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Simpson’s paradox: A collection of examples from road safety studies and emergency medicine
No full textRune Elvik, Simpson’s paradox: A collection of examples from road safety studies and emergency medicine,
Transportation Research Interdisciplinary Perspectives, Volume 31, 2025, 101471, ISSN 2590-1982, https://doi.org/10.1016/j.trip.2025.101471.Simpson’s paradox, first described in 1951, denotes a reversal of a difference or ratio when data for several groups are added up. This paper illustrates the paradox by means of examples taken from road safety studies and emergency medicine. These examples are only intended to show how the paradox can arise. It is not known how common the paradox is or how often it goes undetected. If undetected, it can lead to erroneous conclusions, for example that women have a higher accident rate than men, when in each group formed according to annual driving distance the opposite is the case. The reversal of the difference occurs because there is an interaction between gender, driving distance and accident rate. Women drive shorter than men, and shorter driving distances are associated with higher accident rates than longer driving distances.Simpson’s paradox: A collection of examples from road safety studies and emergency medicinepublishedVersio
Who buys public transport accessible housing? Residential sorting in the Oslo region
No full textErik Bjørnson Lunke, Lars Böcker, Who buys public transport accessible housing? Residential sorting in the Oslo region, Transportation Research Part D: Transport and Environment, Volume 139, 2025, 104595, ISSN 1361-9209, https://doi.org/10.1016/j.trd.2025.104595.This article investigates whether public transport (PT) accessibility is related to socioeconomic residential sorting in the Oslo region. There is widespread concern that PT services contribute to gentrification and exclusionary processes, although empirical evidence for this is limited. This study uses detailed dwelling transaction data and estimates conditional logit models on residential purchases among different income groups. The results show that the effect of PT accessibility on dwelling selection varies as the life course progresses. Families with children and older households display lower effects of PT accessibility on residential choice than young, childless households. At the same time, PT accessibility increases the likelihood of dwelling purchase more for high-income households than for households with a lower income. These results confirm that PT accessibility is a valued and limited residential asset, one that households with more economic resources are better able to obtain.Who buys public transport accessible housing? Residential sorting in the Oslo regionpublishedVersio
Comparing national road safety culture among bus drivers in Norway and Ghana
No full textTor-Olav Nævestad, Enoch F. Sam, Jenny Blom, Anthony Fiangor, Lars E. Egner, Rune Elvik, Comparing national road safety culture among bus drivers in Norway and Ghana, Transportation Research Procedia, Volume 89, 2025, Pages 271-284, ISSN 2352-1465, https://doi.org/10.1016/j.trpro.2025.05.061.
Peer-review under responsibility of the scientific committee of the African Transport Research Conference 2024 (ATRC-2024)The study compares national road safety culture (RSC) among bus drivers in Norway and Ghana, based on bus driver survey data in the two countries (n=285 and 281), interview data (n=11 and 19) and field work. The point of departure is the very different road safety contexts in the two countries; with Norway being a high-income country with the best road safety level in the world, and Ghana as a low-income country with a far higher road fatality rate than Norway. We compare national RSC in the two countries, to examine factors that might explain the different levels of road fatalities. Our results indicate an RSC with more traffic violations, especially aggressive violations, among drivers in Ghana than in Norway. We also find a relationship between RSC and road safety violations, and between road safety violations and accident involvement. Thus, our study indicates that national RSC is important, as it is related to road safety violations, which in turn is related to accident involvement. Interview data indicates that the bus drivers in Ghana describe the traffic they typically drive in as “hectic”, “stressful” and “bad”. We suggest that this may be related to factors influencing road user interaction, e.g. overcrowded roads during rush-hours due to insufficient capacity and poor road infrastructure. Fieldwork data indicate a more chaotic traffic environment in Ghana than in Norway, at least in urban settings, with a road system that is less in line with safe system principles, and a higher tolerance of risk.Comparing national road safety culture among bus drivers in Norway and GhanaVolvo Research and Educational Foundations (VREF)publishedVersio
Exploring the general acceptance factor for shared automated vehicles: the impact of personality traits and experimentally altered information
Full text linkAasvik O, Ulleberg P and Hagenzieker M (2025) Exploring the general acceptance factor for shared automated vehicles: the impact of personality traits and experimentally altered information. Front. Psychol. 16:1531386. doi: 10.3389/fpsyg.2025.1531386Introduction: Shared automated vehicles (SAVs) could significantly enhance public transport by addressing urban mobility challenges. However, public acceptance of SAVs remains under-studied, particularly regarding how informational factors and individual personality traits influence acceptance. Methods: This study explores SAV acceptance using data from an experimental survey of 1902 respondents across Norway. Participants were randomly presented with different informational conditions about SAV services, manipulating vehicle autonomy (fully autonomous vs. steward onboard), seating orientation (facing direction of travel vs. facing other passengers), and ethnicity of co-passengers. Personality traits from the Five Factor Model (FFM) and Social Dominance Orientation (SDO) were assessed. The General Acceptance Factor (GAF), derived from the Multi-Level Model of Automated Vehicle Acceptance (MAVA), was used as the primary outcome measure. Results: No significant main or interaction effects were found from the experimentally altered information conditions. However, personality traits significantly influenced acceptance. Specifically, higher openness and agreeableness positively predicted SAV acceptance, while higher neuroticism and social dominance orientation negatively predicted acceptance. Discussion: The absence of experimental effects suggests either a limited role of the manipulated factors or insufficiently robust manipulations. Conversely, the substantial impact of personality traits highlights the importance of psychological factors, particularly trust, openness, and social attitudes, in shaping SAV acceptance. These findings emphasize the need for tailored communication strategies to enhance SAV uptake, addressing specific psychological profiles and fostering trust in automation.Exploring the general acceptance factor for shared automated vehicles: the impact of personality traits and experimentally altered informationpublishedVersio
