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Sökning: WFRF:(Erlingsson Sigurdur 1960 )

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1.
  • Ståhle, Alexander, et al. (författare)
  • Designguide för Smarta gator
  • 2022
  • Bok (övrigt vetenskapligt/konstnärligt)abstract
    • Designguiden för smarta gator konkretiserar hur de fyra megatrenderna urbanisering, digitalisering, samhällsförändringar och miljöförändringar leder till nya krav och utformningsprinciper för framtidens gator. Guiden är tänkt att fungera som en inspiration och ett underlag för att förnya svensk gatupolicy på nationell, regional och kommunal nivå.Guiden innehåller utöver en inledning följande kapitel: en historisk tillbakablick (gatans utveckling), gatans användning, gatans delar, gatans design, designprocessen, guidens genomförande.
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2.
  • Afridi, Amjad, et al. (författare)
  • Management of municipal street network in Sweden : results from a national survey
  • 2024
  • Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 395-396
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Management of street networks is different from state roads due to its multifunctional role in society. This requires timely maintenance of the street network to improve socioeconomic development. Municipalities in Sweden are responsible for the management of about 42000 km of street network in their jurisdiction. Maintenance budget and resources vary from municipality to municipality depending on their network size, geographical location, and population density. A questionnaire was sent to all 290 municipalities across the country to investigate the street network and pavement management practices at the municipal level. An in-depth interview of 14 municipalities took place afterwards. A total of 51% of responses were officially received to highlight the frequently and infrequently occurring pavement distresses and their causes. Furthermore, the study highlights the maintenance approaches and allocation of budget to manage the street network. Lastly, the study highlights the factors which need to be addressed to improve street network management.   Visual assessment of pavements is common and the use of pavement management system (PMS) is not only limited but also lacks pavement performance prediction models. Common pavement distresses are excessive formation of potholes, surface unevenness and alligator distress among the municipalities. Frequent causes of distress include the ageing of the street network, heavy vehicles, patching and high traffic flow. Furthermore, cold climate and population density are important factors in the degradation process. Allocation of maintenance and reconstruction budget is relatively high in municipalities located in the north. Densely populated municipalities have higher taxpayers’ contributions to maintenance and reconstruction. Other major issues are limited resources and maintenance of budget, which adversely affect the maintenance backlog and the choice of maintenance alternatives, ultimately the decision-making. This restricts the use of preventive maintenance among the municipalities. Municipalities are required to improve the frequency and quality of pavement data collection, enhance the sophistication of PMS by using pavement deterioration models, and increase the maintenance budget and resources. An insight into the capabilities of municipalities would help in long-term strategic planning and effective utilisation of the maintenance budget to improve the street network across the country.  
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3.
  • Afridi, Muhammad Amjad, et al. (författare)
  • Municipal street maintenance challenges and management practices in Sweden
  • 2023
  • Ingår i: Frontiers in Built Environment. - : Frontiers Media S.A.. - 2297-3362. ; 9
  • Tidskriftsartikel (refereegranskat)abstract
    • The municipal street network acts as a multifunctional asset by providing people, vehicles and public services with a well-functioning infrastructure. To keep it in good condition, optimal maintenance measures are required which would result in an efficient use of taxpayers' money. This paper investigates the street network deterioration processes and the management practices that the municipal administrations have applied in Sweden. The study is based on a survey with Swedish municipalities using questionnaires and complementary interviews. The answers provide insight into a wide range of common pavement distresses and deterioration factors, along with pavement management practices. The study identifies that potholes, surface unevenness and alligator cracking are the most cited challenges, while pavement ageing, heavy traffic and patches are the most noted causes. Similarly, the cold climate and population density are influential factors in pavement deterioration. Allocation of the maintenance and rehabilitation and reconstruction budget is higher in the northern part of the country as well as in densely populated municipalities. Condition data collection and use of commercial Pavement Management Systems (PMS) are limited. Addressing the challenges effectively may be possible through the enhancement of the budget, feasible/clear guidelines from municipal councils/politicians, and reducing the gap between street network administrations and utility service providers.
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4.
  • Afridi, Muhammad Amjad (författare)
  • Municipal street pavement maintenance and management practices in Sweden
  • 2024
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • A well-functioning street network is pivotal in the socio-economic development of a region. Street networks not only facilitate the movement of people and goods but also allocate space for utility services. Maintaining the street network in good condition and meeting the sustainability targets necessitate implementing optimal street maintenance strategies, leading to an efficient utilization of taxpayers' money. The objectives of this Licentiate thesis are to analyse pavement management practices and challenges faced by Swedish municipalities, specifically focusing on asphalt concrete (AC) pavements within street networks. Additionally, it seeks to integrate a sustainability tool into pavement maintenance to select maintenance measures that contribute to sustainability goals at the municipal street network management level. Furthermore, the study aims to enhance municipal-level pavement maintenance approaches through the implementation of machine learning (ML) models within a pavement management system (PMS). Within this context, three individual studies were conducted—two case studies and a survey involving Swedish municipalities. One case study explores sustainability framework application, whereas the other investigates the utilization of ML models in municipal AC pavement maintenance. The survey investigates the practices and challenges faced by municipal street network administrations in AC pavement maintenance.The sustainability framework SUNRA (Sustainability National Road Administrations) was adopted by the Swedish Transport Administration (STA) with a primary emphasis on promoting sustainability in pavement management on state-level roads. In this study, the framework has been tested, applied and further streamlined to be applicable for setting sustainability targets and monitoring sustainability performances at the project level within both the STA and municipal contexts. The aim was to simplify the framework so it is appropriate for investment, re-investments, maintenance and operation projects and also to enhance its applicability for various users. The study additionally explored how the framework could contribute to sustainability, identified the drivers and barriers for its application, and examined its applicability and adaptability to projects of varying complexities. The results indicate that the framework can be readily utilized and adapted for investment, reinvestment, maintenance, and operational pavement projects during the planning stage. Additionally, it is also suitable for small municipal establishments, construction or reconstruction of residential areas, and regular maintenance.A web-based questionnaire survey was disseminated to municipalities across the country to gather first-hand insights into the current practices and challenges associated with street maintenance at the municipal level in Sweden. Survey responses were received from 147 of the 290 (51%) municipalities nationwide. The study reveals that predominant pavement distress encompasses potholes, surface unevenness, and alligator cracking, with the most prevalent causes being pavement ageing, heavy traffic, and patches. Likewise, cold climate and population density serve as influential factors contributing to pavement deterioration. The automated survey methods for collecting pavement condition data, such as road surface scanning vehicles and application of commercial PMS, are very limited. On the contrary, the windshield method, a subjective approach for pavement condition assessment, is widely adopted among municipalities utilizing PMS. The allocation of the budget for maintenance, rehabilitation and reconstruction is higher in the northern regions of the country, as well as in densely populated municipalities.Manually collected pavement condition data for the years 2014 and 2018 were acquired from Skellefteå municipality to assess the performance of ML models in comparison to the observed pavement condition index (PCI) of the street network. In this context, the supervised ML models Linear Regression (LR), Random Forest (RF), and Neural Network (NN) were employed in conjunction with several variable combinations. The RF model, utilizing paired variables of pavement age (A) and pavement distresses (D) data, consistently demonstrated higher accuracy compared to the other models for residential streets. However, RF models constructed with paired variables of A and traffic (T) consistently outperformed other models in the context of non-residential streets. The significance of input variables fluctuates based on the model's complexity and the pavement performance objective. Nonetheless,  variable A consistently emerges as the predominant factor for predicting PCI in both residential and non-residential street models. Further evaluation of the models and simplification of the SUNRA framework to enhance pavement performance and sustainability are recommended. 
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5.
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6.
  • Ahmed, Abubeker, 1981-, et al. (författare)
  • Full scale accelerated pavement tests to evaluate the performance of permeable and skeletal soil block pavement systems
  • 2016
  • Ingår i: The Roles of Accelerated Pavement Testing in Pavement Sustainability. - Cham : Springer International Publishing. - 9783319427973 - 9783319427966 ; , s. 131-144
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • The increasing proportion of paved surface due to urbanization means that the conditions for urban trees and vegetation to survive have deteriorated. Factors such as air pollution, poor drainage, and the lack of usable soil for root growth contribute to the short life expectancy of urban trees. To meet this challenge, several permeable and "structural" or "skeletal soils" have been developed as alternatives to the typical compacted soil required to bear the weight of vehicular traffic in urban areas. The main objective of this study is to evaluate the resistance to permanent deformation of permeable and skeletal soil pavement structures based on full scale accelerated pavement tests (APT) using a heavy vehicle simulator (HVS). Interlocking paving stones of various types were used as permeable surface layer for the test structures. The results demonstrated that the permeable test structures exhibited higher permanent deformation than the corresponding impervious structures. The skeletal soil with bituminous base layer, however, produced performance comparable to the impervious reference test structures.
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7.
  • Ahmed, Abubeker, 1981-, et al. (författare)
  • Iron sand as a frost protection layer : thickness design charts
  • 2022
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Frost depths and frost heaving calculations were performed to prepare design charts and tables for the iron sand (järnsand) layer thickness design for roads typically used for residential area, parking lots and other low to medium traffic roads, and for ground insulation. A segregation potential based frost design method was employed to generate the design charts and tables. The segregation potential method allows the prediction of both frost heaving and frost penetration depth of a pavement structure for a prescribed winter temperature profile or freezing index. Thus, the iron sand layer thickness design tables/charts for roads were prepared for different levels of maximum permitted heaving criteria of 50, 80, 100, and 120 mm. Whereas for ground insulation, a design chart/table was prepared to eliminate any frost action in the ground. In addition to the frost design calculations, two triaxial tests were conducted to evaluate the bearing capacity of the iron sand material. The limited test results indicated that, the bearing capacity of iron sand is similar to conventional sand both in terms of stiffness as well as permanent deformation behavior.
