delivered to remote locations due to the time/temperature dependence of conventional bitumen rubber technologies. NCRT provides opportunities to supply the reacted crumb rubber products over long distances. Clients that were prepared to embrace the improved bitumen rubber technology were exceptionally intrigued by the increased flexibility and the warm mix asphalt benefit that NCRT provides. Case studies where NCRT was used since 2012 in the construction of roads (both asphalt and sprayed seal applications) will be discussed in this paper. The purpose of this paper is to inform the contractors, consulting engineering fraternity and clients of the benefits observed, opportunities created, increased flexibility and reduced risk associated to the next generation of crumb rubber based modified binders. NCRT presents the Roads Industry with a more durable bitumen rubber in applications ranging from grit seal, single seals, double seals and through all asphalt gradations.]]></description>
      <pubDate>Fri, 22 Apr 2016 11:17:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1404855</guid>
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    <item>
      <title>Incorporating heavy vehicles into seal designs</title>
      <link>https://trid.trb.org/View/1404782</link>
      <description><![CDATA[The foremost challenge facing spray seal designers and practitioners is the performance of sprayed seals under the increasing numbers of large heavy vehicles on major transportation routes connecting capital cities and in rural areas, particularly in Australia. The objective of this paper is twofold. Firstly, the loadings permitted on single, tandem and triaxle groupings have been calculated such that the multiple axles cause the same damage as the more lightly loaded single axles. This is based on pavement theory. However, do these axle groupings and loadings that cause the same damage to a pavement, cause different damage to a sprayed seal? Would one triaxle cause the same spray seal wear as a single axle? If not, should the increase in multiple axles influence the way that heavy vehicles are accounted for in the seal design process? The paper investigates these questions by analysing data obtained under the Australian Accelerated Loading Facility. Secondly, it would be simple for seal designers if the pavement design concept of ESAs could be input into heavy-vehicle seal design. The concept of ESAs is interconnected with the 4th power law, which has been variously derived with definitions of pavement damage such as vertical elastic deformation (Benkelman beam), plastic deformation (rutting) and a pavement serviceability index (roughness). Vertical elastic deflection, rutting and roughness are not typical failure modes for sprayed seals or chip seals. Does a load damage exponent of 4 apply to sprayed seal wear? Should it be 3.1 or 2.0?]]></description>
      <pubDate>Fri, 22 Apr 2016 11:12:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/1404782</guid>
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    <item>
      <title>Seal design improvement for low volume roads</title>
      <link>https://trid.trb.org/View/1372585</link>
      <description><![CDATA[The current version of the Austroads sprayed seal design method was published in 2006 and has been in use for the last nine years. During recent times, a number of sprayed sealing practitioners have indicated that the basic voids factor for single/single seals in the current Austroads sprayed seal design method is too high for low volume roads. To address these concerns, a questionnaire was initially distributed to jurisdictions and local councils to determine the extent of the concerns. The results obtained during a literature review of the derivation of Austroads basic voids factor for single/single seals, and the equivalent factor in the New Zealand seal design method, were used as a basis to propose changes to the Austroads basic voids factor.  The responses to the questionnaire indicated that the main issue associated with the Austroads sprayed seal design method was that the basic voids factor for single/single seals was too high for low volume roads. The results obtained during the literature review indicated that the Austroads basic voids factor has developed empirically over time based on observations by sealing experts and practitioners, while the current New Zealand equivalent factor is based on quantitative measurements obtained during an extensive series of road trials. As the New Zealand equivalent of the basic voids factor was based on quantitative measurements, the New Zealand seal design approach was used to propose changes to the Austroads basic voids factor.  A new version of the Austroads basic voids factor has been proposed for single/single seals which will require lower basic voids factors to be used for low volume roads. The new version of the Austroads basic voids factor was compared with recent Australian seal data/observations in order to investigate whether its use would result in issues with sprayed seals. Based on these comparisons, it appears unlikely that use of the new version of the Austroads basic voids factor will result in issues with sprayed seals.]]></description>
      <pubDate>Thu, 22 Oct 2015 09:46:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1372585</guid>
    </item>
    <item>
      <title>The effect of SBS morphology on field prformance and test results</title>
      <link>https://trid.trb.org/View/1147360</link>
