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    <title>Transport Research International Documentation (TRID)</title>
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <title>Kravställning av dubbstift för att reducera slitage och partikelemissioner</title>
      <link>https://trid.trb.org/View/2440095</link>
      <description><![CDATA[The use of studded tyres during wintertime can cause significant wear of road surfaces. Some fraction of this wear is released in the form of airborne particulates, affecting the air quality in urban areas. The studs of today's winter tyres are manufactured from hard metal containing Cobalt. Cobalt is a material that should be phased out from an environmental perspective both at the use phase as well as the manufacturing phase. The project aims to study alternative Cobalt free hard metal studs that in the future also can reduce the particulate emissions. The alternative hard metal studs will be evaluated in existing laboratory test equipment for particulate emission and wear studies of the tyre to road contact. A comparative simplified life cycle analysis will also be performed to compare the environmental consequences of changing to the alternative stud material from the today Cobalt based hard metal one. The final goal of the project is to be able to legislate the studded tyres stud allowable material content (Cobalt) and material properties as hardness. This to reduce the particulate emissions as well as road wear, with a withstand capability to remove the ice on the roads.]]></description>
      <pubDate>Thu, 10 Oct 2024 14:38:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2440095</guid>
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    <item>
      <title>Finite element analysis of studded tyre performance on snow: a study of traction</title>
      <link>https://trid.trb.org/View/2373788</link>
      <description><![CDATA[This paper presents a finite element analysis (FEA) model of a studded tyre rolling on snow. The model takes into account the mechanical properties of both the tyre and the snow, as well as the interactions between them. The FEA simulations were performed using single set of 99 studs with constant compaction depth, and the results were compared to experimental data. The study found that the studded tyre was able to significantly improve traction on snow-covered roads by a minimum factor of 1.17 at −50% slip and a maximum factor of 1.5 at an interval of 50% to 100% slip, compared to non-studded tyre, and that the FEA model accurately predicted the tyre’s behaviour in these conditions. The results of this study can be used to optimise the design of studded tyres and to improve the safety of vehicles in snowy conditions.]]></description>
      <pubDate>Tue, 11 Jun 2024 13:17:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/2373788</guid>
    </item>
    <item>
      <title>Piggiga pendlare : conditions for increased use of winter tires on bicycles</title>
      <link>https://trid.trb.org/View/2389054</link>
      <description><![CDATA[As Europe pushes for more sustainable and active transportation, cycling emerges as a viable solution to address public health, traffic congestion, and environmental concerns. However, winter months see a decline in cycling participation in Nordic countries, primarily due to the associated discomforts and risks of cycling on icy/snowy roads. In Sweden, falls due to slippery conditions account for a significant portion of cycling-related injuries. One potential solution is the use of winter bicycle tires, designed to provide better traction in these conditions. Despite their proven benefits, the adoption rate of these tires remains low, attributed to factors like cost, availability, and lack of awareness. This report compiles findings from various stakeholders in Sweden, including municipalities, transport agencies, and cycling organisations, to understand the landscape of winter tire usage. Surveys and focus group discussions reveal barriers to adoption and potential strategies to promote winter tire use. The overarching conclusion underscores the need for a multi-faceted approach, combining awareness campaigns, economic incentives, and public-private partnerships, to foster a culture of safe winter cycling in Sweden. The final report has been prepared with financial support from the Skytfonden, Swedish Transport Administration. Positions, conclusions and working methods in the report reflect the author and do not necessarily correspond with the Swedish Transport Administration's positions, conclusions and working methods within the subject area of the report.]]></description>
      <pubDate>Mon, 10 Jun 2024 14:05:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2389054</guid>
    </item>
    <item>
      <title>Test av åretruntdäck : väggrepp på is och snö samt barmark</title>
      <link>https://trid.trb.org/View/2389007</link>
