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  • 1.
    Antonson, Hans
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Blomqvist, Göran
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Mårdh, Selina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Crash Barriers and Driver Behavior: A Simulator Study2013In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 14, no 8, p. 874-880Article in journal (Refereed)
    Abstract [en]

    Objective: The study examines how drivers experience a conventional W-beam guardrail (metal crash barrier) along both sides of narrow versus wider roads (single carriageway with 2 lanes) in terms of stress, feelings, and driving patterns and whether subjective experience concurs with the actual driving patterns captured by the quantitative data.

    Methods: The study used different methods to capture data, including the VTI Driving Simulator III (speed and lateral vehicle position) in conjunction with electrocardiogram (ECG) data on heart rate variability (HRV) and questionnaires (oral during driving and written after driving). Eighteen participants-8 men and 10 women-were recruited for the simulator study and the simulator road section was 10 km long.

    Results: Driving speeds increased slightly on the wider road and on the road with a crash barrier, and the lateral driving position was nearer to the road center on the narrower road and on the road with a crash barrier. The HRV data did not indicate that participants experienced greater stress due to road width or due to the presence of a crash barrier. Participant experience captured in the oral questionnaires suggested that road width did not affect driver stress or driving patterns; however, the written questionnaire results supported the simulator data, indicating that a wider road led to increased speed. None of the participants felt that crash barriers made them feel calmer.

    Conclusions: We believe that there is a possibility that the increased speed on roads with crash barriers may be explained by drivers’ sense of increased security. This study demonstrates that an experimental design including experience-based data captured using both a simulator and questionnaires is productive. It also demonstrates that driving simulators can be used to study road features such as crash barriers. It seems more than likely that features such as street lamps, signs, and landscape objects could be tested in this way. © 2013 Copyright Taylor and Francis Group, LLC.

  • 2.
    Bolling, Anne
    et al.
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Validering av METOR i tätort1997Report (Other academic)
  • 3.
    Brüde, Ulf
    et al.
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Trafiksäkerhetseffekter av åtgärder och tillståndsförändringar2008Report (Other academic)
    Abstract [en]

    This study has been performed by VTI by commission of the Road Traffic Inspectorate in Sweden. The objective has been to scrutinise, discuss, compile and comment on measures, changes in conditions and effects concerning both the road, the vehicle and the road user. One further objective has been to relate, as far as possible, the effects/changes to the actual development of fatalities in traffic, in the first place over the period 1996-2006. It is found that for many factors, the conditions, measures and associated effects are insufficiently known. This is especially true for changes over time. This is unsatisfactory since, at the same time, there is strong evidence that these factors have, or may have, a considerable impact and that it is a high proportion of all traffic fatalities which are affected - either positively or negatively. We do not know about changes in conditions regarding speeds, person km travelled by age and gender, alcohol in traffic, use of mobile telephones when driving, and attitudes and deliberate traffic violations. There are no data for changes concerning risk for car drivers of different ages and genders. Effects concerning fatalities are insufficiently known for changes in traffic mileage (all other factors being constant), changes in economic conditions (effects apart from impact on traffic mileage), automatic traffic safety control speed cameras, certain physical measures, the aggregate effect of more recent vehicles, measures to influence alcohol in traffic, and attitude modification. There are no data for simultaneous analysis of accidents/injuries/fatalities, as well as for exposure, speed, road, vehicle and road user.

  • 4.
    Eriksson, Jan R
    et al.
    Swedish National Road and Transport Research Institute.
    Björketun, Urban
    Swedish National Road and Transport Research Institute.
    Edwards, Henrik
    Swedish National Road and Transport Research Institute.
    Karlsson, Rune
    Swedish National Road and Transport Research Institute.
    Sandström, Jessica
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Ågren, Bertil
    Swedish National Road and Transport Research Institute.
    Dokumentation av NÄTRA-undersökningen: en undersökning av näringslivets transporter med bil i Stockholms län 19982000Report (Other academic)
  • 5.
    Eriksson, Jenny
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Lindborg, Eva
    Trafikanalys.
    Adell, Emeli
    Trivector .
    Holmström, Andreas
    Trafikanalys.
    Silvano, Ary P.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Nilsson, Annika
    Trivector .
    Henriksson, Per
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Wiklund, Mats
    Trafikanalys.
    Dahlberg, Lina
    Trivector.
    New Ways of Collecting Individual Travel Information: Evaluation of data collection and recruitment methods2018Report (Other academic)
    Abstract [en]

    The overall purpose of the project is to conduct a demonstration study that shows how two data collection methods that have been developed to collect travel survey data perform in the field, and how they perform compared with traditional TS (i.e., postal questionnaires and/or telephone interviews). The project is also intended to provide a better understanding of the ways in which different recruitment methods of respondents can be used so that future TS can be more cost effective.

    The two collection methods tested consist of a mobile app and an online questionnaire with a map to assist the respondents to identify travel destinations. Three recruitment methods were used, i.e., recruitment via random sampling, a web panel, and crowdsourcing. The portion of the random sample that received an online questionnaire was divided into two groups. Half the group was given no incentive, while the other half received a gift card worth SEK 100 after answering the questioner. Those who were recruited via a web panel and were to use the mobile app were rewarded in the form of a gift card worth SEK 100 if, at minimum, they made corrections to trips made on one day registered in the mobile app. A nonresponse analysis was performed of the random sample for both the online questionnaire and the mobile app. Cost estimates for each collection method and recruitment method were also performed, as were uncertainty estimates.

    Overall, the study shows that the mobile app registered significantly more trips per respondent than did the online questionnaire, while the distances travelled were comparable. There are several possible interpretations of this. One is that people who responded to the online questionnaire either forget about and/or combined short trips (particularly trips made for the purposes of leisure or shopping, and using the travel modes walking and car). One presumable explanation for this is that it is easier to confirm/correct the trips that the mobile app suggests than it is to recall and enter all trips in an online questionnaire. Another possible interpretation is that people responding to different data collection methods have different travel patterns. Yet another explanation is connected to technique issues regarding the different data collection methods.

  • 6.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Hrelja, Robert
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Henriksson, Per
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Co-operation between police and social treatment services offering treatment to drink and drug drivers: experience in Sweden2011In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 12, no 1, p. 9-17Article in journal (Refereed)
    Abstract [en]

    Objective: To describe and analyze a measure that has been introduced in Sweden with the objective of quickly offering treatment for the alcohol or drug problems suspected drink or drug drivers may have. The goal of the measure is that every suspected drink or drug driver shall, as soon as apprehended by the police, be offered contact with the social services or the dependency care and treatment service, which can offer a consultation and, if needed, suitable treatment.

    Method: Interviews and questionnaire surveys, as well as forms that describe the treatment received by each individual case.

    Results: About 20 percent of all those who receive the offer from the police accept contact with the social services or the care and treatment service, and approximately 40 percent of these also attend the consultation. There is a favorable fundamental attitude to the method among the participating authorities. However, some shortcomings in application are revealed. One example concerns drug drivers who are offered contact with the social services or the care and treatment service to a considerably lesser extent than drink drivers. Another neglected group are the people who are at first suspected of drink driving but are later found to have an alcohol concentration below the legal limit. Compared with those who have an alcohol concentration above the legal limit, this group is offered contact to a lesser extent and also have a lower propensity to accept the offer.

    Conclusions: The results indicate a strong support for the method from involved authorities, but participation could be improved by giving more attention to neglected groups.

