Marjan Hagenzieker - Academia.edu (original) (raw)

Papers by Marjan Hagenzieker

Minds and Machines

The paper presents a framework to realise “meaningful human control” over Automated Driving Syste... more The paper presents a framework to realise “meaningful human control” over Automated Driving Systems. The framework is based on an original synthesis of the results of the multidisciplinary research project “Meaningful Human Control over Automated Driving Systems” lead by a team of engineers, philosophers, and psychologists at Delft University of the Technology from 2017 to 2021. Meaningful human control aims at protecting safety and reducing responsibility gaps. The framework is based on the core assumption that human persons and institutions, not hardware and software and their algorithms, should remain ultimately—though not necessarily directly—in control of, and thus morally responsible for, the potentially dangerous operation of driving in mixed traffic. We propose an Automated Driving System to be under meaningful human control if it behaves according to the relevant reasons of the relevant human actors (tracking), and that any potentially dangerous event can be related to a hu...

Human Factors issues with automated driving systems (ADS) are becoming more apparent with the inc... more Human Factors issues with automated driving systems (ADS) are becoming more apparent with the increasing prevalence of automated vehicles on the public roads. As automated driving demands increased performance of supervisory skills of the driver, rather than vehicle handling skills, a mismatch occurs between the demand and supply of the drivers' skillset. Therefore, it has been suggested that drivers should at all times have meaningful human control (MHC) over ADS. The basic idea behind MHC is derived from the debate on autonomous weapon systems, and entails three essential components: human operators are (1) making informed, conscious decisions, (2) sufficiently informed about lawfulness of an action and its context, and (3) properly trained, to ensure effective control over the use of ADS. This paper presents definitions, components and potential human roles within ADS, from an interdisciplinary and a MHC perspective. The ideas presented in this paper are valuable to both designers, manufacturers, and road operators, as well as policy makers, driving licensing bodies, and lawyers and insurers, and our future research into these topics will deliver usable results for all stakeholders.

To create a safer environment for bicyclists and pedestrians, the usefulness of different types o... more To create a safer environment for bicyclists and pedestrians, the usefulness of different types of kerbs as a separation between these two modes has been questioned by both researchers and practitioners. Right angled kerbs pose risks to cyclists due to their height but are assumed to separate them well from pedestrians. Sloped and levelled kerb types are more forgiving but allow road traffic users to move onto each other's infrastructure, creating a potential risk of collision. We examined the effects of different types of kerbs on cyclists' and pedestrians' behaviour. This is operationalized as a road user moving onto another traffic user's infrastructure (i.e. crossing the kerb). A total of 14,502 bicyclists and 3,578 pedestrians at 12 different locations in Amsterdam were observed. We also examined the motives for crossing the kerb, and some smaller studies were carried out on corners and intersections and in some other Dutch cities for making comparisons. The res...

European Journal of Transport and Infrastructure Research, 2021

High pre-World-War-2 modal shares of cycling in European countries sharply decreased during the p... more High pre-World-War-2 modal shares of cycling in European countries sharply decreased during the post-war decades. In the 1990s, European governments introduced policies to increase bicycle use. However, a database or longitudinal study on the development of bicycle use in European countries is lacking. The goal of this paper is to examine to what degree the amount of cycling has increased over the past decades, also in the context of potentially competing modes. Distances travelled per capita according to National Travel Surveys have been collected and were aggregated to seven 4-year periods between 1990 and 2017. Multilevel regression analyses on distance travelled per capita by bicycle, on foot, by public transport, and by passenger car were conducted for all countries. Additionally, analyses were conducted for which the 14 countries with data on bicycle use were divided in three groups categorised according to distance cycled per capita at the beginning of the study period. Dista...

Partially and fully automated vehicles (AVs) are being developed and tested in different countrie... more Partially and fully automated vehicles (AVs) are being developed and tested in different countries. These vehicles are being designed to reduce and ultimately eliminate the role of human drivers in the future. Most fatal accidents of vulnerable road users (VRUs), pedestrians, cyclists and mopeds, involve a motorized vehicle. In addition, most of the accidents involving VRUs and motorized vehicles happen at road crossings. By replacing human-driven vehicles with automated vehicles, the human role will be altered and reduced which could lead to an increase in traffic safety. However, drivers are not the only ones who will have to adapt to automated vehicles, other road users, such as pedestrians and cyclists, will have to interact with vehicles with various levels of automation, too. Pedestrians and cyclists will still be humans and might behave in an unpredictable manner which could lead to unsafe behaviors. The main goal of this paper is to propose a theoretical framework which desc...

