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  • 1.
    Anund, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Kecklund, Göran
    Karolinska Institutet.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute.
    Hjälmdahl, Magnus
    Swedish National Road and Transport Research Institute.
    Åkerstedt, Torbjörn
    Stockholms universitet, Karolinska Institutet.
    The alerting effect of hitting a rumble strip: a simulator study with sleepy drivers.2008In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 40, no 6, p. 1970-6Article in journal (Refereed)
    Abstract [en]

    A moving base driving simulator experiment was carried out in order to investigate the effects of milled rumble strips on driver fatigue. There were rumble strips both at the edge line and centre line. Four different physical designs of milled rumble strips (yielding noise values from 1.5 to 16 dBA) and two placements on shoulder were used in the experiment. Sound and vibrations from real milled rumble strips were reproduced in the simulator. In total 35 regular shift workers drove during the morning hours after a full night shift. The main results showed an increase in sleepiness indicators (EEG alpha/theta activity, eye closure duration, standard deviation of lateral position, subjective sleepiness) from start to before hitting the rumble strip, an alerting effect in most parameters (not subjective sleepiness) after hitting the strip. The alertness enhancing effect was, however, short and the sleepiness signs returned 5 min after the rumble strip hit. Essentially no effects were seen due to type of strip. It was concluded that various aspects of sleepiness are increased before hitting a rumble strip and that the effect is very short-lived. Type of strip, as used in the present study did not have any effect.

  • 2.
    Carlsson, Arne
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Enviroment and traffic analysis.
    Björketun, Urban
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Säker framkomlighet: trafiksäkerhetseffekter på mitträfflade vägar2012Report (Other academic)
    Abstract [en]

    Within the project “Safe accessibility” initiated by the Swedish Transport Administration, development of the use of rumble strips as a measure for improved traffic safety is carried out. Rumble strips are placed in the centre line on roads wider than 7 metres and with a speed limit of 80 km/h or higher. At the request of the Swedish Transport Administration, VTI has completed a study analysing the effect of such rumble strips on the road. The main purpose with central rumble strips is to “wake up” drivers who for some reason unintentionally are starting to pass the middle line. Earlier studies abroad and Swedish in-depth fatal accident studies indicate that this measure would have a positive safety effect, especially on running off the road to the left and head-on accidents. The aim of this report is to study the accident rates on roads which have been equipped with rumble strips in the middle. The most important parameter to study is the rate of fatalities or seriously injured road users (FSI-rate) after the measure (performance of rumble strips) compared to the FSI-rate before the measure. It should also have been desirable to study the course of accidents of the actual accident types. However, it has not yet been possible to perform such studies due to uncertain accuracy in the accident spot determination and description of the accident course. The analysis is based on information about the location of roads with rumble strips from the regional offices of the Swedish Transport Administration and accident data from the data base STRADA in the period 2003–2009. The work is a before/after-study in which accident rate before the milling of rumble strips in the middle of the road is compared with the period after. Some of the roads have been equipped with automatic speed cameras during the project. In the present summary, mainly results from roads which were not equipped with speed cameras are accounted for; 212 objects of the total length of 2,570 km. But 17 of these 212 objects have got a reduction of speed limit in September 2008. Thus there are 195 objects with unchanged speed limit, which consist the main results of the study.

  • 3.
    Dukic, Tania
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Björketun, Urban
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Kettwich, Carmen
    Karlsruhe Institute of Technology.
    Yahya, Mohammad Reza
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Patten, Christopher
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Tapani, Andreas
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Inverkan av elektroniska reklamskyltar på trafiksäkerhet: en studie på E4 i Stockholm2011Report (Other academic)
    Abstract [en]

    The present report presents four studies that were conducted with the aim to evaluate how electronic billboards (ERS) affect traffic safety. Study 1 is a literature review to examine how billboards impact road safety. The conclusions from the review showed that animated pictures and the location of the billboards have a major impact on driver behaviour as well as that darkness and adverse weather conditions can create glare which makes driving difficult especially for older drivers.

    The second and third studies compared the speed and the number of accidents before and after the installation of the billboards. Neither difference in traffic volume nor in average speed could be demonstrated. There was nothing in the studied accidents to suggest that the accident was affected by a billboard.

    The fourth sub-study is a field study investigating 41 drivers (driving and visual behaviour) on the E4 as they pass the billboards. Results showed several cases of visual distraction. The results also show a negative attitude to the billboards for a majority of the drivers.

    In summary, no effects from the billboards on traffic safety could be showed at the macro level. However, the effects of visual distraction must be taken into consideration and investigated further before deciding whether billboards will be implemented on Swedish roads.

  • 4.
    Elvik, Rune
    et al.
    Institute of Transport Economics.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Hels, Tove
    Rigspolitiet, Denmark.
    van Schagen, Ingrid
    SWOV Institute for Road Safety Research, Netherlands.
    Updated estimates of the relationship between speed and road safety at the aggregate and individual levels2019In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 123, p. 114-122Article in journal (Refereed)
    Abstract [en]

    Recent studies of the relationship between the speed of traffic and road safety, stated as the number of fatalities and the number of injury accidents, are reviewed and their results synthesised by means of meta-analysis. All studies were based on data fully or partly for years after 2000. Previously proposed models of the relationship between the speed of traffic and road safety, including the Power Model and an Exponential Model, are supported. Summary estimates of coefficients show that the relationship between speed and road safety remains strong. The Power Model and the Exponential Model both fit the data very well. The relationship between speed and road safety is the same at the individual driver level as at the aggregate level referring to the mean speed of traffic.

  • 5.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute.
    Gustafsson, Susanne
    Swedish National Road and Transport Research Institute.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute.
    Impact of Nonresponse and Weighting in a Swedish Survey2007In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 1993, p. 80-88Article in journal (Refereed)
    Abstract [en]

    Results from travel surveys, together with traffic monitoring programs, serve as a basis for policy decisions and evaluations. Correct interpretation of the survey results is therefore of vital importance, and the impact of different sources of error needs to be investigated. This paper presents a study of nonresponse errors in a Swedish travel survey. Survey methodologists have addressed the problem of nonresponse for a long time, and several methods have been developed to reduce possible bias. Particularly common are different weighting methods based on auxiliary information. However, the performance of these techniques is based on how well the chosen auxiliary variables can explain the response behavior. The aims of the present study were to (a) investigate whether the mobility of nonrespondents differs from the mobility of respondents and (b) determine whether weighting reduces possible nonresponse bias. A weighting technique called calibration was used. The travel survey was based on a mail questionnaire, and the response rate was about 53%. Nonrespondents were contacted by telephone and asked a selected number of questions from the original questionnaire. Results show that mobility did differ between respondents and nonrespondents for some of the travel modes. The effect of calibration was generally small and inconsistent; the bias was reduced in some cases and increased in others. Nevertheless, calibration is recommended if procedures for calculating the weights are readily available.

  • 6.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System. VTI.
    Förslag på metod för att mäta den subjektiva upptäcktsrisken med avseende på rattfylleribrott2017Report (Refereed)
    Abstract [sv]

