| 1. |
- Carlson, Annelie, 1969-, et al.
(författare)
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Effekten på rullmotstånd av vatten och snö på vägytan
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rullmotstånd uppkommer vid interaktionen mellan vägyta och däck och utgör en del av det färdmotstånd som ett fordon behöver överkomma för att röra sig framåt. De av vägytans egenskaper som anses ha störst betydelse för rullmotstånd är makrotextur och ojämnhet längs med vägen. Men även vatten och snö på vägytan bidrar till att påverka rullmotståndet. Nederbörd som ligger kvar på vägen innebär att hjulen behöver drivas genom och flytta undan vatten eller snö, vilket ger ett ökat motstånd.Syftet med rapporten är att göra en kunskapssammanställning om hur rullmotståndet påverkas av vatten och snö på vägbanan. Litteratur har sökts i databaser över vetenskapliga artiklar och rapporter och via kompletterande sökningar på internet för att hitta ytterligare material. En genomgång har gjorts av cirka 50 rapporter och artiklar som publicerats från 1970-talet fram till 2018.Sammanställningen visar att vatten och snö på vägytan kan ha en betydande effekt på rullmotståndet. För vatten på vägytan används ofta hastighet, temperatur och vattendjup som förklarande variabler. För att beskriva snöns påverkan på rullmotståndet används snödjup, snöns densitet, däckens kontaktyta med vägbana som förklarande variabler. En osäkerhet i resultaten av de fältstudier som redovisats är att flera har genomförts under 70- och 80-talet. Sedan dess har såväl mätmetoder som mätutrustning utvecklats och förbättrats. Även däckens egenskaper har förbättrats, vilket i sig har haft en effekt på rullmotståndet. För att få mätdata för rullmotstånd i snö och vatten som är anpassat för däck och fordon som används på vanliga vägar idag, behöver därför nya mätningar genomföras som använder de senast utvecklade mätmetoderna och ny mätutrustning. Det skulle minska osäkerheten i mätresultat och ge aktuell information som kan användas för att uppdatera sambanden mellan bränsleförbrukning och vatten och snö på vägytan.
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| 2. |
- Carlson, Annelie, 1969-, et al.
(författare)
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Fordonsemissionsmodellen PHEM : förstudie om att inkludera vägytans betydelseför rullmotstånd och bränsleförbrukning
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rullmotståndet är en viktig komponent vid beräkning av bränsleförbrukning och emissioner. Denna rapport redovisar alternativ till metodutveckling för att med mikrosimuleringmodellen PHEM bättre kunna beakta vägytans påverkan på ett fordons rullmotstånd. Betydelsen av vägytans egenskaper har tidigare gjorts med modellen VETO där det går att ange specifika egenskaper hos vägen. Dessa möjligheter gör att VETO passar bra för analyser av hur vägens egenskaper påverkar bränsleförbruk-ningen. Samma möjligheter finns inte i PHEM. De utvecklingsalternativ som berörs i rapporten är att: (1) ändra källkoden till PHEM så att möjligheten att inkludera vägytans egenskaper blir samma som i VETO; (2) att i PHEM:s indatafiler lägga till en kolumn som ersätter rullmotståndet som beräknas av PHEM med ett rullmotstånd som beräknas på annat sätt och därmed kan koppla till vägytans egenskaper; (3) att ersätta rullmotståndsdelen i PHEM med motsvarande block i VETO med viss förenkling och (4) att sätta in ett referensfall från VETO i PHEM och göra övriga justeringar i efterhand med hjälp av VETO. Alternativen (1) till och med (3) ändrar rullmotståndsdelen men behåller allt övrigt inom PHEM medan (4) omfattar fler simuleringar. Alternativ (3) och (4) kräver inte någon ändring av källkoden.
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| 3. |
- Carlson, Annelie, 1969-, et al.