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8.
  • Ahmed, Abubeker W, 1981-, et al. (författare)
  • Impact of longer and heavier vehicles on the performance of asphalt pavements : A laboratory study
  • 2018
  • Ingår i: Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017. - : CRC Press/Balkema. - 9781138295957 ; , s. 483-490
  • Konferensbidrag (refereegranskat)abstract
    • Historically, Longer and Heavier Vehicles (LHVs) have been permitted to operate in Sweden. Since 1996 and as of the beginning of 2015, the maximum gross vehicle weight of 60 tons and a length of up to 25.25 m have been permitted. The Swedish Transport Administration has decided to further increase the maximum gross vehicle weight to 74 tons and studies are undergoing to evaluate the impact of the proposed LHVs on existing transport infrastructure. To this end, repeated load triaxial tests and indirect tensile fatigue tests were conducted on selected conventional asphalt mixtures to investigate and quantify the impact of single, tandem and tridem axle configurations on permanent deformation and fatigue performances of conventional asphalt pavements. In addition, fatigue tests for selected LHV scenarios were conducted. This paper presents the results of the laboratory tests and simulations conducted. The test results have clearly demonstrated the impact of the different axle configurations on the rutting and fatigue performances of the mixture. Furthermore, such results can explain the significance of axle configuration on modelling the rutting and fatigue performances of asphalt pavements.
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9.
  • Ahmed, Abubeker W, 1981-, et al. (författare)
  • Impact of tire types and configurations on responses of a thin pavement structure
  • 2018
  • Ingår i: Advances in Materials and Pavement Performance Prediction. - London : CRC Press. - 9781138313095 ; , s. 271-274
  • Konferensbidrag (refereegranskat)abstract
    • The objective of this study was to assess the impact of tire and tire configurations on the responses of a thin asphalt pavement structure by means of full-scale tests using a Heavy Vehicle Simulator (HVS). A total of six different types of tires, four single and two dual tire configurations, were investigated. The structure was instrumented to measure tensile strains at the bottom of the asphalt layer and vertical stresses and strains in the unbound base, subbase and subgrade layers. The results indicated that, in general, single tire configurations produced higher tensile strain at the bottom of the asphalt layer and higher vertical stresses and strains in unbound base, subbase and subgrade layers.
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10.
  • Andersson-Sköld, Yvonne, 1957-, et al. (författare)
  • Development of the SUNRA Tool to Improve Regional and Local Sustainability of the Transportation Sector
  • 2022
  • Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 14:18, s. 11275-
  • Tidskriftsartikel (refereegranskat)abstract
    • To fulfil the global sustainable development goals (SDGs), achieving sustainable development is becoming urgent, not least in the transportation sector. In response to this, the sustainability framework Sustainability National Road Administrations (SUNRA) was developed to contribute to improving the sustainability performance of national road administrations across Europe. In the present study, the framework has been tested, applied and further developed to be applicable for target setting and follow-up at the project level at both the Swedish Transport Administration (STA) and at municipal levels. The aim was a framework relevant for investment, re-investments, maintenance and operation projects and also to make it more user applicable. The study also investigated how the framework can contribute to sustainability, identified drivers and barriers for applying the framework and examined whether the framework can be applied and adapted to projects of different complexities. The adaptations and developments were done in collaboration between researchers and practitioners. The results show that the framework could easily be used and adapted for investment, re-investment, maintenance and operation projects in the planning stage, as well as for small municipal establishments, construction or reconstruction of residential areas and frequent maintenance. The framework contributes to increased awareness on sustainability, and it provides a common structure and transparency on how infrastructure project goals/targets are set and fulfilled. The framework can also be applied to follow the fulfilment of the goals/targets and thereby adapt the project to better fulfil the goals. Identified barriers include the lack of obligations and lack of experience in using sustainability frameworks.
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11.
  • Andersson-Sköld, Yvonne, 1957-, et al. (författare)
  • Ramverk för att prioritera och bedöma nyttan av klimatanpassningsåtgärder
  • 2023
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Klimatförändringarna är idag påtagliga och även om vi snabbt får ner utsläppen av växthusgaser kommer fler, mer omfattande och mer kostsamma klimatrelaterade händelser att inträffa alltmer ofta. Kostnaderna inom den svenska transportsektorn för klimatrelaterade händelser som skadar gator, vägar, spår-/järnväg, med flera sårbara delar av infrastrukturen är stora redan idag och förväntas öka. Översvämningar, bränder och skador till följd av väderrelaterade händelser på anläggningar resulterar bland annat i minskad framkomlighet och en ökad risk för olyckor. För att upprätthålla transportsystemets funktion är det därför viktigt att vi vidtar riskreducerande åtgärder för att minska sannolikheten och omfattningen av negativa konsekvenser av både dagens klimat- och väderrelaterade händelser men framför allt för att hantera framtida klimatrelaterade händelser. Det är nödvändigt att säkerställa transportsystemets funktion vid extrema väderhändelser, och under perioder av långvarig nederbörd, långvariga värmeböljor och förändrade nederbördsmönster. Det gäller också att redan idag möjliggöra anpassningsåtgärder för att hantera långsiktiga förändringar som höjd havsvattennivå och grundvattennivåer, som påverkar infrastrukturens framkomlighet och livslängd.I denna rapport presenteras sammanfattande resultat och en sammanfattning av hur ett ramverk för att utvärdera klimatrelaterade effektsamband har använts. Med effektsamband avses att identifiera, bedöma och värdera klimatrelaterade risker och riskreducerande åtgärder. I denna rapport är fokus på att identifiera, bedöma och utvärdera effektiviteten av klimatrelaterade åtgärder. Resultatet av det framtagna ramverket kan användas för att analysera riskreducerande åtgärders effekter, det vill säga för att bedöma om det är relevant att genomföra en åtgärd, när i tiden den bör genomföras samt för att bedöma vilken åtgärd som är mest relevant att genomföra. De risker som beaktas genom fallstudier innefattar brandrisk, olycksrisk på gator och vägar på grund av nollgenomgångar eller värme, översvämning, erosion och skred och påverkan på vägkonstruktionen (spårbildning, bärighet och utmattning), solkurvor och risker vid kraftiga vindar. Testerna har innefattat faro- och riskidentifiering, riskanalys, identifiering och utvärdering av möjliga åtgärder. Exempel på fallstudier är Gävleregnet 2021, ett skyfall i Kungsbacka kommun 2019, erosionsrelaterade förändringar under lång tid vid Österdalälven och beräkningar av påverkan av temperatur, fuktighet och förändringar i tjälförändringsmönster på vägkonstruktionen vid E10 vid Svappavaara. I en av de fallstudier som sammanfattas i rapporten redovisas även en monetär värdering och känslighetsanalys. Ramverket har också legat till grund för en diskussion avseende klimatrelaterade risker kopplade till elförsörjning.
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12.
  • Andersson-Sköld, Yvonne, 1957-, et al. (författare)
  • Sunra för lokal och regional infrastruktur : prototypen Sulri : Version 2022
  • 2022
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Sunra (Sustainability: National Road Administrations) är Trafikverkets beslutstödsverktyg som utvecklats för att användas i väg- och järnvägsprojekt genom att sätta en ambitionsnivå för olika hållbarhetsaspekter och följa upp arbetet mot dessa på ett strukturerat sätt. I denna avrapportering beskrivs resultatet av fortsatt utveckling av Sunra anpassat för lokal och regional infrastruktur. Resultatet är prototyperna Sulri (Sustainability Local and Regional Infrastructure) och Sulri-frekvent. Sulri-frekvent är avsett att användas för mer frekventa projekt, som till exempel asfaltering av befintliga gator. Sulri också är tänkt för projekt som är lite mer komplexa såsom att tänka om eller planera nytt som till exempel att förbättra för aktivt resande, att klimatanpassa ett område eller att anpassa en gata, en plats eller ett område efter andra behov. Men Sulri kan i princip användas även för mer frekventa eller mindre projekt. I denna rapport beskrivs en första version av Sulri. Rapporten visar på hur verktyget ska användas. Därefter redovisas i kapitel 3 de teman och aspekter som beaktas inom Sulri och underliggande frågeställningar som utgör resultatet av de uppdateringar som gjorts i denna version. I bilaga 2 ges motsvarande redovisning för Sulri-frekvent. I bilaga 1 redovisas relevanta underlag för de olika teman och aspekter som beaktas i Sulri.
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13.
  • Canon Falla, Gustavo, et al. (författare)
  • Characterization of unbound granular materials within a mechanistic design framework for low volume roads
  • 2017
  • Ingår i: Transportation Geotechnics. - : Elsevier Ltd. - 2214-3912. ; 13, s. 2-12
  • Tidskriftsartikel (refereegranskat)abstract
    • Unbound granular materials (UGM), used in base and subbase layers, play a major role in the structural performance of low volume roads (LVR) with a thin asphalt surface layer. A prerequisite for a proper design of such roads is the development of reliable testing techniques to simulate the behavior of UGMs under conditions similar to those that occur when subjected to traffic. Therefore, there is a need for simple and economical test methods to characterize the mechanical behavior of UGM under the action of high traffic loads. This paper presents a methodology for the experimental characterization of UGMs with a focus on mechanistic design. The results of a test campaign aimed at characterizing the elastic and plastic behavior of UGM are shown. The laboratory tests were performed using a new volumetric compaction tests and the triaxial test. Based on the results of the tests, a new classification method for UGMs intended to be used in the base course of thin asphalt pavements is suggested. 
