Norwegian Institute of Transport Economics

Oslo, Norway

Norwegian Institute of Transport Economics

Oslo, Norway

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Hoye A.,Norwegian Institute of Transport Economics
Accident Analysis and Prevention | Year: 2013

The present study has replicated the results from a previous meta-analysis by Erke (2009) [Erke, A., 2009. Red light for red-light cameras? A meta-analysis of the effects of red-light cameras on crashes. Accident Analysis & Prevention 41 (5), 897-905.] based on a larger sample of RLC-studies, and provides answers to the criticisms that were raised by Lund et al. (2009) [Lund, A.K., Kyrychenko, S.Y., Retting, R.A., 2009. Caution: a comment on Alena Erke's red light for red-light cameras? A meta-analysis of the effects of red-light cameras on crashes. Accident Analysis and Prevention 41, 895-896.] against the previous meta-analysis. The addition of recent studies to the meta-analysis and a more thorough investigation of potential moderator variables lead to a slight improvement of the estimated effects of RLC in the previous meta-analysis. The present study found a non-significant increase of all crashes by 6% and a non-significant decrease of all injury crashes by 13%. Right-angle collisions were found to decrease by 13% and rear-end collisions were found to increase by 39%. For right-angle injury collisions a decrease by 33% was found and for rear-end injury collisions a smaller increase was found (+19%). The effects of RLC are likely to be more favorable when RLC-warning signs are set up at main entrances to areas with RLC enforcement than when each RLC-intersection is signposted. The effects of RLC may become more favorable over time, this could however not be investigated empirically. Several results indicate that spillover effects may occur for right-angle collisions, but most likely not for rear-end and other crashes. If spillover effects do not occur for rear-end crashes, which increase at RLC intersection, this would be a positive result for RLC. However, the results seem to be affected to some degree by publication bias and the effects may therefore be somewhat less favorable than indicated by the results from meta-analysis. © 2013 Elsevier Ltd. All rights reserved.


Elvik R.,Norwegian Institute of Transport Economics
Accident Analysis and Prevention | Year: 2011

This paper shows that the meta-analysis of bicycle helmet efficacy reported by Attewell, Glase, and McFadden (Accident Analysis and Prevention 2001, 345-352) was influenced by publication bias and time-trend bias that was not controlled for. As a result, the analysis reported inflated estimates of the effects of bicycle helmets. This paper presents a re-analysis of the study. The re-analysis included: (1) detecting and adjusting for publication bias by means of the trim-and-fill method; (2) ensuring the inclusion of all published studies by means of continuity corrections of estimates of effect rely on zero counts; (3) detecting and trying to account for a time-trend bias in estimates of the effects of bicycle helmets; (4) updating the study by including recently published studies evaluating the effects of bicycle helmets. The re-analysis shows smaller safety benefits associated with the use of bicycle helmets than the original study. © 2011 Elsevier Ltd All rights reserved.


Hjorthol R.,Norwegian Institute of Transport Economics
Ageing and Society | Year: 2013

Previous research has shown that mobility and the ability to leave the home are among the essential aspects of older people's quality of life. However, surveys of older people's access to transport resources and the impact of mobility on welfare and wellbeing are few. Many previous studies are based on small samples or qualitative data. The questions addressed in this paper are how transport resources are distributed among different groups of older people, to which degree the transport needs of these groups are met and how this is related to their wellbeing. The empirical analysis is based on a Norwegian nationwide survey among 4,723 respondents 65 years and older. The respondents were asked about their access to transport resources, both private and public, health problems connected to use of transport modes, their daily activities and mobility, their uncovered transport needs and the importance of different activities for their life quality. The analysis reveals great differences between groups; especially between men and women, but also between different age groups and by different place of living. The special transport offered by the local authorities is seen as insufficient, and with increasing age a great deal of older people have low mobility and an uncovered transport need that reduces their life quality. © Cambridge University Press 2012.