    Syftet med det här projektet har varit att föreslå en metod för att utvärdera förändringar i polisens arbetssätt med avseende på rattfylleriövervakning. Huvudsakligen handlar det om att mäta den subjektiva upptäcktsrisken, men utvärdering av polisens arbetssätt och kommunikation föreslås också. Det finns två viktiga delar i polisens strategi för övervakning: kontroller och kommunikation. Den sammantagna effekten av detta behöver utvärderas men man bör även titta på de olika delarna var för sig. I detta pm föreslås därför en utvärdering med tre olika delstudier. För var och en av delstudierna förutsetts att man gör både före- och eftermätningar i dels det område där arbetssättet förändras och dels i ett kontrollområde. Vi är dock medvetna om detta är en ideal situation som kanske inte är möjlig i praktiken. Om en utvärdering kommer att genomföras kan därför förslaget behöva modifieras för att passa de förutsättningar som då råder. De tre olika delstudierna är: Delstudie 1: Utvärdering av polisens implementering Den här delstudien är uppdelad i två nivåer där syftet med nivå 1 är att studera hur polisen ändrat sitt arbetssätt och syftet med nivå 2 är att studera vad som fungerat bra och mindre bra i implementeringen från polisens perspektiv. Nivå 1 är nödvändig för att tolka resultatet av övriga delar i utvärderingar och nivå 2 är en fördjupad utvärdering. Exempel på data som föreslås samlas in är: var och när kontroller genomförs, resultatet av kontrollerna samt informationsspridning till allmänheten. Dessutom föreslås intervjuer med poliser på olika befattningar som deltagit i implementeringen. Delstudie 2: Enkätstudie För att mäta den subjektiva upptäcktsrisken hos förare i allmänhet föreslås en enkätstudie där ett frågeformulär skickas ut via post till ett slumpmässigt urval ur körkortsregistret eller befolkningsregistret (frågorna ska också kunna besvaras som en webbenkät). Målgruppen är personer som har körkort för minst en typ av motorfordon och som också framfört något fordon det senaste året. Ett förslag på utformning av en enkät med 14 frågor har tagits fram. Två frågor behandlar den subjektiva upptäcktsrisken, en som avser upptäcktsrisk på en övergripande nivå och en som avser upptäcktsrisk i fem specifika situationer. Resten av enkäten består av bakgrundsfrågor och frågor om bland annat riskmedvetenhet, normer, om man själv eller någon man känner har blivit stoppad i en kontroll och om man fått information om kontroller via media. Delstudie 3: Utvärdering av kommunikation i sociala medier Syftet med den här delstudien är att bedöma hur väl polisen lyckas nå ut med sitt budskap. Vi föreslår att man samlar in följande typ av information: omfattningen av polisens aktiviteter på sociala medier, spridning, innehåll och karaktär på kommentarerna. Det huvudsakliga syftet med utvärderingen är att mäta subjektiv upptäcktsrisk hos förarpopulationen och jämföra om den har förändrats före och efter att polisen har genomfört förändringar som rör rattfylleriövervakningen. För att uppnå syftet är det nödvändigt att genomföra åtminstone nivå 1 i delstudie 1 (utvärdering av polisens implementering) och delstudie 2 (enkätstudie). Övriga delar är dock också mycket viktiga för att förstå helheten och vi förordar därför att alla delar i utvärderingen genomförs.

  • 7.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Injured motorcyclists in Sweden: Where do the crashes occur and what factors influence the injury severity?2018In: Proceedings of 7th Transport Research Arena TRA 2018, April 16-19, 2018, Vienna, Austria, 2018Conference paper (Refereed)
    Abstract [en]

    Trends in traffic fatalities show that the development for motorcyclists has fallen behind other road users. It is therefore crucial to improve traffic safety for this road user group. The study analyses where in the road network motorcyclists are injured and whether injury severity differs between parts of the network. Injury severity is also examined in relation to other variables such as age, gender, and motorcycle engine performance (i.e., power-to-weight ratio). The results indicate that motorcyclists, relatively more often than passenger car occupants, are injured on low-volume roads that are not subject to any major safety improvements. It is therefore crucial to also encourage other safety measures targeting rider behaviour and vehicle safety. Moreover, analyses of injury severity indicate that, in multiple-vehicle crashes involving motorcycles, the odds of being killed or severely injured are lower on roads with median barriers (i.e., motorways and 2+1 roads) than on two-lane roads.

  • 8.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Skadade motorcyklister: en analys av var i vägnätet som motorcyklister skadas och skadornas svårhetsgrad2014Report (Other academic)
    Abstract [en]

    The main aim of the study was to examine where on the road network motorcyclists are injured. Accidents involving four-wheelers (ATVs, quad bikes) have also been studied, although to a lesser degree. The study is based on police reported injury accidents in Sweden during the period 2003–2012. The results show that motorcyclists, to a greater degree than car occupants, are injured within built-up areas. The same is not true for drivers of four-wheelers. Injury patterns are distributed in the same way as for car occupants between built-up and non built-up areas. Killed and severely injured motorcyclists are overrepresented in accidents at intersections when compared to occupants of passenger cars. The opposite is true for injured four-wheeler drivers who are overrepresented on road sections. The exposure of motorcycle traffic on different parts of the road network is largely unknown. It is therefore, in general, not possible to calculate injury risks. However, when compared to other roads, there seems to be an increased risk of being killed or severely injured on roads with a 70 km/h speed limit.

  • 9.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Gundlegård, David
    Linköpings universitet.
    Ringdahl, Rasmus
    Linköpings universitet.
    Utvärdering av hastighetsmätningar med blåtandssensorer: jämförelse med data från MCS (Motorway Control System)2018Report (Other academic)
    Abstract [en]

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

    The results from the study show that:

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

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

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

  • 10.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute.
    Gustafsson, Susanne
    Swedish National Road and Transport Research Institute.
    Kvalitetsgranskning av TSU92-, en undersökning om resvanor: en studie av urvalsfel, bortfallsfel och mätfel2007Report (Other academic)
    Abstract [sv]

    TSU92- is a travel survey that started in 1992 with the aim to increase the knowledge of travels made by unprotected road-users. The survey is still focused on these groups, but questions of other transport modes are also included. An evaluation of the quality of the survey is presented in this report and measures to improve the quality are suggested. The study is limited to sampling errors, nonresponse errors, and measurement errors. The evaluation has been conducted as three separate studies. The aim of the study of sampling errors was to establish variance formulae for estimating the size of the errors and to calculate these variances. The aim of the study of nonresponse error was to examine whether respondents and nonrespondents differ with respect to travel habits and, to examine whether calibration reduces possible nonresponse errors. Calibration is a weighting method that are used to compensate for nonresponse. A follow up study of the nonrespondents was conducted to answer these questions. The aim of the study of measurement errors was to examine the extent of the problem with incorrectly filled-in questionnaires, and to try to understand how respondents think when the answer the questions.

  • 11.
    Forsman, Åsa
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Yahya, Mohammad Reza
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Enjalbert, Simon
    UNIVAL.
    Cassani, Mirella
    KITE.
    Amantini, Aladino
    KITE.
    Lai, Frank
    University of Leeds.
    Kecklund, Lena
    MTO Säkerhet AB.
    Arvidsson, Marcus
    MTO Säkerhet AB.
    Results from the analysis and input to the development and validation of the statistical models2011Report (Other academic)
    Abstract [en]

    The aim of Deliverable 5.1 of the ITERATE project is to present results of analyses made of the data collected in the ITERATE WP4 driving simulator experiments. The ITERATE WP4 driving simulator experiments consisted of train and car driving experiments carried out on a portable car/train driving simulator platform and in full scale car and train driving simulators. The analyses conducted and presented in this deliverable consist of hypothesis testing, cluster analysis and development of a procedure for estimation of parameters of relationships in the WP6 UMD simulation model. Findings from the analyses show that country was found to be an important factor in both the car and train driving experiment. Significant effects of the factor workload were also established in many of the events analysed. The conclusion of comparisons between the data collected in the portable and full scale simulators is that the ITERATE portable driving simulator platform is a suitable tool to studying underlying factors controlling driver behaviour at least for the car diving. However, there were differences between the portable and full scale train simulators. These differences have to be considered in later stages of the project. The next step within the ITERATE project is to estimate relevant relationships in the WP6 UMD simulation model based on the findings of the analyses presented in this deliverable. The analyses presented will also be important as inspiration for other studies outside of the present project with the ITERATE driving simulator dataset as an important source of data.

  • 12.
    Gustafsson, Susanne
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Forward, Sonja
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Larsson, Jörgen
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Simonsson, Lennart
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Sörensen, Gunilla
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vägtrafikens hastigheter: kunskapsinventering2012Report (Other academic)
    Abstract [en]

    In order to achieve the interim target for road safety it is necessary that compliance of speed limits increases at the road network. VTI has been commissioned by the Swedish Transport Administration to analyse major problems and challenges concerning velocity, and to identify key areas for action.

    Through a review of available knowledge about speed, and gain of new knowledge from focus group discussions we found that different types of incentives are needed for both private motorists and professional drivers to hold the speed.

    Both education and information are important to motivate the driver to act correctly and create a norm in society that deprecates speed violations. However, this should occur in combination with speed monitoring and technical measures.

  • 13.
    Gustafsson, Susanne
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Användning och behov av effektsamband i tätort: Resultat från en enkät2012Report (Other academic)
    Abstract [sv]

    Som en del i projektet ”Effektsamband för vägtransportsystemet – kartläggning av användning samt uppdatering av effekter för tätort” har en enkätstudie genomförts. Syftet med enkäten var att kartlägga användning och behov av effektsamband i tätorter med ett speciellt fokus är på Trafikverkets publikationsserie Effektsamband för vägtransportsystemet.

    Enkätens målgrupp var personer som arbetar med trafikåtgärder i tätort i kommuner, kommunala bolag, statliga verk eller myndigheter, privata företag och på högskola/universitet. Den omfattande enkäten besvarades av drygt 500 personer, varav vardera ca 40 procent hade sin arbetsgivare i någon kommun eller i privat företag.

