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  • Liu, Chengxi
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Tapani, Andreas
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Kristoffersson, Ida
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Rydergren, Clas
    Linköpings universitet.
    Jonsson, Daniel
    KTH.
    En transportmodell med fokus på cykeltrafik: modellutveckling och scenarioanalyser2019Report (Other academic)
    Abstract [en]

    Encouraging the use of active travel modes such as walking and cycling is vital for ensuring a sustainable urban development. In many European metropolitan areas, cycling is becoming increasingly popular within the recent decades. On the other hand, large-scale transport models, which serve as the main tools for policy evaluation and cost-benefit analysis, are often designed for modelling motorised travel modes such as private car and public transport. This study presents a tourbased transport model to better model cycling demand and supply. First, it uses a detailed bicycle network containing more than 200,000 links, covering the whole Greater Stockholm Area. Second, the model utilizes a refined zoning system with totally 5 808 zones each of the size of 250 m×250 m covering the entire Greater Stockholm Area. Third, the model is estimated on the newest Stockholm travel survey 2015, and therefore the model can represent travel behaviour that is up-to-date. In addition to the improvements mentioned above, the model also considers cycling as an access travel mode to a trip by public transport. Therefore, the model treats cycling and public transport as both competing and complementary modes, and the model is capable of evaluating the impact of an improvement in bicycle infrastructure on cycling, as well as on cycling to public transport stations. The model is then validated against bicycle count data from the City of Stockholm. Six scenarios are tested according to the investment plan from the City of Stockholm. The results show that the investments have a limited effect on modal shift but a moderate effect on the existing cyclists' route choice, travel time and generalised cost.

  • Niska, Anna
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Blomqvist, Göran
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Sopsaltning av cykelvägar i teori och praktik: erfarenheter från utvärderingar i svenska kommuner2019Report (Other academic)
    Abstract [en]

    To encourage people to cycle during winter and at the same time reduce the number of single bicycle crashes, a high winter maintenance service level is needed. Traditionally in Sweden, ploughing and gritting is used for winter maintenance of cycleways and footways. In recent years, a method using a front-mounted power broom for snow clearance and salt for de-icing (commonly called “sweepsalting”) has become popular for winter maintenance of cycleways in Swedish municipalities. Linköping was the first municipality to test the method, already in 1999. Today, municipalities from Umeå in the north to Malmö in the south are applying the method with a variation in methods, equipment and strategies. In this project earlier research has been complemented with detailed field studies in Linköping and Stockholm, theoretical knowledge as well as practical experiences from several Swedish municipalities. The objective has been to provide a better understanding regarding pros and cons of “sweep-salting” as well as the equipment, methods and strategies appropriate under various conditions. The studies presented in this report show that when working successfully, the sweep-salting method creates a bare surface with higher friction than traditional ploughing and gritting. Measures must be done in time and the operating speed adjusted according to the prevailing conditions. In mild weather brine is sufficient, but with lower temperatures and heavy snowfall larger amounts of salt is needed and pre-wetted or dry salt must be used. For the method to work properly, the bicycle path construction should be of good condition without cracks or other damages in the surface. The equipment for sweep-salting needs to be further developed for a higher efficiency.

  • Grumert, Ellen
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Bernhardsson, Viktor
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Ekström, Joakim
    Linköpings universitet.
    Gundlegård, David
    Linköpings universitet.
    Ringdahl, Rasmus
    Linköpings universitet.
    Tapani, Andreas
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Variabla hastighetsgränser för Stockholms motorvägsnät: effekter av alternativa algoritmer och möjligheter till styrning genom estimerade trafiktillstånd2019Report (Other academic)
    Abstract [en]

    Variable speed limits are commonly used on Stockholm’s urban motorways, and it is part of the Stockholm Motorway Control System (MCS). The goal of today’s system is to reduce the risk of accidents during congested conditions, traffic jams etc. This is done by updating the speed limits shown on variable message signs based on a measured average speed at fixed detectors. As the demand for travel in Stockholm during peak-hours exceeds the available capacity in the road network, the need for an efficient traffic system is high. Variable speed limit systems have the possibility to contribute to increased efficiency, but since today’s system aims to increase safety, effects that lead to increased efficiency are limited. Further, in todays’ variable speed limit systems there are a large dependency of precise and available measurements from stationary detectors to be able to display speed limits that reflects the current traffic conditions. The purpose of this report is to investigate alternative control algorithms to decide on the variable speed limits to be displayed at variable message signs on the urban motorway of Stockholm.