Transportation Research Interdisciplinary Perspectives, 2021

Will pedestrians cross the road before an automated vehicle? The effect of drivers' attentiveness... more Will pedestrians cross the road before an automated vehicle? The effect of drivers' attentiveness and presence on pedestrians' road crossing behavior

Accident Analysis & Prevention, 2020

In order to overcome the shortcomings of crash data a number of surrogate measures of safety have... more In order to overcome the shortcomings of crash data a number of surrogate measures of safety have been developed and proposed by various researchers. One of the most widely used temporal indicators is time-to-collision (TTC) which requires the road users to be on a collision course. Road users that are strictly speaking not on a collision course actually might behave and take evasive actions as if they were, thus indicating that such nearmiss situations might also be relevant for safety analysis. Taking that into account, a more flexible indicator T 2 , which does not require the two vehicles to be on a collision course, describes the expected time for the second road user to arrive at the conflict point. Recently extreme value theory (EVT) offering two approaches, block maxima (BM) and Peak over Threshold (POT), has been applied in combination with surrogate indicators to estimate crash probabilities. Most of this research has focused on testing BM and POT as well as validating various surrogate safety indicators by comparing model estimates to actual crash frequencies. The comparison of collision course indicators with indicators including crossing course interactions and their performance using EVT has not been investigated yet. In this study we are seeking answers to under what conditions these indicators perform better and whether they are transferable. Using data gathered at a signalized intersection focusing on left-turning and straight moving vehicle interactions our analysis concluded that the two indicators are transferable with stricter threshold values for T 2 and that POT gives more reasonable results.

Transportation Research Interdisciplinary Perspectives, 2020

The tram is a sustainable mode of transport. However, tram tracks are often shared with vulnerabl... more The tram is a sustainable mode of transport. However, tram tracks are often shared with vulnerable road users (VRUs) such as pedestrians and cyclists. In this mixed environment, accidents between trams and VRUs are very rare but severe at the same time. Previous studies have acknowledged that tram driving is a complex and very demanding task. Yet, subjective notions of traffic safety that are more connected with the behavior of tram drivers, have never been quantified. This is important in order to better interpret the challenges that tram drivers face. To do so, a stated preference experiment was designed in which tram drivers in Athens rated their perceived safety and driving stress of different driving scenarios on a 7-point Likert Scale. The driving scenarios were presented to the tram drivers using static images. According to the estimated perceived safety model, the alignment type (such as exclusive, semi-exclusive), the existence and the type of pedestrian crossing and the volume of VRUs influence tram drivers' perceived safety. Driving stress was affected mainly by arrival delay and load of standing passengers. Route familiarity also appeared as an important factor, that influences driving stress. No statistically significant correlation between perceived safety and driving stress was observed. One explanation for this is that experienced tram drivers believe that they are ready to respond properly in a section that they perceive as unsafe, if they are familiar with it. If there is no familiarity, tram drivers lack confidence and therefore driving stress is increased.

Transportation Research Part F: Traffic Psychology and Behaviour, 2020

What will cyclists do in future conflict situations with automated cars at intersections when the... more What will cyclists do in future conflict situations with automated cars at intersections when the cyclist has the right of way? In order to explore this, short high-quality animation videos of conflicts between a car and a cyclist at five different intersections were developed. These videos were 'shot' from the perspective of the cyclist and ended when a collision was imminent should the car or the bicyclist not slow down. After each video participants indicated whether they would slow down or continue cycling, how confident they were about this decision, what they thought the car would do, and how confident they were about what the car would do. The appearance of the approaching car was varied as within-subjects variable with 3 levels (Car type): automated car, automated car displaying its intentions to the cyclists, and traditional car. In all situations the cyclist had right of way. Of each conflict, three versions were made that differed in the moment that the video ended by cutting off fractions from the longest version, thus creating videos with an early, mid, and late moment for the cyclist to decide to continue cycling or to slow down (Decision moment). Before the video experiment started the participants watched an introductory video about automated vehicles that served as prime. This video was either positive, negative, or neutral about automated vehicles (Prime type). Both Decision moment and Prime type were between subject variables. After the experiment participants completed a short questionnaire about trust in technology and trust in automated vehicles. 1009 participants divided in nine groups (one per Decision moment and Prime) completed the online experiment in which they watched fifteen videos (5 conflicts  3 car types). The results show that participants more often yielded when the approaching car was an automated car than when it was a traditional car. However, when the approaching car was an automated car that could communicate its intentions, they yielded less often than for a traditional car. The earlier the Decision moment, the more often participants yielded but this increase in yielding did not differ between the three car types. Participants yielded more often for automated cars (both types) after they watched the negative prime video before the experiment than when they watched the positive video. The less participants trusted technology, and the capabilities of automated vehicles in particular, the more they were inclined to slow down in the conflict situations with automated cars. The association between trust and yielding was stronger for trust in the capabilities of automated vehicles than for trust in technology in general.