Elvik R.,Norwegian Institute of Transport Economics
Accident Analysis and Prevention | Year: 2010

This paper examines the stability of long-term trends in the number of traffic fatalities in eight highly motorised countries: Norway, Sweden, Denmark, Finland, The Netherlands, Great Britain, Australia and The United States. In all these countries, the number of traffic fatalities reached a peak around 1970-1972 and has since declined. The decline has, however, been irregular and fairly long periods of stagnation or even increase in the number of fatalities have occurred in all countries. A stable trend is defined in this paper as a trend that remains unchanged and therefore can be used to successfully predict the future number of fatalities by means of extrapolation. It is concluded that the trends towards fewer fatalities in the countries selected have not been stable and that even trend lines that fit past trends very closely are usually worthless for predictive purposes. An attempt was made to identify factors influencing long-term trends by fitting negative binomial regression models to fatality data. Although some of the models fitted the data marginally better than simple trend lines, these models are not necessarily more useful for predicting future trends than simple trend lines, since using the models for prediction requires that future changes in all explanatory variables must be predicted. The chief lesson is that past trends do not provide a reliable basis for predicting future developments with respect to the number of traffic fatalities. © 2009 Elsevier Ltd. All rights reserved.


Vaa T.,Norwegian Institute of Transport Economics
Accident Analysis and Prevention | Year: 2014

The present meta-analysis is based on 16 studies comprising 32 results. These studies provide sufficient data to estimate relative accident risks of drivers with ADHD. The overall estimate of relative risk for drivers with ADHD is 1.36 (95% CI: 1.18; 1.57) without control for exposure, 1.29 (1.12; 1.49) when correcting for publication bias, and 1.23 (1.04; 1.46) when controlling for exposure. A relative risk (RR) of 1.23 is exactly the same as found for drivers with cardiovascular diseases. The long-lasting assertion that "ADHD-drivers have an almost fourfold risk of accident compared to non-ADHD-drivers", which originated from Barkley et al.'s study of 1993, is rebutted. That estimate was associated with comorbid Oppositional Defiant Disorder (ODD) and/or Conduct Disorder (CD), not with ADHD, but the assertion has incorrectly been maintained for two decades. The present study provides some support for the hypothesis that the relative accident risk of ADHD-drivers with comorbid ODD, CD and/or other conduct problems, is higher than that of ADHD-drivers without these comorbidities. The estimated RRs were 1.86 (1.27; 2.75) in a sample of ADHD-drivers in which a majority had comorbid ODD and/or CD compared to 1.31 (0.96; 1.81) in a sample of ADHD-drivers with no comorbidity. Given that ADHD-drivers most often seem to drive more than controls, and the fact that a majority of the present studies lack information about exposure, it seems more probable that the true RR is lower rather than higher than 1.23. Also the assertion that ADHD-drivers violate traffic laws more often than other drivers should be modified: ADHD-drivers do have more speeding violations, but no more drunk or reckless driving citations than drivers without ADHD. All accident studies included in the meta-analysis fail to acknowledge the distinction between deliberate violations and driving errors. The former are known to be associated with accidents, the latter are not. A hypothesis that ADHD-drivers speed more frequently than controls because it stimulates attention and reaction time is suggested. © 2013 Elsevier Ltd. All rights reserved.


Nordbakke S.,Norwegian Institute of Transport Economics
Journal of Transport Geography | Year: 2013

To gain a deeper understanding of the opportunities for mobility in old age, this study examines the everyday travel needs, travel practices and activity participation of older women in an urban setting and it explores the complex links between barriers, strategies and options for mobility in old age. The analysis is based on results from four focus groups of women aged 67-89 living in Oslo, Norway's capital. Mobility is defined here as the ability to choose where and when to travel and which activities to participate in outside the home in everyday life. To understand the potential opportunities for mobility of older women in urban areas, we proposed a conceptual framework in which opportunities for mobility in old age can be analyzed consistently with the capability approach to wellbeing that was developed by Amartya Sen. With its focus on the importance of choice and individual action, the capability approach is especially relevant for making explicit how " opportunities for mobility" is not a fixed structure but is something that is managed, shaped and directed by the individual-in this context, older women. The study enabled the identification of individual and contextual factors that influence the opportunities for mobility as well as strategies developed for overcoming barriers to mobility in old age. The study shows how individual resources, contextual conditions and strategies are interlinked and how they form a " pool of capabilities for mobility" that is, opportunities for mobility that older women can draw onto mediate and shape their mobility. © 2012 Elsevier Ltd.