    Generell användning av underlag och behov av stöd för att beskriva åtgärders effekter inom tätort

    Det kan konstateras att det är en låg andel av respondenterna som anser att de generellt har tillgång till ett bra underlag för att beskriva en åtgärds effekter inom tätort. De underlag man främst använder är ganska informella, dvs. praktisk erfarenhet och goda exempel från andra, snarare än färdiga handböcker, såsom TRAST, Rätt fart i staden, GCM-handboken, Åtgärdskatalog för säker trafik i tätort och Trafikverkets effektsamband för vägtransportsystemet. En majoritet av respondenterna anger dock att de önskar handböcker som främsta stöd för att beskriva en åtgärds effekter inom tätort.

    Det är mer vanligt att respondenterna tar fram kostnader för olika typer av åtgärder än att de beräknar effekter för olika typer av åtgärder eller gör samhällsekonomiska beräkningar vid prioritering av olika typer av åtgärder.  De verktyg som används är främst för samhällsekonomiska analyser, kapacitetsanalyser, trafikprognoser och trafiknätsanalyser.

    Respondenterna anger att det saknas information/kunskap om hur man beräknar effekter för en kombination av olika åtgärder inom tätort och att det saknas information/kunskap om hur man väger ihop olika typer av effekter för en åtgärd. En stor andel av respondenterna har behov av ytterligare stöd för att beskriva en åtgärds effekter, främst inom nybyggnation och förbättringsåtgärder, gång och cykel samt kollektivtrafik. 

    Användning och upplevelser samt behov av utveckling när det gäller Trafikverkets Effektsamband för vägtransportsystemet

    Trafikverkets publikationsserie Effektsamband för vägtransportsystemet har, jämfört med exempelvis VGU (Vägars och gators utformning), en mycket låg användning. Publikationsserien används i högre utsträckning av konsulter än av personer som arbetar i kommuner eller kommunala bolag. Katalogerna Nybyggnation och förbättring av vägar och gator samt Gemensamma förutsättningar används i högre utsträckning än de andra katalogerna (Kollektivtrafik, Drift och underhåll, Sektorsuppgifter och myndighetsutövning). I första hand används Trafikverkets publikationsserie som ett uppslagsverk. En hel del använder den också för val och motivering av åtgärd, effektbedömning för nybyggnation och förbättringsåtgärder samt samhällsekonomiska kalkyler.

    Tillgängligheten på Trafikverkets hemsida upplevs som bättre än användbarheten för åtgärder inom tätort. Samtliga fem kataloger upplevs som bättre vad gäller innehåll än struktur. Sämst upplevs katalogerna vara när det gäller uppdateringar. Den katalog som upplevs som bäst när det gäller innehåll, struktur och uppdateringar är Nybyggnation och förbättring av vägar och gator.

    Inom de flesta områden finns ett behov av att utveckla de flesta effekter när det gäller tätort, undantaget är goodwill för den egna organisationen. Effekter för trafikbuller anses också, jämfört med andra effekter, vara tillräckligt utvecklade.  

    Inom Trafikverkets katalog Nybyggnation och förbättring av vägar och gator finns störst utvecklingsbehov när det gäller effekter för oskyddade trafikanter, exploateringseffekter och effekter för trängsel.

    Inom området Gång och cykel finns störst utvecklingsbehov av effekter när det gäller tillgänglighet för cyklister och gående till målpunkter i tätort samt trafiksäkerhet och trygghet.

    Störst utvecklingsbehov inom katalogen Kollektivtrafik finns när det gäller effekter för regional utveckling och tillgänglighet för kollektivtrafiken till målpunkter i tätort samt trygghet. 

    Inom området Mobility management/Hållbart resande finns störst utvecklingsbehov när det gäller effekter för överflyttning från bil till gång och cykel samt överflyttning från bil till kollektivtrafik.

    Inom katalogen Drift och underhåll anses störst utvecklingsbehov finnas av effekter för trafiksäkerhet, oskyddade trafikanter och kostnader. 

    Störst utvecklingsbehov inom området Logistik och godstransporter finns gällande effekter för tillgänglighet till målpunkter vid lastning och lossning av gods liksom effekter för trängsel, kostnader och omlastningscentral/ logistikcentra.

    Slutsatser

    De områden som visar på mest utvecklingsbehov av effektsamband och där det finns anledning att gå vidare när det gäller framtagning/publicering av effektsamband i tätort är:

    • ·        Oskyddade trafikanter (fotgängare och cyklister)
      • o   Tillgänglighet
      • o   Trafiksäkerhet
      • o   Trygghet

     

    • ·        Hållbart resande (mobility management)
      • o   Kollektivtrafik (bl.a. överflyttning från bil)
      • o   Gång och cykel (bl.a. överflyttning från bil)

     

    • ·        Drift och underhåll
      • o   Trafiksäkerhet
      • o   Oskyddade trafikanter

    Utvecklingsbehov finns också när det gäller effekter för en kombination av olika åtgärder eller hur man väger ihop olika typer av effekter för en åtgärd.

    Publiceringsformen för effektsamband bör, enligt respondenterna, vara i form av handböcker. Även beräkningsverktyg och checklistor efterfrågas. Det som är viktigt är att sambanden är tydliga och enkla att använda samt lättillgängliga, gärna även webbaserade.

     

  • 14.
    Hjort, Urban
    et al.
    Department of Mathematical Statistics, Chalmers University of Technology.
    Vadeby, Anna
    Linköpings universitet, Matematisk statistik.
    The empirical KL-measure of MCMC convergenceManuscript (preprint) (Other academic)
    Abstract [en]

    A new measure based on comparison of empirical distributions for sub sequences or parallel runs and the full sequence of Markov chain Monte Carlo simulation, is proposed as a criterion of stability or convergence. The measure is also put forward as a loss function when the design, including the proposal function, of a Markov chain is optimised. The comparison of empirical distributions is based on a Kullback-Leibler (KL) type distance over value sets defined by the output data. The singularity problem for such a measure is removed in a simple way.

    The leading term in a series expansion of the measure gives an interpretation in terms of the relative uncertainty of cell frequencies measured by their average coefficient of variation. The validity of the leading term is studied by simulation in two analytically tractable cases with Markov dependency and selected acceptance rates. The agreement between the leading term and the KL-measure is close, in particular when the simulations are extensive enough for stable results. Comparisons with established criteria turn out favourably in examples studied.

  • 15.
    Hjorth, Urban
    et al.
    Chalmers Tekniska Högskola.
    Vadeby, Anna
    Linköpings universitet.
    Subsample distribution distance and McMC convergence2005In: Scandinavian Journal of Statistics, ISSN 0303-6898, E-ISSN 1467-9469, Vol. 32, no 2, p. 313-326Article in journal (Refereed)
    Abstract [en]

    A new measure based on comparison of empirical distributions for sub sequences or parallel runs and the full sequence of Markov chain Monte Carlo simulations, is proposed as a criterion of stability or convergence. The measure is also put forward as a loss function when the design of a Markov chain is optimized. The comparison is based on a Kullback–Leibler (KL) type distance over value sets defined by the output data.

    The leading term in a series expansion gives an interpretation in terms of the relative uncertainty of cell frequencies. The validity of this term is studied by simulation in two analytically tractable cases with Markov dependency. The agreement between the leading term and the KL-measure is close, in particular when the simulations are extensive enough for stable results. Comparisons with established criteria turn out favourably in examples studied.

  • 16.
    Hjälmdahl, Magnus
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport.
    Vadeby, Anna
    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.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Ceder, Gunnel
    National Board for Forensic Medicine, Linköping.
    Woxler, Per
    Östergötlands Läns Landsting, Psykiatriska kliniken.
    Kronstrand, Robert
    Linköpings universitet, Avdelningen för läkemedelsforskning.
    Effects of d-amphetamine on simulated driving performance before and after sleep deprivation2012In: Psychopharmacology, ISSN 0033-3158, E-ISSN 1432-2072, Vol. 222, no 3, p. 401-411Article in journal (Refereed)
    Abstract [en]

    Stimulant drugs are commonly abused and also used to promote wakefulness, yet their effects on driving performance during sleep deprivation have not been thoroughly researched in experimental studies. The aims were to assess the effects on fundamental driving parameters during simulated driving of two doses of d-amphetamine and further to assess the interaction between d-amphetamine and sleep deprivation. A double-blind, placebo-controlled experiment including 18 healthy male volunteers was conducted. The participants felt more alert when taking a dose of d-amphetamine than when taking placebo, and the effect was stronger for the higher dose. However, the data did not show any evidence that taking d-amphetamine prevented the subjects from becoming successively sleepier during the night. A significant main effect of the dose was found for three out of the five primary indicators where the lower dose led to improved driving. These indicators were crossing-car reaction time, and coherence and delay from a car-following event. Regarding sleep deprivation, a main effect was found for four of the primary indicators and three of the secondary indicators. The results showed overall impaired driving with respect to standard deviation of lateral position and delay in reaction time when the sleep-deprived conditions were compared to the alert condition. We found no interactions between dose and sleep deprivation for any of the performance indicators. Our results suggest that administration of d-amphetamine does not compensate for impairment of driving due to fatigue. The positive effects of 10 mg were not further improved or even sustained when increasing the dose to 40 mg.