Transportation Research Part F: Traffic Psychology and Behaviour, 2018

Interaction between pedestrians and automated vehicles A Wizard of Oz experiment

Journal of Transportation Safety & Security, 2019

Cyclists may have incorrect expectations of the behaviour of automated vehicles in interactions w... more Cyclists may have incorrect expectations of the behaviour of automated vehicles in interactions with them, which could bring extra risks in traffic. This study investigated whether expectations and behavioural intentions of cyclists when interacting with automated cars differed from those with manually driven cars. A photo experiment was conducted with 35 participants who judged bicycle-car interactions from the perspective of the cyclist. Thirty photos were presented. An experimental design was used with between-subjects factor instruction (two levels: positive, neutral), and two within-subjects factors: car type (three levels: roof name plate, stickerthese two external features indicated automated cars; and traditional car), and series (two levels: first, second). Participants were asked how sure they were to be noticed by the car shown in the photos, whether the car would stop, and how they would behave themselves. A subset of nine participants was equipped with an eye-tracker. Findings generally point to cautious dispositions towards automated cars: participants were not more confident to be noticed when interacting with both types of automated cars than with manually driven cars. Participants were more confident that automated cars would stop for them during the second series and looked significantly longer at automated cars during the first.

Transportation Research Part F: Traffic Psychology and Behaviour, 2016

When driven at low speeds, cars operating in electric mode have been found to be quieter than con... more When driven at low speeds, cars operating in electric mode have been found to be quieter than conventional cars. As a result, the auditory cues which pedestrians and cyclists use to assess the presence, proximity and location oncoming traffic may be reduced, posing a safety hazard. This laboratory study examined auditory localisation of conventional and electric cars including vehicle motion paths relevant for cycling activity. Participants (N = 65) in three age groups (16-18, 30-40 and 65-70 year old) indicated the location and movement direction (approaching versus receding) of cars driven at 15, 30 and 50 km/h in two ambient sound conditions (low and moderate). Results show that low speeds, higher ambient sound level and older age were associated with worse performance on the location and motion direction tasks. In addition, participants were less accurate at determining the location of electric and conventional car sounds emanating from directly behind the participant. Implications for cycling safety and proposals for adding extra artificial noise or warning sounds to quiet (electric) cars are discussed.

Transport Reviews, 2015

The growing popularity of electric devices and the increasing number of hybrid and electric cars ... more The growing popularity of electric devices and the increasing number of hybrid and electric cars have recently raised concerns about the use of auditory signals by vulnerable road users. This paper consolidates current knowledge about the two trends in relation to cycling safety. Both a literature review and a crash data analysis were carried out. Based on a proposed conceptual model, knowledge gaps are identified that need to be addressed for a better understanding of the relation between limitations on auditory information while cycling. Results suggest that the concerns regarding the use of electronic devices while cycling and the advent of hybrid and electric vehicles are justified. Listening to music and conversing on the phone negatively influence cyclists' auditory perception, selfreported crash risk and cycling performance. With regard to electric cars, a recurring problem is their quietness at low speeds. Implications of these findings in terms of cycling safety are discussed. Search terms "cycling", "cyclist(s)", "cycling safety" or "pedestrian(s)", "pedestrian safety" were included in all searches and combined with "music", "mobile/cell phone(s)", "distraction" or "media devices".

Accident Analysis & Prevention, 2014

Scientific literature lacks a model which combines exposure to risk, risk, and the relationship b... more Scientific literature lacks a model which combines exposure to risk, risk, and the relationship between them. This paper presents a conceptual road safety framework comprising mutually interacting factors for exposure to risk resulting from travel behaviour (volumes, modal split, and distribution of traffic over time and space) and for risk (crash and injury risk). The framework's three determinants for travel behaviour are locations of activities; resistances (generalized transport costs); needs, opportunities, and abilities. Crash and injury risks are modelled by the three 'safety pillars': infrastructure, road users and the vehicles they use. Creating a link in the framework between risk and exposure is important because of the 'non-linear relationship' between them, i.e. risk tends to decrease as exposure increases. Furthermore, 'perceived' risk (a type of travel resistance) plays a role in mode choice, i.e. the perception that a certain type of vehicle is unsafe can be a deterrent to its use. This paper uses theories to explain how the elements in the model interact. Cycling is an area where governments typically have goals for both mobility and safety. To exemplify application of the model, the paper uses the framework to link research on cycling (safety) to land use and infrastructure. The model's value lies in its ability to identify potential consequences of measures and policies for both exposure and risk. This is important from a scientific perspective and for policy makers who often have objectives for both mobility and safety.

European Monitoring Centre for Drugs and Drug Addiction, 2012

Relative and absolute validity of a driving simulator were assessed regarding effects on mean spe... more Relative and absolute validity of a driving simulator were assessed regarding effects on mean speed and speed variation during distracting secondary tasks, and normal driving. 16 participants drove the same route four times, twice in a simulator and twice in the real world. They performed way finding tasks, using either a paper map or a route guidance system, and mobile phone conversation tasks. Furthermore, driving without secondary tasks on other road segments in the two methods was compared. As both mean speed and standard deviations of speed were not equivalent, absolute validity could not be established. However, as effects found in the experimental conditions varied in the same directions, evidence for relative validity was provided. It is concluded that driving performance regarding speed under distracting conditions may validly be researched in the driving simulator employed here.