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14.
  • Dinegdae, Yared, 1981-, et al. (författare)
  • Calibrating ERAPave PP with field performance data
  • 2024
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The conventional pavement design approach considers various parameters for the optimization of pavements for the prevailing traffic and environmental conditions. Demands related to technological developments, climate adaptation and infrastructure resilience are expected to influence the way pavements are designed and constructed. For this, better and improved flexible pavement design tools are required. ERAPave performance prediction (PP) which is a mechanistic-empirical (M-E) pavement design tool is currently under development with the goal of addressing the several challenges facing the pavement industry. This paper calibrates the permanent deformation prediction approach in ERAPave PP using pavement performance data from actual field pavements. As traffic volume is observed to have a significant influence on predicted results, separate calibration was performed for medium-to-high-volume and low-volume traffic categories. A global calibration factor is used for this purpose, significantly improving the accuracy of the prediction for both categories. Prediction accuracy can be improved further through the consideration of observed rut depth variability.  
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15.
  • Dinegdae, Yared, 1981-, et al. (författare)
  • ERAPave PP calibration using field pavement sections
  • 2024
  • Ingår i: Sammanställning av postrar från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Introduction - ERAPave PPMechanistic-empirical (M-E) pavement performance evaluation toolEmploys enhanced approaches for inputs characterization, pavement response modeling and performance evaluationPredicts distresses such as permanent deformation, fatigue cracking, frost heave and studded tire wearUnder consideration by the Swedish and Norwegian Transport Administration as a possible successor to existing methods
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16.
  • Dinegdae, Yared, 1981-, et al. (författare)
  • Evaluation of ERAPave PP permanent deformation models using APT
  • 2023
  • Ingår i: International Journal on Road Materials and Pavement Design. - : Taylor & Francis. - 1468-0629 .- 2164-7402.
  • Tidskriftsartikel (refereegranskat)abstract
    • Permanent deformation is one of the failure modes considered in the analysis and design of flexible pavements. ERAPave performance prediction (PP) which is a mechanistic empirical (ME) pavement design tool utilises two distinct models for the prediction of permanent deformation in the bound and unbound granular layers including subgrade. This paper aims to calibrate these models using pavement response and performance data from accelerated pavement testing (APT) structures. Material properties such as layer modulus were established through an optimisation that involves both falling weight deflectometer (FWD) and pavement response measurements. Based on the predicted performance results, a separate set of calibration was performed for permanent deformation development in moist and wet moisture conditions. The calibrated models have resulted in predictions that are in good agreement with observed performances. Furthermore, the model parameters successfully captured the initial densification behaviour and the associated sensitivity with axle load level.
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17.
  • Dinegdae, Yared, 1981-, et al. (författare)
  • Evaluation of Permanent Deformation Models for Flexible Pavements Using Accelerated Pavement Testing
  • 2020
  • Konferensbidrag (refereegranskat)abstract
    • Several models are currently available for the prediction of permanent deformation in flexible pavements. These models are intended for different analysis conditions and require extensive calibration and validation before use. The aim of this article is to evaluate the permanent deformation models incorporated in a Swedish analysis tool (i.e., ERAPave ME) for flexible pavements. Measured response and performance data from an accelerated pavement testing using heavy vehicle simulator is used for this purpose. Pavement response is computed using a multi-layered linear elastic analysis tool while stress-dependency is accounted in the prediction of permanent deformation. A general good agreement has been observed between measured and computed responses. The same is true for observed and predicted permanent deformations. The permanent deformation prediction is achieved using model parameters that are unique to each layer and loading level.
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18.
  • Dinegdae, Yared, 1981-, et al. (författare)
  • Toward a Comprehensive Pavement Reliability Analysis Approach
  • 2023
  • Ingår i: Transportation Research Record. - : Sage Publications. - 0361-1981 .- 2169-4052. ; 2677:7, s. 680-692
  • Tidskriftsartikel (refereegranskat)abstract
    • Reliability has been incorporated in pavement design tools to account for input variability influence on predicted performance. As they are not based on a probabilistic method of uncertainty propagation, the reliability analysis methodologies that are currently implemented in pavement performance tools lack rigor and robustness. This paper investigates the potential of three reliability analysis methodologies for pavement application: the Pavement ME reliability analysis methodology, Monte Carlo simulation (MCS), and the first-order reliability method (FORM). The MCS and FORM involve a response surface method for the generation of a second-order surrogate model. The investigation was performed using inputs and performance data from accelerated pavement testing structures. Inputs that were identified as significant were characterized as random variables and their associated variability was established using measured structural and material properties. Pavement performance with respect to rutting was predicted using the ERAPave performance prediction tool, while MCS was used to generate the actual variability of the distress. The reliability analysis results have shown that a comprehensive reliability analysis methodology is required that effectively captures input variabilities and the error associated with surrogate models.
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19.
  • Erlingsson, Sigurdur, 1960-, et al. (författare)
  • Characteristic of unbound granular materials and subgrades based on multi stage RLT testing
  • 2017
  • Ingår i: Transportation Geotechnics. - : Elsevier Ltd. - 2214-3912. ; 13, s. 28-42
  • Tidskriftsartikel (refereegranskat)abstract
    • The unbound granular layers (UGM's) and the subgrade of a pavement structure provide a significant support for the structure as a whole. Hence the mechanical properties of these materials are important for the overall performance of the structure. These materials exhibit both non-linear stress dependency and their mechanical properties are highly affected by their moisture content. This paper describes two of the most important material properties of the unbound layers of the pavements, i.e. the resilient and the permanent deformation properties. The stress dependency of UGMs can be captured by the universal model or the enhanced model by Cary and Zapata (2011) for materials with high fine content. The Bishop's effective stress approach can be used for high fine content materials for estimating the effect of suction. UGMs and subgrade materials are further highly dependent on moisture content. Either the AASHTO sigmoidal model can be used to describe the moisture dependency or the simple exponential model described in this paper. The paper further discusses four models to characterize the accumulation of permanent deformation with the number of load repetitions in repeated load triaxial (RLT) testing. The models are all developed to fit single stage (SS) RLT test results but have been extended to fit multi-stage (MS) RLT test results with the aid of the time hardening scheme. The advantage of the MS RLT tests over the SS RLT tests is that it applies a range of stress paths on a single specimen, thus taking into account the effect of stress history and reducing the time and effort required to test a separate specimen for each stress path.
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20.
  • Erlingsson, Sigurdur, 1960-, et al. (författare)
  • Correlating Air Freezing Index and Frost Penetration Depth : A Case Study for Sweden
  • 2020
  • Ingår i: Lecture Notes in Civil Engineering. - Cham : Springer. ; , s. 847-857, s. 847-857
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • The determination of frost penetration is one of the main requirements in considering environmental effects in pavement design in cold regions. At the present time, the frost depth of pavements in Sweden is estimated computationally using computer software which approximates the heat equation by finite difference. Due to the geographical positioning of Sweden, a wide range of air freezing index and frost penetration depths were observed with lower values in the south and higher values in the north. This paper introduces a simplified design chart which is obtained by empirically correlating the air freezing index estimated from temperature measurements by 44 local meteorological stations to the maximum frost penetration depth obtained by 49 RWIS Road Weather Information Station data. The results are classified depending on their location and the climatic zones defined by the Swedish pavement design codes. Nonlinear prediction intervals are implemented to provide a range of possible frost penetration depths since local site conditions are not taken into account. Further research is required to consider local on-site effects such as frost susceptibility of pavement materials, the thermal conductivity of layers, access to water and snow covering.
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21.
  • Erlingsson, Sigurdur, 1960- (författare)
  • Geotechnical challenges in Iceland
  • 2019
  • Ingår i: 17th European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2019 - Proceedings. - : International Society for Soil Mechanics and Geotechnical Engineering. - 9789935943613 ; , s. 27-51
  • Konferensbidrag (refereegranskat)abstract
    • The geotechnical challenges in Iceland are in many aspects unusual. The geological setting of the country is unique and has a great influence on the local geotechnical conditions. Iceland lies on the divergent boundary between the Eurasian plate and the North American plate formed by the Mid-Atlantic Ridge. This has created a landmass with active volcanoes, geothermal areas and zones of high seismicity. The bedrock is relatively young and mainly basaltic. It has been built up of relatively thin lava layers during eruptions. It is frequently highly jointed with irregular interlayers. The horizontal stresses in the rock mass are furthermore very low. The soil layers consist mainly of non-cohesive materials, often created in catastrophic events such as glacial floods, and are therefore often loosely packed. This paper gives a short overview of the geotechnical conditions in the country and additionally describes several geotechnical engineering projects. Some geotechnical challenges due to climate change will also be briefly discussed. © The authors and IGS: All rights reserved, 2019
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22.
  • Erlingsson, Sigurdur, 1960-, et al. (författare)
  • Mechanistic rutting modelling of a LTPP road structure
  • 2019
  • Ingår i: Pavement and Asset Management. - : CRC Press/Balkema. - 9780367209896 ; , s. 241-249
  • Konferensbidrag (refereegranskat)abstract
    • A new Mechanistic-Empirical (M-E) approach is under development to predict the structural degradation of road structures as a function of time. The aim is that the method will become one of the backbones in a new pavement asset management system. The calculation scheme is based two main steps; i) a response calculation step for the different traffic loads applied taking into account the ambient climate and ii) a performance prediction step where pavement degradation is predicted in time steps and thereafter accumulated over the entire design period of the pavement structure. The paper describes the approach briefly and is thereafter demonstrated by a calculation of the degradation of an arterial road in Southern Sweden and compared with measurements from the Swedish Long Term Pavement Performance (LTPP) database. The arterial road had reached the critical 15 mm rut after 18 years in operation. The analysis shows that the rutting development can be simulated adequately although the calculations show slower rate than the measurements towards the end of the simulated period.