      <description><![CDATA[All-season tyres have previously not been approved for use as winter tyres in Sweden but are now allowed after a change of regulations in 2019. To compare the grip of this type of tyre with regular winter and summer tires, brake tests were conducted for 14 different all-season tyres on packed snow and ice, as well as on dry and wet asphalt. The tyres were selected to be representative of the available all-season tyres on the Swedish market. The results show large differences in braking grip between different all-season tires. Some tyres perform more like European non-studded winter tyres, and others more like summer tyres, which seems to be a conscious choice by the various manufacturers. On average, the braking distance of all-season tyres on snow is clearly longer than that of both Nordic and European non-studded winter tyres, and although there are all-season tyres that are similar to European winter tyres on snow, others perform significantly worse. On ice, the braking grip of all-season tyres is much worse compared to the Nordic non-studded reference tyre. Our assessment is that the ice grip is generally too poor to constitute a safe alternative on Swedish winter roads, and that one of the winter-approved all-season tyres performed just as bad as one of the summer tyres on ice is remarkable. There is a correlation between low rolling resistance and poor ice grip, which indicates that measures to reduce rolling resistance can have a negative impact on the ice grip of this type of tyre. Braking performance on dry and wet asphalt for all-season tyres are widespread, with the best all-season tyres performing equally with summer tyres, and the worst being about the same level as the best of the Nordic winter tyres. We can therefore not recommend all-season tyres as an alternative to winter and summer tyres.]]></description>
      <pubDate>Mon, 10 Jun 2024 14:05:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2389007</guid>
    </item>
    <item>
      <title>Traction Performance of Transit and Paratransit Vehicles on Ice and Snow Surfaces</title>
      <link>https://trid.trb.org/View/2160516</link>
      <description><![CDATA[In this study, the traction performance of transit and paratransit vehicles was evaluated on snow and ice surfaces. Field tests were conducted in Fairbanks, Alaska, using three types of vehicles: 1) a 41-passenger transit bus; 2) a 32-passenger transit bus, and 3) a 9-passenger paratransit vehicle. Each vehicle was tested for different combinations of tire types that included highway tires, snow tires, studded-siped tires, highway 3-rib tires, all-season tires, and snow siped tires. Winter traction performance was evaluated using a number of tests that included stopping distance, starting traction, hill-climbing, cornering, and controllability. Results indicate that winter traction performance is significantly influenced by vehicle type, tire combination used, and the road surface condition (compacted snow or ice). Research findings and recommendations for appropriate tire combinations that are most suitable for winter traction are presented.]]></description>
      <pubDate>Wed, 26 Apr 2023 09:18:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2160516</guid>
    </item>
    <item>
      <title>Användning av begreppet bergtyp i Sverige : delrapport 1 för ny klassificering av bergtyp i Sverige</title>
      <link>https://trid.trb.org/View/2145750</link>
      <description><![CDATA[Today (at least until 2022) the general classification of rock materials for roads and earthworks is determined by the Nordic ball mill (abrasion from studded tyres) in three levels. The classification is called rock type (1 to 3). Rock type 1: Nordic ball mill-value, AN, is less than 18, Rock type 2, AN 18 to 30 and Rock type 3: AN over 30.  Since 2004, when Sweden started to adopt European standards for building materials, it has not longer been possible to have requirements for unbound layers and aggregates to the Nordic ball mill (unless for wearing coarse aggregates). The objective of this project is to find a new way of classification according to proper properties and levels.  This report, which is from the first part of the project, describes how the term rock type is used in Sweden. It has been investigated in requirements and procurement documents and how and to what extent the industry's actors use the term (rock type). A few persons with different roles, such as consultants, client representatives, authorities, laboratories, and higher education institutions have responded to questionnaires or have been interviewed.  AMA Anläggning 20 is the requirement document that primarily uses the concept of rock type. Then there are some other documents that make references to the AMA Anläggning and thereby indirectly use the term. Except for some consultants and some people at the Swedish Transport Administration, the interest and use are generally low in the concept of rock type. There is greater interest in a new rock-type classification system than there is in the current one among those who have provided answers. There is also often a demand for increased usability.]]></description>
      <pubDate>Mon, 03 Apr 2023 16:47:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2145750</guid>
    </item>
    <item>
      <title>Potential policy instruments and measures against microplastics from tyre and road wear : mapping and prioritisation</title>
      <link>https://trid.trb.org/View/2075174</link>