Introduction vs. price change of road toll – a panel data analysis of revealed preferences
No full textStian Brosvik Bayer, Stefan Flügel, Introduction vs. price change of road toll – a panel data analysis of revealed preferences, Research in Transportation Economics, Volume 112, 2025, 101592, ISSN 0739-8859, https://doi.org/10.1016/j.retrec.2025.101592.Cordon-based congestion charging systems effectively reduce traffic, with initial implementations often achieving 15–20 % reductions in vehicle volumes, as observed in Singapore, London, and Stockholm. However, subsequent toll increases typically produce much smaller elasticities, a phenomenon known as "Large Elasticity at Introduction" (LEI). This suggests that introducing tolls on previously free roads triggers stronger behavioral responses than adjusting toll rates on already tolled roads.
This study explores LEI using mode-choice data from a panel of 2814 commuters in the Stavanger urban area, collected before and after substantial changes to the toll-cordon system in October 2018. Employing random utility models, we test linear and log-transformed cost specifications to investigate the roles of diminishing sensitivity and the zero-price effect.
Our findings indicate that diminishing sensitivity to cost, captured by a log-transformed specification, is more critical to explaining LEI than a strict zero-price discontinuity. Real-world data confirm strong responses to new tolls at city-center cordons (16–18 % traffic reductions) but weaker responses at previously tolled municipal borders (4 %). These results emphasize that LEI is largely driven by non-linear cost sensitivity, suggesting that introducing low tolls in areas with robust modal alternatives can achieve substantial congestion reductions without requiring steep price hikes.publishedVersio
Supply-side challenges and research needs on the road to 100% zero-emissions vehicle sales
No full textAlan Jenn et al 2025 Prog. Energy 7 022002.
Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.In this review paper, we delve into the supply-side challenges and considerations for transitioning to 100% zero-emission vehicles (ZEVs), weaving together an analysis of batteries, vehicle production, charging infrastructure, and relevant supply-side policies. We begin by examining the innovations and environmental impacts of lithium mining and recycling, highlighting the need for robust frameworks to ensure sustainable battery production. Our exploration of vehicle production reveals important issues regarding labor dynamics and global competitiveness. Our investigation into charging infrastructure reveals complexities in deployment models and access, reflecting broader societal and economic considerations. Lastly, a critical evaluation of policies across various jurisdictions provides insights into the effectiveness and potential improvements needed to support the ZEV transition. We emphasize the need for coordinated efforts and further research, particularly in areas such as end-of-life considerations for batteries and the alignment of international production standards. Our findings contribute to a comprehensive understanding of the supply-side landscape for ZEVs and underscore the essential research directions to ensure a responsible and successful electrification of the transportation system.Supply-side challenges and research needs on the road to 100% zero-emissions vehicle salesacceptedVersio
Determination of riding comfort on cycleways using a smartphone application
No full textAnna Niska, Leif Sjögren, Peter Andrén, Christian Weber, Tineke de Jong, Aslak Fyhri, Determination of riding comfort on cycleways using a smartphone application, Journal of Traffic and Transportation Engineering (English Edition), Volume 11, Issue 4, 2024, Pages 747-760, ISSN 2095-7564, https://doi.org/10.1016/j.jtte.2023.05.010.Well maintained cycleways will encourage more people to cycle, as the condition of cycleways is important for the safety, accessibility and riding comfort of cyclists. Despite that, only a few models used to describe the quality of service for cyclists take the surface condition into account. Objective measuring methods are needed to enable reliable and effective assessment of surface conditions, and measurable performance criteria related to the needs of cyclists should be developed. The purpose of this study has been to test the reliability and validity of using accelerometers in smartphones to assess the riding comfort on cycleways. A smartphone application converting three-dimensional accelerometer measurements into a single indicator for cycleways has been used to assess road surfaces in two field studies, in Sweden and Norway, respectively. Both studies assessed test sections of varying quality. To relate the measurements to subjective riding comfort assessments by cyclists, recruited cyclists collected quantitative data using the app, whilst also rating their perceived riding comfort by completing a survey. Measurements were also related to standard road surface condition indicators, generated from a road surface tester equipped with 19 laser sensors: international roughness index (IRI), mega- and macrotexture. The results show that it is possible to describe the unevenness of a cycleway using the technology present in smartphones. A software application can be used to collect and analyse data from the acceleration sensors in the phone, which can then be used to describe the riding comfort of cyclists. It is mainly the unevenness in the 50–1000 mm size-range that create the greatest discomfort for cyclists, and intermittent vibrations are perceived as more uncomfortable than more evenly distributed vibrations. Therefore, IRI is not a relevant measurement for describing the riding comfort of cyclists.Determination of riding comfort on cycleways using a smartphone applicationpublishedVersio
How do Car Owners Familiarize and Adapt to Unfamiliar Vehicle Technologies?