In this study, a meta-analytic approach was used to analyse effects of Advanced Cruise Control (A... more In this study, a meta-analytic approach was used to analyse effects of Advanced Cruise Control (ACC) on driving behaviour reported in seven driving simulator studies. The effects of ACC on three consistent outcome measures, namely, driving speed, headway and driver workload have been analysed. The indicators of speed, headway and workload have been chosen because they are assumed to be directly affected by the ACC support, their relationship with road safety is reasonably established and they are the most frequently used outcome measures in the sample of analysed studies. The results suggest that different operational settings of ACC that are important for the level of support provided by the system, are significant for the effects ACC have on various aspects of driving behaviour, i.e. on mean driving speed and mean time headway. The obtained effect sizes clustered in two groups, with more intervening ACCs having the effects of an increased driving speed and decreased mean time head...

Proceedings of the 5th International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle Design : Driving Assessment 2009, 2009

To monitor novice driver performance in the first years of solo driving, a test aimed at assessin... more To monitor novice driver performance in the first years of solo driving, a test aimed at assessing speed adaptation to the traffic situation was developed and evaluated. The Adaptation Test consisted of 18 traffic scenes presented in two (almost) identical photographs, which differed in one single detail, increasing the situation's complexity. The difference in reported speed between the two pictures was used as an indication of drivers' adaptation of speed to the complexity of the traffic situation. A previous study showed that novice, unsafe and overconfident drivers, as identified in an on-road driving assessment, performed worse on the Adaptation Test (i.e. less often reported a lower speed in the more complex situation). The analysis of new data in this paper shows no correlation between performance on the Adaptation Test and self-reported crashes, and that after two years, experienced drivers had improved their performance on the Adaptation Test just as much as novice drivers.

Transportation Research Part F: Traffic Psychology and Behaviour, 2018

Research in different domains has shown that people categorize oneself and others as ingroup (''u... more Research in different domains has shown that people categorize oneself and others as ingroup (''us") and outgroup (''them") members, resulting in group-based stereotyping and attribution errors that may adversely affect social behaviour. To determine whether such patterns also exist in road traffic, we conducted an experimental web-based survey using scenarios of unregulated traffic settings in which the type of other road user was varied (cyclist vs. car driver). We investigated whether road users who described themselves predominantly as either a car driver (N = 330) or a cyclist (N = 315) would (1) report having more in common with members of their respective ingroups than outgroups, (2) be more negative about their respective outgroup than ingroup in terms of their expectations about other road users, (3) make more dispositional and less circumstantial attributions about an outgroup member who failed to yield right of way than about an ingroup member, and (4) show more willingness to raise traffic fines for the outgroup than for the ingroup. Results showed both self-described car drivers and cyclists reported having more in common with their ingroup than with their outgroup. Self-described car drivers were also least inclined to expect to be given right of way by cyclists as compared to car drivers, while selfdescribed cyclists were less inclined than self-described car drivers to expect car drivers to yield right of way. Self-described car drivers were more inclined to make dispositional attributions about cyclists' rule breaking behaviour and less inclined to attribute these to circumstances compared to rule breaking on the part of car drivers, and were most inclined to disadvantage their outgroup compared to their ingroup in terms of raising traffic fines. Since dispositional attributions are more likely to lead people to behave aggressively, our findings suggest that cyclists, who are arguably among those most dependent on the goodwill and forgivingness of drivers of motorised vehicles, may be less likely to receive it. This means that although both self-described cyclists and car drivers may distinguish between ingroups and outgroups in traffic, this distinction may have much more complicated implications than the simple terms ''us" and ''them" might imply.

Proceedings of the 4th International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle, 2007

Inadequate self-assessment, and specifically, overestimation of skill, results in insufficient ad... more Inadequate self-assessment, and specifically, overestimation of skill, results in insufficient adaptation to task demands, which can manifest itself on different levels of the driving task. A total of 130 drivers (83 novice and 47 experienced drivers) participated in an on-road driving assessment. Their performance in this assessment (i.e., fail or pass) was compared to the participants' reported confidence in their driving skills (i.e., high or low confidence), resulting in three calibration groups: a) well-calibrated drivers (reported confidence matched performance on assessment), b) overconfident drivers (high confidence but failed assessment) and c) insecure drivers (low confidence but passed assessment). Furthermore, participants completed a questionnaire which focused on choices made on the strategic and manoeuvring level of the driving task. No significant difference was found between the calibration groups for the strategic level. Overconfident drivers reported significantly more violating behaviour than the well-calibrated and the insecure drivers. At the manoeuvring level, overconfident drivers showed significantly less instances of adaptation to traffic complexity. In conclusion, the current study suggests that overconfidence is related to inadequate adaptation to task demands.