      <description><![CDATA[In this report potential policy instruments and measures against microplastics from tyre and road wear are mapped, identified, and prioritised. The report has been produced within the framework of a Swedish government assignment that the Swedish National Road and Transport Research Institute (VTI) received in December 2017 to develop and disseminate knowledge about microplastics from road traffic. The assignment states, among other things, that VTI should identify and evaluate potentially effective policy instruments and measures aimed at limiting emissions.  The aim of the report is to identify potential policy instruments and measures that can reduce the load of microplastics from tyre and road wear on the environment, and to assess which should be prioritised for in-depth investigation or knowledge building. The report covers policy instruments and measures that reduce emissions, spread, and effects of microplastic particles from tyres and road markings in the environment, as well as those that contribute to increasing knowledge in the field. It contains 35 policy instrument and measure headings under which the potential policy instruments or measures concerned are specified. A total of 58 specified policy instruments and measures have been described and ranked based on assessed priority. The focus is on policy instruments and measures that help reduce the generation and emissions of tyre particles. This is motivated by the fact that tyre wear is by far the largest source of microplastics from road traffic and that it is generally most effective to take action at the source.  Since there is insufficient knowledge on the impact of microplastics from tyre and road wear the risk, and thereby the need for action, cannot be assessed. Further, the lack of knowledge about the effectiveness of identified policy instruments and measures does not make it possible to set informed priorities between them on objective grounds. The assessments nevertheless made of which should be prioritised (due to assessed need of knowledge and preventive measures) are therefore more or less rough.  The prioritisation of the policy instruments and measures has taken place at the levels highly prioritised, prioritised and not prioritised. In most cases, more knowledge is needed before they can be evaluated, or implemented, which is why proposals leading to direct action cannot be given. More than 40 percent of them are about promoting research or development in specific areas or in general.  In conclusion, there are many potential instruments and measures to reduce the load of microplastics from tyre and road wear that have been considered to be more or less relevant for various reasons. Among the 20 that we have given high priority to, we find some particularly interesting. They are those relating to 1) reduced amount of road traffic, 2) driving behaviour, 3) tyre wear propensity 4) air pressure and wheel settings, 5) regulation of hazardous substances, 6) collection of tyre particles while driving, 7) sustainable handling of road surface water, and 8) knowledge building for the assessment of risks and need for action.]]></description>
      <pubDate>Fri, 02 Dec 2022 11:40:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/2075174</guid>
    </item>
    <item>
      <title>Potentiella styrmedel och åtgärder mot mikroplast från däck- och vägslitage : kartläggning och prioritering</title>
      <link>https://trid.trb.org/View/1948885</link>
      <description><![CDATA[In this report potential policy instruments and measures against microplastics from tyre and road wear are mapped, identified, and prioritised. The report has been produced within the framework of a Swedish government assignment that the Swedish National Road and Transport Research Institute (VTI) received in December 2017 to develop and disseminate knowledge about microplastics from road traffic. The assignment states, among other things, that VTI should identify and evaluate potentially effective policy instruments and measures aimed at limiting emissions.  The aim of the report is to identify potential policy instruments and measures that can reduce the load of microplastics from tyre and road wear on the environment, and to assess which should be prioritised for in-depth investigation or knowledge building. The report covers policy instruments and measures that reduce emissions, spread, and effects of microplastic particles from tyres and road markings in the environment, as well as those that contribute to increasing knowledge in the field. It contains 35 policy instrument and measure headings under which the potential policy instruments or measures concerned are specified. A total of 58 specified policy instruments and measures have been described and ranked based on assessed priority. The focus is on policy instruments and measures that help reduce the generation and emissions of tyre particles. This is motivated by the fact that tyre wear is by far the largest source of microplastics from road traffic and that it is generally most effective to take action at the source.]]></description>
      <pubDate>Fri, 06 May 2022 17:07:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/1948885</guid>
    </item>
    <item>
      <title>Physical and economic impacts of studded tyre use on pavement structures in cold climates</title>
      <link>https://trid.trb.org/View/1903547</link>