Full text linkUhlving, Vibeke M, Alena Høye, and Kjell Vegard Weyde. 2024. “How Do Car Owners Familiarize and Adapt to Unfamiliar Vehicle Technologies?” Findings, May. https://doi.org/10.32866/001c.116293.Many drivers lack relevant knowledge about advanced driver assistance systems (ADAS), and how they learn about ADAS is mainly haphazard. We conducted interviews with six experts from the automobile industry and eight drivers. Few drivers actively engage with ADAS features and settings in their vehicles and many fail to check or familiarize themselves with ADAS in an unfamiliar car. Moreover, the research highlights that it is not rare for drivers to misinterpret typical ADAS responses as technical issues.How do Car Owners Familiarize and Adapt to Unfamiliar Vehicle Technologies?acceptedVersio
Cost-benefit assessments of an e-bike subvention programme in Oslo, Norway
No full textKnut Veisten, Aslak Fyhri, Askill Harkjerr Halse, Hanne Beate Sundfør, Cost-benefit assessments of an e-bike subvention programme in Oslo, Norway, Transportation Research Part A: Policy and Practice, Volume 180, 2024, 103974, ISSN 0965-8564, https://doi.org/10.1016/j.tra.2024.103974.In an attempt to increase the bicycle share in transport in Oslo, the municipality launched an e-bike subvention programme in 2016. One thousand persons were to receive a 20% subvention if they bought an e-bike, by registering via a municipal webpage on a first come first served basis. Nearly 700 ended up buying a subsidised e-bike. A connected research project surveyed subvention recipients and non-recipients, including registration of daily transport by cycle/e-bike, walk, car, and public transport, before the programme took effect, with a similar surveying after most of those qualifying for subvention had bought their e-bike. In this paper we assess the effects of the e-bike subvention in a cost-benefit analysis. The cost-benefit analysis compares the cost of carrying out the e-bike subvention programme against the benefits due to transport mode shift and increased active travel. The benefits, the changes in monetised external effects, comprise two main elements: the health effect from active travel and the congestion, emissions, etc. caused by cars and larger vehicles. Differently from former studies, we take into account that transport mode changes following from a bicycle project will normally not imply only shift from private car to bicycling, but also shifts from walking and public transport to cycling. Moreover, some of the negative external effects from private cars and public transport vehicles are already internalised via taxation and can be deducted from the calculations. Our ex-post assessment of the implemented e-bike programme indicates that the benefits in the year of implementation probably surpassed the costs of the programme. The benefit calculation was relatively robust to alternative assumptions for the road transport (the share of electric cars, the occupancy in public transport, and the share of congested travel), but relatively less robust to altered assumption about the active travel. However, if there is an impact of the e-bike subvention programme beyond the implementation year, we have underestimated the benefits.Cost-benefit assessments of an e-bike subvention programme in Oslo, NorwaypublishedVersio
Walk further and access more! Exploring the 15-minute city concept in Oslo, Norway
No full textMahsa Akrami, Marcin Wojciech Sliwa, Maja Karoline Rynning, Walk further and access more! Exploring the 15-minute city concept in Oslo, Norway, Journal of Urban Mobility, Volume 5, 2024, 100077, ISSN 2667-0917, https://doi.org/10.1016/j.urbmob.2024.100077. (https://www.sciencedirect.com/science/article/pii/S2667091724000074)The 15-minute city theory has recently become a popular paradigm in urban development. It claims that everyone should have access to the essential services, facilities and green spaces within a 15-minute walk. This article tests this concept in Oslo, Norway using a mixed-methods approach, based on a Geographical Information Systems (GIS) analysis of accessibility, review of relevant plans, interviews with planners and a case study of the Hovinbyen area. The objective was to find out to what extent Oslo is a 15-minute city, and discuss how this concept can be integrated in urban planning strategies more generally. The study shows that the central part of Oslo is already a 15-minute city, and that several areas are transforming in this direction. However, many suburban neighborhoods have low accessibility scores, and, according to the plans, will likely not change much in the future. This article argues that the 15-minute city concept cannot serve as the main development strategy, but such an analysis can be useful as a diagnostic study or to assist planning in rapidly changing areas or city extensions. The concept can therefore be considered as a flexible tool to support other planning strategies that share the same goals and ambitions. Any interventions that such accessibility analyses suggest should be contextualized and developed in combination with other qualitative assessments and in partnership with local communities.Walk further and access more! Exploring the 15-minute city concept in Oslo, NorwaypublishedVersio