Minds and Machines

The paper presents a framework to realise “meaningful human control” over Automated Driving Syste... more The paper presents a framework to realise “meaningful human control” over Automated Driving Systems. The framework is based on an original synthesis of the results of the multidisciplinary research project “Meaningful Human Control over Automated Driving Systems” lead by a team of engineers, philosophers, and psychologists at Delft University of the Technology from 2017 to 2021. Meaningful human control aims at protecting safety and reducing responsibility gaps. The framework is based on the core assumption that human persons and institutions, not hardware and software and their algorithms, should remain ultimately—though not necessarily directly—in control of, and thus morally responsible for, the potentially dangerous operation of driving in mixed traffic. We propose an Automated Driving System to be under meaningful human control if it behaves according to the relevant reasons of the relevant human actors (tracking), and that any potentially dangerous event can be related to a hu...

Human Factors issues with automated driving systems (ADS) are becoming more apparent with the inc... more Human Factors issues with automated driving systems (ADS) are becoming more apparent with the increasing prevalence of automated vehicles on the public roads. As automated driving demands increased performance of supervisory skills of the driver, rather than vehicle handling skills, a mismatch occurs between the demand and supply of the drivers' skillset. Therefore, it has been suggested that drivers should at all times have meaningful human control (MHC) over ADS. The basic idea behind MHC is derived from the debate on autonomous weapon systems, and entails three essential components: human operators are (1) making informed, conscious decisions, (2) sufficiently informed about lawfulness of an action and its context, and (3) properly trained, to ensure effective control over the use of ADS. This paper presents definitions, components and potential human roles within ADS, from an interdisciplinary and a MHC perspective. The ideas presented in this paper are valuable to both designers, manufacturers, and road operators, as well as policy makers, driving licensing bodies, and lawyers and insurers, and our future research into these topics will deliver usable results for all stakeholders.

To create a safer environment for bicyclists and pedestrians, the usefulness of different types o... more To create a safer environment for bicyclists and pedestrians, the usefulness of different types of kerbs as a separation between these two modes has been questioned by both researchers and practitioners. Right angled kerbs pose risks to cyclists due to their height but are assumed to separate them well from pedestrians. Sloped and levelled kerb types are more forgiving but allow road traffic users to move onto each other's infrastructure, creating a potential risk of collision. We examined the effects of different types of kerbs on cyclists' and pedestrians' behaviour. This is operationalized as a road user moving onto another traffic user's infrastructure (i.e. crossing the kerb). A total of 14,502 bicyclists and 3,578 pedestrians at 12 different locations in Amsterdam were observed. We also examined the motives for crossing the kerb, and some smaller studies were carried out on corners and intersections and in some other Dutch cities for making comparisons. The res...

European Journal of Transport and Infrastructure Research, 2021

High pre-World-War-2 modal shares of cycling in European countries sharply decreased during the p... more High pre-World-War-2 modal shares of cycling in European countries sharply decreased during the post-war decades. In the 1990s, European governments introduced policies to increase bicycle use. However, a database or longitudinal study on the development of bicycle use in European countries is lacking. The goal of this paper is to examine to what degree the amount of cycling has increased over the past decades, also in the context of potentially competing modes. Distances travelled per capita according to National Travel Surveys have been collected and were aggregated to seven 4-year periods between 1990 and 2017. Multilevel regression analyses on distance travelled per capita by bicycle, on foot, by public transport, and by passenger car were conducted for all countries. Additionally, analyses were conducted for which the 14 countries with data on bicycle use were divided in three groups categorised according to distance cycled per capita at the beginning of the study period. Dista...

Partially and fully automated vehicles (AVs) are being developed and tested in different countrie... more Partially and fully automated vehicles (AVs) are being developed and tested in different countries. These vehicles are being designed to reduce and ultimately eliminate the role of human drivers in the future. Most fatal accidents of vulnerable road users (VRUs), pedestrians, cyclists and mopeds, involve a motorized vehicle. In addition, most of the accidents involving VRUs and motorized vehicles happen at road crossings. By replacing human-driven vehicles with automated vehicles, the human role will be altered and reduced which could lead to an increase in traffic safety. However, drivers are not the only ones who will have to adapt to automated vehicles, other road users, such as pedestrians and cyclists, will have to interact with vehicles with various levels of automation, too. Pedestrians and cyclists will still be humans and might behave in an unpredictable manner which could lead to unsafe behaviors. The main goal of this paper is to propose a theoretical framework which desc...