      <description><![CDATA[In cold regions like Alaska of USA, Canada and the northern parts of Europe, using studded tyres is common among the public when driving in icy and snowy conditions. However, studded tyres cause extensive wear to asphalt pavement, reducing pavement life. This study addresses the physical and economic impacts of winter studded tyres on the roadway system to better inform decision makers as they develop alternative solutions and future polices. The approach is applied in a case study from a sample of Alaska statewide road segments. Surveys were employed to examine the extent of the use of studded tyres and cost-effective alternatives. A pavement life-cycle cost review was established considering several variables to discover a realistic cost of roadway resurfacing and rehabilitation. Wear rates due to studded tyres and rut rates due to wheel loads were found for different highway classes. The results indicate higher average wear rates due to studded passenger vehicles on freeways than average rut rates due to heavy wheel loads. The results also indicate lower average wear rates on arterial and collector roads. The estimates show that studded tyre use reduced asphalt surface life by about 7 years on the selected freeway sample in the case study, which is about 47% loss in pavement life based on the initial design life of 15 years. Other road classes experienced lower reductions in service life. Finally, cost analysis was provided to reflect the impact of studded tyres on the state's budget. Countermeasures were suggested, which in turn may help other cold regions develop strategies on the use of new winter tyre technology.]]></description>
      <pubDate>Mon, 28 Feb 2022 09:42:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1903547</guid>
    </item>
    <item>
      <title>Influence Of Roof-Rack, Trailer Etc On Automobile Fuel Consumption and Exhaust Emissions, Measured On-The-Road</title>
      <link>https://trid.trb.org/View/1780078</link>
      <description><![CDATA[Fuel consumption, NO and NOx were monitored using on board apparatus during road driving at constant speeds, for a gasoline passenger car with TWC. Exhaust gas concentrations (ppm) of nitrogen oxides were translated into mass emission values (g/km) by methods previously reported [1, 2, 3 and 4]. In addition to standard vehicle configuration, the experiments included driving with studded tyres, trailer, roof-rack and ski-box. Also, the influence of windy conditions was studied.         Generally speaking the use of extra equipment, and also higher speed, entailed raised fuel consumption. The NOx emissions, however, did not exhibit a corresponding dependence. Calculated NO2/NOx ratios (v/v) varied between 0.01 and 0.03.]]></description>
      <pubDate>Thu, 09 Dec 2021 10:12:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/1780078</guid>
    </item>
    <item>
      <title>New method of calculating emissions from tyre and brake wear and road abrasion</title>
      <link>https://trid.trb.org/View/1894991</link>
      <description><![CDATA[In 2014, the Swedish emission factors used for particulate matter from road abrasion were reviewed as a consequence of remarks made by the Swedish Transport Administration (STA) regarding PM2.5 emission factors for studded tyres. The review resulted in revised emission factors from road abrasion, and it also concluded that Sweden should base its estimates from tyre and brake wear and road abrasion on a more robust model that also takes meteorology into account. In the current project, the SIMAIR model system was used to develop a new method to estimate non-exhaust PM emissions from road traffic in Sweden. The new methodology takes into account several factors that have not been considered in previous estimates, such as meteorology, regional variations and measured PM10 concentrations in urban street canyons for model verification. Annual emission factors for PM10 were obtained for eight different regions covering all of Sweden for the years 2008–2014.]]></description>
      <pubDate>Wed, 01 Dec 2021 14:50:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1894991</guid>
    </item>
    <item>
      <title>Calibration of the Swedish studded tyre abrasion wear prediction model with implication for the NORTRIP road dust emission model</title>
      <link>https://trid.trb.org/View/1777964</link>
      <description><![CDATA[An experimentally based prediction model of road abrasion wear due to studded tyres is available in Sweden and has been found to work well. However, it has not been validated since 2007, and since then road surfaces and tyre design have developed, and the question has arisen regarding the model’s current validity. The abrasion wear model is used in the NORTRIP emission model (NOn-exhaust Road Traffic Induced Particle emission modelling), and the effect of a recalibrated abrasion wear model on the emission model is shown. In this paper, the abrasion wear model is compared to full-scale field measurements at several recently constructed roads in Sweden to investigate its validity, while also proposing changes to allow for continued use. It is concluded that the model overestimates the wear and an update is suggested. In addition, the impact on NORTRIP emission predictions is briefly investigated. There were also indications that NORTRIP is affected by the abrasion model overestimating the contribution of pavement wear to the particle emissions.]]></description>
      <pubDate>Mon, 05 Apr 2021 17:08:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1777964</guid>
    </item>
    <item>
      <title>Tyre/road interaction : a holistic approach to the functional requirements of road surfaces regarding noise and rolling resistance</title>
      <link>https://trid.trb.org/View/1737819</link>