      <description><![CDATA[The phase morphology of polystyrene-block-butadiene-block-styrene (SBS) polymer modified binders was studied using a fluorescence microscope and dynamic shear rheometer (DSR). The morphology at high temperature was determined by rapidly cooling small samples, and thus 'freezing' the morphology in microscope slides and in DSR samples. As SBS binders are cooled from their manufacturing temperature there is an increasing tendency for a single phase structure (if one is present) to become a two-phase structure with irregular globules of SBS distributed in an asphaltene-rich phase. The morphology of field samples of asphalts and sprayed seals was also studied and shown to be determined, in the case of asphalt, by the relatively slow cooling rate of the binder during transport and compaction. On the other hand, sprayed seal binders cool rapidly and their morphology reflects that present in the binder at spraying temperatures. Thus the same binder may have different properties when used in an asphalt and a seal. It is, therefore, desirable to ensure that the morphology in specification test samples is the same as that in the field application of a binder. This may mean modifying sample preparation procedures. The compatibility of the bitumen used to manufacture an SBS binder had an important effect on morphology, with incompatible bitumens forming globular particles but binders made with compatible bitumens retaining a homogeneous appearance. Morphology appeared to have little effect on viscosity but could have a major effect on elasticity. Rutting performance is unlikely to be influenced by morphology since it has been shown to be related to binder viscosity. Fatigue testing of asphalt beams with different morphology binders suggested that morphology might affect fatigue life.]]></description>
      <pubDate>Tue, 28 Aug 2012 08:59:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1147360</guid>
    </item>
    <item>
      <title>Introductory remarks to session 16, surfacing and skidding i</title>
      <link>https://trid.trb.org/View/1210143</link>
      <description><![CDATA[This paper briefly analyses the following papers: developments in the design of bituminous plant mixes (dickinson=ej); the effect of the combined aggregate grading on the voids properties and laboratory stability of bituminous concrete (giffen=jc); design and use of asphalt mixes (phillips=bl and bethune=jd); the design of sprayed single seals (potter=jl and church=m); skid resistance of steelworks slags as road surfacing stone (heaton=bs richards=sr and lanigan=pg and hart=at).]]></description>
      <pubDate>Sat, 25 Aug 2012 00:07:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1210143</guid>
    </item>
    <item>
      <title>The design of sprayed single seals</title>
      <link>https://trid.trb.org/View/1210142</link>
      <description><![CDATA[Design of sprayed single seals has been based for many years on hanson's theory which assumes that a one stone thick layer of single sized chippings will be compacted eventually by traffic to a 20 per cent void condition. It will be shown that compaction alone is unlikely to result in total voids in the stone layer falling below 35-40 per cent.  Reduction of effective voids below this figure is due to embedment into the underlying pavement. This paper gives data on actual compaction (void reduction) of a number of seals in South Australia under varying traffic and pavement conditions. The design should be based on hardness (resistance to embedment) of the pavement and loading (traffic).  An attempt is made to provide a design approach while recognising that long term data are still required (a).]]></description>
      <pubDate>Sat, 25 Aug 2012 00:07:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1210142</guid>
    </item>
    <item>
      <title>Preliminaries towards reexamination of spray seal design</title>
      <link>https://trid.trb.org/View/1193367</link>
      <description><![CDATA[The present design method for spray seals is based on the assumed characteristics of single layers of aggregate used in single sprayed seals. The paper suggests this may not be ideal today, in view of laboratory and field studies.  A local awareness of this problem has prompted internal investigation into the voids characteristics of sealing stone over the past 10 - 15 years.  This paper should be regarded as preliminary to further study. Findings so far suggest variance with present assumptions on orientation of particles.  Voids depend on the shape and source of aggregate, but can depend on the size (ald) of aggregate.  The report investigates the embedment and wear of aggregate, and suggests rational design methods to be developed accounting for embedment and wear.  It suggests two possible approaches to revised seal design.]]></description>
      <pubDate>Fri, 24 Aug 2012 13:17:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1193367</guid>
    </item>
    <item>
      <title>Bituminous surfacing - design of sprayed works</title>
      <link>https://trid.trb.org/View/1190086</link>
      <description><![CDATA[The paper describes the design methods used by the Main Roads Department of Western Australia in sprayed bituminous surfacings.  Primers, primerseals, seals, reseals and enrichments are described.  Design methods for both hot and cold sprayed works are discussed.  Reference is made to the MRDWA's design manuals for primersealing using graded aggregate and cutback bitumen and for sealing and resealing with single size aggregates (a).]]></description>
      <pubDate>Fri, 24 Aug 2012 11:04:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1190086</guid>
    </item>
    <item>
      <title>Cost effective roads in rural Western Australia</title>
      <link>https://trid.trb.org/View/1187479</link>
      <description><![CDATA[The development of rural Australia has been greatly assisted by the evolution of techniques for the construction of a large network of cost effective roads.  Typically these roads are constructed from naturally occurring local materials and surfaced with a minimum cost single or double coat, sprayed bitumen seal.  A single coat chip seal is the most commonly used, and such roads normally carry up to 2000 vehicles per day, although some carry over 5000 vehicles per day.  A low cost road technology has evolved during the last 60 to 70 years but these roads are by no means short term or temporary roads.  The techniques used by the main roads department of Western Australia to construct long lengths of road carrying light traffic are described.]]></description>
      <pubDate>Fri, 24 Aug 2012 07:21:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/1187479</guid>
    </item>
    <item>
      <title>Update of the Austroads sprayed seal design method</title>
      <link>https://trid.trb.org/View/1156294</link>