    The goal is to increase efficiency compared to today's system. Two different road stretches with different complexity and different traffic conditions, resulting in two different types of congestion, are studied. Thereby, the studied control algorithms on the two road stretches are chosen based on the possibility of solving a specific problematic traffic situation in the best way. Hence, the studied control algorithms might differ for the two road stretches. Furthermore, for one of the roads stretches it is investigated if estimation of the traffic state can be used as input to the control algorithm as a complement to missing and erogenous measurements from stationary detectors in order to improve the calculations of the variable speed limits. The control algorithms are evaluated with microscopic traffic simulation and the method developed in the project Mobile Millenium Stockholm (MMS), using a macroscopic traffic flow model together with a Kalman filter, is used for estimation of the traffic state.

  • Said, Safwat F.
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Lundberg, Thomas
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Rahman, Shafiqur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Carlsson, Håkan
    Swedish National Road and Transport Research Institute, Infrastructure, Measurement technology and engineering workshop.
    McGarvey, Terence
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Ahmed, Abubeker
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Enocksson, Carl-Gösta
    Trafikverket.
    Utförandets inverkan på hållbarhet för beläggningslager2019Report (Other academic)
    Abstract [en]

    Non-destructive testing in quantifying the asphalt pavement layers homogeneity can be used for the quality assurance in paving contracts. This paper summarizes the findings from a field study on segregation in bituminous pavement mixes that relates pavement layer surface texture to the homogeneity of the paved bituminous layer by distinguishing mix segregated area. The mean profile depth (MPD) values of paved layer were measured. Based on these values three locations on the road were identified having low, intermediate and high MPD values. Thereafter, cored samples were tested for stiffness modulus before and after moisture conditioning by performing the moisture induced sensitivity test (MIST). Results clearly showed that the samples from the locations with high MPD values were mostly affected by the moisture conditioning for which the stiffness moduli were significantly reduced. The samples with high MPD values had the highest air voids as well. Thus, this study demonstrated that construction quality described by segregation in the paved asphalt mix has a significant impact on the moisture sensitive performance of pavements. A limited number of falling weight deflectometer (FWD) measurements were performed at positions with different degree of separation in the road base layer. There was a tendency for the effect of separation in the road base layer on FWD even though there was a variation in data. The strong correlation between the MPD values and change in stiffness modulus also suggests that the measurements of the MPD values can be a reliable and non-destructive method for evaluating the construction quality of a pavement and in developing the quality assurance criteria based on pavement performance that can be used in paving contracts.

  • Hjort, Mattias
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Mönsterdjupets inverkan på väggrepp på is för släpvagnsdäck till tunga fordon: jämförande tester2019Report (Other academic)
    Abstract [en]

    In Sweden the current regulation for minimum tread depth for heavy vehicles in the winter period is different for trailer axles compared to drive or steer axles. While the requirement for the latter axles are 5 mm tread depth, on trailer axles 1,6 mm is required.

    The purpose of this study has been to investigate whether there is reason to increase the tread depth requirement for heavy vehicle trailer tyres during the winter period in Sweden, and if so, suggest a new tread depth limit. The study was limited to ice conditions, and ice grip for a number of different trailer tyres with different tread depth was measured on smooth ice in VTI’s tyre test facility.

    Before conducting the test there was no clear hypothesis for how the ice grip would be affected by a lower tread depth. An increase of the grip, as well as a decrease, were both possible outcomes for a diminished tread depth.

    Four different tire models in a dimension common for heavy vehicle trailer tyres (385/55-R22.5) were chosen for the tests. Every model was tested in a new state, as well as with 5, 3, and 1.6 mm tread depth. It was decided to use naturally worn tyres which meant that in total 16 different tyres were used in the study. The difficult task of finding identical tyre models and dimensions with specified tread depth forced us to also include some tyres with the larger profile (285/65-R22.5). This is however not considered to affect the results of the test. All the tyres were winter tyres, and most of them were also marked with the 3PMSF symbol, which means that they have passed a standardized grip test on snow.