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23.
  • Erlingsson, Sigurdur, 1960-, et al. (författare)
  • Responses and performance of flexible pavements in cold climate due to heavy vehicle loading
  • 2018
  • Ingår i: Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017. - : CRC Press/Balkema. - 9781138295957 ; , s. 451-457
  • Konferensbidrag (refereegranskat)abstract
    • Four instrumented test road structures have been built in northern Sweden about 100 km north of the Arctic Circle. The climate consists of cold winters and mild summers with a long spring thaw period. The pavement structures differs in material quality ranging from conventional to polymer modified structures. The objective of the test structures is to see the difference in their behaviour and performance due to the heavy loading in the ambient artic climate. Each test section is instrumented that includes pressure cells and strain sensors that measure the pavement response to external loading. Climatic variables are further monitored through a weather station as well as temperature and moisture sensors installed in the road structure. Response measurements have been carried out using 90 tons vehicles consisting of a single wheel steering axle, and triple dual wheel tridem axles. Rutting development has been monitored through four years showing some difference between the structures rutting development.
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24.
  • Erlingsson, Sigurdur, 1960-, et al. (författare)
  • Stiffness of sandy sites using the Multichannel Analysis of Surface Waves method
  • 2017
  • Ingår i: ICSMGE 2017. - : 19th ICSMGE Secretariat. ; , s. 593-597
  • Konferensbidrag (refereegranskat)abstract
    • Multichannel Analysis of Surface Waves (MASW) is seismic exploration method to evaluate shear wave velocity profiles of near-surface soil materials based on analysis of horizontally travelling Rayleigh waves. The MASW method has been applied at four loose sandy sites in South Iceland providing shear wave velocity (VS) profiles for the uppermost 25 m at each site. The VS-profile obtained for one of the test sites was compared to empirical profiles estimated on the bases of CPT measurements carried out at the site. The results indicate that the MASW profile corresponds adequately well to the empirical estimations, strengthening the results obtained by MASW. However, further comparison of MASW and CPT data is needed in order to evaluate the overall applicability of existing CPT-VS correlations at Icelandic sand sites.
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25.
  • Erlingsson, Sigurdur, 1960-, et al. (författare)
  • Testplatser för 74 ton tunga fordon : två instrumenterade tunna vägkonstruktioner
  • 2018
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Denna rapport beskriver i korthet installeringen av vägteknisk instrumentering samt klimatsensorer på två testplatser i Norrbottens län. Båda testplatserna kan klassas som tunna vägöverbyggnader. Den ena strukturen ligger längs Lv373 strax öster om Långträsk och den andra på Lv515 strax söder om korsningen vid Lv373. Huvudsyftet med testplatserna är att få bättre information om hur de nya 74 ton tunga fordonen påverkar vägarna. Detta skall göras genom att mäta konstruktionernas respons vid passerande lastbilar och vid belastning med fallviktsapparat.Den vägtekniska instrumenteringen består av töjningsgivare i tvärgående samt längsgående riktning för bestämning av dragtöjning i beläggningens underkant samt vertikala töjningsgivare för att bestämma varje lagers trycktöjning. Dessutom är spänningsmätare inlagda i överbyggnaden för att mäta den vertikala spänningen på två nivåer. Datainsamling om det lokala klimatet görs med hjälp av tjäl- och fuktstav samt temperaturgivare i beläggningen. En SMHI väderstation ligger omkring 15 km nordnordöst om testplatserna och trafikverket har en VViS-station som ligger längs Lv373 öster om testplatserna. De första responsmätningarna är planerade under sommaren 2018.
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26.
  • Erlingsson, Sigurdur, 1960-, et al. (författare)
  • The Svappavaara road test sections : field coring and laboratory tests
  • 2015
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • This report describes laboratory testing of specimens taken from four new instrumented test road sections that have been built on E45 close to the Svappavaara municipality in Norrbotten County in Northern Sweden. The structures are located about 100 km north of the Arctic Circle in a climate that is characterized by long cold winters and short mild summers. The four test sections were built in a conventional manner. Each structure is about 200–250-metre-long with a central 100-metre-long part defined as the actual test section. All structures are in total 60 centimetres in thickness resting on top of a 70-centimetre-thick old existing road. The bitumen bound part of all the four structures consists of four layers; a thin surface course layer, two binder layers and a road base layer. All structures have the same wearing course, TSK 16 with a standard 160/220 penetration grade bitumen. The main difference between the structures lies in the binder as well as the two road base layers. As a part of the monitoring programme drilled asphalt specimens were taken in 2013 from the road structure and tested at VTI's material testing laboratory in Linköping. Furthermore, samples were taken from the unbound base course and tested. This report presents the test results for asphalt bound layers as well as for the unbound base course. For the bound layers the testing procedure included volumetric properties, stiffness modulus and fatigue tests for the different types of conventional and polymer modified asphalt mixtures. The tests were conducted in accordance with the Swedish or the equivalent European standards. For the unbound base course fundamental properties were estimated as well as stiffness and permanent deformation properties for different moisture contents.
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27.
  • Erlingsson, Sigurdur, 1960-, et al. (författare)
  • The Svappavaara road test sections : instrumentation
  • 2014
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • This report describes four new instrumented test road sections that have been built on E45 close to the Svappavaara in Norrbotten County in Northern Sweden. The structures are located about 100 km north of the Arctic Circle in a climate that is characterized by long cold winters and short mild summers. Norrbotten County is a sparsely populated area where the pavement structures consist of thin pavements with relatively low traffic volume. A new ore deposit, the Kaunisvaara project, was opened in 2012, meaning that the ore will be transported along the existing road network about 160 kilometers to where it will be transferred to a railway. The ore operator has received a permit to use 90 ton vehicles instead of the permissible 60 tons, consisting of a single wheel steering axle and triple dual wheel tridem axles to transport the iron ore. When the ore processing will be in full operation around 66.000 journeys per year will pass over the network, or on average about 7–8 passes per hour with about seven and a half minutes between the passes. Due to this new ore transport it will be necessary to strengthen the local road network. As part of the process to evaluate the performance of a suitable pavement structure these four instrumented test road structures have been selected and built. The structures are instrumented with road performance and climate sensors. The structures will be monitored over the years to come, though the details of the monitoring programme have not yet been decided. Each test section is around 200 metres long, consisting of a 100 metres long inner part that constitutes the intrinsic test section. The structures were built and instrumented in the summer of 2012 except for the wearing course that was placed in the summer of 2013 along with the temperature sensors that are placed in the asphalt layers. The instrumentation in each section consists of Emu coils for vertical strain measurement devices, soil pressure cells for vertical stress measurements and tensile strain gauges located at the bottom of the bound road base layer. In addition there are moisture rods located in three of the structures and a temperature (frost) rod located in structure 3. A weather station (2527 Svappavaara) operated by the Transport Administration is located 3.2 kilometre south-east of the test site.
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28.
  • Erlingsson, Sigurdur, 1960- (författare)
  • Tunga trafikens samhällsekonomiska kostnader : accelererade tester av tre vägkonstruktioner
  • 2017
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Regeringen (Näringsdepartementet) har gett VTI uppdraget att ta fram och uppdatera kunskapsunderlag om trafikens samhällsekonomiska kostnader. En del i detta arbete är att ta fram ett säkrare underlag om effektsambanden mellan trafiklast (axellast) och nedbrytning av vägkonstruktioner.I denna rapport redogörs för undersökningar av effektsamband mellan axellaster och nedbrytning av vägkonstruktioner för tre vägtyper (konstruktioner) som testas med en lastbilssimulator (Heavy Vehicle Simulator, HVS) där tre olika lastnivåer, 40, 50 och 60 kN (motsvarande 8, 10 och 12 tons axellaster), har används för att undersöka lastnivåens inverkan på nedbrytningen. Konstruktionerna har olika bärighet där den första är starkast (tjockast överbyggnad) och den sista vekast (tunnaste överbyggnaden). Som ett mått på nedbrytningen har utnyttjats lutning i tillväxt i spårdjup när man har passerat den initiala (exponentiella) tillväxten och den kan uppskattas som att den ökar linjärt med antal överfarter. Spårdjup har använts som mått på nedbrytningen eftersom det ansågs som den mest relevanta nedbrytningsmekanismen för dessa relativt tunna vägkonstruktioner. Jämförelse med fjärde potensregeln har sedan gjorts som en grund för skattningen. Försöken har utförts i VTI:s testhall i Linköping under konstanta klimatförhållanden för att minska antal variabler och renodla resultaten.
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29.
  • Everton, José, et al. (författare)
  • Freeze-thaw influence on the water retention capacity of silty sand subgrades
  • 2022
  • Ingår i: Proceedings of the 11th International Conference on the Bearing Capacity of Roads, Railways and Airfields. - London : CRC Press. - 9781003222897 ; , s. 122-131
  • Konferensbidrag (refereegranskat)abstract
    • Fine-grained materials are associated with a higher water retention capacity due to their higher surface energy in comparison with coarser materials. That characteristic is connected to why fine-grained materials also yields more suction when drying. In addition, seasonal variation of the water table subjects fine-grained subgrades to different moisture contents, varying the suction built in the subgrade, consequently affecting its mechanical characteristics. As fine-grained materials are frequently frost susceptible, they can cause issues to the whole pavement cross-section related to Freeze-Thaw (F-T) actions, widely known as frost heave and thaw weakening. This study will seek to investigate if subsequent cycles of closed-system F-T can permanently alter the unsaturated behaviour of fine-grained materials, using as background their Soil Water Retention Capacity obtained using a pressure plate apparatus. Such issues may become more common with permafrost areas being subjected to freeze and thaw cycles due to climate change or extraordinary events creating the circumstances to F-T where it is currently not observed. Two silty sands with low plasticity were tested, and the results show a reduced water retention capacity (WRC) after closed-system F-T cycles. Considering that matric suction changes the state of stress of soils, the findings suggest an impact in the resilient modulus (Mr ) not only seasonally, as it is well established, but also after seasonal freezing and thaw events.