      <description><![CDATA[Increased fuel consumption, increased greenhouse gas emission, diminishing real-estate prices and increased health issues are some of  the negative effects on the climate, on the environment and on the society from tyre/road rolling resistance and noise. The first two aspects are affected by energy dissipation in the tyre/pavement contact and are related to rolling resistance. The other two aspects, real-estate property prices and health and comfort issues, are related to noise. This thesis uses a holistic approach to analyse functional properties of the tyre/road contact interaction. It studies how measures taken for different functional properties may correlate and studies the limits in evaluation of mitigation strategies considering the precision in available measurement methods. The investigative work included an examination of how reproducible CPX measurements are for evaluating tyre/road noise. Furthermore, the procedure for rubber hardness correction was subjected to a specific evaluation. Noise and rolling resistance measurements were performed on drums and the results were compared to on-road measurements for 50 different tyre models. Additionally, the consistency of rolling resistance measurements on roads was evaluated. Two mitigation strategies are discussed in this thesis: (i) selection of tyres, and (ii) grinding of road surfaces. For the first strategy, more than 600 CPX and more than 500 rolling resistance measurements were carried out with 50 different tyre models to evaluate potential gain in selecting the best tyres. For the second strategy 8 road sections were ground and the effect of grinding was evaluated with respect to noise and rolling resistance. The results indicate that when the CPX method is performed correctly, it can consistently evaluate tyre/road noise. Recommendations on how uncertainty in the CPX method can be reduced are included in the thesis. Additionally, recommendations on how the tyre rubber hardness measurements can be improved are also discussed, which is relevant not only for noise measurements but also for rolling resistance measurements. The selection of tyres is the mitigation strategy that has the largest potential to reduce noise and rolling resistance, yet it can take time to be implemented. On the other hand, surface grinding leads to substantial noise and rolling resistance reductions and can more readily be implemented. Noise and rolling resistance measurements on roads were compared to measurements on drums and no correlation was found. This indicates that drum results cannot be directly compared to tyre performances on roads. Values presented on the EU tyre lables were shown to not correlate to on-road measurements; this calls for a re-examination of the tyre labelling procedures. Regarding labelling of road surfaces, results in this thesis indicate that reliable acoustical properties can be obtained with the CPX method in a reproducible way and suggests that acoustical labelling of road surfaces is feasible with a precision of 1 dB.]]></description>
      <pubDate>Tue, 08 Sep 2020 14:38:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1737819</guid>
    </item>
    <item>
      <title>Road surface and tyre interactionfunctional properties affecting road dust load dynamics and storage</title>
      <link>https://trid.trb.org/View/1737818</link>
      <description><![CDATA[Particulate matter is a problem for human health, where several relationships between negative health effects and air pollution has been found, including, but not limited to, respiratory diseases, lung cancer and cardiovascular diseases. In countries where studded tyres are used, for example Sweden, Norway and Finland, and where traction sanding is used, particles from abrasion wear of pavements and crushing of traction sand contribute significantly to PM 10 . The thesis has several objectives, where a broader aim is to investigate the complex road surface and tyre system regarding abrasion wear of pavements and the impact on abrasion wear particles and road dust. The thesis also aims to put these aspects in relation to other, equally complex, aspects coming from or affected by the road surface and tyre interaction which include noise, rolling resistance and friction. This is done through some more specific objectives and limitations described in the thesis. The thesis also has the fundamental aim to act as a starting point to reach a more holistic approach to understand the functional performance of the road surface and tyre interaction which has been done in cooperation with Vieira and the results he publishes in his thesis. The road surface and tyre interaction consist of a complex contact system which is affected by both tyre properties and the road surface course properties, including both its inherent material properties and the road surface characteristics, as well as the surrounding environment and any interface consisting of for example water, slush, snow, ice or sand and so on. The surface wear course has several functions which is dependent on the inherent material properties. The wear course must resist several degradation processes, including chipping, different types of deformation, different types of cracking as well as abrasion wear due to studded tyres to mention some. The surface course construction and the traffic characteristics affect the particle generation, where the surface course properties that govern the resistance against abrasion wear also affect the generation of wear particles. Other aspects which are affected by the road surface and tyre interaction is the generation of noise and the rolling resistance. Noise has, as for particles, an negative impact on health and the road surface and tyre interaction is the dominating source from about 15 km/h to 25 km/h for light traffic and from about 30 to 35 km/h for heavy traffic. Several mechanisms generate or amplifies the noise and is connected to the surface characteristics such as the macrotexture. Rolling resistance is the conversion of mechanical energy to heat for a rolling tyre and