(författare)
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The effect of water and snow on the road surface on rolling resistance
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rolling resistance is due to the interaction between road surface and tires and forms part of the driving resistance that a vehicle needs to overcome to move forward. Those of the road surface properties that are seen as most important for rolling resistance are macro texture and unevenness along the road. But water and snow on the road surface also contribute to the rolling resistance. Precipitation that remains on the road means that the wheels need to be driven through and displace water or snow, and this leads to increased resistance. In addition, water cools more efficiently than air, which has an effect on the behavior of the tires as their viscoelastic properties are temperature dependent. The tires work at a lower temperature in the presence of precipitation, which in itself increases the resistance. Speed, temperature and water depth are the explanatory variables often found in the literature to describe the effect on rolling resistance due to water on the road surface. It has been shown that rolling resistance increases with increasing speed, increasing water depth and decreasing tire temperature. The results indicate that the effect can be significant, with measurements showing an increase of 30 to 40 percent of the rolling resistance coefficient depending on the speed and thickness of the water film. However, the literature in the area is relatively limited, and the reason for this is probably linked to the difficulties that exist in measuring and modeling the rolling resistance effect in water. These difficulties are due to, among other things, measuring the depth of the water film and the temperature of the tires and that the temperature of the tires needs to be stable during measurements. Studying the impact of snow on rolling resistance also involves some difficulties in that there are many different types of snow with varying properties and behavior during deformation. Data available is also limited and the relationships are not sufficiently developed so that they can be fully used to describe the behavior of the snow with respect to deformation and load. The complexity of the impact of snow on rolling resistance means that a combination of theoretical calculations and field studies is needed to determine the values of the components included. However, some studies have been carried out that aim to explain the impact of snow, both theoretical and via field measurements. The explanatory variables often used are snow depth, snow density and tire contact surface with road surface. In general, the results show that snow has a large effect on the resistance and that it should therefore be considered, especially in areas where snow remains on the ground for a long time.
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| 4. |
- Ran, Maoping, et al.
(författare)
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Pavement enveloped texture profile calculation and it's impact on pavement skid resistance
- 2019
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Ingår i: Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition). - : Editorial Department of Journal of Chang'an University (Natural Science Edition). - 1671-8879. ; 39:5, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- To analyze tire-road contact characteristics and the effect of the contact on pavement skid resistance, the two-dimensional discrete data of the road texture profile was measured using the road surface tester, and the enveloped profile was calculated using the indentor method in MATLAB. Based on the enveloped profile, texture parameters such as mean profile depth (MPD), macro texture indices calculated with texture level (LMa), and mega texture indices calculated with texture level (LMe) were calculated, and comparisons were made between these and the original profile. Then, the correlation between the friction value (longitudinal friction coefficient, LFC), and the calculated texture parameters considering the original and enveloped texture profiles were analyzed.The results show that the calculated texture parameters with the enveloped profile have a high correlation with those calculated with the original profile, the determination coefficient R2 is higher than 0.85. The calculated MPD value with the enveloped profile shows a significant decrease, compared to that calculated with the original profile, and the larger the original MPD value, the greater the decrease in the envelope contour MPD value. The calculated texture level indices with the enveloped profile are also reduced when compared to the original. The decline rate of LMa is about 10% higher than LMe. The variable parameter S from the indentor method has a significant impact on the enveloped texture parameters, texture parameters with a smaller S show a higher decline. The determination coefficients between friction value LFC and calculated pavement texture parameters with the enveloped profile improved significantly compared with the original, with an increase of approximately 35% in MPD and 23% in LMa. The research results can provide a reference for studying the effect of tire-road contact characteristics on road performance.
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| 5. |
- Sandberg, Ulf, 1946-, et al.
(författare)
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Acoustic lifecycle study of the double-layer porous asphalt on E4 in Huskvarna, Sweden
- 2018
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Ingår i: INTER-NOISE 2018 - 47th International Congress and Exposition on Noise Control Engineering. - : Institute of Noise Control Engineering.