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30.
  • Fladvad, Marit, et al. (författare)
  • Modelling the response of large-size subbase materials tested under varying moisture conditions in a heavy vehicle simulator
  • 2022
  • Ingår i: International Journal on Road Materials and Pavement Design. - : Taylor & Francis. - 1468-0629 .- 2164-7402. ; 23:5, s. 1107-1128
  • Tidskriftsartikel (refereegranskat)abstract
    • Pavement design methods must be able to predict the behaviour of pavement materials at increased moisture levels due to climate changes causing increased precipitation and more intense rainfall events. This paper intends to examine the influence of moisture and gradation on pavement response. An instrumented accelerated pavement test (APT) has been conducted on two thin flexible pavement structures with unbound base course and subbase materials using a heavy vehicle simulator (HVS). The two pavement structures were identical except for the gradation of the subbase material, where one had a 0/90 mm curve with a controlled fines content, and the other had an open-graded 22/90 mm curve. The APT was conducted using constant dual-wheel loading, and three different groundwater (GW) levels were induced in order to change the moisture content in the structures. The HVS was stopped regularly for carrying out response measurements from the instrumentation. The analysis is focussed on the response of the unbound aggregate layers to varying moisture levels in the pavement structure. The increased GW level causes a substantial increase in rutting. Conflicting results are found regarding the development of stresses and strains throughout the APT. Two models, linear elastic and non-linear elastic, is employed to model the responses from the pavement structures.
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31.
  • Fladvad, Marit, et al. (författare)
  • Performance of unbound pavement materials in changing moisture conditions
  • 2020
  • Ingår i: Lecture Notes in Civil Engineering. - Cham : Springer. - 9783030552350 ; , s. 70-79
  • Konferensbidrag (refereegranskat)abstract
    • Expected climate changes will in many areas represent a shift towards increased precipitation and more intense rainfall events. This may lead to increased moisture within road structures and possible overloading of road drainage systems. Pavement design methods must therefore be able to predict the behaviour of pavement materials at increased moisture levels. An instrumented accelerated pavement test (APT) has been conducted on two thin flexible pavement structures with coarse-grained unbound base course and subbase materials using a heavy vehicle simulator (HVS). The two pavement structures were identical except for the grain size distribution of the subbase material, where one had a dense 0/90 mm curve with a controlled fines content, and the other had an open-graded 22/90 mm curve. The APT was conducted using constant dual wheel loading, and three different groundwater levels were induced in order to change the moisture content in the structures. The HVS was stopped regularly for carrying out response measurements from the instrumentation. The analysis is focussed on the response and the performance of the unbound aggregate layers to varying moisture levels in the pavement structure.
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32.
  • Fladvad, Marit, et al. (författare)
  • Permanent deformation modelling of large-size unbound pavement materials tested in a heavy vehicle simulator under different moisture conditions
  • 2022
  • Ingår i: International Journal on Road Materials and Pavement Design. - : Taylor and Francis Ltd.. - 1468-0629 .- 2164-7402. ; 23:5, s. 1157-1180
  • Tidskriftsartikel (refereegranskat)abstract
    • Climate changes alter the environmental conditions which pavement design is based on, invalidating empirical design methods. Transition to mechanistic design requires the ability to model the behaviour of pavement materials under relevant environmental conditions. An accelerated pavement test (APT) is designed to test two instrumented pavement structures under moisture conditions which are altered by raising the groundwater table (GWT). Open-graded and well-graded subbase materials are used to investigate the effect of gradation on moisture dependency. Pavement response behaviour is modelled using a non-linear elastic (NLE) approach. Accumulation of permanent deformation under different moisture conditions is calculated by two models and compared to measured surface rutting. Moisture transport through the structures differs due to the subbase gradation. Increased GWT accelerates the accumulation of permanent deformations in both structures, identified by both models. One model provides a significantly better fit to the subgrade deformations and the width of the rutting profile.
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33.
  • Fladvad, M., et al. (författare)
  • Unbound pavement materials' response to varying groundwater table analysed by falling weight deflectometer
  • 2021
  • Ingår i: Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields. - London : CRC Press. - 9781003222880 ; , s. 409-418
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Expected climate changes will in many areas represent a shift towards increased precipitation and more intense rainfall events. This may lead to increased moisture within road structures and possible overloading of road drainage systems. Pavement design methods must therefore be able to predict the behaviour of pavement materials at increased moisture levels. An instrumented accelerated pavement test (APT) has been conducted on two thin flexible pavement structures with coarse-grained unbound base course and subbase materials using a heavy vehicle simulator (HVS). The two pavement structures were identical except for the particle size distribution (PSD) of the subbase materials, where one had a dense 0/90 mm curve with a controlled fines content, and the other had an open-graded 22/90 mm curve. The APT was conducted using constant dual wheel loading, and three different ground- water levels were induced in order to change the moisture content in the structures. Falling weight deflectometer (FWD) measurements were conducted at each groundwater level during the APT. Additional FWD measurements were conducted as the groundwater was lowered after the APT loading was finished. The moisture content in the unbound materials was con- tinuously measured throughout the test. The analysis is focussed on the response of the unbound aggregate layers to varying moisture levels in the pavement structures. Analysis results show how the dense- and open-graded materials respond to the moving groundwater table, and how this affects the deflection of the full structures.
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34.
  • Larsson, Martin, et al. (författare)
  • Condition assessment of cycle path roughness and evenness using a bicycle measurement trailer
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The riding comfort of cyclists related to roughness and unevenness of cycle path surfaces has unfortunately not been given enough attention in the indices used to predict cyclists’ perceptions of roadway environments. This is partly due to the lack of condition assessment methods specifically adapted to the speed and space limits on cycle paths, and a need for developing metrics that describe the perceived comfort of cyclists rather than that of car users. In this paper a novel method, the Bicycle Measurement Trailer (BMT), is proposed to bridge this gap. Eight different surface types, ranging from gravel and different sized concrete block pavements to asphalt concrete in different conditions, have been assessed with regards to roughness. Four of these surfaces were also used for the assessment of their longitudinal evenness. The accuracy and repeatability of the BMT were evaluated. Finally, five different metrics (Dynamic Comfort Index, Evenness Coefficient, 0.5 m Straight Edge, International Roughness Index and Root Mean Square), were calculated from the collected data and assessed. The main findings suggest that the BMT has a high accuracy at normal and high cycling speeds when compared to the standardized road measuring system, Road Surface Tester, and a high level of repeatability at normal cycling speed. The surfaces could be ranked according to their roughness, and the longitudinal evenness was successfully analysed from the collected data. In conclusion, the BMT could be a valuable tool to assess the cycle path surface condition in relation to how cyclists perceive the riding comfort.
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35.
  • Larsson, Martin, et al. (författare)
  • Condition assessment of cycle path roughness and evenness using a bicycle measurement trailer
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The riding comfort of cyclists related to roughness and unevenness of cycle path surfaces has unfortunately not been given enough attention in the indices used to predict cyclists’ perceptions of roadway environments. This is partly due to the lack of condition assessment methods specifically adapted to the speed and space limits on cycle paths, and a need for developing metrics that describe the perceived comfort of cyclists rather than that of car users. In this paper a novel method, the Bicycle Measurement Trailer (BMT), is proposed to bridge this gap. Eight different surface types, ranging from gravel and different sized concrete block pavements to asphalt concrete in different conditions, have been assessed with regards to roughness. Four of these surfaces were also used for the assessment of their longitudinal evenness. The accuracy and repeatability of the BMT were evaluated. Finally, five different metrics (Dynamic Comfort Index, Evenness Coefficient, 0.5 m Straight Edge, International Roughness Index and Root Mean Square), were calculated from the collected data and assessed. The main findings suggest that the BMT has a high accuracy at normal and high cycling speeds when compared to the standardized road measuring system, Road Surface Tester, and a high level of repeatability at normal cycling speed. The surfaces could be ranked according to their roughness, and the longitudinal evenness was successfully analysed from the collected data. In conclusion, the BMT could be a valuable tool to assess the cycle path surface condition in relation to how cyclists perceive the riding comfort.
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36.
  • Larsson, Martin, et al. (författare)
  • Condition assessment of cycle path texture and evenness using a bicycle measurement trailer
  • 2023
  • Ingår i: The international journal of pavement engineering. - : Informa UK Limited. - 1029-8436 .- 1477-268X. ; 24:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Cyclists' riding comfort, related to pavement texture and unevenness, has not been thourougly investigated, partly due to the lack of condition assessment methods specifically adapted to the speed and space limits on cycle paths. Metrics that better describe the perceived comfort of cyclists, rather than that of car users, are needed. In this paper a novel method, the Bicycle Measurement Trailer (BMT), is proposed to bridge this gap. Eight different cycle path surface types have been assessed with regards to pavement texture and for four of these surfaces the longitudinal evenness was assessed. The accuracy and repeatability of the BMT were evaluated. Finally, five different metrics (Dynamic Comfort Index, Evenness Coefficient, 0.5 m Straight Edge, International Roughness Index and Root Mean Square), were calculated from the collected data and assessed. The main findings suggest that the BMT has a high accuracy at normal and high cycling speeds and a high level of repeatability at normal cycling speed. The surfaces could be ranked according to texture, and the evenness was successfully analysed. In conclusion, the BMT could be a valuable tool to assess the cycle path surface condition in relation to bicycle riding comfort.