  • 7.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Kronstrand, Robert
    Swedish National Road and Transport Research Institute.
    Förslag till förbättringar av rattfylleristatistiken i Sverige: underlag till uppdrag att förbättra beskrivningen av vägtrafikolyckornas hälsopåverkan2008Report (Other academic)
    Abstract [en]

    In June 2006, the Swedish Road Administration was mandated by the Government to improve the description of the health effects of road traffic accidents. Under the terms of this mandate, a proposal was to be made as to how the recording of alcohol and drug related accidents can be improved, and how sample surveys of the prevalence of drivers under the influence of alcohol and/or drugs should be performed. This note describes the data used for these parts of the mandate. One common condition for both these parts is that possible screening methods for drivers under the influence of narcotics should be studied. In order to measure the proportion of traffic mileage travelled by drink/drug drivers, the investigation should be organised as a statistical sample survey where the police check drivers at sites selected at random. As regards selection in time, it may be reasonable to use quota sampling. In the present situation, we do not consider that it is possible to carry out regular surveys of drug driving. If the regulations are amended so that routine controls can be performed, and if the police begin to use screening instruments for drug tests, regular surveys can be performed. These surveys can then be integrated with the investigations regarding alcohol, by requiring the stopped drivers to give samples for both alcohol and for drugs.

  • 8.
    Gustafsson, Mats
    et al.
    Swedish National Road and Transport Research Institute.
    Berglund, Carl Magnus
    Swedish National Road and Transport Research Institute.
    Forsberg, Bertil
    Swedish National Road and Transport Research Institute.
    Forsberg, Inger
    Swedish National Road and Transport Research Institute.
    Forward, Sonja
    Swedish National Road and Transport Research Institute.
    Grudemo, Stefan
    Swedish National Road and Transport Research Institute.
    Hammarström, Ulf
    Swedish National Road and Transport Research Institute.
    Hjort, Mattias
    Swedish National Road and Transport Research Institute.
    Jacobson, Torbjörn
    Swedish National Road and Transport Research Institute.
    Johansson, Christer
    Ljungman, Anders
    Nordström, Olle
    Swedish National Road and Transport Research Institute.
    Sandberg, Ulf
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Öberg, Gudrun
    Swedish National Road and Transport Research Institute.
    Effekter av vinterdäck: en kunskapsöversikt2006Report (Other academic)
    Abstract [en]

    Choice of winter tyres has, from mainly being a matter of safety and economic costs for wearing of road pavements, during later years also become a matter of inhalable particles formed during pavement wear from studded tyres and their negative effects on public health. Further, the tyres' effects on environment and noise have been illustrated in several studies. The issue is also complicated by the fact that tyre choice effects on traffic safety have several components, including such diverging parameters as friction and behaviour. Finally all aspects have to be evaluated from a socioeconomic point of view for society to be able to decide which kind of distribution of tyre types that is the most profitable. This report is a summary of current knowledge in this complex research field.

  • 9.
    Hedström, Ragnar
    et al.
    Swedish National Road and Transport Research Institute.
    Möller, Staffan
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Vinterklimatmodell för järnvägssektorn: en förstudie2007Report (Other academic)
    Abstract [sv]

    The aim of this report is to make an initial survey of disruptions to rail traffic in winter. This survey is used in studying the prospects for submitting a project application to Banverket, the authority responsible for rail traffic in Sweden. The total cost of the effects or consequences that affect rail traffic because of the winter climate can be broken down into several items. First and foremost, there are the direct costs of Banverket for winter maintenance and the direct costs of the train operators. To this must be added the indirect costs incurred by passengers and freight customers. The size of these indirect costs in a socio-economic perspective depends on the extent of the delays and the way the delays are valued in monetary terms by passengers and freight customers. We have scrutinised the approach and the model structure for the road sector that are set out in the Winter Model. This model will soon be used on the national road network to describe the most important socio-economic effects of various strategies and measures in winter road management. With this as the starting point, a first draft for an effect model for the winter management of rail infrastructure has been drawn up. We believe that this effect model will be found valuable for structuring and analysing the impact of winter on the various elements of rail infrastructure.

  • 10.
    Henriksson, Per
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Loukopoulos, Peter
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Wiklund, Mats
    Trafikanalys.
    Utvärdering av kurser för förare av sportmotorcyklar: kursdeltagarnas behållning och effekten på försäkringsrapporterade skador2011Report (Other academic)
    Abstract [en]

    VTI has evaluated further training courses offered by the Swedish Motorcyclists Association (SMC) to riders of super-sport motorcycles. This was done through two substudies. In the first study, a series of telephone interviews were performed with persons who participated in the courses in 2007. The aim with this qualitative part of the study was to identify what respondents recalled from their participation in the courses, what they learned from them, and how the aims of the course have been interpreted.

    The second study included a follow-up of insurance reported claims during the period 2007-2009. Two groups were compared: those who participated in SMC further training course and those who did not participate in any such course.

    From the interview study, it was found that the course structure, i.e. practical exercises interleaved with discussions, received largely positive comments. Riding a motorcycle on public roads was seen as significantly different to riding on a designated track or course, which is why not all aspects of the further training course were viewed as relevant for speeds and circumstances that arise in normal traffic conditions. Some suggestions for improvement dealt with greater individual feedback, use of video cameras, and distribution of printed course material in advance.

    According to the follow-up study of insurance reported claims, no significant difference existed between those who completed the course/courses and those who have not passed SMC further training course. Any traffic safety effect of the SMC's courses for sport motorcycle riders was thus not possible to detect by the available data material.

  • 11.
    Hjort, Mattias
    et al.
    Swedish National Road and Transport Research Institute.
    Thorslund, Birgitta
    Swedish National Road and Transport Research Institute.
    Sundström, Jerker
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Öberg, Gudrun
    Swedish National Road and Transport Research Institute.
    Bussars trafiksäkerhet vintertid2008Report (Other (popular science, discussion, etc.))
    Abstract [en]

    Earlier studies have shown that buses are overrepresented at accidents during winter road conditions compared to other vehicle types. Hence, the traffic safety of buses during the wintertime has been studied in more detail. The study comprised the following parts: - Gripping power studies on ice in VTI's tyre test facility. - Accident study and a survey of the use of tyre. - Focus group to gain knowledge about dangerous situations. - Driving simulator study to test the importance of the tyres during problematic situations.

    Tests in VTI's tyre test facility on smooth ice did not show any significant difference between summer tyres and non-studded winter tyres, while studded tyres exhibit a better ice grip than non-studded tyres. Nor did driving simulator tests when driving on ice covered road under the influence of heavy wind from the side show a difference between summer tyres and non-studded winter tyres. Also in these tests the studded tyres were superior to the non-studded. If studded tyres are used only on one axle, the driving simulator study showed that during side wind the ability to steer is important. The accident study showed that the buses that have summer tyres on the steering axle and winter tyres on the drivé axle has the lowest estimated accident risk, although it is not statistically significant. The buses equipped with studded tyres on both axles could not be statistically analysed since only 2 accidents occurred on bare roadways, and none on icy/snowy roadways, while at the same time the buses in this category drive a lot on icy/snowy roadways. This probably makes these buses the safest on winter roadways. From the focus groups it was clear that the time table has a great influence on the creating of stress and the demands on the drivers to keep the speed even during slippery roadways. Many bus drivers experience large problems with bad snow clearance, or other winter maintenance. At the same time there is a large consciousness among the drivers that it is always their own way of handling the vehicle that is the determining factor for traffic safety. The drivers were expressing a lack of further education and practical exercises with buses on slippery roads.

