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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>
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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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      <title>Anaerobic digestion of verge cuttings for transport fuel</title>
      <link>https://trid.trb.org/View/846839</link>
      <description><![CDATA[Roadside verges need to be cut for both safety and ecological reasons. This requires energy, currently acquired from fossil fuels with associated release of carbon dioxide (CO2). Leaving the cuttings in place has a detrimental effect on plant species richness; removal leads to increased biodiversity but produces green waste for disposal. This paper describes a model to determine the energy efficiency and surplus energy yield from the use of verge cuttings as a feedstock for anaerobic digestion. The model is scaleable and could be used by national and local authorities to find ways of reducing fossil fuel consumption. Although based on UK data, the same principles can be applied anywhere with roadside verges or similar sources of green cuttings. The model uses results from trials in Powys, Wales to determine the feasibility of collection and the potential methane yield of the cuttings. The results indicate that verge material can be collected in a manner that is both CO2 neutral and produces more energy than that required for cutting, transporting and processing. The nature of the fuel produced means the process is self-sustaining—biogas can be used to fuel vehicles required for cutting and transport and to provide heat and electricity for the anaerobic digestion process.]]></description>
      <pubDate>Tue, 29 Jan 2008 10:12:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/846839</guid>
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    <item>
      <title>Hydraulic conductivity of tyres in landfill drainage systems</title>
      <link>https://trid.trb.org/View/843110</link>
      <description><![CDATA[Whole or shredded scrap tyres are sometimes proposed as an alternative to conventional aggregates in landfill drainage systems. Landfill basal drainage systems are, however, subjected to large overburden stresses from the overlying waste, which may compress a tyre drainage layer, thereby reducing its porosity and hence its effectiveness. Previous work has indicated that tyre drainage layers will remain effective under high stresses, but tests have in the main been restricted to small (<100mm) shred sizes. The use of coarser shreds or even whole tyres for landfill drainage systems may be advantageous as they are more economical to produce and may be less prone to clogging than smaller shreds. The results of large-scale (2m diameter) tests to investigate the variation in hydraulic conductivity (permeability) with stress of 50, 200 and 450mm nominal tyre shreds are compared with data from the literature for smaller-size shreds test procedures and whole tyres. Tests were carried out at vertical stresses up to 600kPa, representing landfill depths of up to about 60m. Potential errors in laboratory test procedures are highlighted and the influence of scale and the relative test chamber to particle size on the result is discussed. It is concluded that a chamber to particle size ratio of at least 6 is needed with a rigid  walled permeameter, if errors owing to peripheral flow effects are to be avoided. Relationships between shred size and drainage properties were investigated: no clear correlation between tyre shred size and drainage properties in the particle size range 50-450mm is found. Whole tyres, however, generally have a slightly higher hydraulic conductivity, while samples containing a significant  proportion of material less than 20mm in size have a generally lower hydraulic conductivity at a given vertical stress than clean samples of larger shreds.]]></description>
      <pubDate>Mon, 07 Jan 2008 11:35:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/843110</guid>
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    <item>
      <title>Compressibility of tyres for use in landfill drainage systems</title>
      <link>https://trid.trb.org/View/838993</link>
      <description><![CDATA[Whole or shredded scrap tyres are sometimes proposed as an alternative to conventional aggregates in landfill drainage systems. Landfill basal drainage systems are, however, subjected to large overburden stresses from the overlying waste, which may compress a tyre drainage layer reducing its porosity and hence its effectiveness. Previous work has indicated that tyre drainage layers will remain effective under high stresses, but tests have in the main been restricted to small (<100mm) shred sizes. The use of coarser shreds or even whole tyres for landfill drainage systems may be advantageous as they are more economical to produce and may be less prone to clogging than smaller shreds. In this paper, the results of largescale (2m sample diameter) tests to investigate the compressibility of 50, 200 and 450mm nominal-size tyre shreds are compared with data from the literature for smaller-size shreds and whole tyres. Tests were carried out at vertical stresses up to 600 kPa, representing landfill depths of up to about 60 m. Generally whole tyres and larger-size segments compress more in overall volume terms on initial loading than smaller size shreds. At vertical stresses greater than about 80 kPa, however, the differences on a graph of dry density or porosity plotted against vertical stress are much smaller. The proportion of voids that are not free-draining decreases with compression for whole tyres, as cup-like structures capable of retaining water flatten out. For tyre chips, the proportion of non-drainable voids increases with compression, suggesting that flow pathways are being lost. The dependence of the compressive behaviour of tyres and tyre chips on the particle shape is discussed, and the need for a more detailed and rigorous way of characterising particle size and shape is highlighted. (A)]]></description>