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37.
  • Larsson, Martin, 1982- (författare)
  • Cycle paths’ degradation processes and surface condition assessment
  • 2023
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • A shift in modal share from car driving to cycling has many benefits, both from individual- and societal perspectives, e.g., better health from an increase in physical activity, lower levels of pollution and congestion. However, there are also some potential problems with such a shift. Cyclists have a higher risk of traffic incidents per travelled kilometre than car drivers. This risk needs to be minimized for an optimal transition to more cycling. A smooth surface with good friction on the cycle path is not only important for the traffic safety of the cyclists but also for their comfort and level of service. Potholes, cracks, and bumps are frequent obstructions on the cycle paths. These are all maintenance-related deficiencies associated with the degradation of the structure. In general, the knowledge on degradation of roads is good, as there is a long tradition of investigation into the degradation factors. Cycle paths, even though constructed with similar materials and techniques as the roads, are however not designed in the same way as roads, mainly since they will not be subjected to the same traffic load. Thus, one purpose of this licentiate thesis is to identify degradation factors specific for cycle paths, through a state-of-the-art literature study. This literature review is complemented by two papers, where Paper A analyses the distress found on Swedish municipal cycle paths and Paper B evaluates a novel method for condition assessments on cycle paths related to cycling comfort—the Bicycle Measurement Trailer. The review and papers are meant to act as the basis for the general aim of the PhD-project, namely, to develop more knowledge on the degradation of cycle paths. This knowledge is needed to improve the structural design approaches and maintenance strategies for cycle paths and to give guidance for preventive measures to inhibit degradation. A literature search in the national and international transport research databases was conducted, along with consultations in guidelines and handbooks on cycle infrastructure, in particular the official guidelines ofTrafikverket (the Swedish Transport Administration). Paper A is based on a state-of-practice survey in the Swedish municipalities where the stated distress modes and causes were analysed with respect to climatic and population data. The most common distress modes on municipal cycle paths in Sweden from previous studies—cracks, surface unevenness and edge deformation—were confirmed. The municipalities with main urban areas with a population of 60,000–120,000 habitants stand out from the general trend in that they seem to have less distress on their cycle paths. Further investigations are needed to find the main reasons behind this. For Paper B, field tests were conducted to establish the accuracy and repeatability of the proposed condition assessment tool, and the collected data was used to assess five different metrics for longitudinal evenness of cycle paths. The Bicycle Measurement Trailer was found to be a promising technique for condition assessment on cycle paths as it shows a high accuracy when compared to the standardized road measuring system, Road Surface Tester. The repeatability is also high. More studies are however needed to evaluate its ability to detect different distress modes. Such studies should proceed from the Evenness Coefficient metric. The conclusions of the thesis suggest that the structural design principles for cycle paths in present guidelines are insufficient for the optimization of the construction of cycle paths. They appear to be an adaptation of the structural design principles of low-traffic car roads rather than being developed specifically for cycle paths. The empirical-based models to calculate the estimated traffic load compared to the permitted traffic load are not accurate for structures with thin asphalt pavements (<75mm). Models that better describe the behaviour of thin asphalt structures, especially with respect to climate, should be developed. It should also be further investigated if the maximum load criterion is optimal with respect to the heavy vehicles that exert this load. The risk of damage to the structure from such extreme loads is at its highest when the load bearing capacity of the structure is at its lowest, i.e., the spring thawing period. More studies need to be conducted to determine the load bearing capacity of cycle path structures with different runoff and drainage conditions in this period of the year. The condition assessment manual Bära eller brista should also be updated with a section on root infiltration of cycle paths.
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38.
  • Larsson, Martin, et al. (författare)
  • Degradation of Cycle Paths—A Survey in Swedish Municipalities
  • 2022
  • Ingår i: CivilEng. - : MDPI. - 2673-4109. ; 3:2, s. 184-210
  • Tidskriftsartikel (refereegranskat)abstract
    • There is a need to move society in a sustainable direction. One way to contribute to thismove is to change to more sustainable transport modes, such as cycling. To increase cycling, theinfrastructure is important, and good quality cycle paths are needed. However, little is known aboutthe degradation of cycle paths. This paper aims to investigate what modes of pavement distressare found on municipal cycle paths in Sweden, and what probable mechanisms lie behind suchdistress; these are determined based on questions from a state-of-practice survey, interviews, and aliterature review. The main findings are that the most commonly stated distress modes are surfaceunevenness followed by longitudinal cracks, and the most commonly stated causes of distress areageing, followed by structural interventions, and roots and vegetation. The results also show that forseveral distress modes, there are probable connections with climatic factors such as temperature andmoisture, as well as with the population size of the urban areas. Objective data are needed regardingtraffic load and the climatic factors that affect cycle paths, along with information on their structuraldesign, to better understand their degradation.
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39.
  • Lundberg, Joacim, 1991-, et al. (författare)
  • Calibration of the Swedish studded tyre abrasion wear prediction model with implication for the NORTRIP road dust emission model
  • 2021
  • Ingår i: The international journal of pavement engineering. - : Taylor and Francis Ltd.. - 1029-8436 .- 1477-268X. ; 22:4, s. 432-446
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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40.
  • Lundberg, Joacim (författare)
  • Road Surface and Tyre Interaction : Functional Properties affecting Road Dust Load Dynamics and Storage
  • 2020
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Luftburna partiklar (PM) är ett problem för människans hälsa, där flertalet samband mellan negativa hälsoeffekter finns mellan luftföroreningar finns, bland annat för respiratoriska sjukdomar, lungcancer och kardiovaskulära sjukdomar med flera. I länder där dubbdäck används, till exempel Sverige, Finland och Norge, och sandning av vägar och gator genomförs vintertid för att säkerställa god friktion kommer en betydande andel av partiklarna från vägslitage och nedkrossning av sand vilket bidrar till PM10. Mängden som icke-avgaspartiklar bidrar med till PM10 varierar med lägst nivåer på landsbygd och högst nivåer i vägnära miljöer.Avhandlingen har flertalet mål, där ett bredare mål är att undersöka det komplexa väg-ytadäcksystemet gällande vägslitage och dess inverkan på genererandet av slitagepartiklar och vägdamm, inklusive transporten och lagringen av vägdamm på vägytan. Avhandlingen syftar även att sätta in dessa aspekter i relation till andra lika komplexa funktionella parametrar som kommer av eller påverkas av vägyta-däckinteraktionen såsom bullergenerering, rullmotstånd och fiktion. Detta görs genom några mer specifika mål och begränsningar som beskrivs i avhandlingen. Avhandlingen har även det fundamentala syftet att agera som en start för att nå ett holistiskt helhetsgrepp för att förstå den funktionella prestandan som krävs för väg-ytadäckinteraktionen, vilket har genomförts i samarbete med Vieira och det som han publicerar i sin avhandling.Vägyta-däckinteraktionen utgörs av ett komplex kontaktsystem, som påverkas av både däckegenskaper och vägens egenskaper, dels ingående material och vägytans karaktär, samt omkringgivande miljö och eventuella mellanlager av till exempel vatten, slask, snö, is eller sand och grus med mera.Slitlagret, eller vägbeläggningen, har flera funktioner som beror på de ingående materialens egenskaper. Beläggningen måste motstå flertalet olika nedbrytningsprocesser, inklusive stensläpp, olika typer av deformation, olika typer av sprickor och slitage från dubbdäck bland annat.Beläggningens konstruktion och trafikens sammansättning och egenskaper påverkar även partikelgenereringen, där beläggningsegenskaperna som styr nötningsmotståndet mot dubbdäckslitage även påverkar genereringen av slitagepartiklar.Andra aspekter som påverkas av vägyta-däckinteraktionen är genereringen av buller och fordonets rullmotstånd. Buller har likt partiklar negativa hälsoeffekter och vägyta-däckinteraktionen är den dominerande källan till trafikbuller från ungefär 15 - 25 km/h för lätta fordon och från ungefär 30 - 35 km/h för tunga fordon. Flertalet mekanismer ger upphov eller förstärker bullret, och flera är kopplade till ytans beskaffenhet såsom makrotexturen. Rullmotstånd är omvandlingen av mekanisk energi till värme för ett rullande däck och påverkas av både däckets och vägytans deflektion och deformation, och påverkas även av vägytans beskaffenhet av t.ex. ojämnheter och makrotexturen. Rullmotståndet ör kopplat till bränsleförbrukningen och därigenom till avgasemissioner. En annan funktionell egenskap för vägytan är friktionen som påverkas av vägytans beskaffenhet av både mikro- och makrotexturen.Det finns flertalet åtgärder för att minska vägdamm och PM10. Åtgärderna kan vara preventiva eller avhjälpande. I avhandlingen beskrivs åtgärder riktade mot att förändra trafiksituationen och däckanvändningen, byte av vägbeläggning, städning av vägytan och dammbindning.Flertalet metoder har använts i studierna som diskuteras i avhandlingen och består av en storskalig vägsimulator, användandet av lasermätsystem för bestämning av vägslitage respektive textur, dels en prediktionsmodell för dubbdäcksslitage och den nordiska NORTRIP-modellen för modellering av icke-avgasemissioner från vägtrafik. Även ett kommersiellt trafiksystem