  • 12.
    Hjort, Mattias
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Öberg, Gudrun
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Bus accidents in wintertime2010In: PIARC 2010 XIII International Winter Road Congress, February 8-11, 2010, Quebec, Canada: proceedings, 2010Conference paper (Refereed)
    Abstract [en]

    Buses in Sweden have a low accident risk. However, statistics from 1996 - 2002 indicate that the number of bus accidents in Sweden with personal injuries have been increasing by 4% yearly. Buses also have a higher percentage of accidents that occur on ice/snow covered roads than other vehicles. In Sweden passenger cars must be equipped with winter tyres during the winter period. There is no such regulation for heavy vehicles, and many buses are using summer tyres all around the year. The present project had the purpose of looking at the bus-winter problem in more detail, with the main focus on tyres. Four different studies were carried out: tyre tests, focus group discussions, driving simulator tests and an accident study. Here is given a short summary concerning methods and conclusions of each sub project.

    Tyre tests on smooth ice did not show any significant difference between summer tyres and non-studded winter tyres, while studded tyres exhibits a better ice grip than non-studded tyres. Nor did driving simulator tests with driving on ice covered road under the influence of heavy wind from the side show a difference between summer tyres and non-studded winter tyres. Also in these tests studded tyres were superior to non-studded. Accident statistics indicate that buses with summer tyres on the steering axle and winter tyres on the drive axle have the lowest estimated accident risk, which is in accordance with the results in a previous study. The results are however not statistically significant due the low number of accidents. Three focus groups were carried out and the importance of the tyres for traffic safety during winter was discussed. It is however hard from the gathered discussion material to estimate just how important the tyres really are. The results do not warrant a winter tyre regulation for heavy vehicles, and a restriction of the use of studded tyres for buses would probably have negative consequences on traffic safety.

  • 13.
    Hrelja, Robert
    et al.
    Swedish National Road and Transport Research Institute.
    Forsman, Åsa
    Swedish National Road and Transport Research Institute.
    Forsberg, Inger
    Swedish National Road and Transport Research Institute.
    Henriksson, Per
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Utvärdering av projektet Nationell samverkan mot alkohol och droger i trafiken enligt Skelleftemodellen: syntesrapport2009Report (Other academic)
    Abstract [en]

    The Skellefte Model is a project whose purpose is to reduce the number of repeated drunk driving offences by improving cooperation between the police, social services, addiction treatment systems, county administrative boards, public prosecutors, judges and the criminal justice system. The project's key concept is that suspected drunk drivers must come into contact with municipal social services or be taken care of by the county council addiction treatment system as quickly as possible, and preferably within 24 hours after being apprehended and questioned by the police. The evaluation indicates that the Skellefte Model is socio-economically beneficial. A majority of those who are working in the project also believe that the model works well, but that there are numerous problems, such as administrative problems and routines, a need to better embed the model among administrators, etc. The evaluation also shows that there is room for improvement in the handling of drugged drivers. The results differ greatly from county to county. The inter-county differences are likely due to factors such as when the project began and discrepancies in terms of the application of routines, motivation and embedment among employees. They may also be attributable to some extent to the fact that some aspects of the Skellefte Model are being applied in different ways and adapted to disparate local and regional conditions.

  • 14.
    Ihs, Anita
    et al.
    Swedish National Road and Transport Research Institute.
    Grudemo, Stefan
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Vägytans inverkan på körkomforten: bilisters monetära värdering av komfort2004Report (Other academic)
    Abstract [sv]

    The decision support system for the maintenance of paved roads, PMS, of the

    Swedish National Road Administration comprises a number of models for

    estimating the costs of road management authorities, road users and society

    at large. In 1998 VTI was commissioned by the Road Administration to carry

    out a comprehensive project with the objective of revising and augmenting

    these traffic effect models. The project is entitled "Traffic effects of the

    road surface" and has comprised a number of subprojects. The primary aim of

    this study has been to investigate, in a field study, the relationship

    between the roughness of the road surface (expressed in terms of the

    International Roughness Index IRI, with the units mm/m) and the perceived

    driving comfort of motorists, as well as their willingness to pay for

    improved driving comfort. 50 test subjects were asked to drive a car over

    nine 500 m long sections with different surface standards. The mean of the

    measured IRI on these road sections varies from 0.8 mm/m on the smoothest

    section to 10.5 mm/m on the roughest. In conjunction with the investigation,

    the test subjects were interviewed by a test leader. During the interview,

    they were asked which factors are significant for driving comfort and how

    they perceived driving comfort on the different sections. The state/condition

    of the asphalt surfacing was considered to have the greatest significance,

    followed by the car and the behaviour of other road users. Density of traffic

    was considered to have the least significance. The test subjects were also

    asked to say what significance different defects in the surfacing had on

    driving comfort. What is most important for a comfortable car journey is that

    there are no holes/depressions in the surfacing. This is followed by ruts,

    roughness that causes vibrations, and bumps and subsidence. The test subjects

    were asked to make a general assessment of driving comfort on a five-degree

    scale during their drive over the nine sections. A clear relationship was

    found between the assessment that the test subjects made and the measured

    IRI, i.e. the higher the IRI, the worse driving comfort was judged to be.

    The physical impact caused by the different surface standards of the test

    sections was also investigated by placing a dummy equipped with triaxial

    accelerometers in the passenger seat of the car that drove over the test

    sections. The willingness of the test subjects to pay for improved comfort

    associated with the condition of the road surface was also investigated by

    three methods: Stated Preference (Choice) and Contingent Valuation Method

    (driving comfort versus petrol price and trip time). A relatively high

    willingness to pay was obtained, but the methods gave very different results.

    It has therefore been impossible to posit a comfort cost model on the basis

    of these. This requires further studies and development of the methods.

  • 15.
    Ihs, Anita
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Gustafsson, Mika
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Eriksson, Olle
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Sjögren, Leif
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Road user effect models: the influence of rut depth on traffic safety2011Report (Other academic)
    Abstract [en]

    There are currently no satisfactory effect models for calculating the consequences and costs for road users of different maintenance strategies. The main problems identified by the Transport/Road Administrations in Finland, Sweden, Norway and Estonia, are the relationship between road surface condition and accidents, the effect of the most important state parameter rut depth on road user costs, as well as the role of road-user costs/effects of a road network that is mostly in good condition. These are problems that must be resolved in order to better justify budget allocation for road maintenance. VTI has therefore on commission by the Finnish Transport Administration and with funding from the other Transport/Road Administrations conducted a study to determine the influence of rut depth effects on the accident risk of road users. Separate analyses were made of data from Sweden, Finland and Norway, respectively. It was assumed that the accident risk also depends on other road condition variables, such as longitudinal unevenness, texture, cross slope, geographic location (country), vehicle flow, climate, weather, etc. A model approach was chosen that could address the impact of all these other road condition variables, and the possible interactions between them, on the accident risk. It was assumed that the relationship between accident risk and rut depth is not necessarily a linear function, why rut depth was divided into several categories. It was also agreed that separate equations should be derived for different speed and AADT (Annual average daily traffic) classes. Rut depth categories, as well as speed and AADT classes were chosen to match each country's strategies for maintenance. The overall conclusion of the analysis is that the data does not support any general rules for a maintenance scheme. There are no results to show that deeper ruts generally tend to increase the accident risk. Nor are there results that show that ruts have the same influence on the accident risk for different AADT classes at a given speed or vice versa. There seems to be at increased risk for ruts ? about 15 mm in the highest speed class, but the results differ between AADT classes and are not similar in adjacent speed classes, making the results difficult to understand and less useful to specify the rules for maintenance. For the Norwegian data this trend can not be seen in the highest speed class (> = 90 km/h), but then this speed class differs from the Swedish and Finnish highest speed classes (> = 110 km/h roads and motorways, respectively).