Elvik R.,Norwegian Institute of Transport Economics
Annual Review of Public Health | Year: 2012

This review summarizes current knowledge regarding the effects of speed limit enforcement on public health. Speed limits are commonly used around the world to regulate the maximum speed at which motor vehicles can be operated on public roads. Speed limits are statutory, and violations of them are normally sanctioned by means of fixed penalties (traffic tickets) or, in the event of serious violations, suspension of the driver's license and imposition of prison sentences. Speed limit violations are widespread in all countries for which statistics can be found. Speeding contributes more to the risk of traffic injury than do other risk factors for which estimates of population-attributable risk are available. Traffic speed strongly influences impact speed in crashes and therefore has major implications for public health. © 2012 by Annual Reviews. All rights reserved.


Elvik R.,Norwegian Institute of Transport Economics
Accident Analysis and Prevention | Year: 2010

Some road safety problems have persisted for a long time in nearly all motorised countries, suggesting that they are not easily solved. This paper documents the persistence over time of five such problems: the high risk of accidents involving young drivers; the high risk of injury run by unprotected road users; risks attributable to incompatibility between different types of vehicles and groups of road users; differences in risk between different types of traffic environment and speeding. A taxonomy of road safety problems is developed in order to identify characteristics of problems that can make them difficult to solve. It is argued that if a problem is not perceived as a problem, is attributable to a misguided confidence in road user rationality, involves social dilemmas, or is closely related to the physics of impacts then it is likely to be difficult to solve. Problems to which biological factors contribute are also likely to be difficult to solve. The characteristics that can make a problem difficult to solve are to some extent present for all the five problems shown to be persistent in this paper. © 2009 Elsevier Ltd.


Hoye A.,Norwegian Institute of Transport Economics
Accident Analysis and Prevention | Year: 2015

The safety effects of section control were investigated at 14 sites in Norway. A before-after study was conducted with the empirical Bayes method in order to control for regression to the mean (RTM). Effects of trend, volumes, speed limit changes and speed cameras at some of the sites in the before period are controlled for as well. For injury crashes a non-significant reduction by 12% was found. The number of killed or severely injured was found to be significantly reduced by 49% at the section control sites. The results indicate that the crash reductions in tunnels (most of which are undersea tunnels with section control on steep downhill segments) are at least of the same magnitude as on open roads. The results are consistent with findings from speed measurements, although the crash reductions are larger than one would expect as a result from the speed reductions. Downstream of the section control sites (up to 3 km in each direction) injury crashes were found to be significantly reduced by 46%. The number of KSI downstream of the section control sites is too small for drawing any conclusions. It is concluded that section control is effective in reducing both speed and crashes, especially serious crashes, and that spillover effects (crash reductions at non-enforcement sites) are more likely to occur than crash migration. The size of the effects that were found should be interpreted with caution because of the relatively short after periods for some of the sites and the sensitivity of the results to the outcomes of individual crashes. © 2014 Elsevier Ltd.


Elvik R.,Norwegian Institute of Transport Economics
Accident Analysis and Prevention | Year: 2014

This paper reviews game-theoretic models that have been developed to explain road user behaviour in situations where road users interact with each other. The paper includes the following game-theoretic models:A general model of the interaction between road users and their possible reaction to measures improving safety (behavioural adaptation).Choice of vehicle size as a Prisoners' dilemma game.Speed choice as a co-ordination game.Speed compliance as a game between drivers and the police.Merging into traffic from an acceleration lane as a mixed-strategy game.Choice of level of attention in following situations as an evolutionary game.Choice of departure time to avoid congestion as variant of a Prisoners' dilemma game.Interaction between cyclists crossing the road and car drivers.Dipping headlights at night well ahead of the point when glare becomes noticeable.Choice of evasive action in a situation when cars are on collision course. The models reviewed are different in many respects, but a common feature of the models is that they can explain how informal norms of behaviour can develop among road users and be sustained even if these informal norms violate the formal regulations of the traffic code. Game-theoretic models are not applicable to every conceivable interaction between road users or to situations in which road users choose behaviour without interacting with other road users. Nevertheless, it is likely that game-theoretic models can be applied more widely than they have been until now. © 2013 Elsevier Ltd. All rights reserved.

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