  • 17.
    Ifver, Jan
    et al.
    Transportstyrelsen.
    Amin, Khabat
    Transportstyrelsen.
    Berg, Hans-Yngve
    Transportstyrelsen.
    Larsson, Peter
    Transportstyrelsen.
    Forsman, Åsa
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Lindholm, Magnus
    Trafikverket.
    Strandroth, Johan
    Trafikverket.
    Sternlund, Simon
    Trafikverket.
    Berg, Ylva
    Trafikverket.
    Analys av trafiksäkerhetsutvecklingen inom vägtrafik 2013: Målstyrning av trafiksäkerhetsarbetet mot etappmålen 20202014Report (Other academic)
  • 18.
    Ifver, Jan
    et al.
    Transportstyrelsen.
    Larsson, Peter
    Transportstyrelsen.
    Vadeby, Anna
    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.
    Lindholm, Magnus
    Trafikverket.
    Strandroth, Johan
    Trafikverket.
    Sternlund, Simon
    Trafikverket.
    Berg, Ylva
    Trafikverket.
    Analys av trafiksäkerhetsutvecklingen 2012: målstyrning av trafiksäkerhetsarbetet mot etappmålen 20202013Report (Other academic)
    Abstract [sv]

    Utvecklingen mot trafiksäkerhetsmålen för vägtrafiken år 2020 följs upp genom årliga rapporter. Denna rapport är den femte uppföljningen. I rapporten redovisas och analyseras trafiksäkerhetsutvecklingen under 2012. Liksom tidigare år analyseras utfallet i antalet dödade och skadade samt för ett antal utpekade indikatorer. Rapporten utgör underlag för 2013 års resultatkonferens i Stockholm den 24 april.

  • 19.
    Ifver, Jan
    et al.
    Transportstyrelsen.
    Larsson, Peter
    Transportstyrelsen.
    Vadeby, Anna
    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.
    Melkersson, Maria
    Transportstyrelsen.
    Berg, Ylva
    Trafikverket.
    Strandroth, Johan
    Trafikverket.
    Lindholm, Magnus
    Trafikverket.
    Analys av trafiksäkerhetsutvecklingen 2011: målstyrning av trafiksäkerhetsarbetet mot etappmålen 20202012Report (Other academic)
  • 20.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Eriksson, Olle
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Forsman, Åsa
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Design and analysis of semi-controlled studies2016In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517Article in journal (Refereed)
    Abstract [en]

    Semi-controlled studies provide a hybrid approach in between controlled experiments and naturalistic driving studies. As in controlled experiments, the researcher can assign participants to groups, select the route and define the tasks, but the participants are given more freedom when it comes to if, when, where and how to perform the tasks. Increased flexibility makes it possible to investigate how drivers use tactical behaviour to accommodate task execution. The disadvantage is decreased control and more complicated analyses.

    The main objective of this paper is to discuss how to analyse data obtained in semi-controlled studies.The analysis of data from a semi-controlled study include three types of variables:

    • variables that describe the experimental design
    • variables that describe the tactical choices of the participants
    • operational variables such as speed, lateral position or glance behaviour

    To analyse the three types of variables a two-step procedure is suggested. First, the tactical indicators are analysed with regard to the experimental design. Second, the operational indicators are analysed and the tactical indicators are used to divide participants into sub-populations.

    The semi-controlled design does not need any new statistical procedures to be developed. It is more important that the analysis conditions on the initial properties and not on structures that happen to occur during the experiment, like where the participant chose to do a certain task.We recommend to use the semi-controlled study method when investigating questions involving adaptive and compensatory behaviour on the tactical level. It is especially useful if causal relationships are of interest, if the data collection should be accelerated in comparison to naturalistic studies, and if certain geographical locations definitely should be included.

  • 21.
    Larsson, Jörgen
    et al.
    Swedish National Road and Transport Research Institute.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute.
    Förlåtande sidoområde: en litteraturstudie2006Report (Other academic)
    Abstract [sv]

    Single vehicle accidents are the type of accident that has the largest proportion of fatalities in traffic. About one third of all fatal accidents are single vehicle accidents. The aim of this study is to increase knowledge of how roadside areas should be designed so that the consequences of driving off the road will not be so serious as to cause death or severe injuries. The results are to provide data in formulating future regulations.

  • 22.
    Lassarre, Sylvain
    et al.
    INRETS, France.
    Dozza, Marco
    Jamson, Samantha
    Lai, Frank
    Saad, Farida
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Trent, Victor
    Brower, Rino
    Carsten, Oliver
    Disilvestro, Alessandra
    Feenstra, Philippus
    Hogema, Jeroen
    Lenard, James
    Minett, Claire
    Morris, Andrew
    Noort, Martijn van
    Schrijver, Jeroen
    Taddei, Alessandro
    Data analysis and modelling2008Report (Other academic)
    Abstract [en]

    This deliverable on data analysis provides guidance and general principles for: - pre-testing to check the usability of the system and the feasibility of the evaluation process, - controlling the consistency of the chain and the precision with different sampling schemes, - modelling the impact for each indicators and for an integrated evaluation including a systemic and multidisciplinary interpretation of the effects, - integrating and controlling the quality of space-time data from various sources (numerical, video, questionnaires), - selecting the appropriate statistical techniques for data processing, PI estimation and hypothesis testing in accordance to the list of indicators and experimental design, - scaling up from experimental data and identified models to population and network level. Experimentalists stress the role and importance of a preliminary field test in FOT. Three main objectives have been defined to make a preliminary diagnosis of usability of the systems and to check the relevance and feasibility of the evaluation process. These preliminary tests are very important for the practical deployment of the FOT as well as for the overall scientific evaluation process.

  • 23.
    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.

  • 24.
    Linder, Astrid
    et al.
    Swedish National Road and Transport Research Institute.
    Dukic, Tania
    Swedish National Road and Transport Research Institute.
    Hjort, Mattias
    Swedish National Road and Transport Research Institute.
    Mårdh, Selina
    Swedish National Road and Transport Research Institute.
    Sundström, Jerker
    Swedish National Road and Transport Research Institute.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute.
    Methods for evaluation of Electronic Stability Control (ESC): a literature review2007Conference paper (Refereed)
  • 25.
    Linder, Astrid
    et al.
    Swedish National Road and Transport Research Institute.
    Kircher, Albert
    Swedish National Road and Transport Research Institute.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute.
    Nygårdhs, Sara
    Swedish National Road and Transport Research Institute.
    Intelligent Transport Systems (ITS) in passenger cars and methods for assessment of traffic safety impact: a literature review2007Report (Other academic)
    Abstract [en]

    The background for this study is that many Intelligent Transport Systems (ITS) are currently introduced in passenger vehicles aiming at providing increased traffic safety. This provides a need to assess the traffic safety effects from these systems. The question that this report highlights is how these systems are designed and how the effects are evaluated. The review resulted in identification of 300 references of which the most relevant are found in this report. The report contains a description of the background of why and how 20 systems or groups of systems have been developed, in which vehicles they can be found, a short technical description of how they work, publication of traffic safety effects and future development plans. Regarding statistical methods, an overview of how they work and the results when using these methods on ITS are described. In addition, the report contains a summary of ways of assessing safety effects from areas such as food, nuclear power and pharmaceutical industries. The conclusion is that there are currently many different ways of supporting the driver in the task of driving the vehicle. Regarding the impact on traffic safety of these systems it is still an open question which evaluation methods to use.

  • 26.
    Peters, Björn
    et al.
    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.
    Forsman, Åsa
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Tapani, Andreas
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics. Linköpings universitet, Kommunikations- och transportsystem.
    Developing a unified model of driving behaviour for cars and trains2012In: Human factors of Systems and Technology / [ed] D. de Waard, N. Merat, A.H. Jamson, Y. Barnard and O.M.J. Carsten, Maastricht: Shaker Publishing , 2012, p. 343-357Chapter in book (Refereed)
  • 27.
    Silvano, Ary P.
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Forsman, Åsa
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    A pilot study aiming to increase speed compliance of taxi drivers in Sweden2018Conference paper (Refereed)
    Abstract [en]

    Speed is one of the most key factor that increases the accident risk and injury severity (Nilsson, 2004). Therefore, speed limits are set to guide to choose the right speed based on the road environment. However, compliance level is in general low which means that many drivers choose to drive faster than the speed limit when traffic condition is not congested. Mannering (2009) points out that there is a general disrespect to keep speed limits worldwide. An increase in the compliance level of taxi drivers could potentially influence the chosen speed of other drivers on the roads. It is therefore important to study and quantify compliance level of taxi drivers.