  • 16.
    Ihs, Anita
    et al.
    Swedish National Road and Transport Research Institute.
    Velin, Hans
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Vägytans inverkan på trafiksäkerheten: data från 1992-19982002Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    The main objective of this study has been to provide the Swedish National

    Road Administration's (SNRA) pavement management system (PMS) with new models

    describing the relation between traffic safety and road surface condition. In

    the accident cost model used today, the only road surface parameter is rut

    depth and only ruts deeper than 10 mm are considered to have any influence on

    traffic safety. The relation is then linear and accident cost increases with

    increasing rut depth. The investigation carried out is based on data from the

    road surface measurements made by SNRA on state roads between 1992 and 1998

    and accidents reported by the police during the same period. Precipitation

    data has also been used. Regression analyses have mainly been used. The

    dependent Y-variable was accident ratio (accidents/100 million axle pair

    kilometres). Independent X-variables were rut depth (mm) and/or unevenness

    expressed as International Roughness Index (IRI in mm/m). The material has

    been divided into several different classes, such as traffic flow and

    precipitation classes. Using linear regression with rut depth as the only

    independent variable, it was found that the accident ratio is independent of

    rut depth. Divided into summer and winter periods, there is a tendency that

    the accident ratio decreases during summer and increases during winter with

    increasing rut depth. With linear regression with IRI as the only independent

    variable, it is found that the accident ratio increases with increasing

    unevenness for most divisions of data. This also applies when only accidents

    with personal injuries and fatal accidents are studied. By multiple linear

    regression with rut depth and IRI as independent variables, it was found that

    the accident ratio decreases with increasing rut depth and increases with

    increasing unevenness for most divisions of the material. Even though the

    data from the whole state road network is included in the analyses, 95% of

    the material represents roads with a rut depth less than 15.4 mm and an IRI

    value less than 5.1 m/m. The consequence is that the estimated linear

    relations are valid only for roads of such a good standard. A variance

    analysis that has been carried out does not, however, support the theory that

    the accident risk on the roads with the deepest ruts should differ

    dramatically from that on the roads with shallower ruts. The analysis does,

    though, show that the higher the IRI value the higher the accident risk.

  • 17.
    Linder, Astrid
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Dukic, Tania
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Hjort, Mattias
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Matstoms, Ylva
    Swedish National Road and Transport Research Institute.
    Mårdh, Selina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Sundström, Jerker
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Östlund, Joakim
    Swedish National Road and Transport Research Institute.
    Methods for the evaluation of traffic safety effects of Antilock Braking System (ABS) and Electronic Stability Control (ESC): a literature review2007Report (Other academic)
    Abstract [sv]

    In today's vehicles, active safety systems are introduced addressing a large variety of safety issues such as providing optimal stability control, braking effect, preventing spin and rollover, as well as collision avoidance, to mention just a few. In this study a literature review was performed in order to establish how the traffic safety performances of active safety systems with focus on Antilock Braking System (ABS) and Electronic Stability Control (ESC) are assessed. The areas covered were statistical evaluation, testing and driver behaviour. The literature review showed that in particular statistical methods, based on odds ratios, had been used in order to evaluate the traffic safety effect. In order to evaluate the effect of ESC in physical testing there are several test methods described in this report. Estimations of driver behaviour effects have been carried out by surveys among vehicle owners. Experiments performed in field or in simulator have also been found in the literature. From EU projects a variety of measures and test methods are available for assessment of driver behavioural effects.

  • 18.
    Lundkvist, Sven-Olof
    et al.
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Nygårdhs, Sara
    Swedish National Road and Transport Research Institute.
    Fotgängares upptäckbarhet i mörker vid övergångsställen2004Report (Other academic)
    Abstract [sv]

    En metod för studium av fotgängares upptäckbarhet vid övergångsställen i mörker på gator med stationär belysning har testats. Metoden innebär att från svart/vita foton gör försökspersoner jämförande bedömningar av upptäckbarheten vid ett antal par av övergångsställen. Från dessa observationer beräknas oddset för att ett övergångsställe bedöms ge bättre upptäckbarhet än ett annat. Datainsamlingsmetoden visade sig fungera tillfredsställande men bör modifieras något. Bland annat ska bakgrundsvariabler som beskriver vägytans ljushet mätas fysikaliskt, t.ex. belysningsstyrkan mot vägytan och ytans reflexionsegenskaper. Analysmetoden fungerar, även om den kan anses vara något ovanlig och komplicerad. Traditionella metoder, såsom variansanalys och liknande, kan inte användas på grund av att observationerna inte är oberoende. I stället måste data analyseras med en s.k. logoddsmetod. Resultaten från denna metodstudie visar att inte endast beläggningsytans luminans är avgörande för upptäckbarheten, utan även övergångsställets utformning. Således visade det sig att en insnävning av övergångsstället, så att fotgängaren väntar i förarens siktlinje, ger goda möjligheter för upptäckt. Även ett övergångsställe på gata med ljus gatsten, men utan insnävning, innebar god upptäckt av fotgängaren. Ett ytterligare resultat är att separatbelysning av övergångsstället fungerar dåligt om fotgängaren passerar bakom övergångsstället.

  • 19.
    Möller, Staffan
    et al.
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Väglagsobservationers representativitet1994Report (Other academic)
  • 20.
    Niska, Anna
    et al.
    Swedish National Road and Transport Research Institute.
    Nilsson, Annika
    Trivector Traffic AB.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Ahlström, Petra
    Björketun, Urban
    Swedish National Road and Transport Research Institute.
    Söderström, Liselott
    Robertson, Kerstin
    Swedish National Road and Transport Research Institute.
    Metoder för skattning av gång- och cykeltrafik: kartläggning och kvalitetsbedömning2010Report (Other academic)
    Abstract [en]

    This report summarises the needs for, and the procedures applied in, estimating the share of total travel represented by pedestrian and cycle traffic, and comprises an analysis of existing data in the form of travel surveys and flow measurements. Different methods are compared, and the significance of the differences between the methods for monitoring pedestrian and cycle travel is discussed. Both the method as such with its definitions and limitations, and the quality of the various phases in its implementation, play a part. This has consequences in comparisons between different places and also for monitoring over time. Most local authorities have some type of target with regard to cycle traffic, while target formulations for pedestrian traffic are less frequent. To increase the cycling share of total travel is the most common target, however, seldom followed up, and the numbers of cyclists at certain points are measured instead. Travel surveys and traffic flow measurements measure different things, and may draw different conclusions. The measurements may show that people cycle more than ever before, while travel surveys show that the cycling share is decreasing. Both conclusions may be right, and they reflect the importance of the methods employed, and also of the units. The unit "share" is made up of more components than pedestrian and cycle traffic as such, and depends above all on the total travel. It is therefore not only the proportions that are of interest but, for example, also the number of journeys per person.