Transportation Research Interdisciplinary Perspectives, 2021

Will pedestrians cross the road before an automated vehicle? The effect of drivers' attentiveness... more Will pedestrians cross the road before an automated vehicle? The effect of drivers' attentiveness and presence on pedestrians' road crossing behavior

Accident Analysis & Prevention, 2020

In order to overcome the shortcomings of crash data a number of surrogate measures of safety have... more In order to overcome the shortcomings of crash data a number of surrogate measures of safety have been developed and proposed by various researchers. One of the most widely used temporal indicators is time-to-collision (TTC) which requires the road users to be on a collision course. Road users that are strictly speaking not on a collision course actually might behave and take evasive actions as if they were, thus indicating that such nearmiss situations might also be relevant for safety analysis. Taking that into account, a more flexible indicator T 2 , which does not require the two vehicles to be on a collision course, describes the expected time for the second road user to arrive at the conflict point. Recently extreme value theory (EVT) offering two approaches, block maxima (BM) and Peak over Threshold (POT), has been applied in combination with surrogate indicators to estimate crash probabilities. Most of this research has focused on testing BM and POT as well as validating various surrogate safety indicators by comparing model estimates to actual crash frequencies. The comparison of collision course indicators with indicators including crossing course interactions and their performance using EVT has not been investigated yet. In this study we are seeking answers to under what conditions these indicators perform better and whether they are transferable. Using data gathered at a signalized intersection focusing on left-turning and straight moving vehicle interactions our analysis concluded that the two indicators are transferable with stricter threshold values for T 2 and that POT gives more reasonable results.

Transportation Research Interdisciplinary Perspectives, 2020

The tram is a sustainable mode of transport. However, tram tracks are often shared with vulnerabl... more The tram is a sustainable mode of transport. However, tram tracks are often shared with vulnerable road users (VRUs) such as pedestrians and cyclists. In this mixed environment, accidents between trams and VRUs are very rare but severe at the same time. Previous studies have acknowledged that tram driving is a complex and very demanding task. Yet, subjective notions of traffic safety that are more connected with the behavior of tram drivers, have never been quantified. This is important in order to better interpret the challenges that tram drivers face. To do so, a stated preference experiment was designed in which tram drivers in Athens rated their perceived safety and driving stress of different driving scenarios on a 7-point Likert Scale. The driving scenarios were presented to the tram drivers using static images. According to the estimated perceived safety model, the alignment type (such as exclusive, semi-exclusive), the existence and the type of pedestrian crossing and the volume of VRUs influence tram drivers' perceived safety. Driving stress was affected mainly by arrival delay and load of standing passengers. Route familiarity also appeared as an important factor, that influences driving stress. No statistically significant correlation between perceived safety and driving stress was observed. One explanation for this is that experienced tram drivers believe that they are ready to respond properly in a section that they perceive as unsafe, if they are familiar with it. If there is no familiarity, tram drivers lack confidence and therefore driving stress is increased.

Transportation Research Part F: Traffic Psychology and Behaviour, 2020

What will cyclists do in future conflict situations with automated cars at intersections when the... more What will cyclists do in future conflict situations with automated cars at intersections when the cyclist has the right of way? In order to explore this, short high-quality animation videos of conflicts between a car and a cyclist at five different intersections were developed. These videos were 'shot' from the perspective of the cyclist and ended when a collision was imminent should the car or the bicyclist not slow down. After each video participants indicated whether they would slow down or continue cycling, how confident they were about this decision, what they thought the car would do, and how confident they were about what the car would do. The appearance of the approaching car was varied as within-subjects variable with 3 levels (Car type): automated car, automated car displaying its intentions to the cyclists, and traditional car. In all situations the cyclist had right of way. Of each conflict, three versions were made that differed in the moment that the video ended by cutting off fractions from the longest version, thus creating videos with an early, mid, and late moment for the cyclist to decide to continue cycling or to slow down (Decision moment). Before the video experiment started the participants watched an introductory video about automated vehicles that served as prime. This video was either positive, negative, or neutral about automated vehicles (Prime type). Both Decision moment and Prime type were between subject variables. After the experiment participants completed a short questionnaire about trust in technology and trust in automated vehicles. 1009 participants divided in nine groups (one per Decision moment and Prime) completed the online experiment in which they watched fifteen videos (5 conflicts  3 car types). The results show that participants more often yielded when the approaching car was an automated car than when it was a traditional car. However, when the approaching car was an automated car that could communicate its intentions, they yielded less often than for a traditional car. The earlier the Decision moment, the more often participants yielded but this increase in yielding did not differ between the three car types. Participants yielded more often for automated cars (both types) after they watched the negative prime video before the experiment than when they watched the positive video. The less participants trusted technology, and the capabilities of automated vehicles in particular, the more they were inclined to slow down in the conflict situations with automated cars. The association between trust and yielding was stronger for trust in the capabilities of automated vehicles than for trust in technology in general.