is affected by both the road surface and tyre deflections and deformations and are affected by the surface characteristics such as unevenness and the macrotexture. The rolling resistance is linked to fuel consumption and in extension to exhaust emissions. Another functional property is the friction which is affected by the road surface characteristics by the micro- and macrotexture. There are several measures to reduce road dust loads and PM 10 . The measures can be either preventive or mitigative. Measures aimed at changing the traffic situation and the tyre usage, changing of the road surface wear course, cleaning of the road surface and dust binding are described. Several methods has been used in the studies discussed in the thesis and consist of a large-scale road simulator, the usage of laser measurement systems for determination of road abrasion wear and texture respectively, a prediction model for studded tyre abrasion wear and the NORTRIP model for modelling of non-exhaust particle emissions from road traffic. Also used was a commercial system for traffic measurements and a method for determining the proportion of studded tyre usage. Road dust was sampled and quantified using the WDS (Wet Dust Sampler) method and the collected dust was quantified and characterised using a laboratory method and by using laser granulometry.  Turbidity was used as an approximation of the road dust load. Five papers are appended to the thesis. The first paper describes the calibration of the Swedish studded tyre abrasion wear prediction model and the effect it has on the NORTRIP model, in which the abrasion wear model is implemented. The second paper describes the macrotexture of different surface wear courses and how different texture measures could be used to describe the potential dust storage capability. The third paper investigate the WDS-method regarding its performance regarding water and how the water performance theoretically affects potential dust losses. The fourth paper describe the spatial and temporal variation of road dust for six winter and spring seasons in Stockholm, Sweden, for several streets with SMA (Stone Mastic Asphalt) pavements. The fifth paper describe a similar investigation performed in Linköping, Sweden, during one winter and spring season for a double layered porous asphalt and for an SMA which acted as a reference. When applicable, the results from Linköping was compared to those from Stockholm. The results showed that the abrasion wear modelling overestimated the abrasion wear by approximately 50% which caused the NORTRIP model to overestimate the contribution from the abrasion wear to the particle emissions, which was not surprising. However, it is not likely that the NORTRIP model gets a decrease of the emissions 50% since the road surface and tyre interaction is complex and several aspects affects the abrasion wear and the resulting generation and storage of road dust, including, but not limited to, polishing of the road surface, increased abrasion wear for wet surfaces. The results from the WDS investigation showed that the method seems to function well, given the limitations of the study. The largest water loss was the water retained on the road surface. It also seems like most of the dust is collected. The discussions also consider how the WDS method uses water and the strengths and weaknesses this has compared to dry sampling methods. The results from the spatial and temporal variation of the road dust loads in Stockholm showed that there are differences between seasons and there is a difference between the dust loads in the wheeltracks and between wheeltracks. In some cases, differences were seen between the streets with large variations, which could be expected since the road dust load is dependent on the traffic characterization, road operation, deposition of material on the surface and the meteorology.  Another result was that an increasing macrotexture seemed to result in an increase in dust loads. The macrotexture was, generally, lower between the wheeltracks and higher in the wheeltracks, which was not surprising due to the traffic impact on the texture development. The macrotexture was, however, only measured at a single occasion. The repaving of a SMA surface course to a more abrasion resistant SMA surface course resulted in a higher dust load compared the before the repaving, while visual observation of the road surface implied a rougher macrotexture. This could, however, have been affected by an increased abrasion wear which occur during the first winter season due to a higher initial abrasion wear. The results in Linköping showed similar temporal and spatial variations as in Stockholm for the investigated SMA surface course. It was also discussed how the double layered porous pavements construction affect the particle transport processes. In the comparison between Stockholm and Linköping, it was suggested that the dust binding and cleaning in Stockholm affect the dust load since these measures are not performed in Linköping which is possibly reflected in the dust loads in and between wheeltracks. How different texture measures could be used to characterize the road surface texture and its connection to the dust load storage was also discussed, including a discussion of which measures that could be used. It is, however, also noted that the measures discussed the measure that should be used is not necessarily discovered yet. The discussion also mention the lack of a holistic approach regarding the road surface and tyre interaction which