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Konferensbidrag (refereegranskat)abstract
- In 2010 a double-layer porous asphalt concrete (DPAC) pavement was constructed on the E4 motorway through the Swedish city Huskvarna. Earlier experience in Sweden indicated that it was feasible to obtain a high initial noise reduction but due to the widespread use of studded tires in winter, clogging and ravelling created losses of around 2 dB per year, with an expected acoustical lifetime of only 3 years. However, the improved pavement in Huskvarna finally exceeded lifetime and durability expectations by at least 100 %. The first two years, noise reduction fell from the initial 7-8 dB just marginally, compared to an average-age SMA 16 pavement. Now after its 7th year, the pavement had reached its acoustical end of life, with an average noise reduction loss of 0.5 dB per year. This is considered as a break-through for low noise pavements exposed to the winter climate in Sweden and road traffic with most light vehicles equipped with studded tires. This paper presents results of annual noise measurements using the CPX method over the entire lifetime on the DPAC compared to the reference set of SMA 16 pavements. This includes the effects of grinding, cleaning and rejuvenation trials on certain test sections.
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| 6. |
- Vieira, Tiago, 1984-, et al.
(författare)
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A round robin test on the close-proximity method : Comparison of results from four different CPX trailers measuring tyre/road noise properties of 10 Swedish road surfaces
- 2020
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Ingår i: Noise Control Engineering Journal. - : Institute of Noise Control Engineering. - 0736-2501 .- 2168-8710. ; 68:6, s. 421-440
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Tidskriftsartikel (refereegranskat)abstract
- The standardization of the CPX method and the reference tyres in 2017 has made it possible to measure tyre/road noise in a standard and repeatable way. However, the reproducibility of the CPX method is still not well known. A trailer comparison in the Netherlands in 2017 indicated that different trailers led to comparable results, but only two road surfaces were used, and all measurements were made close in time and location. In practical measurements, more variations in CPX equipment occur, and it is not possible to predetermine a specific measurement day. This study used four trailers of different designs, and measurements were made over a time period of 90 days, which may happen in practical measurements. The trailers and road surfaces are described, and variations between measurements are analyzed. The maximum CPX level difference between trailers when taking the sample means (average without corrections for different number of observations on the surfaces) was 1.57 dB for tyre H1 and 1.29 dB for tyre P1, which is comparable to the uncertainty values in ISO 11819-2:2017. A statistical analysis showed that the estimated main effects, adjusted for imbalance in the sampling design, for three of the four trailers did not differ more than 0.41 dB, while the fourth trailer, having an unreliable calibration, differed by 0.94 dB from the others. This article shows the relevance of the corrections found in the standards and that having an enclosure over the tested tyres leads to a slightly sharper peak in the frequency spectra.
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| 7. |
- Vieira, Tiago, 1984-, et al.
(författare)
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A round robin test on the Close-Proximity method: Comparison of results from four different CPX trailers measuring tyre/road noise properties of 10 Swedish road surfaces
-
Ingår i: Noise Control Engineering Journal. - 0736-2501 .- 2168-8710.
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Tidskriftsartikel (refereegranskat)abstract
- The publication in 2017 of ISO documents 11819-2 (CPX method) and 11819-3 (reference tyres) has made it possible to conduct measurements of noise properties of road surfaces in a standard and repeatable way. However, it is still not well-known what variations one may expect between different CPX equipment. A comparison of CPX trailers in the Netherlands in 2017 indicated that different trailers led to comparable results, but only two road surfaces were used, and all measurements were made close in time and location. In practical measurements, more variations in CPX equipment occurs and measurements on a certain test surface cannot take place on a predetermined day or even week. This study used four CPX trailers, of different designs, and the measurements were made over a time period of 90 days; something that may well happen whenever an authority or organization orders a CPX measurement. In this paper the test equipment and tested road surfaces are described, and the variations between measurements are analyzed. The maximum CPX level difference between participating equipment when taking the sample means (average without any correction for different number of observations on the surfaces etc) was 1.57 dB for tyre H1 and 1.29 for tyre P1, which is comparable to the typical uncertainty values found in the standard ISO 11819-2:2017. A statistical analysis indicated that the main effects (adjusted for imbalance in the sampling design) on noise levels for three of the four CPX trailers did not differ more than 0.41 dB between each other while the fourth trailer, that had an unreliable calibration, differed from the other three in 0.94 dB. The paper also shows the relevance and importance of applying the corrections found in the standards and that having an enclosure over the tested tyres leads to a slightly sharper peak in the frequency spectra.
