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  • Carlson, Annelie
    et al.
    Linköpings universitet.
    Vieira, Tiago
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Effekten på rullmotstånd av vatten och snö på vägytan2018Report (Other academic)
    Abstract [en]

    Rolling resistance depends on the interaction between road surface and tire and forms part of the driving resistance a vehicle needs to overcome to move forward. The road surface properties considered the most important for rolling resistance are macro textures and unevenness along the way. But water and snow on the road surface will also affect the rolling resistance. Precipitation remaining on the road surface means the wheels need to be driven through and move water or snow, which gives increased resistance.

    The purpose of the report is to provide an overview of the state of knowledge about how the rolling resistance is affected by water and snow on the road surface. Literature has been sought in databases of scientific articles and reports, and also on the internet. A review has been made of about 50 reports and articles published from the 1970s to 2018.

    The overview shows that water and snow on the road surface can have a significant effect on the rolling resistance. For water on the road surface, speed, temperature and water depth are often used as explanatory variables. To describe the snows impact on the rolling resistance, the explanation variables use snow depth, snow density, tire contact surface with the ground. An uncertainty in the results of the studies reported is that several have been implemented in the 70's and 80's. Since then, measuring methods as well as measuring equipment have been developed and improved. The tire properties have also improved, which has had an effect on the rolling resistance. Therefore, to obtain snow and water rolling resistance measurement data for tires and vehicles used on normal roads today, new measurements should be made using the most recent measurement methods and measurement equipment. This would reduce the uncertainty in measurement results and provide current information that can be used to update the relationship between fuel consumption and water and snow on the road surface.

  • Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Gundlegård, David
    Linköpings universitet.
    Ringdahl, Rasmus
    Linköpings universitet.
    Utvärdering av hastighetsmätningar med blåtandssensorer: jämförelse med data från MCS (Motorway Control System)2018Report (Other academic)
    Abstract [en]

    The aim of this project was to compare vehicle speed measurements using Bluetooth detection with radar measurements from a Motorway Control System (MCS). Of particular interest was to evaluate whether the method could be used in before-after studies of road safety measures such as speed cameras or other speed reducing measures.

    The results from the study show that:

    • The penetration rate varies between 12 and 16 percent depending on the site and whether it is a weekday or weekend.

    • Bluetooth measurements provide stable results with respect to average vehicle speed at diurnal level. Comparisons with MCS data show that the results of the two methods follow each other well and the difference between methods is about the same from day to day.

    • Speed measurements with Bluetooth sensors are judged to be sufficiently reliable, on the evaluated road type, to be used in before-after studies of various road safety measures.

  • Hjort, Mattias
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Niska, Anna
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Mätning av cykeldäcks friktionsegenskaper som underlag för simuleringsstudier2018Report (Other academic)
    Abstract [en]

    In this project measurements of a bicycle tyre on an asphalt surface have been carried out in the VTI stationary tyre testing facility, in order to provide slip curves describing friction properties of the tyre. The measurement results have then been used to obtain tyre parameters for simulation purposes. The following tyre parameters have been measured: cornering stiffness, camber stiffness, brake slip stiffness and lateral relaxation length.

    The tested tyre generated a maximum friction level of approximately 1.0 on the asphalt. Typical values of the tyre parameters were: normalized cornering stiffness 0.3; standardized camber stiffness 0.01; standard brake slip stiffness 250. Compared to the few previously published measurements on bicycle tyres, cornering stiffness was generally about 50 percent higher than previously reported. The values for camber stiffness correspond well to the values shown by a racing tyre study but are 25–50 percent lower than the values measured on more normal tyres in another study. For brake slip stiffness there are no previous measurements to compare with. Measurement of the lateral relaxation length was unfortunately affected by problems with the measuring equipment and we could not determine the relaxation length with the desired accuracy. From the measurements, we estimate the relaxation length to 200–300 mm for the tested tire, which is a factor 2–3 to greater than reported in the only earlier study that measured relaxation length for bicycle tyres.

  • Arvidsson, Anna K
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Vintermodellen 2018: uppdatering av Olycksmodellen inklusive uppdateringar av värderingar till ASEK 6.12018Report (Other academic)
    Abstract [en]

    This report is a compilation of the work done of recalculating the relations/connections for accident risks and their distribution on different winter road conditions in different climate zones. These accident risks are based on accidents having occurred between the years 2007 and 2017. In this project, an update of the accident assessments has been made according to ASEK 6.1 (analysis method and socioeconomic calculation values for the transport sector) Due to this change, the Swedish Transport Administration has changed the valuation of road traffic accidents with accident consequences according to Strada (Swedish Traffic Accident Data Acquisition), instead of consequences as reported by police reports. The new update of the Accident Model has updated accident risks, accident distributions and accident consequences and seems to be realistic and the program is working in a correct way.

  • Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Hastigheter på kommunala gator i tätort: resultat från mätningar år 20172018Report (Other academic)
    Abstract [en]

    The aim of the present study is to report the changes between the years 2016 and 2017 concerning driver speed levels and speed limit compliance on the main municipality streets. The year 2012 was the starting year for the measurement series, and in 2017 a fifth follow-up was performed. Only the main municipality streets with speed limits between 40 kilometers per hour and 70 kilometers per hour were included. The measurements were made during the month of September in 23 different municipalities in Sweden.

    The results show that in 2017 the space-mean-speed for all vehicles on the main municipality roads was 47 kilometers per hour. With respect to speed violations, overall, 67 per cent of drivers obeyed the speed limit 2017. The lowest speed limit compliance was found on roads with a speed limit of 40 kilometers per hour, where only 53 per cent of the traffic obeyed the speed limit; 66 per cent obeyed the speed limit on 50 kilometers per hour roads, 81 per cent on 60 and 70 kilometers per hour roads.

    In conclusion, the space-mean-speeds in urban areas are below the legal speed limit, but the lack of speed compliance remains a problem, especially on streets with speed limit 40 kilometers per hour. Primarily, the speed limit compliance on roads with lower speed limits must be improved in order to reach the goal of 80 per cent compliance by 2020.

  • Tschan, Georg F.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Invasiva arter och transportinfrastruktur: en internationell kunskapsöversikt med fokus på vägar och växter2018Report (Other academic)
    Abstract [en]

    With the introduction of a new EU regulation in 2015 all member states have to take action against invasive alien species (IAS). Since the transport sector contributes heavily to IAS spread and establishment, it needs dedicated research and action plans. This report reviews the international literature on IAS within transport-related environments, identifies national research needs in Sweden and recommends strategies for successful countermeasures against IAS. The basic terminology and principles of invasion biology are explained, followed by an extensive review of dispersal via terrestrial transportation networks. Motor vehicles were found to be a significant contributor to long-distance dispersal and the spread of alien and invasive species. However, widely varying methods, scope and study localities of previously published studies make direct comparisons difficult. New, empirical and more systematic studies are needed to investigate the spread of IAS via the transportation network. To illustrate the need for an individual evaluation, three example species are presented in detail (Heracleum mantegazzianum, Lupinus polyphyllus, Ambrosia artemisiifolia), and other problematic groups are discussed. Available tools and information systems that can be used for documentation and control are presented. It is imperative that alien and not only already invasive species are considered. Furthermore, a national blacklist should be created which is regularly updated, and the inclusion of specialists as well as the general public is needed to counteract the negative consequences of IAS.

  • Dukic Willstrand, Tania
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Pereira Cocron, Marta
    TU Chemnitz.
    Griesche, Stefan
    DLR.
    Strand, Niklas
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Troberg, Sonja
    Scania.
    Zanovello, Luca
    Ducati.
    Nikolau, Stella
    CERTH.
    Collecting end-user needs regarding driver statebased automation in ADAS&ME project2018Conference paper (Other academic)
  • Dukic Willstrand, Tania
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Pereira Cocron, Marta
    TU Chemnitz, Germany.
    Griesche, Stefan
    DLR, Germany.
    Strand, Niklas
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Troberg, Sonja
    Scania, Sweden.
    Zanovello, Luca
    Ducati, Italy.
    Collecting end-users needs regarding driver state-based automation in the ADAS&ME project2018Conference paper (Refereed)
    Abstract [en]

    The EU funded project ADAS&ME (Adaptive ADAS to support incapacitated drivers & Mitigate Effectively risks through tailor made HMI under automation) develops adapted Advanced Driver Assistance Systems. A web based survey was designed to collect the opinion of ADAS&ME end-users about automated functions that could support the driver/rider during different driving tasks. In total, 1094 persons answered the survey. The results reveal that most of the participants had heard of automated functions previously, and that about half of them also had experience using such functions. Several participants indicated concerns about data security. Furthermore, the results give an insight into how end-users perceive automation and what they see as advantages and limitations for implementation of automated driving systems corresponding to the ADAS&MEs’ goals.