    Both brake and steer test were conducted. Five different grip related attributes were investigated: peak friction at braking, friction at locked wheel braking, cornering stiffness, cornering peak friction, and cornering friction with large slip angle

  • Göransson, Nils-Gunnar
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Uppföljning av vägars tekniska tillstånd: lägesrapport för observationssträckor ingående i det svenska LTPP-projektet till och med december 20182019Report (Other academic)
    Abstract [en]

    The objective of this project is to collect and deliver high quality road data primarily for use in the development of performance prediction models. Monitoring of the LTPP (Long Term Pavement Performance) sections (100-metre-long) started in 1984 on commission of the Swedish Road Administration. The aim is primarily to focus on road deterioration caused by heavy traffic. The project started with a limited amount of sections and have in 2018 increased to 698 sections distributed over 66 sites. All sections are part of the Swedish national road network. During the years, some sections have become redundant and therefore a number of replacement sections are included. Budget restrictions in 2000 resulted in a review of the sections and a 25 percent reduction in monitoring was implemented. Despite this decrease, the project purpose could still be maintained. By retaining the most strategically important routes and reducing the number of surveys useful high-quality data could still be obtained from the sections left in the monitoring program. In addition, the introduction of median barriers on some sections (to facilitate traffic separation) has meant a disqualification of suitability. At the start of 2019, 297 sections distributed over 33 sites will remain active.

    The following activities are included in the monitoring programme:

    Distress surveys. Annual surveys are carried out by walking over the sections. During the survey all distresses and surface defects are recorded. The grading of the distresses and defects are based on a national distress manual.

    • Calculation of an annual crack index. The index is calculated from the type of crack, crack distress grade and crack propagation and is included, in table form, in the database.

    Road surface monitoring. Financial restrictions limit the monitoring to every second year. However, the development of rut and longitudinal unevenness follow a relatively linear trend, so monitoring every second year is considered acceptable in this case.

    • Measurement of the bearing capacity (KUAB-FWD). The capacity is measured on all new sections and after any maintenance measures.

    Cross section profiling (PRIMAL-profiling) is no longer carried out.

    • Collection of climate data from SMHIs automatic weather observation stations.

    • Collection of traffic data normally every fourth year.

    • Quality control check of all collected data before being entered into the LTPP-2018 data base (Microsoft Access 2007–2016).

  • Wallén Warner, Henriette
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Patten, Christopher
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Sörensen, Gunilla
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Shared space: utifrån olika åldersgruppers perspektiv2019Report (Other academic)
    Abstract [en]

    A shared space, in the context of road transport, often refers to an area that is shared by unprotected and protected road users and is intended to facilitate a living city space for everyone. The purpose of this study was to investigate how young, middle-aged and elderly people experience shared space from a pedestrian perspective, but also to investigate whether, and if so, how an alternative design of the area (with or without large flower pots) affects their experience. In the study, two different methods were combined; an eye tracking study and a Q-study. The Q method is a research method that is used in psychology and social sciences to investigate people's subjective views on a particular matter, phenomenon or topic. In this study, the Q method is used to investigate pedestrian experiences of two different design configurations - with or without large flower pots deployed - on the Fiskaretorget (eng. Fisherman’s Square) in Västervik. A total of 37 participants, divided into the three age groups, participated in the study, which was carried out at the Fiskaretorget and an adjacent non-signal-regulated pedestrian crossing in Västervik. About half of the participants carried out the experiment with, and half without large flower pots placed on the square. The results of the eye tracking study show that middle-aged pedestrians seemed to experience increased risk awareness, in the absence of the traditional division between unprotected and protected road users. Young and older, on the other hand, looked about the same amount of traffic-related objects, regardless of whether there were large flower pots placed or not. At the same time, the Q-study shows that pedestrians, regardless of age, did not experience any great uncertainty on this type of common areas. The perceived uncertainty, which nevertheless existed, was further reduced with large flower pots that recreated the traditional division with clear zones or stretches, pedestrians can stay in a relatively car-free area while the motor vehicles get clear paths to travel along. Based on these results, we recommend that, instead of a shared space design, designing common areas should have clear safe zones where pedestrians can stay in relatively car-free areas.