Anna Vadeby


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Research results from Anna


Traffic safety effects of new speed limits in Sweden

Driving speeds affect the risk of being involved in a crash and the injury severity as well as the noise and exhaust emissions. Starting 2008, the Swedish Transport Administration performed a review of the speed limits on the national rural road...

Changes in speed distribution

This study investigated the effect of applying two aggregated models (the Power model and the Exponential model) to individual vehicle speeds instead of mean speeds. This is of particular interest when the measure introduced affects different parts...

Speed compliance on municipality streets

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...

Safe accessibility

This report studies the traffic safety effects of four different measures implemented on rural roads in Sweden. The measures investigated are:milled centerline rumble strips on rural 2-lane roadsnarrow 2+1 roads with median barrierdivided roads...

Traffic safety effects of narrow 2+1 roads with median barrier in Sweden

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...

Safe accessibility

In this project, rut depth development studies were carried out on road sections subjected to three specific types of traffic safety measure. The measures, implemented through the Swedish Transport Administration’s "Safe accessibility" project,...

Safe accessibility

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...

Design and analysis of semi-controlled studies

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...

Self-explaining roads

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...

Towards a European Guideline for Speed Management Measures in Work Zones

Speed management in work zones is important to ensure that the driver safely can navigate the vehicle through the work zone routing. The ASAP project, Appropriate Speed saves All People, was designed to address this issue, with its specific focus on...

Traffic safety effects of new speed limits in Sweden

The effects of speed, both positive and negative, make speed a primary target for policy action. Driving speeds affect the risk of being involved in a crash and the injury severity as well as the noise and exhaust emissions. Starting 2008, the...

Speed compliance on municipality streets

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...

New speed limits in Sweden

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...

Evaluation of New Speed Limits in Sweden

The study sought to estimate changes in actual driving speed occurring after new speed limits were introduced in Sweden’s rural road network. The effects of speed limit changes were estimated for 7 groups of roads of different types and initial...

Speed compliance on municipality streets

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...

Injured motorcyclists

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...

Speed distribution and traffic safety measures

A main  traffic  safety  priority in  many  countries  is  implementing measures  that reduce  road  user  speed  and increase  speed limit compliance. This study compares changes in the  speed distribution  and estimated accident risk brought about...

Safe accessibility

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...

Speed management in Sweden

Between 2008 and 2011, the Swedish Transport Administration reviewed the speed limits on the state rural road network in Sweden. Guidelines were established for different types of roads, and the long-term vision was that speed limits should be...

Traffic safety and speed dispersion

This study describes the state of knowledge in terms of speed distribution and traffic safety. Real changes in speed-distribution and estimated accident risk for three different traffic safety measures are studied. The aim is to gain a better...

Effects of d-amphetamine on simulated driving performance before and after sleep...

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...

Road traffic speeds

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...

Traffic safety effects of milled rumble strips in the middle of the road

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...

Evaluation of the new speed limits

Starting 2008, the Swedish Transport Administration performs a review of the speed limits on the state rural road network in Sweden. This study presents results from speed measurements made before and after the changes of speed limits in Phase 2...

Effects of dextroamphetamine on simulated driving performance before and after sleep...

Stimulant drugs are commonly abused and also used to promote wakefulness, yet their effects on driving performance during sleep deprivation have been poorly studied in experimental studies. We aimed to assess the effects on fundamental driving...

Speed of motorcyclists - levels and changes on roads with new speed limits

The sub-target that 80 per cent of all road users should drive within current speed limits was introduced in order to reach the national traffic safety target of a maximum of 220 traffic fatalities by 2020. The target applies to passenger cars,...

Evaluation of the new speed limits

The Swedish Transport Administration estimated prior to the speed limit review that an increased or reduced speed limit of 10 km/h would result in an actual increase or decrease of 4 km/h for passenger vehicles. The change for heavy goods vehicles...

Car drivers’ perceptions of electronic stability control (ESC) systems

As a way to reduce the number of car crashes different in-car safety devices are being introduced. In this paper one such application is being investigated, namely the electronic stability control system (ESC). The study used a survey method,...

Effects of billboards on traffic safety

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...

Results from the analysis and input to the development and validation of the statistical...

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...

Results from the analysis and input to the development and validation of the statistical...

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...

Sleepiness and prediction of driver impairment in simulator studies using a Cox...

Cox proportional hazard models were used to study relationships between the event that a driver is leaving the lane caused by sleepiness and different indicators of sleepiness. In order to elucidate different indicators' performance, five different...

Data analysis and modelling

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...

The alerting effect of hitting a rumble strip

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...

Intelligent Transport Systems (ITS) in passenger cars and methods for assessment of...

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....

Compilation of 34 traffic safety measures

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...

Impact of Nonresponse and Weighting in a Swedish Survey

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...

Subsample distribution distance and McMC convergence

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...

Modeling of relative collision safety including driver characteristics

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...

Computer based statistical treatment in models with incidental parameters

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...

Estimation in a model with incidental parameters

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...

Including driver characteristics in a model of relative collision safety

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...

Modelling and inference of relative collision safety in cars

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...

The empirical KL-measure of MCMC convergence

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...

On Gibbs sampler and Metrolopolis-Hastings applied to pairwise poisson and car crash data

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...