      <pubDate>Mon, 22 Oct 2007 10:08:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/838993</guid>
    </item>
    <item>
      <title>Performance of photo-catalytic paving blocks made from waste</title>
      <link>https://trid.trb.org/View/838992</link>
      <description><![CDATA[Preliminary studies at The Hong Kong Polytechnic University showed that concrete paving blocks made from local waste materials (including construction/demolition waste and waste glass cullet) can be used to remove nitrous oxide (NO) when titanium dioxide (TiO2) was incorporated in the mix design. To determine the effectiveness of the photo-catalytic paving block when used in field conditions, a batch of factory-produced photocatalytic paving blocks was produced and used in an actual site trial. The air quality of the field testing site was continuously monitored to analyse the effect of the blocks towards the surrounding air quality. The observations showed that nitrogen oxide (NOx) concentrations were reduced by 13% at ground level and by 10% at the breathing zone. After a period of four months the blocks were removed from test site and taken back to the laboratory to analyse whether their ability to remove NO had been degraded. The results showed a decrease in performance of 23%, which is low compared with tests on similar products. (A)]]></description>
      <pubDate>Mon, 22 Oct 2007 10:08:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/838992</guid>
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    <item>
      <title>Groundwater impacts from coal ash in highways</title>
      <link>https://trid.trb.org/View/838991</link>
      <description><![CDATA[Coal combustion products (CCPs), traditionally treated as wastes, can be successfully used in road construction in a variety of ways. When CCPs are used in roadway construction, however, leaching of trace elements into groundwater can be a concern. The current paper describes a model that can be used to evaluate the impacts of leaching on groundwater for typical roadways in the USA. Three analytical solutions to the advection– dispersion–reaction equation are combined to develop a method for assessing impacts to groundwater caused by leaching of trace elements from CCPs used in highway subgrade, subbase and base layers. The solutions were combined into a computer program (WiscLEACH) with a Windows® graphical user interface. The analytical method was compared to predictions made with HYDRUS-2D, a software package for simulating flow and transport in variably saturated media. Predictions made with the analytical method were also compared to field data from a highway test section where the subgrade was stabilised with coal fly ash. Parametric analyses made with the method indicate that maximum concentrations in groundwater occur near the groundwater table (GWT) and the centreline of the pavement. Peak groundwater concentrations decrease as depth to groundwater increases, the thickness of the byproducts layer decreases, the seepage velocity in the vadose zone decreases or the seepage velocity in groundwater increases. Variables having the greatest influence on maximum concentrations in groundwater are depth to the GWT, thickness of the CCP layer, hydraulic conductivity of the least conductive layer in the vadose zone, hydraulic conductivity of the aquifer material and the initial concentration in the CCP layer. (A)]]></description>
      <pubDate>Mon, 22 Oct 2007 10:08:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/838991</guid>
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    <item>
      <title>Interdisciplinary perspectives on environmental appraisal and valuation techniques</title>
      <link>https://trid.trb.org/View/820359</link>
      <description><![CDATA[Techniques of environmental appraisal and valuation play an important role in the context of sustainability assessment. They are at the heart of methods for quantifying economic and social costs and benefits, as well as the direct ecological impacts that are an inevitable sideeffect of material 'progress'. Concepts such as the physical life cycle of products and processes, and the need for clearly defined system boundaries, are key elements in environmental problem-solving. However, some economists would claim that, as a 'normative' discipline, their methods can be extended to incorporate all of society's environmental concerns. In contrast, engineers and environmental professionals have at times argued that economic techniques (such as cost benefit analyses) may well obscure the impacts of different courses of action, and that decision makers consequently become less well informed rather than the reverse. Aggregate decision criteria, for example, often conceal the weighing of various impacts. By contrast, the sort of 'prescriptive' analytical tools emanating from engineering and the physical sciences can provide alternative insights that complement those that spring from economics. These include thermodynamic (energy and exergy) analysis and environmental life-cycle assessment. A range of interrelated environmental project appraisal techniques is therefore examined in order to determine their relative merits. Practical examples involving resource (energy and hydraulic oil) use, pollutant emissions, and waste disposal and recycling (of hydraulic oils) indicate that many of these methods can play an important evaluative role as part of an interdisciplinary toolkit within a general systems framework. Nevertheless, caution needs to be used when adopting economic and engineering analysis techniques so as to ensure that they are fit for their sustainability purpose. (A)]]></description>