  • 21.
    Nordström, Olle
    et al.
    Swedish National Road and Transport Research Institute.
    Wallman, Carl-Gustaf
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Wretling, Peter
    Swedish National Road and Transport Research Institute.
    Öberg, Gudrun
    Swedish National Road and Transport Research Institute.
    Tunga fordons däckanvändning: effekter vid vinterväglag1999Report (Other academic)
  • 22.
    Sjögren, Leif
    et al.
    Swedish National Road and Transport Research Institute.
    Lundberg, Thomas
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Acceptance testing for road surface monitoring vehicles in Finland2008Report (Other academic)
    Abstract [en]

    VTI has carried out acceptance testing of companies that would like to do road surface monitoring in Finland. This has been done on commission of the Finnish Road Administration. This kind of acceptance testing has been done in Sweden by VTI in cooperation with the Swedish Road Administration several times (four times). With the experience of the tests in Sweden a test method adjusted for the Finnish needs have been composed. The purpose of the method is to accept or reject the participating companies for doing either object or network measurements or both. This is done by checking the validity and repeatability for the object part and the reproducibility for the network part. The tests for the object part involve measurements at test sections including measuring with reference methods as well as repeated measurements on a route. For the reproducibility test, done at the network measuring acceptance, runs with different combinations of vehicles and drivers/operators are carried out. The tests give answers to questions like: - The technical skill to measure according to the procurement specifications. - The ability and type of organisation to take care of and process data under given circumstances like this test. - The ability to deliver data of right quality in time. To be accepted as a contractor of network level measurements the company also has to be accepted for object measurements.

  • 23.
    Sörensen, Gunilla
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Åtgärder för att minska hastighet förbi vägarbetsplatser: utvärdering baserad på tre fältförsök2011Report (Other academic)
    Abstract [en]

    A state-of-the-art literature survey concerning the improvement of road-work safety has previously been carried out. A list of potential new measures was produced and several of these were prioritized, for further investigation, by the Swedish Road Administration. The investigations of three of these prioritized measures are documented in this report: - Intelligent congestion warning system, - Dynamic message sign (DMS), - Optical speed bars. The measures were tested in field at real road-works and all three measures, each in their own way, have the potential to increase traffic safety at road-work zones. In the report, questions that remain to be answered are highlighted and some alternative designs of the measures are proposed.

  • 24.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Forward, Sonja
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Car drivers’ perceptions of electronic stability control (ESC) systems2011In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 43, no 3, p. 706-713Article in journal (Refereed)
    Abstract [en]

    As a way to reduce the number of car crashes different in-car safety devices are being introduced. In this paper one such application is being investigated, namely the electronic stability control system (ESC). The study used a survey method, including 2000 private car drivers (1000 driving a car with ESC and 1000 driving a car without ESC). The main objective was to investigate the effect of ESC on driver behaviour. Results show that drivers report that they drive even more carelessly when they believe that they have ESC, than when they do not. Men are more risk prone than women and young drivers more than older drivers. Using the theory of planned behaviour the results show that attitude, subjective norm and perceived control explain between 62% and 67% of driver’s variation of intentions to take risks. When descriptive norm was added to the model a small but statistically significant increase was found. The study also shows that more than 35% erroneously believe that their car is equipped with an ESC system. These findings may suggest that driver behaviour could reduce the positive effect ESC has on accidents. It also shows that drivers who purchase a new car are not well informed about what kind of safety devices the car is equipped with. These findings highlight the need for more targeted information to drivers.

  • 25.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Forward, Sonja
    Swedish National Road and Transport Research Institute.
    Personbilsförares förväntningar och föreställningar om låsningsfria bromsar och antisladdsystem2009Report (Other academic)
    Abstract [sv]

    The views of car drivers concerning antilock brakes (ABS) and electronic stability control (ESC) systems, and their experience of these, have been studied. A study has also been made of their intentions to behave in a certain way in three critical driving situations. The investigation was performed as a questionnaire survey sent by post to 1 000 car drivers with an electronic stability control system and to 1 000 drivers of similar cars without an electronic stability control system. The investigation was carried out in the autumn of 2008. A total of 959 questionnaires were answered, i.e. a response rate of 48%. The results show that about 90% of the car drivers with an electronic stability control system know that the car is equipped with the system. If the car drivers without an electronic stability control system in the car are studied, more than 35% erroneously state that the car has the system. Almost all drivers (over 95%) are aware that they have antilock brakes. In the above risk situations, the drivers consistently state that they are more likely to take a risk when they think they have the support system, than when they do not have one. The increased tendency to take risks is approximately the same for all the three situations. The results show that men are more riskprone than women. As regards the age, there is a consistent pattern that the youngest age group is always represented in the age group or age groups which have the highest tendency to take risks. It is also shown that when "Theory of planned behaviour" is used, the intentions of between 41-70% of the drivers are explained by the model.

  • 26.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Allvarliga funktionsstörningar i baninfrastrukturen: beräkning av effekter på tågtrafiken2003Report (Other academic)
    Abstract [en]

    The track infrastructure installations of the railway transport system are at times subjected to stresses which give rise to such serious faults or damage that traffic must be stopped, or cause such serious disturbances that trains must be cancelled. Examples are falls of overhead contact lines, fire in interlocking systems or flooding of the track bed. It is obviously impossible to create a system where such situations never occur, but an attempt can be made to allocate operational and maintenance work in such a way that the probability of such occurrences is reduced to a minimum on those track installations where the impact in the form of comprehensive traffic disturbances is greatest. Extensive damage to the interlocking system of the rail transport system causes comprehensive disturbances. One example of such damage which gave rise to serious consequences is when the interlocking system at Jaerna station burned down the week after midsummer in 2000. A microsimulation tool for rail traffic, RailSys, which had been developed in Germany, was used to simulate the consequences of the fire. Simulations were also made for rail traffic flows both higher and lower than those that applied after the fire. Lowering of the highest permitted speed through a track infrastructure installation is one example of the reduction in potential capacity. The delays which then occur can in some situations be recouped through somewhat higher speeds on other parts of the system. Sometimes this is not possible, but the delays which nevertheless occur may be so small that all planned train movements can be carried out. In a lot of circumstances, however, delays are so extensive that rolling stock assignment is affected and trains must be cancelled. Alternatively, the potential capacity may become so low that all planned train movements cannot be carried out. When faults or damage occur to the signalling system, the highest permitted speed is sometimes reduced to 40 km/h. This may also occur when the bearing strength of the permanent way is reduced or when the track is in a bad condition. The authors have studyied how traffic is affected when the highest permitted speed is reduced to 40 km/h on a number of sections of the Svealand Line between Nykvarn and Eskilstuna in Soedermanland.