    Public authorities (e.g., police, road administration offices) aim to enforce speed compliance levels on public roads. Speed enforcement campaigns can include police speed control interventions, speed camera surveillance, education campaigns. As a part of this pilot study, police officers plan to meet taxi company representatives to discuss current speed compliance levels an agree on new approaches which can increase compliance levels of taxi drivers

    The aim of the study is thus to investigate a new method aiming to increase speed compliance of taxi drivers involving an agreement between the police and taxi representatives.

  • 28.
    Tapani, Andreas
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Forsman, Åsa
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Mohammad-Reza, Yahya
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Enjalbert, Simon
    UNIVAL.
    Cassani, Mirella
    KITE.
    Amantini, Aladino
    KITE.
    Lai, Frank
    University of Leeds.
    Kecklund, Lena
    MTO.
    Arvidsson, Marcus
    MTO.
    Results from the analysis and input to the development and validation of the statistical models2011Report (Other academic)
    Abstract [en]

    The aim of Deliverable 5.1 of the ITERATE project is to present results of analyses made of the data collected in the ITERATE WP4 driving simulator experiments. The ITERATE WP4 driving simulator experiments consisted of train and car driving experiments carried out on a portable car/train driving simulator platform and in full scale car and train driving simulators. The analyses conducted and presented in this deliverable consist of hypothesis testing, cluster analysis and development of a procedure for estimation of parameters of relationships in the WP6 UMD simulation model. Findings from the analyses show that country was found to be an important factor in both the car and train driving experiment. Significant effects of the factor workload were also established in many of the events analysed. The conclusion of comparisons between the data collected in the portable and full scale simulators is that the ITERATE portable driving simulator platform is a suitable tool to studying underlying factors controlling driver behaviour at least for the car diving. However, there were differences between the portable and full scale train simulators. These differences have to be considered in later stages of the project. The next step within the ITERATE project is to estimate relevant relationships in the WP6 UMD simulation model based on the findings of the analyses presented in this deliverable. The analyses presented will also be important as inspiration for other studies outside of the present project with the ITERATE driving simulator dataset as an important source of data.

  • 29.
    Thomas, Fridtjof
    et al.
    Swedish National Road and Transport Research Institute.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute.
    Sammanställning av 34 trafiksäkerhetsåtgärder2007Report (Other academic)
    Abstract [en]

    VTI compiles here the available knowledge about 34 traffic safety measures that have been utilized in Sweden the past decades. These measures belong to the domains of speed management, alcohol, seat belts, physical infrastructure, road users and vehicles. We group the traffic safety measures based on the reasoning underlying Haddon's matrix. This way of classifying accidents is described and we draw upon its underlying logic to classify the 34 traffic safety measures. The Swedish Road Administration's traffic safety work is guided by the so called Vision Zero. The Ministry of Enterprise, Energy and Communications issued on April 9, 1999, a short program containing eleven topics for increased traffic safety. This program became operational for the Swedish Road Administration and we evaluate therefore the here described 34 traffic safety measures based on the eleven topics in that program. Traffic safety measures in the physical infrastructure such as separation of meeting lanes, roundabouts, and separated strokes for bicycles and pedestrians have to be viewed as the most efficient ones. However, these measures are costly when compared to measures targeting the socio-economic environment such as legislation and enforcement. Therefore the here described measures should be evaluated based on an assessment of the cost-effectiveness of the various measures. Such studies remain to be carried out for a number of traffic safety measurements, but this is beyond the scope of this project.

  • 30.
    Vadeby, Anna
    Linköpings universitet, Matematisk statistik.
    Computer based statistical treatment in models with incidental parameters: inspired by car crash data2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bootstrap and Markov chain Monte Carlo methods have received much attention in recent years. We study computer intensive methods that can be used in complex situations where it is not possible to express the likelihood estimates or the posterior analytically. The work is inspired by a set of car crash data from real traffic.

    We formulate and develop a model for car crash data that aims to estimate and compare the relative collision safety among different car models. This model works sufficiently well, although complications arise due to a growing vector of incidental parameters. The bootstrap is shown to be a useful tool for studying uncertainties of the estimates of the structural parameters. This model is further extended to include driver characteristics. In a Poisson model with similar, but simpler structure, estimates of the structural parameter in the presence of incidental parameters are studied. The profile likelihood, bootstrap and the delta method are compared for deterministic and random incidental parameters. The same asymptotic properties, up to first order, are seen for deterministic as well as random incidental parameters.

    The search for suitable methods that work in complex model structures leads us to consider Markov chain Monte Carlo (MCMC) methods. In the area of MCMC, we consider particularly the question of how and when to claim convergence of the MCMC run in situations where it is only possible to analyse the output values of the run and also how to compare different MCMC modellings. In Metropolis-Hastings algorithm, different proposal functions lead to different realisations. We develop a new convergence diagnostic, based on the Kullback-Leibler distance, which is shown to be particularly useful when comparing different runs. Comparisons with established methods turn out favourably for the KL.

    In both models, a Bayesian analysis is made where the posterior distribution is obtained by MCMC methods. The credible intervals are compared to the corresponding confidence intervals from the bootstrap analysis and are shown to give the same qualitative conclusions.

    List of papers
    1. Modelling and inference of relative collision safety in cars
    Open this publication in new window or tab >>Modelling and inference of relative collision safety in cars
    1998 (English)Licentiate thesis, monograph (Other academic)
    Abstract [en]

    We propose a new mathematical model for relative collision safety in cars. Our present research is restricted to head-on crashes between two cars and we try to determine how much of the injury risk in a crash that depends on car model. The relative risks include the driver populations of the different car models. When two cars crash they are exposed to the same force, but the damage severity is different depending on various factors such as car mass, change of speed and design of the car. To explore the relative risks between different car models, we build a model where we let car mass, change of speed and design of the car explain the injury outcome in the crashes. The mathematical model we use is a birth process where we let the states correspond to the injury classes. A data base containing police reported traffic accidents and hospital information is used to explore the relationships in our model.

    A bootstrap analysis is made to produce a picture of the uncertainty of the estimates. The uncertainty from the bootstrap analysis is compared to the asymptotic estimate of the uncertainty given by the inverse of an information sub-matrix.

    Place, publisher, year, edition, pages
    Linköping: Linköpings Universitet, 1998. p. 51
    Series
    Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 685
    Keywords
    Collision, Mathematical model, Head on collision, Injury, Risk, Car
    National Category
    Mathematical Analysis
    Research subject
    90 Road: Vehicles and vehicle technology, 91 Road: Vehicle design and construction; 80 Road: Traffic safety and accidents, 85 Road: Personal injuries
    Identifiers
    urn:nbn:se:vti:diva-7103 (URN)91-7219-200-3 (ISBN)
    Available from: 2013-01-07 Created: 2014-09-16 Last updated: 2016-02-22Bibliographically approved
    2. The empirical KL-measure of MCMC convergence
    Open this publication in new window or tab >>The empirical KL-measure of MCMC convergence
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    A new measure based on comparison of empirical distributions for sub sequences or parallel runs and the full sequence of Markov chain Monte Carlo simulation, is proposed as a criterion of stability or convergence. The measure is also put forward as a loss function when the design, including the proposal function, of a Markov chain is optimised. The comparison of empirical distributions is based on a Kullback-Leibler (KL) type distance over value sets defined by the output data. The singularity problem for such a measure is removed in a simple way.

    The leading term in a series expansion of the measure gives an interpretation in terms of the relative uncertainty of cell frequencies measured by their average coefficient of variation. The validity of the leading term is studied by simulation in two analytically tractable cases with Markov dependency and selected acceptance rates. The agreement between the leading term and the KL-measure is close, in particular when the simulations are extensive enough for stable results. Comparisons with established criteria turn out favourably in examples studied.

    Keywords
    Calculation, Simulatin, Mathematical model
    National Category
    Natural Sciences
    Research subject
    SAB, T Mathematics
    Identifiers
    urn:nbn:se:vti:diva-7102 (URN)
    Available from: 2013-01-07 Created: 2014-09-16 Last updated: 2016-02-22Bibliographically approved
    3. On Gibbs sampler and Metrolopolis-Hastings applied to pairwise poisson and car crash data
    Open this publication in new window or tab >>On Gibbs sampler and Metrolopolis-Hastings applied to pairwise poisson and car crash data
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    We address the use of MCMC methods in the presence of incidental parameters. Two different models are studied, one pairwise Poisson model and a model for car crash data. In both models, a Bayesian analysis is made where the posterior density is obtained by MCMC methods. The empirical KL-measure is used to diagnose convergence. Credible intervals for structural parameters are computed in both models and compared to the corresponding confidence intervals obtained by frequentist analysis. Although some differences are observed, the methods give qualitatively the same conclusions.