      <pubDate>Mon, 10 Sep 2007 13:33:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/820359</guid>
    </item>
    <item>
      <title>Sustainable waste management—what and how?</title>
      <link>https://trid.trb.org/View/820358</link>
      <description><![CDATA[Historically, 'developed' societies have adopted a linear approach to the use of resources, with natural assets being processed, used and ultimately discarded as wastes with little if any thought being given to the capacity of the environment either to maintain the supply of resource at one end or receive the waste at the other. Although governments and the public are now more aware of the problems this creates, the current focus is often on meeting legislative targets rather than the more fundamental goals of sustainable resource management and care for the environment. This paper argues that 'waste' should be viewed as part of a resource cycle that includes extracting materials and energy from the environment, refining raw materials and producing goods, consuming and using goods and then eventually returning materials to the environment. Each process has inputs (materials and energy) and outputs (products, energy and waste). Waste outputs from one process can sometimes be used as resource inputs to another, or even the same, process. Sustainability principles require that resources are used with maximum efficiency while they are within the human part of the cycle, and that they are returned to the environment in a way that enables them to be extracted and used again something that at present happens only rarely, haphazardly and on a geological timescale. Options for sustainable resource management are reviewed and appraised, with reference mainly to household waste. It is argued that the management of interim and residual 'wastes' should be based on the most energy or resource efficient option for individual components of the waste stream; this might involve reuse, materials recovery, energy recovery or safe disposal of different components at different stages of the resource cycle. (A)]]></description>
      <pubDate>Mon, 10 Sep 2007 13:33:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/820358</guid>
    </item>
    <item>
      <title>Use of waste tyre bales to construct a flood embankment</title>
      <link>https://trid.trb.org/View/797744</link>
      <description><![CDATA[A case study in the use of tyre bales in the design of a UK flood embankment is presented and the legal, technical and environmental issues are briefly discussed. A few major risks in the use of tyre bales in a flood prevention embankment—such as possible buoyancy of the tyre bale under water, possible piping of underlying soil and overlying capping soils due to their extremely high permeability, possible rebound of the bales upon release or deterioration of metal ties, release of unacceptable leachate to the controlled water from old tyres—were taken into consideration in the design stage and necessary steps and precautions were adopted. The use of tyre bales on the project provided a cost-effective and environmentally sustainable solution and has potentially paved the way for other applications. The pilot project scheme, which is now complete, has used around 1 million tyres, which is approximately 10% of the total number of tyres that would normally go to landfill in any one year in the UK. (A)]]></description>
      <pubDate>Wed, 17 Jan 2007 08:50:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/797744</guid>
    </item>
    <item>
      <title>Using china clay waste in sprayed concrete</title>
      <link>https://trid.trb.org/View/787147</link>
      <description><![CDATA[The extraction of china clay produces large quantities of waste material including coarse sand, waste rock, overburden and micaceous residue. The current annual rate of waste generation in the UK is approximately 20 Mt. In the UK china clay extractionis concentrated in the south-west of England and the total volume of stockpiled waste in this relatively small area is estimated at 500 Mt. Current utilisation for this waste as secondary aggregate is restricted to a limited number of uses in local markets, which are now saturated. In order to increase usage levels and reduce the landfill burden, new and alternative uses for this waste material are required. This paper describes a study undertaken to evaluate the potential of using waste china clay sand as an aggregate for dry-mix sprayed concrete applications, primarily as a concrete repair material. In addition, the project explored the possible enhancement of some of the properties by using mica and metakaolin, which are alsoby-products of china clay production .The evaluation was undertaken by characterising the physical properties of the waste sand, developing a variety of concrete mix designs and conducting site trials to assess performance. The programme also examined the effect of additions (silica fume and metakaolin), admixtures (accelerators and superplasticisers) and polypropylene fibres. The project was able to identify the best mix design as a result of the trials and grade the mixes in terms of performance for spraying ability, compressive strength and durability .The results of the study show that the use of china clay sand aggregate for dry-mix sprayed concrete is effective and the natural sand grading of this aggregate is suited very well to this application. Also, the use of metakaolin as an addition to a sprayed concrete mix provides enhanced durability characteristics to the mix at the same time as improving its spraying performance. (A)]]></description>