simultaneously consider effect such as abrasion wear particles, noise and rolling resistance. Some measures seem to be of interest to improve at least two aspects simultaneously, for example the usage of a double layered porous pavement or texture optimisation. Different strength and weaknesses are discussed for the different mechanisms affecting the different aspects as well as how some mechanisms should be further studies from other perspectives, for example noise mechanisms which may be interesting from a particle perspective. The thesis ends with giving some suggestions for continued research to increase the knowledge. This concern abrasion wear modelling and road dust emission modelling where the road surface texture should be considered. Also suggested is that mechanisms from other aspects of the road surface and tyre interaction, for example those affecting noise, also should be investigated and be used to explain mechanisms related to road dust generation and suspension. Several combined investigations are suggested for studying several aspects from or affecting the road surface tyre interaction simultaneously, including noise, rolling resistance, the road surface characteristics, road abrasion wear, abrasion nwear particles, the road dust loads, the suspension of particles and friction which is required to finally achieve the holistic knowledge required to at least minimise conflicts of interest between different functional properties for road surface courses.]]></description>
      <pubDate>Tue, 08 Sep 2020 14:38:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1737818</guid>
    </item>
    <item>
      <title>ROMA :state assessment of road markings in Denmark, Norway and Sweden : results from 2017</title>
      <link>https://trid.trb.org/View/1706565</link>
      <description><![CDATA[Assessment of the performance of road markings are carried out regularly to various degrees in the Nordic countries. During the coming years, the Nordic certification system for road marking materials will come into force, which means that a documented product approval (i.e. certification) will be required for use of the material on roads managed by the national road authorities. The requirements are introduced successively as the existing contracts expire. The aim of this project is to monitor and follow up how road marking quality is influenced by the introduction of the certification system in Denmark, Norway and Sweden. If the performance does not develop as expected, continuous assessments give the opportunity to react and adjust the requirements in the future. Furthermore, the aim is to show possible differences in road marking performance between the three countries, similar regions in the three countries and TEN-T-roads. The study is based on mobile road assessment measurements carried out in Denmark, Norway and Sweden by Ramböll AB. In total 71 road objects were measured in Denmark, 101 in Norway and 436 in Sweden. The following variables were studied: retroreflectivity of dry and wet road markings, relative visibility of dry and wet road markings, relative pre-view-time (pvt) of dry and wet road markings and cover index. The results show that the retroreflectivity requirement of dry road markings is roughly fulfilled in 50 % of the measured objects. The retroreflectivity is a little bit higher for lane and centre lines. Some retroreflectivity values are low, e.g. on motor-way edge lines in Denmark. However, this is compensated for by a large area, which nevertheless means good visibility. The opposite: edge lines on Swedish two-lane roads have high retroreflectivity, which would imply good visibility. However, the road marking area is small, thus reducing the visibility in comparison with both Danish and Norwegian edge lines. Regarding wet road markings, road markings in Norway has have higher retroreflectivity than in Denmark and Sweden for every road class. The cover index is significantly lower in Denmark than in Norway and Sweden. This fact may be explained the use of studded tyres in the two last mentioned countries, which might lead reconditioning of the road markings more often. A comparison between the performance on the Trans-European Transport Network (TEN-T) and other roads showed that there are only minor differences between the TEN-T and other roads in Denmark and Norway, while in Sweden the retroreflectivity has somewhat higher levels for the TEN-T network (175 mcd/m2/lx compared to 162 mcd/m2/lx). The results for visibility show larger differences between TEN-T or non-TEN-T and for all countries the visibility is higher for the TEN-T net- work. The pre-view-time in Denmark and Norway is lower on the measured TEN-T roads while in Sweden there is no significant difference between the road types. For all countries, the mean speed limit is higher on the TEN-T roads than on other roads, which leads to shorter pre-view-time. In the first year of the project, it is not possible to study any effect of the Nordic certification system for road markings. However, in the coming years, some effects, hopefully positive, would be possible to register. In conclusion, there is no large difference in road marking performance in the three countries. The only significant difference is the poor visibility of edge lines on two-lane roads in Sweden and the good performance of wet road markings in Norway.]]></description>
      <pubDate>Thu, 14 May 2020 09:44:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/1706565</guid>
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