    Keywords
    Accident rate, Statistics, Analysis (math), Method
    National Category
    Probability Theory and Statistics
    Research subject
    80 Road: Traffic safety and accidents, 812 Road: Collation of accident statistics
    Identifiers
    urn:nbn:se:vti:diva-7101 (URN)
    Available from: 2013-01-07 Created: 2014-09-16 Last updated: 2016-02-22Bibliographically approved
    4. Estimation in a model with incidental parameters
    Open this publication in new window or tab >>Estimation in a model with incidental parameters
    2002 (English)Report (Other academic)
    Abstract [en]

    We study the maximum likelihood method together with bootstrap analysis and other uncertainty measures in a situation with both structural and incidental parameters and a rather simple parametric setting. Our purpose is to study methods that can be generalised to and used in more complicated situations of similar nature.

    Two different approaches to the incidental parameters are treated, one deterministic and one random. Both approaches are shown to give similar results. When analysing the asymptotic properties of the estimator of the structural parameter, the profile likelihood, the delta method and the bootstrap analysis seem to be equally good in the deterministic case. The bootstrap also works well with a random interpretation of the incidental parameters.

    Publisher
    p. 18
    Series
    LiTH-MAT-R, ISSN 0348-2960 ; 02
    Keywords
    Statistics, Calculation
    National Category
    Probability Theory and Statistics
    Research subject
    SAB, T Mathematics
    Identifiers
    urn:nbn:se:vti:diva-8302 (URN)
    Available from: 2013-01-07 Created: 2016-02-03 Last updated: 2016-02-22Bibliographically approved
    5. Including driver characteristics in a model of relative collision safety
    Open this publication in new window or tab >>Including driver characteristics in a model of relative collision safety
    2000 (English)Report (Other academic)
    Abstract [en]

    When the relative collision safety between different car makes has been estimated, it has been shown that a person's age and sex influence the injury risk in accidents that are otherwise similar. In an earlier work, relative collisionsafety in cars are studied. That model is now expanded by introducing parameters related to the driver's age and sex. Different models are compared and the "best" model is chosen by a likelihood-ratio-test. The estimated relative risks compensated for the driver's age and sex are compared to the relative risks without such information. The uncertainties of the different estimates are studied by a bootstrap analysis.

    Publisher
    p. 18
    Series
    LiTH-MAT-R, ISSN 0348-2960 ; 19
    Keywords
    Driver, Age, Man, Woman, Properties, Mathematical model, Accident, Risk
    National Category
    Probability Theory and Statistics
    Research subject
    80 Road: Traffic safety and accidents, 812 Road: Collation of accident statistics; 80 Road: Traffic safety and accidents, 85 Road: Personal injuries
    Identifiers
    urn:nbn:se:vti:diva-8303 (URN)
    Available from: 2013-01-07 Created: 2016-02-03 Last updated: 2016-02-22Bibliographically approved
  • 31.
    Vadeby, Anna
    Linköpings universitet, Matematisk statistik.
    Estimation in a model with incidental parameters2002Report (Other academic)
    Abstract [en]

    We study the maximum likelihood method together with bootstrap analysis and other uncertainty measures in a situation with both structural and incidental parameters and a rather simple parametric setting. Our purpose is to study methods that can be generalised to and used in more complicated situations of similar nature.

    Two different approaches to the incidental parameters are treated, one deterministic and one random. Both approaches are shown to give similar results. When analysing the asymptotic properties of the estimator of the structural parameter, the profile likelihood, the delta method and the bootstrap analysis seem to be equally good in the deterministic case. The bootstrap also works well with a random interpretation of the incidental parameters.

  • 32.
    Vadeby, Anna
    Linköpings universitet, Matematisk statistik.
    Including driver characteristics in a model of relative collision safety2000Report (Other academic)
    Abstract [en]

    When the relative collision safety between different car makes has been estimated, it has been shown that a person's age and sex influence the injury risk in accidents that are otherwise similar. In an earlier work, relative collisionsafety in cars are studied. That model is now expanded by introducing parameters related to the driver's age and sex. Different models are compared and the "best" model is chosen by a likelihood-ratio-test. The estimated relative risks compensated for the driver's age and sex are compared to the relative risks without such information. The uncertainties of the different estimates are studied by a bootstrap analysis.

  • 33.
    Vadeby, Anna
    Linköpings universitet, Matematisk statistik.
    Modeling of relative collision safety including driver characteristics2004In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 36, no 5, p. 909-917Article in journal (Refereed)
    Abstract [en]

    We propose a new mathematical model for relative collision safety in cars. Our present research is restricted to head-on crashes between two cars and we try to determine how much of the injury risk in a crash depends on the car make. Previous work shows that a person’s age and sex influence the injury risk in accidents that are otherwise similar. To explore the relative risks between different car makes we build a model where we let the car mass, change of speed, design of the car and the driver’s age and sex explain the injury outcome in the crashes.

    The mathematical model we use is a birth process where the states correspond to the injury classes. A database containing police reported traffic accidents and hospital information is used to explore the relationships in our model. Different models are compared and the “best” model is chosen by a likelihood ratio test. The estimated relative risks compensated for the driver’s age and sex are compared to the relative risks with the driver population included. The uncertainties of the different estimates are studied by a bootstrap analysis.

  • 34.
    Vadeby, Anna
    Linköpings universitet, Matematisk statistik.
    Modelling and inference of relative collision safety in cars1998Licentiate thesis, monograph (Other academic)
    Abstract [en]

    We propose a new mathematical model for relative collision safety in cars. Our present research is restricted to head-on crashes between two cars and we try to determine how much of the injury risk in a crash that depends on car model. The relative risks include the driver populations of the different car models. When two cars crash they are exposed to the same force, but the damage severity is different depending on various factors such as car mass, change of speed and design of the car. To explore the relative risks between different car models, we build a model where we let car mass, change of speed and design of the car explain the injury outcome in the crashes. The mathematical model we use is a birth process where we let the states correspond to the injury classes. A data base containing police reported traffic accidents and hospital information is used to explore the relationships in our model.

    A bootstrap analysis is made to produce a picture of the uncertainty of the estimates. The uncertainty from the bootstrap analysis is compared to the asymptotic estimate of the uncertainty given by the inverse of an information sub-matrix.

  • 35.
    Vadeby, Anna
    Linköpings universitet.
    On Gibbs sampler and Metrolopolis-Hastings applied to pairwise poisson and car crash dataManuscript (preprint) (Other academic)
    Abstract [en]

    We address the use of MCMC methods in the presence of incidental parameters. Two different models are studied, one pairwise Poisson model and a model for car crash data. In both models, a Bayesian analysis is made where the posterior density is obtained by MCMC methods. The empirical KL-measure is used to diagnose convergence. Credible intervals for structural parameters are computed in both models and compared to the corresponding confidence intervals obtained by frequentist analysis. Although some differences are observed, the methods give qualitatively the same conclusions.

  • 36.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Traffic safety effects of narrow 2+1 roads with median barrier in Sweden2016Conference paper (Refereed)
    Abstract [en]

    Deaths on rural roads are a serious road safety problem. Due to the risks imposed by high speeds, multi-functionality, lower infrastructure safety and mix of different road users, rural roads are often dangerous roads with relatively high risk levels compared to motorways. In Sweden, a special road safety concern during the 1990’s was the large amount of fatal and serious crashes on rural 13 m wide 2-lane roads. The solution proved to be a redesign to a 2+1 road usually with a median barrier. Starting 2009, this solution was also applied on rural roads with road width of about 9 – 10 meters. A 2+1 road with median barrier has a continuous three-lane cross section with alternating passing lanes to allow defined sections of overtaking, the two directions of travel separated by a flush divider with a median barrier. Comparing 13 meter wide 2+1 roads with narrow 2+1 roads (9 m), the main difference is the length and frequency of passing lanes. For narrow 2+1 roads, the share of passing lanes varies between 15 – 30% compared to about 40% for the 13-meter roads.

    The main objective of this study is to evaluate the traffic safety effects of these narrow 2+1 roads. A before and after study with control group is performed based on crash statistics from the Swedish crash data base STRADA. Using a control group, the results have been adjusted for the general road safety trend and changes of traffic volumes. In addition, a limited Empirical Bayes study was done to adjust for regression to the mean.