Transportation Research Part F: Traffic Psychology and Behaviour, 2018

Interaction between pedestrians and automated vehicles A Wizard of Oz experiment

Journal of Transportation Safety & Security, 2019

Cyclists may have incorrect expectations of the behaviour of automated vehicles in interactions w... more Cyclists may have incorrect expectations of the behaviour of automated vehicles in interactions with them, which could bring extra risks in traffic. This study investigated whether expectations and behavioural intentions of cyclists when interacting with automated cars differed from those with manually driven cars. A photo experiment was conducted with 35 participants who judged bicycle-car interactions from the perspective of the cyclist. Thirty photos were presented. An experimental design was used with between-subjects factor instruction (two levels: positive, neutral), and two within-subjects factors: car type (three levels: roof name plate, stickerthese two external features indicated automated cars; and traditional car), and series (two levels: first, second). Participants were asked how sure they were to be noticed by the car shown in the photos, whether the car would stop, and how they would behave themselves. A subset of nine participants was equipped with an eye-tracker. Findings generally point to cautious dispositions towards automated cars: participants were not more confident to be noticed when interacting with both types of automated cars than with manually driven cars. Participants were more confident that automated cars would stop for them during the second series and looked significantly longer at automated cars during the first.

Transportation Research Part F: Traffic Psychology and Behaviour, 2016

When driven at low speeds, cars operating in electric mode have been found to be quieter than con... more When driven at low speeds, cars operating in electric mode have been found to be quieter than conventional cars. As a result, the auditory cues which pedestrians and cyclists use to assess the presence, proximity and location oncoming traffic may be reduced, posing a safety hazard. This laboratory study examined auditory localisation of conventional and electric cars including vehicle motion paths relevant for cycling activity. Participants (N = 65) in three age groups (16-18, 30-40 and 65-70 year old) indicated the location and movement direction (approaching versus receding) of cars driven at 15, 30 and 50 km/h in two ambient sound conditions (low and moderate). Results show that low speeds, higher ambient sound level and older age were associated with worse performance on the location and motion direction tasks. In addition, participants were less accurate at determining the location of electric and conventional car sounds emanating from directly behind the participant. Implications for cycling safety and proposals for adding extra artificial noise or warning sounds to quiet (electric) cars are discussed.

Transport Reviews, 2015

The growing popularity of electric devices and the increasing number of hybrid and electric cars ... more The growing popularity of electric devices and the increasing number of hybrid and electric cars have recently raised concerns about the use of auditory signals by vulnerable road users. This paper consolidates current knowledge about the two trends in relation to cycling safety. Both a literature review and a crash data analysis were carried out. Based on a proposed conceptual model, knowledge gaps are identified that need to be addressed for a better understanding of the relation between limitations on auditory information while cycling. Results suggest that the concerns regarding the use of electronic devices while cycling and the advent of hybrid and electric vehicles are justified. Listening to music and conversing on the phone negatively influence cyclists' auditory perception, selfreported crash risk and cycling performance. With regard to electric cars, a recurring problem is their quietness at low speeds. Implications of these findings in terms of cycling safety are discussed. Search terms "cycling", "cyclist(s)", "cycling safety" or "pedestrian(s)", "pedestrian safety" were included in all searches and combined with "music", "mobile/cell phone(s)", "distraction" or "media devices".

Accident Analysis & Prevention, 2014

Scientific literature lacks a model which combines exposure to risk, risk, and the relationship b... more Scientific literature lacks a model which combines exposure to risk, risk, and the relationship between them. This paper presents a conceptual road safety framework comprising mutually interacting factors for exposure to risk resulting from travel behaviour (volumes, modal split, and distribution of traffic over time and space) and for risk (crash and injury risk). The framework's three determinants for travel behaviour are locations of activities; resistances (generalized transport costs); needs, opportunities, and abilities. Crash and injury risks are modelled by the three 'safety pillars': infrastructure, road users and the vehicles they use. Creating a link in the framework between risk and exposure is important because of the 'non-linear relationship' between them, i.e. risk tends to decrease as exposure increases. Furthermore, 'perceived' risk (a type of travel resistance) plays a role in mode choice, i.e. the perception that a certain type of vehicle is unsafe can be a deterrent to its use. This paper uses theories to explain how the elements in the model interact. Cycling is an area where governments typically have goals for both mobility and safety. To exemplify application of the model, the paper uses the framework to link research on cycling (safety) to land use and infrastructure. The model's value lies in its ability to identify potential consequences of measures and policies for both exposure and risk. This is important from a scientific perspective and for policy makers who often have objectives for both mobility and safety.

European Monitoring Centre for Drugs and Drug Addiction, 2012

Relative and absolute validity of a driving simulator were assessed regarding effects on mean spe... more Relative and absolute validity of a driving simulator were assessed regarding effects on mean speed and speed variation during distracting secondary tasks, and normal driving. 16 participants drove the same route four times, twice in a simulator and twice in the real world. They performed way finding tasks, using either a paper map or a route guidance system, and mobile phone conversation tasks. Furthermore, driving without secondary tasks on other road segments in the two methods was compared. As both mean speed and standard deviations of speed were not equivalent, absolute validity could not be established. However, as effects found in the experimental conditions varied in the same directions, evidence for relative validity was provided. It is concluded that driving performance regarding speed under distracting conditions may validly be researched in the driving simulator employed here.