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| 8. |
- Vieira, Tiago, 1984-, et al.
(författare)
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Acoustical performance of winter tyres on in-service road surfaces
- 2019
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Ingår i: Applied Acoustics. - : Elsevier Ltd. - 0003-682X .- 1872-910X. ; 153, s. 30-47
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to excessively high noise levels is a relevant health problem in Europe and road traffic noise is the most widespread noise source. When considering cold climate countries, the available scientific literature on noise emission properties of winter tyres is still very limited. In order to contribute into filling this knowledge gap, this paper investigates the acoustical performance of different types of tyres, with focus on winter tyres, on different road surfaces, at different speeds, and with different states of wear. The results indicate that studded winter tyres have, indeed, an increased noise level at frequencies between 315 Hz and 10 kHz, having a significantly different response especially at frequencies higher than 4 kHz. The acoustical response also depends on the tyre type when comparing different road surfaces, as a result of conflicting vibrational and aerodynamic noise generation mechanisms. Additionally, the relationship between labelled and measured values was explored, however, no statistically significant relationship was found between them (and labelling is not applied for studded tyres). A frequency spectrum correction was attempted based on previous measurements on an ISO track, which reduced the difference between measured and labelled values, however, further investigation is still required to properly understand differences between label and road measurements, where the label is determined on a test track with a special, smooth surface.
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| 9. |
- Vieira, Tiago, 1984-, et al.
(författare)
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Close Proximity (CPX) Round Robin test : Comparison of results from four different CPX trailers measuring noise properties of 10 Swedish road surfaces
- 2019
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Ingår i: INTER-NOISE 2019 MADRID. - : Spanish Acoustical Society, SEA. - 9788487985317
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Konferensbidrag (refereegranskat)abstract
- The publication in 2017 of ISO documents 11819-2 (CPX method) and 11819-3 (reference tyres) has made it possible to conduct measurements of noise properties of road surfaces in a standard and reproducible way. However, it is still not well-known what differences one may expect between different CPX equipment. A comparison of CPX trailers in the Netherlands in 2017 gave very positive results, but only two road surfaces were used, and all measurements were made close in time. In practical measurements, more variations in CPX equipment occurs and measurements on a certain test surface cannot take place on a certain day or even week. This study used four CPX trailers, of different designs, and the measurements were made over a time period of 90 days; something that may well happen whenever an authority or organization orders a CPX measurement. In this paper the test equipment and tested road surfaces are described, and the first measurement results are presented.
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| 10. |
- Vieira, Tiago, 1984-, et al.
(författare)
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Evaluation air void content of drilled porous asphalt mixture cores using non-destructive X-ray computed tomography
- 2021
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Ingår i: Proceedings Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields. - London : CRC Press. - 9781003222880 ; , s. 48-58
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Tomography technology is not usual when investigating drilled asphalt cores properties. Currently, there is no internationally recognised standard tomography method for asphalt pavements. Tomography provides, however, a non-destructive alternative to traditional, usually destructive, testing of drilled cores. Furthermore, tomography offers possibilities, which traditional laboratory analyses do not. It is not straightforward to distinguish mastic and aggre- gates in tomography results while air void content is less difficult to assess. To have a more reliable assessment of drilled cores properties found by tomography, the method must be carefully planned, executed, and the results compared to those of traditional laboratory methods. In this work, analysis was carried out using six in-situ drilled cores from a double layered porous asphalt pavement. This allowed a comparison of tomography and a standardised conventional laboratory air void measurement on the exact same samples. Comparisons of the air voids found by tomography in all three directions were also carried out, estimating how anisotropic and heterogeneous the samples are, which is not possible using traditional laboratory tests. As few as four tomography slices can give enough precision in the determination of air void content for the porous layers. No more than eight slices per sample were needed in the suggested tomog- raphy method. The statistical results did not indicate that the air void content determined by tomography is different from the laboratory results.
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