    Results from the before and after study show a number of significant effects; the total number of fatalities and seriously injured decreased by 50 % and the total number of personal injury crashes decreased by 21%. The severity consequence (the rate of the number of killed and seriously injured divided by the number of personal injury crashes) decreased by 38%. Looking only at links (excluding intersections), the number of fatalities and seriously injured decreased by 63% and the personal injury crashes by 28%. Correcting for regression to the mean gave very similar results. It should be noted that the after period is still short and a continued follow up will be done during 2015. For almost all of the included road sections, the speed limit was also raised from 90 km/h to 100 km/h when the road was rebuilt to 2+1. No difference in efficiency compared to earlier evaluations of traditional 2 +1 roads with 100 km/h and 40% passing lanes can be observed.

  • 37.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafiksäkerhet och trafiksystem, TST.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Effectiveness and acceptability of milled rumble strips on rural two-lane roads in Sweden2017In: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 9, no 2, article id 29Article in journal (Refereed)
    Abstract [en]

    Purpose: The study sought to estimate the effects of centreline milled rumble strips on rural two-lane roads in Sweden in a wide perspective. Traffic safety effects (i.e., fewer crashes and injuries), driver experience, and driver opinions of centreline milled rumble strip usage on rural roads are investigated.

    Methods: To evaluate the traffic safety effects, an Empirical Bayes study comparing the outcome before and-after the introduction of rumble strips was conducted. This study is based on data from 2003–2012 from the Swedish national traffic accident database, STRADA. To capture driver experience and opinions about milled centreline rumble strips, focus groups and road-side interviews were performed.

    Results: The results indicate a significant decrease in all types of severe injury crashes, a 20% (±13%) reduction in the number of fatalities and seriously injured people (all crash types) and a 27% (±18%) reduction in the number of fatalities and severely injured people in single-vehicle crashes. Participants in focus groups and road-side interviews generally favoured centreline rumble strips on rural roads, and up to 90% of the interviewed motorcyclists and commuters stated that the rumble strips would help improve traffic safety.

    Conclusions: Rumble strips in the centre of two-lane rural roads are a countermeasure to help drivers who are unintentionally about to leave the lane, for example, due to sleepiness or inattention. Based on the results of this study, installing centreline milled rumble strips on two-lane rural roads 8–10 meters wide is a measure to consider to increase safety.

  • 38.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Hastigheter på kommunala gator i tätort: resultat från mätningar 20132014Report (Other academic)
    Abstract [en]

    The purpose of the present study is to develop a method for following up changes in driver speeds on the main municipality streets in urban areas, and to report the results concerning driver speed levels and speed limit compliance after the first two years of measurement. The results show that in 2013 the average speed was 49.3 km/h. When broken down by speed limit, the average travel speed was 39.2 km/h for the 40 km/h speed limit, 46.9 km/h for the 50 km/h speed limit, and 54.9 km/h for the 60 km/h speed limit, and 61.9 km/h for the 70 km/h speed limit. No significant changes in travel speed occurred in comparison with 2012. There was a broad distribution between the speed levels for the various points within each speed limit; this is natural in urban areas, as there are many other factors in addition to the posted speed limit that will affect drivers' speed choices, such as intersection density, road width, and the presence of street parking and pavements. With respect to the proportion of violations, overall a total of 37 per cent of the traffic drove over the speed limit in 2013; that is, 63 per cent of drivers obeyed the speed limit. Speed limit compliance was worst on roads with a speed limit of 40 km/h, where only 53 per cent of the traffic obeyed the speed limit; 61 per cent obeyed the speed limit on 50 km/h roads, 69 per cent on 60 km/h roads, and 77 per cent on 70 km/h roads. Hence it is primarily speed limit compliance on roads with lower

  • 39.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Hastigheter på kommunala gator i tätort: resultat från mätningar 20142015Report (Other academic)
    Abstract [en]

    The aim of the present study is to report the changes between the years 2013 and 2014 concerning driver speed levels and speed limit compliance on the main municipality streets. The year 2012 was the starting year for the measurement series, and in 2014 a second follow-up was performed. Only the main municipality streets with speed limits between 40 km/h and 70 km/h were included. The measurements were made during the month of September in 23 different municipalities. The results show that in 2014 the space-mean-speed for all vehicles on the main municipality roads was 49 km/h. With respect to the proportion of violations, overall, a total of 37 per cent of the traffic drove over the speed limit in 2014; that is, 63 per cent of drivers obeyed the speed limit. The lowest speed limit compliance was found on roads with a speed limit of 40 km/h, where only 54 per cent of the traffic obeyed the speed limit; 61 per cent obeyed the speed limit on 50 km/h roads, 68 per cent on 60 km/h roads, and 77 per cent on 70 km/h roads. In conclusion, the space-mean-speeds in urban areas are below the legal speed limit, but the lack of speed compliance remains a problem. Primarily, the speed limit compliance on roads with lower speed limits must be improved in order to reach the goal of 80 per cent compliance by 2020.

  • 40.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Hastigheter på kommunala gator i tätort: resultat från mätningar 20152016Report (Other academic)
    Abstract [en]

    In 2009 the Swedish Parliament passed a resolution stating that by 2020 the number of fatalities from road traffic crashes should be reduced to half the level in 2007. This corresponds to a maximum of 220 deaths in 2020. In order to monitor progress toward this goal, yearly national follow-up studies are conducted to examine trends in the numbers of people killed and severely injured, along with a number of indicators. One of these indicators is speed limit compliance on the municipality streets; the milestone here is to have at least 80 per cent of all traffic travelling within the speed limit. The aim of the present study is to report the changes between the years 2014 and 2015 concerning driver speed levels and speed limit compliance on the main municipality streets. The annual measurement series started in year 2012 and with the measurement series from 2015, this third follow-up was performed.

  • 41.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Hastigheter på kommunala gator i tätort: resultat från mätningar 20162017Report (Other academic)
    Abstract [en]

    The aim of the present study is to report the changes between the years 2015 and 2016 concerning driver speed levels and speed limit compliance on the main municipality streets. The year 2012 was the starting year for the measurement series, and in 2016 a fourth follow-up was performed. Only the main municipality streets with speed limits between 40 km/h and 70 km/h were included. The measurements were made during the month of September in 23 different municipalities in Sweden.

    The results show that in 2016 the space-mean-speed for all vehicles on the main municipality roads was 47 km/h. With respect to speed violations, overall, 67 per cent of drivers obeyed the speed limit 2016. The lowest speed limit compliance was found on roads with a speed limit of 40 km/h, where only 53 per cent of the traffic obeyed the speed limit; 68 per cent obeyed the speed limit on 50 km/h roads, 72 per cent on 60 km/h roads, and 78 per cent on 70 km/h roads.

  • 42.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Hastigheter på kommunala gator i tätort: resultat från mätningar år 20172018Report (Other academic)
    Abstract [en]

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

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

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

  • 43.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Hastigheter på kommunala gator i tätort: Resultat från mätningar år 20182019Report (Other academic)
    Abstract [en]

    The aim of the present study is to report the changes between the years 2017 and 2018 concerningdriver speed levels and speed limit compliance on the main municipality streets. The year 2012 wasthe starting year for the measurement series, and in 2018 a sixth follow-up was performed. Only themain municipality streets with speed limits between 40 km/h and 70 km/h were included. Themeasurements were made during the month of September in 23 different municipalities in Sweden.

    The results show that in 2018 the space-mean-speed for all vehicles on the main municipality roadswas 46 km/h. With respect to speed violations, overall, 66 per cent of drivers obeyed the speed limit2017. The lowest speed limit compliance was found on roads with a speed limit of 40 km/h, whereonly 53 per cent of the traffic obeyed the speed limit; 66 per cent obeyed the speed limit on 50 km/hroads, 80 per cent on 60 and 79 per cent on 70 km/h roads.

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

  • 44.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Självförklarande gator: samband mellan faktisk hastighet, hastighetsgräns och trafikmiljö2016Report (Other academic)
    Abstract [en]

    The aim of this study was to improve the understanding of the concept of self-explaining roads in urban areas by studying the relationship between speeds at a particular location, the speed limit and the road environment. The relationship between actual speed levels, speed limit and traffic environment has been studied based on earlier speed measurements in 23 different cities and a total of 69 measuring points. In addition, traffic engineers from 73 different municipalities studied photos from 20 different locations and made an assessment of the speed limit at the site, so-called blind estimation.