      <description><![CDATA[The report is an update of earlier Austroads sprayed seal design procedures based on the philosophy of filling voids in the aggregate matrix with binder to a depth of about one half to two thirds the height of the aggregate when laying on its least dimension.  Adjustments and allowances are incorporated in the procedures to cater for aggregate shape, traffic level, embedment, existing surface texture, hardness of existing surfaces and absorption of binder by either aggregates or existing substrate.  The design procedures cover single/single seals and double/double seals with Class 170 bitumen, Class 320 bitumen, multigrade binder, polymer modified binder and emulsions.  Geotextile sprayed seals are also covered.  Brief sections on treatment selection and materials are provided as background to the design processes.]]></description>
      <pubDate>Thu, 23 Aug 2012 01:03:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1156294</guid>
    </item>
    <item>
      <title>Sprayed sealing practice in Australia</title>
      <link>https://trid.trb.org/View/886028</link>
      <description><![CDATA[This paper provides an overview of current sealing practice in Australia, including priming and primersealing, types of sprayed seals and their selection, the current national seal design procedure, and plant and field procedures commonly used.  Asphalt is the preferred treatment in urban areas, on heavily trafficked urban freeways and arterial roads, and areas of high traffic stresses.  Sprayed sealing is the surfacing treatment commonly used in rural areas, and is the most economic type of surfacing for the rural road network.  It is also used for specific applications, such as strain alleviating membranes to minimise crack reflection, on all classes of roads. The main type of sprayed seal is a single layer of binder covered with a single layer of aggregate (single/single seal) used on both new and resurfacing work.  On new work the pavement material is usually locally available gravel, often of marginal quality, with better quality crushed rock material used on the more heavily trafficked roads.  Sprayed seal design as referred to in this paper is the design of rates of application of binder and aggregate spread rates.  The continued success of sprayed seals as a surfacing requires care in choosing an appropriate treatment for the conditions, a high standard of preparation of pavements and attention to detail.  To successfully select and design a sprayed seal requires a mix of engineering and "practical know how".]]></description>
      <pubDate>Mon, 23 Mar 2009 20:29:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/886028</guid>
    </item>
    <item>
      <title>Towards a rational volumetric cape seal design method</title>
      <link>https://trid.trb.org/View/886001</link>
      <description><![CDATA[The current South African design practice of cape seals considers the application of single and slurry seals as separate processes.  This practice can lead to problems of aggregate overspread, over application of bitumen tack-coat resulting in bleeding, or slurry being over-applied.  Subsequently a research project was undertaken to critically evaluate standard design practice.  This study concluded that the voids between the single-sized layer of stone are of paramount importance, as they dictate the binder application rate and the quantity of slurry that can be applied without danger of bleeding.  The research further aimed at establishing a rational volumetric design method based on the voids between the aggregate.  The modified tray test, to determine the effective layer thickness and true void content, forms the basis of the design method.  The model mobile load simulator (MMLS3) was subsequently used to evaluate the design prediction (based on volumetric parameters) and the in-service performance of cape seals.  From the analysis, criteria were identified and limits proposed to control the combined volumetric composition of the single seal and the slurry components of a cape seal to avoid bleeding.  It was confirmed that a maximum total slurry application rate, which avoids bleeding, can be determined.]]></description>
      <pubDate>Mon, 23 Mar 2009 19:38:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/886001</guid>
    </item>
    <item>
      <title>The equivalent heavy vehicle concept in Australian sprayed seal design</title>
      <link>https://trid.trb.org/View/885898</link>
      <description><![CDATA[The foremost challenge facing Australian spray seal designers is the performance of sprayed seals under the increasing numbers of large heavy vehicles on major transportation routes connecting capital cities and in rural areas of New South Wales, Queensland and Western Australia.  It is expected that the Australian freight task will increase by 25 per cent between 2000 and 2010, with most of this increase already occurring.  Based on data collected in rural areas, the traffic adjustment for heavy vehicles was amended in the 2006 update of the Austroads sprayed seal design method.  This paper discusses the investigation currently being conducted into the effect of these large heavy vehicles on sprayed seals, and the concept and development of equivalent heavy vehicles introduced in the Australian design method in 2006.  This paper describes the next steps in rationalising this concept.]]></description>
      <pubDate>Mon, 23 Mar 2009 16:24:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/885898</guid>
    </item>
    <item>
      <title>The evolution of the New Zealand chipseal design methodology</title>
      <link>https://trid.trb.org/View/885897</link>
      <description><![CDATA[The original “scientific” analysis of chipseals and the development of a design methodology was by Hansen in the 1930s in New Zealand (NZ).  This method was based on a single layer of a one sized chip.  The basic concepts are still regarded by most sealing practitioners as valid and they have been adopted by many countries.  This paper describes the evolution of the design methodology in NZ since the 1930s and the reasoning behind the latest revision.  A comparison of application rates of binder used in NZ with Australia, South African and Texas methodologies is given.  The significant changes in the viscosity of the cut back binder used for sealing that have occurred are also described.]]></description>
      <pubDate>Mon, 23 Mar 2009 16:22:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/885897</guid>
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