har nyttjats samt en metod för att bestämma dubbdäcksandelen av trafiken. Vägdamm har samlats in och kvantifierats genom användandet av WDS (Wet Dust Sampler) metoden och det insamlade dammet har beskrivits och karakteriserats med hjälp av en laboratoriemetod och med hjälp av lasergranulometri. Turbiditet har även använts som en approximation av vägdammsförrådet.Fem artiklar finns bifogade till avhandlingen. Den första handlar i korthet om en kalibrering av den svenska prediktionsmodellen för dubbdäckslitage av vägar och dess effekt på NORTRIP-modellen, där slitagemodellen är implementerad. Den andra artikeln handlar om olika vägbeläggningars makrotextur och hur olika mått kan användas för att beskriva den potentiella lagringsförmågan. Den tredje artikeln undersöker WDS-metoden, dels beträffandes dess prestanda gällande vatten samt dels hur detta teoretiskt påverkar eventuella dammförluster. Den fjärde artikeln handlar om den rumsvariationen och tidsvariationen av vägdamm för sex vinter- och vårsäsonger i Stockholm för flera gator med ABS (AsfaltsBetong, Stenrik)-beläggningar. Den femte artikeln genomförde en liknande undersökning under en vinter- och vårsäsong i Linköping för en dubbeldränerande beläggning och för en ABS-beläggning som agerade referens. Resultaten jämfördes med resultaten i Stockholm när det var möjligt.Resultaten visar att slitagemodelleringen överskattade slitaget med ungefär 50%, vilket ledde till att NORTRIP-modellen överskattar bidraget från dubbdäckslitage till partikelemissionerna, vilket inte var förvånande. Dock är det inte troligt att NORTRIP-modellen får motsvarande minskning då vägyta-däckinteraktionen är komplex och flertalet aspekter påverkar slitaget och den efterföljande genereringen och lagringen av vägdamm, såsom polering av vägytan, ökat slitage vid våt vägbana med mera.Resultaten från undersökningen med WDS-metoden visar att metoden verkar fungera väl, givet begränsningarna som fanns i studien. Den största vattenförlusten verkar vara det vatten som lämnas kvar på ytan. Det verkar även som att det mesta av dammet samlas upp. Diskussionen tar även upp hur WDS-metoden använder sig av vatten och vilka för- och nackdelar detta har jämfört med en torr metod.Resultaten från undersökningarna om rumsvariationen och tidsvariationen av vägdammsförrådet i Stockholm visade att det fanns skillnader mellan olika säsonger, och att det fanns en skillnad mellan dammängderna i hjulspåren och mellan hjulspåren. I vissa fall syntes även skillnader mellan de undersökta gatorna med stora variationer, vilket kunde förväntas då dammförrådet beror på trafiksammansättningen, mängden fordon, vägdriften, deposition av material på ytan och meteorologin. Ett annat resultat var att en ökande makrotextur verkade resultera i ett högre dammförråd. Generellt var makrotexturen lägre mellan hjulspåren och högre i hjulspåren, vilket ej var förvånande på grund av trafikens inverkan på texturutvecklingen. Detta var dock enbart uppmätt vid ett tillfälle. Omläggningen av en ABS-beläggning till en mer slittålig ABS-beläggning genomfördes, med ett högre dammförråd som följt jämfört med före omläggningen, samtidigt som okulärbesiktning av vägytan antydde att makrotexturen ökat. Dock kan detta ha påverkats av ett högre slitage vilket inträffar under en beläggnings första vintersäsong på grund av ett extra initialslitage. Resultaten i Linköping visade liknande tids- och rumsvariation som i Stockholm för den undersökta ABS-beläggningen. Vidare diskuterades även hur den dränerande beläggningens konstruktion inverkar på partiklarnas transportprocesser. I jämförelsen föreslogs även att dammbindningen och städningen i Stockholm påverkar dammförrådet, då dessa åtgärder saknas i Linköping, vilket möjligtvis reflekteras i vägdammsförrådet i och mellan hjulspåren.En diskussion förs kring hur olika texturmått kan användas för att karakterisera vägytans textur och hur detta kopplar till dammförrådet, samt vad som kan vara lämpligt att initialt använda, även om det påpekas att måttet som bör användas inte nödvändigtvis är upptäckt än.Diskussionen tar även upp avsaknaden av ett holistiskt helhetsgrepp gällande vägyta-däckinteraktionen som tar samtidig hänsyn till effekter såsom slitagepartiklar, buller och rullmotstånd. Det verkar finnas några åtgärder som kan vara av intresse för att förbättra minst två aspekter samtidigt, till exempel användandet av en dubbeldränerande beläggning eller texturoptimering. En diskussion förs mellan för och nackdelar gällande de olika mekanismerna som påverkar de olika effekterna, samt hur vissa mekanismer bör undersökas närmare utifrån andra perspektiv, till exempel bullermekanismer som kan vara intressanta ur partikelsynpunkt.Avhandlingen ger slutligen flera förslag till fortsatta undersökningar för att öka kunskapen. Detta gäller dels vägslitagemodellering och vägdammsmodellering där även vägytans textur bör beaktas. Vidare bör även mekanismer från andra effekter från vägyta-däckinteraktionen, till exempel de som påverkar buller, även undersökas och användas för att förklara mekanismer relaterade till vägdammsgenerering och uppvirvling. Det föreslås även flertalet gemensamma undersökningar som simultant undersöker flera aspekter, såsom till exempel buller, rullmotstånd, vägytans egenskaper, vägslitage, slitagepartiklar, vägdammsförrådet, uppvirvlingen av partiklar och friktion, vilket krävs för att slutligen åstadkomma det holistiska helhetsgreppet som krävs för att minst minimera intressekonflikter mellan olika funktionsegenskaper för vägbeläggningar.
  •  
41.
  • Lundberg, Joacim, 1991-, et al. (författare)
  • Temporal Variation of Road Dust Load and Its Size Distribution—a Comparative Study of a Porous and a Dense Pavement
  • 2020
  • Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media Deutschland GmbH. - 0049-6979 .- 1573-2932. ; 231:12
  • Tidskriftsartikel (refereegranskat)abstract
    • Resuspension of road dust contributes to air quality issues with resulting health impacts. Limited studies imply that porous pavements can initially mitigate PM10 emissions by acting as a dust trap, but the abrasion wear generates road dust and thus accelerates the clogging processes. In addition, knowledge regarding the impact of pavement types on road dust load dynamics is limited. Road traffic noise can be mitigated using porous pavements, but the use of studded tyres increases the abrasion wear of the pavement as well as increasing the noise emission. Due to this durability problem, porous pavements are rarely used in the Nordic countries where, instead, dense pavements which are abrasion resistant are more common. Linköping municipality, in Sweden, constructed a porous pavement to mitigate road traffic noise. This led to the opportunity to investigate the temporal variation of the dust load dynamics and inherent size distributions over the winter and spring in comparison to those of an adjacent dense pavement. Results, when using the wet dust sampler (WDS) method, showed similar dust load dynamics for the dense and porous pavements. The results were also compared to previous studies using the same method on different dense pavements in Stockholm, Sweden. All locations showed a seasonal variation with higher dust loads during winter and early spring and declining loads towards summer. The size distributions were more complex for the wheel tracks at the porous pavement, having primarily properties of a mixture model compared to the simple size distributions for the dense pavement. On the other hand, the dust load and size distribution were more similar between the porous and dense pavements regarding loads and shapes, indicating a less pronounced but similar behaviour between the surfaces outside of the wheel tracks.
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42.
  • Olafsdottir, Elin Asta, et al. (författare)
  • A Tool for Processing and Inversion of MASW Data and a Study of Inter-session Variability of MASW
  • 2024
  • Ingår i: ASTM geotechnical testing journal. - : ASTM International. - 0149-6115 .- 1945-7545. ; 47:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Multichannel analysis of surface waves (MASW) is a noninvasive active-source technique for determination of near-surface shear wave velocity (VS) profiles. Here we introduce and describe MASWavesPy, an open-source Python package for processing and inverting MASW data, whose design follows an object-oriented paradigm. To assess the performance of the new tool, measurements were conducted at four benchmark sites in Norway, characterized as silt, soft clay, silty sand, and quick clay. The results show that the VS profiles obtained with MASWavesPy compare well with those obtained previously at the respective sites using invasive, noninvasive and laboratory techniques. Furthermore, the efficiency and usability of the new package is superior to previous versions developed by same authors. The software can be accessed through the Python Package Index (PyPI) at https://pypi.org/project/maswavespy/ along with sample data. This work further explores the inter-session variability of MASW measurements for civil engineering applications at soft soil sites. For this purpose, repeated measurements were conducted over a 7-year period at a silty sand site in South Iceland and the recorded time series analyzed using the newly developed tool. The inter-session variability of the analysis results is reported in terms of Rayleigh wave phase velocity, interval VS profiles, and time-averaged VS for reference depths commonly used in practice.
  •  
43.
  • Ólafsdóttir, Elin Ásta, et al. (författare)
  • Application of MASW in the South Iceland seismic zone
  • 2019
  • Ingår i: Geotechnical, Geological and Earthquake Engineering. - Cham : Springer Netherlands. ; , s. 53-66
  • Konferensbidrag (refereegranskat)abstract
    • Multichannel Analysis of Surface Waves (MASW) is a seismic exploration method to evaluate shear wave velocity profiles of near-surface materials. MASW was applied at seven locations in or close to the South Iceland Seismic Zone, providing shear wave velocity profiles for the top-most 15–25 m. The profiles were utilized for seismic soil classification according to Eurocode 8. The results indicated that the sites that are characterized by sandy glaciofluvial, littoral or alluvial sediments fall into category C and the sites where the deposits are cemented to some degree belong to category B. Furthermore, the MASW measurements were used to evaluate the liquefaction potential at a site where liquefaction sand boils were observed during an Mw6.3 earthquake occurring in May 2008. The simplified procedure of assessing cyclic stress ratio to normalized shear wave velocity revealed that liquefaction had occurred down to 3–4 m depth, which is consistent with observations on site.