    The results show that when the relationship between the speed levels and a number of site-specific background variables was studied, the actual speed levels were explained not only by road-specific variables such as speed limits, traffic flow and road type, but also variables that describe the surrounding environment such as type of area (inner city, residential areas, outside city areas) and presence of vulnerable road users. Blind-estimates of speed limits show that it is difficult to estimate a speed limit only by looking at a photo. Roads with speed limit 70 km/h were most easy to estimate (67% hit-rate) and roads with speed limit 60 km/h were most difficult (35% hit-rate). A logistic regression showed that lane width was the most important factor when predicting the speed limit by only looking at a photo.

    The results showed that the probability of a correct estimate of the speed limit increases the narrower the road gets. In conclusion, the concept of self-explaining roads in urban areas is very difficult with the existing speed limits it is not a reality today from a national perspective. It is far from easy for the road users to assess the present speed limit by only looking at the road and traffic environment if they for some reason failed to notice the speed limit sign.

  • 45.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Björketun, Urban
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Carlsson, Arne
    Swedish National Road and Transport Research Institute, Society, environment and transport, Enviroment and traffic analysis.
    Säker framkomlighet: sammanfattande resultat2013Report (Other academic)
    Abstract [en]

    The idea behind rumble strips, that is both shoulder rumble strips and median rumble strips, is to “awaken/alert” the driver who, due to inattention, fatigue or for some other reason, is involuntarily intersecting the median or side lane marker, and to thereby prevent single-vehicle accidents and multivehicle collisions. To prevent serious head-on collisions, ordinary 2-lane roads are rebuilt to meet free 2 +1 roads. This report presents results from the evaluation on two-lane roads with median milled rumble strips, divided roads, motorways with shoulder rumble strips and roads with oncoming traffic separation (referred to as sparse 2+1). Results from accident analyses (before-after study) on roads with median milled rumble strips show that the number of deaths and severe injuries has decreased by roughly 6 per cent. The corresponding decrease for single-vehicle accidents is 14 per cent. These results are significant. Speed measurements show no clear changes in terms of average speed after median rumble strips have been installed. With regard to lateral positioning, the results show that cars travel roughly 5 cm away from the centre line and that the variance of lateral position decreases slightly. This might lead to an increased rutting and wear. In the driver interviews that were conducted, 90 per cent of the drivers considered that median rumble strips contribute to higher traffic safety. With respect to external noise, one study shows that raising the guideline values for road traffic by 5 dB to 65 dB (outdoors) and 40 dB (indoors) in the same way that industrial noise has been addressed would result in a risk wherein the limit values would be exceeded at distances of less than 140 meters (outdoors) and 80 meters (indoors).

  • 46.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Ekström, Camilla
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Gustafsson, Susanne
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic Safety and Traffic System.
    Lundberg, Thomas
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Olstam, Johan
    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.
    Säker framkomlighet: sammanfattande slutrapport 20152016Report (Other academic)
    Abstract [en]

    This report consolidates evaluations performed within the project “Safe accessibility” on behalf of the Swedish Transport Administration. Four different measures implemented on rural roads in Sweden with the aim to increase traffic safety and improve accessibility are investigated. The measures are; milled centerline rumble strips on rural 2-lane roads, shoulder rumble strips on motorways, narrow2+1 roads with median barrier and divided roads (painted 2+1 roads with median rumble strips).As regards traffic safety, all four measures show reductions in the number of fatalities and seriously injured. For milled centerline rumble strips on rural 2-lane roads, they do not have a confining effect on traffic and have no adverse effect on the rate of rutting. For barrier separated roads (2+1), the results indicated that for Average Annual Daily Traffic (AADT) levels greater than 8,000 vehicles, the annual rut depth development rate is about 25 percent higher than for conventional rural roads. With lower AADT levels, differences reduced to between 10–15 percent. Comparisons between divided roads and conventional roads only showed higher annual rut development rates for AADT levels greater than 8,000 vehicles. A study about the effects and consequences of different types of milled rumble strips showed that there are no known arguments for not using the sinus rumble strips. However, further studies on the impact of drivers of heavy vehicles are recommended. Studies of the effect on traffic efficiency showed that the proportion of Heavy Goods Vehicles (HGVs) is an important factor to consider in the design of narrow 2+1 roads and the proportion of HGVs need to be taken into account in the selection of the length of overtaking lanes.

  • 47.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Björketun, Urban
    Säker framkomlighet: trafiksäkerhetseffekter 2013 och 20142016Report (Other academic)
    Abstract [en]

    This report studies the traffic safety effects of four different measures implemented on rural roads in Sweden. The measures investigated are:

    1. milled centerline rumble strips on rural 2-lane roads
    2. narrow 2+1 roads with median barrier
    3. divided roads (painted 2+1 roads with median rumble strips)
    4. shoulder rumble strips on motorways

    The method used is a before and after study with control group based on crash statistics from the Swedish crash data base Strada. Using a control group, the results have been adjusted for the general road safety trend and changes of traffic volumes. In addition, a limited Empirical Bayes study was done to adjust for regression to the mean.

    For milled centerline rumble strips on rural 2-lane roads, results show that when regression to mean is considered, the number of fatalities and seriously injured in single-vehicle crashes on road links are reduced by 24 percent (significant), but the number of injury crashes has not changed significantly.

    For narrow 2+1 roads (9 m wide), the total number of fatalities and seriously injured decreased by 62 percent and the total number of personal injury crashes decreased by 29 percent. Correcting for regression to the mean gave very similar results. It should be noted that the after period is still short and a continued follow-up is recommended.

    In the case of divided roads (painted 2+1 roads with median rumble strips), results show that when regression to mean is considered, the number of fatalities and seriously injured on road links are reduced by 44 percent. If regression to mean is not considered, the effects are smaller (-29%) and not statistically significant.

    For shoulder rumble strips on motorways, the results show that the total number of killed and seriously injured decreased by 16 percent and the number of fatalities and seriously injured in single-vehicle crashes decreased by 25 percent.

  • 48.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Björketun, Urban
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Utvärdering av ändrade hastighetsgränser: långtidseffekter på trafiksäkerhet2015Report (Other academic)
    Abstract [en]

    The Swedish Transport Administration has since 2008 undertaken to review speed limits on the national road network. The aim of this study is predominantly to describe and analyse the long-term traffic safety effect of increased, as well as, reduced speed limits. The evaluation is based on accident rates from the accident data base Strada (Swedish Traffic Accident Data Acquisition) combined with information on roads from National Road database, NVDB. The present study is a before and after study with control group where the change in accident and injury outcome on roads with new speed limits is compared with the corresponding change in the control group. Results show an extensive reduction in fatalities on rural roads with reduced speed limit from 90 to 80 km/h where the number of fatalities decreased by 14 per year, while no significant changes were seen for the seriously injured. On motorways with an increased speed limit to 120 km/h, the number of seriously injured increased by about 15 per year, but the number of deaths is in principle unchanged. The number of seriously injured increased on all types of motorways, but the worst development was seen for narrow motorways (21.5 m wide). For 2 + 1 roads with decreased speed limit from 110 to 100 km/h, the injury accidents decreased by about 10 per year and the seriously injured decreased by about 16 per year. On 2 + 1 roads with increased speed limit from 90 to 100 km/h, the number of injury accidents increased by about 19 per year. In conclusion, the results show that in total about 17 lives per year have been saved on the road network with changed speed limits. The number of seriously injured remain in principle unchanged.

  • 49.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Björketun, Urban
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Carlsson, Arne
    Swedish National Road and Transport Research Institute, Society, environment and transport, Enviroment and traffic analysis.
    Traffic safety effects of sparse 2+1 roads with median barrier2013Conference paper (Other academic)
  • 50.
    Vadeby, Anna
    et al.
    Swedish National Road and Transport Research Institute.
    Brüde, Ulf
    Swedish National Road and Transport Research Institute.
    Korsningsutformning: en kunskapsöversikt2006Report (Other academic)
    Abstract [sv]

    By commission of the Swedish Road Administration, VTI has carried out a study of the literature in order to bring up to date the knowledge concerning the design of road junctions from the standpoint of traffic safety. Mainly junctions of less advanced design and roundabouts have been studied. The measure that has predominated in recent years is to convert junctions into roundabouts. Many studies point out that this is a cost effective measure which reduces both accident risk, injury risk and accident cost. For pedestrians, roundabouts appear to be as safe as other types of junctions, while for cyclists the safety may be either as good as, or worse. It is also shown that reduction of speed has a positive effect on both crash and injury risk. As regards turning lanes, several of the studies confirm earlier results that a left-turn lane is a measure that enhances traffic safety in junctions. New results also points at that even right-turn lanes can reduce both the total number of accidents and the number of injury accidents. Several studies indicate that the angle between the primary and secondary road should be as near 90° as possible, the data in this respect are however contradictory. It is further confirmed that two staggered three-way junctions are preferable to one four-way junction.

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