  • 27.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Förebyggande underhållsåtgärders effekt på järnvägstransportsystemets sårbarhet: försök med delfimetoden2006Report (Other academic)
    Abstract [sv]

    The purpose is to test the hypothesis that the choice of strategy for preventive maintenance of rail infrastructure might affect the amount of serious disruptions in the train traffic. The relation between preventive maintenance and serious train traffic disruptions can be divided into two parts. On one hand it is the relation between the chosen strategy for preventive maintenance and the state of the rail infrastructure. On the other hand it is the relation between the state of the rail infrastructure and the amount of occurring train traffic disruptions. Either the sub relations can be analysed and quantified separately or one might try to perform an analysis without dividing the relation between preventive maintenance and serious train traffic disruptions into two parts. An operational definition of serious disruption in train traffic in this context is that faults or damages on the rail infrastructure cause such severe delays that the planned turnover of train vehicles cannot be maintained, cancelled train traffic or the closure of a railway. Several methods for quantifying serious train traffic disruptions, based on available train traffic data, are suggested. It is clear from these methods that faults or damages on the overhead contact line dominate increasingly as higher weight is put on the larger train delays, while the opposite applies to faults and damages on signal system. The result of a Delphi study is presented, where two scenarios are tested. The purpose of the study is to let experts on maintenance of rail infrastructure judge to what extent the decision of preventive maintenance strategy may affect the amount of occurring train traffic disruptions. The first scenario means that the necessary maintenance strategy in order two reach the target standard for the rail infrastructure is implemented. In the second scenario a maintenance strategy is implemented that is 50 percent more ambitious than the strategy of the first scenario.

  • 28.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Incidenter vid arbete på väg: en sammanställning av olyckstillbud2008Report (Other academic)
    Abstract [en]

    Roadworks are signposted to make road users realise that roadworks are in progress, advise them how they must act and how they can pass the roadworks in a safe manner. In spite of this, incidents and accidents do occur at roadworks where road users are involved. It is important to chart the problems which arise when those working on the road and other road users come into contact. A part of the work is to study the road accidents and incidents that occur at roadworks. To be able to do this, there is a need for relevant statistics concerning such accidents and incidents. Since conditions at roadworks are special, it may be necessary to compile special statistics concerning the road accidents and incidents that occur in connection to these. The aim is to compile statistics concerning incidents at roadworks. These statistics must provide a description of where, when and how the incidents occur. They must also serve as a model for the way in which regular collection of data concerning road accidents and incidents at roadworks can be carried out. Vägverket Produktion, the Production Section of the Swedish Road Administration, collects and compiles reports on incidents and accidents which occur in conjunction with their work on roads. This study comprises about 150 such incidents and accidents collected from 2004 until autumn of 2007. The method employed was to set up, with the support of the descriptions of occurrences, new variables for the compilation of statistics. These variables can then, presumably after a lot of modifications, be used in a more regular reporting of incidents in which all those who perform work on roads take part.

  • 29.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Järnvägstransportsystemets sårbarhet: struktur för modellformulering och metodutveckling2002Report (Other academic)
    Abstract [en]

    During the months of June and July in the summer of 2000, central Norrland was hit by several storms that caused flooding in many areas. In the middle of July, the risk of land slippage was considered so great that several stretches of railway line were closed to traffic. In December 2001 Stockholm suffered a severe snowstorm that had serious consequences for railway traffic, with many departures being cancelled. These are just two indications of the vulnerability of the railway transport system.

    The aim of this paper is to develop a framework to be able to analyse the vulnerability of the railway transport system. A formal definition of a railway transport system's vulnerability is the probability of the system's capacity falling to such a level that traffic is cancelled or is so delayed that the benefit of the transport to travellers or goods customers is not realised.

    A model of the vulnerability of the railway transport system must show how often capacity is so reduced that severe disruptions occur, e.g. that traffic flow can no longer be maintained, or that traffic must be cancelled, and what the reason is.

    The model's structure consists of two parts. The first part describes the reliability of the capacity and the second how the ability to maintain traffic of acceptable quality is affected by changes in capacity.  

  • 30.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Pair comparing method2004Report (Other academic)
    Abstract [sv]

    When studying how a response variable depends on an explanatory variable it

    is convenient to create pairs of matched observations, i.e. pairs consisting

    of two observations that are homogenous, except for the studied explanatory

    variables and the response variable. So, the matching procedure is a method

    with the purpose to control for different nuisance variables. Normally the

    analysis of such studies is straightforward, but it is possible to complicate

    it. Usually an expert that is not necessarily a statistician creates the

    matched pairs. In that case it is also customary that this expert finds one

    pair member suitable in several pairs, which means trouble for the analysing

    statistician. The expert understanding for the statistical problems is

    however limited in most cases. Therefore it has been necessary to develop a

    statistical method for analysing the results from a study with matched pairs,

    where it is allowed for an observation unit to be member of several pairs. An

    obvious consequence of that is that results from pairs with one common pair

    member will be dependent. It is therefore necessary to formulate an analysing

    method that is applicable when there are dependencies between different

    pairs. Another consequence from allowing the same object to occur in several

    pairs is that it may lead to a data set with redundancy. This would be the

    situation if objects a and b form one pair, a and c another and finally b and

    c a third pair. The third pair is just the difference between the two firsts.

    Then it is necessary to find a method that remove redundant pair like b and c

    as well.

  • 31.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Skattning av antal svåra olyckor i små redovisningsområden2004Report (Other academic)
    Abstract [sv]

    Vid insatser för förbättrad trafiksäkerhet, t.ex. ändrad vägutformning för

    bättre hastighetsanpassning eller räcke mellan mötande trafikströmmar, är det

    viktigt att följa olycksutvecklingen för att avgöra om åtgärden har avsedd

    effekt. Uppföljningsperioderna blir ofta väldigt långa om enbart olyckor med

    dödade eller svårt skadade personer betraktas. Det finns ett behov att

    utveckla metoder att följa upp trafiksäkerhetsinsatser i begränsade områden

    som nyttjar mer information än den som finns i frekvensen av antalet olyckor

    med dödade eller svårt skadade personer. En metod för att skatta risken för

    olyckor med dödade eller svårt skadade i små redovisningsområden ska

    utvecklas. Den ska nyttja information om alla olycksfrekvenser, även olyckor

    med enbart lindrig personskada eller egendomsskada. Metodens statistiska

    egenskaper ska analyseras. Två metoder att skatta förväntat antal olyckor med

    dödade eller svårt skadade personer i varje kommun under ett år ska studeras.

    Skattningarna baseras på olycksdata från samma år. Skattningarna är därför

    statistiskt oberoende av antal inträffade olyckor föregående och påföljande

    år. Det betyder att de fångar upp om risken ändras från ett år till ett

    annat. Skattningsmetoderna tillämpas för polisrapporterade olyckor på det

    statliga vägnätet under åren 1994-99. Slutsatsen är att skattningarna i

    genomsnitt har små systematiska fel. Vidare att kvoten mellan skattningarnas

    standardavvikelse och deras värden är drygt 0,03.

  • 32.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Sårbarhet i det svenska järnvägstransportsystemet: en förstudie1999Report (Other academic)
  • 33.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Tema Vintermodell: anpassning av vinterväglagsmodell till empiriska data med censurerade observationer2006Report (Other academic)
    Abstract [sv]

    In the Road Condition Model one wants to be able to predict the transition between different winter road conditions. One such example is the transition from loose snow all across the driving lane to loose snow except in wheel tracks, where the condition is changed to ice or bare road. Each vehicle passing as long as there is loose snow across the whole driving lane will remove a certain amount of loose snow from the developing wheel tracks. The amount of removed loose snow is assumed to vary between different types of vehicles. The Road Weather Information System, RWIS, delivers information on the amount of loose snow falling on the road. The traffic flow is measured by inductive loops. The amount of loose snow in wheel tracks is measured intermittent. Then one has information of traffic flow and the amount of removed loose snow from wheel tracks (determined as the difference between the amount af loose snow falling on the road and the amount remaining in the wheel tracks). Trough regression analysis one can determine the statistical relation between traffic flow and amount of removed loose snow. However, one problem is that on some occasions there is no loose snow at all remaining in the wheel tracks at the time of observation. In that case one can assume that the observed amount of traffic flow would have removed more snow if the snow fall would have been heavier. Those observations are considered censurered since the actual amount of removed loose snow exceeds the observed.