  •  
44.
  • Olafsdottir, Elin Asta, et al. (författare)
  • Combination of dispersion curves from MASW measurements
  • 2018
  • Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier Ltd. - 0267-7261 .- 1879-341X. ; 113, s. 473-487
  • Tidskriftsartikel (refereegranskat)abstract
    • Multichannel analysis of surface waves (MASW) is a seismic exploration method for determination of near-surface shear wave velocity profiles based on analysis of horizontally travelling Rayleigh waves. This paper aims to propose a methodology and recommendations for combining dispersion data from several multichannel records. The dispersion curves are added up within logarithmically spaced wavelength intervals and the uncertainty of the mean phase velocity estimates is evaluated by using classical statistics and the bootstrap. The results indicate that combining multiple dispersion curves, which have been gathered by receiver spreads of different lengths (but with the same midpoint), can increase the investigation depth of the survey, improve its resolution at shallow depth and overall improve the reliability of the results as compared to the use of a single record. Moreover, the uncertainty of the combined mean dispersion curve can be determined and further used to present the shear wave velocity profile with upper and lower boundaries.
  •  
45.
  • Olafsdottir, Elin Asta, et al. (författare)
  • Hybrid non-invasive characterization of soil strata at sites with and without embedded lava rock layers in the South Iceland Seismic Zone
  • 2023
  • Ingår i: Bulletin of Engineering Geology and the Environment. - : Springer. - 1435-9529 .- 1435-9537. ; 82:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The geological setting of Iceland is unusual, with highly jointed rock mass, loose sediments created in glacial outburst floods and eruptions, and layers of lava rock embedded in or overlying soft sediments. This study aims to assess the feasibility of a composite analysis of dispersion and ellipticity curves for characterization of two of the primary classes of soil sites in the South Iceland Seismic Zone. Specifically, it seeks to develop a cost-effective workflow to identify and characterize sites where a layer of lava rock is embedded in the sedimentary stratum at shallow depth, along with deep soil site characterization. Microtremor HVSR (horizontal-to-vertical spectral ratio) is found to be efficient to distinguish between sedimentary sites with and without an embedded lava rock layer. The results further demonstrate the effectiveness of hybrid ellipticity and dispersion curve inversion to characterize soil sites with an embedded layer of lava rock, which results in a strong velocity reversal with depth. Consistent with previous studies, the hybrid dispersion-ellipticity inversion is also found efficient for characterization of sites with a simpler structure.
  •  
46.
  • Olafsdottir, Elin Asta, et al. (författare)
  • Open-source MASW inversion tool aimed at shear wave velocity profiling for soil site explorations
  • 2020
  • Ingår i: Geosciences. - : MDPI AG. - 2076-3263. ; 10:8, s. 1-30
  • Tidskriftsartikel (refereegranskat)abstract
    • The shear wave velocity profile is of primary interest for geological characterization of soil sites and elucidation of near-surface structures. Multichannel Analysis of Surface Waves (MASW) is a seismic exploration method for determination of near-surface shear wave velocity profiles by analyzing Rayleigh wave propagation over a wide range of wavelengths. The inverse problem faced during the application of MASW involves finding one or more layered soil models whose theoretical dispersion curves match the observed dispersion characteristics. A set of open-source MATLAB-based tools for acquiring and analyzing MASW field data, MASWaves, has been under development in recent years. In this paper, a new tool, using an efficient Monte Carlo search technique, is introduced to conduct the inversion analysis in order to provide the shear wave velocity profile. The performance and applicability of the inversion scheme is demonstrated with synthetic datasets and field data acquired at a well-characterized geotechnical research site. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
  •  
47.
  • Rahman, Mohammad Shafiqur, 1978-, et al. (författare)
  • A Model for Predicting Permanent Deformation of Unbound Granular Materials
  • 2015
  • Ingår i: International Journal on Road Materials and Pavement Design. - UK : Taylor & Francis Group. - 1468-0629 .- 2164-7402. ; 16:3, s. 653-673
  • Tidskriftsartikel (refereegranskat)abstract
    • A simple model has been proposed to characterize the accumulation of permanent deformation (PD) in Unbound Granular Materials (UGMs) under cyclic loading of variable magnitudes. The model was developed based on Multi-Stage (MS) Repeated-Load Triaxial (RLT) tests. The material parameters of this model can be evaluated using an MS RLT test. The model was validated by calibrating it for a few UGMs with a range of grain size distributions, moisture contents and degrees of compaction. The calibrated model was further validated by predicting the PD behaviour of some of these UGMs for different stress conditions. Generally, quite satisfactory predictions were obtained with this model with the advantage of reduced effort required for its calibration compared to some existing models. Additionally, the sensitivity of the parameters of this model to moisture, degree of compaction and grain size distribution was investigated with the aim of incorporating them into the model in future.
  •  
48.
  • Rahman, Mohammad Shafiqur, 1978-, et al. (författare)
  • A model for the permanent deformation behavior of the unbound layers of pavements
  • 2021
  • Ingår i: Proceedings Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields. - London : CRC Press. - 9781003222880 ; , s. 277-287
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • This article presents a model for the permanent deformation (PD) behavior of unbound granular materials (UGMs) used in the base and subbase layers of pavement struc- tures. The model was developed based on multistage (MS) repeated load triaxial (RLT) test- ing. This is essentially a modified version of a previously developed model to better suit to field conditions in a simple and effective manner. The model was calibrated for eight com- monly used UGMs using MSRLT tests with a range of moisture contents. For validation, the calibrated models were used to predict the PD behavior of three of the UGMs in MSRLT tests with stress levels and moisture contents different from those used during the calibrations. This model showed better quality of fit when compared with another widely used PD model. The model was further tested successfully for field conditions by capturing the PD behavior of an instrumented pavement test section in a controlled environment using a heavy vehicle simu- lator (HVS) based accelerated pavement testing (APT). Inputs for calibrating the model were based on the readings from the instrumentations. The parameters of the model were adjusted to match the measured data with the predictions. Based on these results for various design conditions, some ranges of values of the material parameters of the model were suggested.
  •  
49.
  • Rahman, Mohammad Shafiqur, 1978-, et al. (författare)
  • High-capacity transport in cities and the impact on the roads
  • 2024
  • Ingår i: Technology Convergence 2023. - : International Forum for Heavy Vehicle Transport & Technology; The International Society for Weigh-In-Motion.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • This paper presents the evaluation of the relative pavement damage caused by a high-capacity transport (HCT) 5 axle truck with respect to three other reference trucks consisting of 4, 3 and 2 axles. The analysis was conducted by simulating the responses of three pavement structures using the pavement analysis tool ERAPave. Two damage criteria of the pavement structures were evaluated: fatigue cracking of the asphalt concrete (AC) layer and permanent deformation of the subgrade. The relative damage caused by the different vehicles were estimated by calculating a damage factor (Dr) following the Asphalt Institute Method. Three loading scenarios of the trucks were analyzed: (a) one way trip with fully loaded trucks, (b) round trip where the return trip consisted of the empty vehicles with lifted axles and (c) round trip where the return trip consisted of the empty vehicles without lifting any axles. The damage factors were calculated for per ton of carried load and were normalized with respect to the 2-axle truck. Results indicate that the relative impacts of the vehicles depend on the structure type and seasons. Generally, the 4-axle truck appeared to be the least damaging one. The HCT 5-axle truck is more damaging than the 4-axle truck, but less damaging than the other two.
  •  
50.
  • Rahman, Mohammad Shafiqur, 1978-, et al. (författare)
  • Impact of introducing longer and heavier vehicles on the bearing capacity of pavement subgrades
  • 2021
  • Ingår i: Proceedings Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields. - London : CRC Press. - 9781003222880 ; , s. 239-249
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Increasing the maximum permissible gross weight of vehicles from 64 tons to 74 tons on Swedish highways may significantly increase deformation in subgrades requiring extensive and expensive measures for maintenance deep down in the structures. Even though the individual axle load remains the same, longer and heavier vehicles will contain higher pro- portions of tandem and tridem axles and the total load will be superposed on to the subgrade resulting in higher deformations. In this study, the relative impact of single, tandem and tridem axles on subgrade deformation was analyzed based on calculations in a pavement design software called ERAPave. Three structures with different layer thicknesses and varying material properties during the spring-thaw and summer period were analyzed. In general, it was observed that the relative impact is dependent on the thicknesses and material properties of the pavement structure and the subgrade. Weaker subgrade is more affected by the tridem axle followed by tandem and single axle. The tridem axle is more damaging to the sub-grade for thicker and stiffer structures. In certain cases, the single axle showed more impact on the top of the subgrade. The tridem axle showed more vertical deflection in all cases that may induce increased fatigue cracking of the asphalt concrete (AC) layer. Duration of loading was higher for the tridem axle which has more damage potential. Thus, for the whole vehicle, con- taining more tridem axles, the effects may be superposed resulting in greater damage. On the other hand, the higher load carrying capacity of the tandem and tridem axle configurations will reduce the number of trips required to carry the same amount of goods. This may compensate for the increased damage to the subgrade and the impact on the life cycle of the pavement.
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