      <pubDate>Mon, 07 Aug 2006 13:32:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/787147</guid>
    </item>
    <item>
      <title>Use of recycled aggregates for cementitious backfill</title>
      <link>https://trid.trb.org/View/787146</link>
      <description><![CDATA[Laboratory and field trials were conducted to assess the performance of cementitious backfill material for reinstatement of trenches and excavations in roads. Backfill material was produced using recycled granular aggregates, pulverised fuel ash and cement. A conventional compacted recycled granular material was used as a control to compare the performance of cementitious backfill. The results showed that recycled granular materials, with a particle size ranging from 5 to 38 mm, could be used to form a cementitious backfill with strengths that comply with the Highway Authorities and Utilities Committee's Specifications for the Reinstatement of Openings in Highways (SROH) for cementitious backfill. This backfill was prepared using conventional mixing plant and was straightforward to install on site. Settlements of trenches with granular backfill up to 1 year of monitoring were found to be higher than the corresponding ones with cementitious backfill. However, settlements for both types of backfill were within the limits of the SROH and did not require any subsequent intervention measures. Although the stiffness of the granular backfill was initially lower than that of the surrounding ground, within a year it had increased to the same level. The cementitious backfill was stiffer than the adjacent ground, but no detrimental effects were observed over the period of monitoring. (A)]]></description>
      <pubDate>Mon, 07 Aug 2006 13:32:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/787146</guid>
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    <item>
      <title>Transport impacts of household waste recycling centres</title>
      <link>https://trid.trb.org/View/787145</link>
      <description><![CDATA[Household waste recycling centres (HWRCs) evolved from civic amenity sites (CAS) introduced by the Civic Amenities Act 1967, and provide householders with an outlet for the disposal of a wide range of materials. Sites are now handling significant volumes of recyclables (66% of total household recyclables), and the transport impacts associated with increasing visitor numbers to HWRCs are of interest to traffic managers and land use planners. The transport logistics associated with servicing sites, including the collection, treatment and disposal of different materials, is complex. The reduction in landfill disposal coupled to more stringent requirements for material recycling and treatment has resulted in short journeys from HWRCs to landfill being replaced by complex road trips to different facilities at various locations. The operational, environmental and social impacts associated with these potential increases in commercial transport activities can be quantified through modelling current and projected fleet operations under various future scenarios. This can be achieved through routing and scheduling applications, which can be used to optimise transportation fleets and identify the optimal locations for waste treatment facilities. This paper provides an overview of the literature, identifying the transport arisings associated with the movement of waste to HWRCs by site users, and from HWRCs to treatment or disposal facilities by service operators. It also discusses the potential impacts on waste transportation from current and impending legislation, and the use of routing and scheduling applications to maximise commercial service vehicle operating efficiency.]]></description>
      <pubDate>Mon, 07 Aug 2006 13:32:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/787145</guid>
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    <item>
      <title>New household waste recycling centre in Blackpool, UK</title>
      <link>https://trid.trb.org/View/787144</link>
      <description><![CDATA[This paper describes the design and construction of Blackpool Council's new household waste recycling centre. The scheme demonstrates the incorporation of sustainability considerations through design, construction and commissioning. Seeking to reduce the amount of household waste sent to landfill sites, the provision of a high-quality facility for recycling will encourage increased sustainability awareness and participation within the community. As a means of delivering a quality scheme, the challenge of ensuring high durability in combination with aesthetic and environmental enhancement has been met with innovation. Use of polymer fibre reinforcement in the heavy-duty apron slabs provides high durability under aggressive service loads. Elsewhere, incorporation of subsurface skips facilitates spatial optimisation and allows significant noise attenuation with minimal visual impact. Where possible, materials won from the demolition of existing time-expired structures were incorporated in the new scheme or distributed for reuse elsewhere. (A)]]></description>
      <pubDate>Mon, 07 Aug 2006 13:32:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/787144</guid>
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