  • 34.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Trafiksäkerhetseffekter av alkolås: en registerstudie2006Report (Other academic)
    Abstract [sv]

    The purpose of this study is to show the potential of improved traffic safety from compulsory alco-lock for those convicted for drink-driving. About 800 of all drivers yearly involved in police reported road accidents with casualties in Sweden are suspected for driving under the influence of alcohol or other drugs. However, many of those drivers have never been convicted for drink-driving, many drivers drive without driving license and many drivers drive cars that are borrowed or stolen. Therefore it is vital to quantify the proportion of the 800 drivers involved in accidents that might be using an alco-lock if that would be compulsory for drivers convicted for drink-driving. One way to assess the potential of improved traffic safety of compulsory alco-lock is to assume that it is drivers with valid or cancelled driving licenses that are affected. The mean number of drivers involved in police reported road accidents with casualties, where the driver has a valid or cancelled driving license and is suspected of drunk driving, is 626 per year, with a 95 percent confidence interval ranging between 605 and 649 drivers. 17 percent of those drivers where convicted for drink-driving at least once during the 10 years preceding the accident and the 95 percent confidence interval is ranging between 16 and 19 percent. A regulation of compulsory alco-locks for drivers convicted of drink-driving is estimated to reduce the number police-reported road accidents with casualties with with 571 during the first ten years, of which 218 are accidents with fatalities or serious personal injuries.

  • 35.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Utvärdering av projektet Nationell samverkan mot alkohol och droger i trafiken enligt Skelleftemodellen: samhällsekonomisk bedömning2009Report (Other academic)
    Abstract [sv]

    The benefit being studied in this socio-economic evaluation pertains to the decrease achieved in the number of traffic accidents involving drunk drivers. Roughly 2% of those who are charged with drunk driving will be involved in a traffic accident while drunk within 10 years after being found guilty of drunk driving. This figure could be reduced were it possible to successfully reduce drug and alcohol use by these perpetrators after they have been found guilty. Acceptance of the offer made under the Skellefte Model is presumed to have such an effect. The effect of the Skellefte Model differs from individual to individual. It is assumed that the Skellefte Model will influence an individual charged with drunk driving to refrain for longer periods from driving while drunk. This would in turn decrease the likelihood of the individual being involved in an accident while drunk from 2% to some lower level, which would be determined by how much longer such periods last, which would in turn entail fewer drug- or alcohol-related accidents. Two scenarios have been studied; one in which the median increase in the length of time without a recurrence of drunk driving equals one week, and another where the median period is one month. A decrease in accidents represents a social benefit. This benefit must be weighed against the costs in the form of person-hours expended in extending the offer to suspected drunk drivers and arranging an interview. These costs have been estimated based on the questionnaire responses. The calculations indicate that if the effect is that the median increase in time without driving drunk equals one week, then each interviewed suspected drunk driver represents a socio-economic loss of roughly SEK 6, while a median time of one month yields a gain of nearly SEK 82. If the median increase in time without drunk driving is one month, a socio-economic gain is achieved, although no fixed costs have been factored into the analysis. The magnitude of the fixed costs ultimately associated with the Skellefte Model is unclear. Two scenarios have been studied, one corresponding to one full-time worker (taking into account earnings for one year and all overheads), another corresponding to two such workers. To cover these costs, a given number of suspected drunk drivers must be questioned annually in accordance with the Skellefte Model. Two scenarios have been studied, with the offer made to 12,000 people and 24,000 people, respectively. Socio-economic calculations have been performed for each combination of scenarios. We find that the socio-economic benefit is positive both when the median increase in time without a recurrence of drunk driving equals at least one month and for the alternatives in which 24,000 suspected drunk drivers are questioned annually or the fixed costs correspond to one full-time worker.

  • 36.
    Wiklund, Mats
    et al.
    Swedish National Road and Transport Research Institute.
    Hjort, Mattias
    Swedish National Road and Transport Research Institute.
    Kartläggning av bussolyckor vintertid2006Report (Other academic)
    Abstract [sv]

    In an earlier VTI study from 1997 in which the tyre usage for heavy vehicles was surveyed, statistics suggested that buses may have a larger problem with slippery roads compared to other vehicle types, like personal cars and heavy trucks. The statistical data was however not large enough to conclude that this is the case. Therefore, the present study was conducted with the aid of accident data for various vehicle types collected from VITS, the information system for traffic safety of the Swedish Road Administration. The information concerns accidents that occurred during seven winters 1995/1996-2001/2002. Corresponding information has also been collected from Finnish accident data. All of the statistical analyses in this study indicate problems with traffic safety for buses on icy or snowy roads. However, none of these results are statistically significant. The statistical uncertainty in these results stems from a low number of accidents, but also from a lack of information regarding the actual travelled distance on different road conditions for the vehicles. It is probably necessary to know the travelled distance on different road conditions for buses to make a conclusion about accident probability for buses on winter roads. We will therefore make inquiries to bus companies in Sweden during the winters 2005/2006 and 2006/2007 concerning the travelled distances on different road conditions to complete the present study.

  • 37.
    Wiklund, Mats
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Simonsson, Lennart
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Forsman, Åsa
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Hallberg, Örjan
    Hallberg Independent Research.
    Johansson, Östen
    Swedish National Road and Transport Research Institute.
    Trafiksäkerhet och konjunktur: modellansatser och litteraturstudie2011Report (Other academic)
    Abstract [en]

    This project includes two subprojects. The objective of the first subproject has been to investigate which types of accidents are most sensitive to the state of the market and which road user groups are involved. The objective of the second subproject was to study certain conditions, such as percentage of heavy vehicles, percentage of young driving licence holders, vehicle milage per age group, etc., and to see how these covary with the state of the market as well as with the resulting number of killed and injured road users.

    An overview of the statistical methods that other researchers have used and which measures of the state of the market they have included in their models is given in this report. It was concluded that unemployment was the most common economic variable, where an increase in unemployment indicates a decrease in the number of killed road users. It was then shown that part of the reduction in the number of fatalities is explained by young drivers' reducing their car use. This applies particulary to the regression in the early 1990s. There is, however, still a remaining effect of unemployment that cannot be explained by young drivers car use. An attempt to compare fatal accidents where the driver behavior has been inappropriate, such as speeding, not using safety belt or being under the influence of drugs, before and in a recession revealed a sometimes surprising similarity. In absolute numbers it seems that some risk-taking drivers may have dropped out of the traffic or changed behaviour in the recession. The number of fatal accidents with more careful drivers has however decreased by a similar degree. Why the number of fatal accidents with risk-taking and more careful drivers decreased by a similar amount, in a relative sense, is not clear.