In this study, a meta-analytic approach was used to analyse effects of Advanced Cruise Control (A... more In this study, a meta-analytic approach was used to analyse effects of Advanced Cruise Control (ACC) on driving behaviour reported in seven driving simulator studies. The effects of ACC on three consistent outcome measures, namely, driving speed, headway and driver workload have been analysed. The indicators of speed, headway and workload have been chosen because they are assumed to be directly affected by the ACC support, their relationship with road safety is reasonably established and they are the most frequently used outcome measures in the sample of analysed studies. The results suggest that different operational settings of ACC that are important for the level of support provided by the system, are significant for the effects ACC have on various aspects of driving behaviour, i.e. on mean driving speed and mean time headway. The obtained effect sizes clustered in two groups, with more intervening ACCs having the effects of an increased driving speed and decreased mean time head...

Proceedings of the 5th International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle Design : Driving Assessment 2009, 2009

To monitor novice driver performance in the first years of solo driving, a test aimed at assessin... more To monitor novice driver performance in the first years of solo driving, a test aimed at assessing speed adaptation to the traffic situation was developed and evaluated. The Adaptation Test consisted of 18 traffic scenes presented in two (almost) identical photographs, which differed in one single detail, increasing the situation's complexity. The difference in reported speed between the two pictures was used as an indication of drivers' adaptation of speed to the complexity of the traffic situation. A previous study showed that novice, unsafe and overconfident drivers, as identified in an on-road driving assessment, performed worse on the Adaptation Test (i.e. less often reported a lower speed in the more complex situation). The analysis of new data in this paper shows no correlation between performance on the Adaptation Test and self-reported crashes, and that after two years, experienced drivers had improved their performance on the Adaptation Test just as much as novice drivers.

Transportation Research Part F: Traffic Psychology and Behaviour, 2018

Research in different domains has shown that people categorize oneself and others as ingroup (''u... more Research in different domains has shown that people categorize oneself and others as ingroup (''us") and outgroup (''them") members, resulting in group-based stereotyping and attribution errors that may adversely affect social behaviour. To determine whether such patterns also exist in road traffic, we conducted an experimental web-based survey using scenarios of unregulated traffic settings in which the type of other road user was varied (cyclist vs. car driver). We investigated whether road users who described themselves predominantly as either a car driver (N = 330) or a cyclist (N = 315) would (1) report having more in common with members of their respective ingroups than outgroups, (2) be more negative about their respective outgroup than ingroup in terms of their expectations about other road users, (3) make more dispositional and less circumstantial attributions about an outgroup member who failed to yield right of way than about an ingroup member, and (4) show more willingness to raise traffic fines for the outgroup than for the ingroup. Results showed both self-described car drivers and cyclists reported having more in common with their ingroup than with their outgroup. Self-described car drivers were also least inclined to expect to be given right of way by cyclists as compared to car drivers, while selfdescribed cyclists were less inclined than self-described car drivers to expect car drivers to yield right of way. Self-described car drivers were more inclined to make dispositional attributions about cyclists' rule breaking behaviour and less inclined to attribute these to circumstances compared to rule breaking on the part of car drivers, and were most inclined to disadvantage their outgroup compared to their ingroup in terms of raising traffic fines. Since dispositional attributions are more likely to lead people to behave aggressively, our findings suggest that cyclists, who are arguably among those most dependent on the goodwill and forgivingness of drivers of motorised vehicles, may be less likely to receive it. This means that although both self-described cyclists and car drivers may distinguish between ingroups and outgroups in traffic, this distinction may have much more complicated implications than the simple terms ''us" and ''them" might imply.

Proceedings of the 4th International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle, 2007

Inadequate self-assessment, and specifically, overestimation of skill, results in insufficient ad... more Inadequate self-assessment, and specifically, overestimation of skill, results in insufficient adaptation to task demands, which can manifest itself on different levels of the driving task. A total of 130 drivers (83 novice and 47 experienced drivers) participated in an on-road driving assessment. Their performance in this assessment (i.e., fail or pass) was compared to the participants' reported confidence in their driving skills (i.e., high or low confidence), resulting in three calibration groups: a) well-calibrated drivers (reported confidence matched performance on assessment), b) overconfident drivers (high confidence but failed assessment) and c) insecure drivers (low confidence but passed assessment). Furthermore, participants completed a questionnaire which focused on choices made on the strategic and manoeuvring level of the driving task. No significant difference was found between the calibration groups for the strategic level. Overconfident drivers reported significantly more violating behaviour than the well-calibrated and the insecure drivers. At the manoeuvring level, overconfident drivers showed significantly less instances of adaptation to traffic complexity. In conclusion, the current study suggests that overconfidence is related to inadequate adaptation to task demands.