  • 38.
    Wiklund, Mats
    et al.
    Swedish National Road and Transport Research Institute.
    Wretling, Peter
    Swedish National Road and Transport Research Institute.
    Register över trafikmätningar: förutsättningar och förslag till utformning1997Report (Other academic)
  • 39.
    Wågberg, Lars-Göran
    et al.
    Swedish National Road and Transport Research Institute.
    Grudemo, Stefan
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Litteraturstudie av däckdubbars effekt på vägslitage, väglag, trafiksäkerhet och miljö2004Report (Other academic)
    Abstract [sv]

    Detta notat är en sammanställning av en litteraturstudie av effekter av  dubbdäcksanvändning. Studerade effekter omfattar slitage friktion, väglag,  säkerhet och miljö. Studien har genomförts under kort tid, ungefär en månad,  vilket innebär att den inte kunnat bli fullständig och heltäckande. Värdering  av effekter har inte ingått i studien. Studien har alltså haft begränsad  omfattning och värdering av effekter har inte kartlagts. Det medför att det  inom ramen för denna studie inte finns utrymme för att genomföra en analys av olika åtgärder för att minska dubbdäcksanvändningen.

  • 40.
    Öberg, Gudrun
    et al.
    Swedish National Road and Transport Research Institute.
    Junghard, Ola
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    En studie av metoder för att beräkna samband mellan dubbdäcksanvändning och trafiksäkerhet1993Report (Other academic)
  • 41.
    Öberg, Gudrun
    et al.
    Swedish National Road and Transport Research Institute.
    Nordström, Olle
    Swedish National Road and Transport Research Institute.
    Wallman, Carl-Gustaf
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Wretling, Peter
    Swedish National Road and Transport Research Institute.
    Tunga fordons däckanvändning: effekter vid is/snöväglag2000Report (Other (popular science, discussion, etc.))
    Abstract [en]

    The following subprojects were included in the investigation into whether the use of winter tyres on heavy vehicles should be a legal requirement in Sweden: • A literary study. • A survey of heavy vehicle tyres, their quality and use. • Gripping power on ice. • Driving properties. • An accident survey. • Economic consequences of a legal requirement. The literary study showed the importance of having good quality tyres of the right type. The project then went on to examine the gripping power on ice of a range of tyres. Studded tyres had the best gripping power. Sipes (transverse cuts in the tyre tread) contribute to good sliding friction properties in unstudded tyres. There were considerable differences in friction properties of the best and worst quality unstudded tyres. Stability, steering and braking properties were studied in test drives on an ice-covered airfield. Studded winter tyres on all wheels delivered far greater braking capacity than unstudded tyres on all wheels. New winter tyres provided much greater braking capacity than half worn summer tyres. There was no significant difference between the alternatives as regards lateral evasion maneuver capacity during optimal steering. When vehicles were undergoing inspection at the test station, questionnaires were distributed to all heavy vehicle drivers at selected locations across the country. The questionnaires indicate that winter tyres are primarily used on the wheels on the driving axel (approximately 60%). Summer tyres are most frequently used on the wheels on the front axles and trailers. The use of studded tyres is low. Accident data from the National Swedish Road Administration has been supplemented by sending out questionnaires to heavy vehicle owners involved in accidents during the winter of 1998-99. The results do not make it possible to draw any conclusions regarding improved levels of road safety should winter tyres be used in icy and snowy road conditions. Studies of gripping power on ice and driving properties show that if driver behaviour did not change with tyre selection, the change from summer to winter tyres would enhance road safety on icy and snowy roads. This means that after this investigation there can be no argument for introducing a legal requirement regarding the use of winter tyres for heavy vehicles. Heavy vehicle tyres should however be improved so that they have the same gripping power as the tyres of light vehicles.

  • 42.
    Öberg, Gudrun
    et al.
    Swedish National Road and Transport Research Institute.
    Velin, Hans
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Effekt av vinterdäcklagen på däckanvändning och olyckor2002Report (Other (popular science, discussion, etc.))
    Abstract [en]

    The aim of this project is to arrive at a preliminary indication of how the use of tyres and traffic safety were changed when the Law on winter tyres was in force; this Law directs that cars, light lorries and buses, of a total weight not exceeding 3.5 tonnes, shall during the period 1 December-31 March, when travelling on a road, be fitted with winter tyres or similar equipment when winter road conditions prevail. This Law came into force on 1 December 1999.

    The use of tyres was investigated at parking sites in Östergötland. Apart from the type of tyre (summer tyres/winter tyres without studs/winter tyres with studs), the year of manufacture, tread depth and stud protrusion were also noted.

    The traffic safety effect of the use of different tyres cannot be investigated directly since information concerning tyres is not included in accident data. The effect was therefore investigated by comparing two winters before the introduction of the Law with two winters when the requirement concerning winter tyres was in force. In order to reduce the influence of other changes, control areas were used. In the north of Sweden, practically all cars had winter tyres before the Law. There should therefore be only a small change in tyre use. Northern Sweden can therefore be used as a control area. In order that there should also be a control area in the south, a request was made to Denmark, where there had also been no change in tyre use, if it would be possible to utilise data from there. In order that the effect of the Tyre Law should be further elucidated, the roads in Sweden where a special winter speed limit was in force during the period concerned were also excluded. Southern Sweden up to a line to the north of the counties of Bohuslän and Uppland was therefore used as test areas.  

  • 43.
    Öberg, Gudrun
    et al.
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Winter tyres: Traffic safety2005Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    During the winter 1993/94, the Swedish National Road Administration received considerable criticism for its winter maintenance and in particular for the high consumption if road salt. This led to discussions on changing the rules for winter maintenance. Some ice or snow was temporary allowed on the roads with high winter maintenance standard. More roads were degraded to lower winter maintenance standard where ice or snow were permanently permitted. In addition, certain changes intended to influence driver behaviour and vehicle equipment for example mandating the use of winter tyres were to be studied. The purpose of the first investigation described in this paper was to calculate the socio-economic consequences that may be expected from a requirement on winter tyres in various circumstances. In the second investigation in this paper the traffic safety effect of the requirement is studied. A requirement of using winter tyres when it is slippery was selected based on facts from the first investigation.

  • 44.
    Öberg, Gudrun
    et al.
    Swedish National Road and Transport Research Institute.
    Wiklund, Mats
    Swedish National Road and Transport Research Institute.
    Nilsson, Jan-Eric
    Swedish National Road and Transport Research Institute.
    Granskning av Vägverkets och Banverkets förslag till drift- och underhållsstrategier2003Report (Other academic)
    Abstract [en]

    The Government has assigned the Swedish Road and Transport Research Institute the task of analysing the content of the proposals for operation and maintenance strategies that the Swedish National Road Administration and Banverket (the Swedish National Rail Administration) have submitted for comment. This memorandum constitutes a report of this assignment.

    Common to both the traffic administrations is the extensive knowledge in the form of descriptions of the road and rail networks’ standard that are available when planning. Important parts of this material have also been supplemented with studies and surveys, and by having the regions themselves work on special issues.

    According to the directives of the Ministry of Industry, Employment and Communications, the two administrations are to devise their own proposals for measures to minimise the cost to the public economy of keeping the infrastructure accessible for traffic. The criteria for when measures are to be applied – which the National Road Administration calls target levels – should therefore be chosen on this basis. The problem here is that it is difficult, and in many cases impossible, on the basis of the available documentation, to determine how the target levels have been chosen, whether this has been done according to public economy principles, or if other considerations have been the guiding principles when determining these limits. For these reasons, it has not been possible in our analysis to ascertain whether a reasonable balance has been achieved between different aspects of the measures proposed with regard to operation.  

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