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Online ISSN 1751-9578 Print ISSN 1751-956X

IET Intelligent Transport Systems

Volume 2, Issue 4, December 2008

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Volume 2, Issue 4

December 2008

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  • Selected Papers from the 1st European Conference on Human Centred Design for Intelligent Transport Systems (HCD 2008)

    • Editorial: Selected Papers from the 1st European Conference on Human Centred Design for Intelligent Transport Systems (HCD 2008)
      Risk awareness and criticality assessment of driving situations: a comparative study between motorcyclists and car drivers
      • Author(s): A. Banet  and  T. Bellet
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 241 –248
      • DOI:  10.1049/iet-its:20080037
      • Type: Article
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      • p. 241 –248 (8)
        The general framework is about risk awareness through the aspect of cognitive abilities – to perceive and assess the criticality of a driving situation – among motorcyclists against car drivers. To study risk awareness, some tools based on video films of road scenes have been developed. The experimental task consists in assessing the criticality of dynamic driving situations, via a Likert scale, and qualifying these situations using Osgood's semantic differential. The results show that, on the whole, motorcyclists consider the sample of driving situations as less critical than car drivers do. The main differences observed between the two populations are presented.
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      Drivers' reactions to sudden braking by lead car under varying workload conditions; towards a driver support system
      • Author(s): T.W. Schaap ; A.R.A. van der Horst ; B. van Arem ; K.A. Brookhuis
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 249 –257
      • DOI:  10.1049/iet-its:20080030
      • Type: Article
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      • p. 249 –257 (9)
        At urban intersections drivers handle multiple tasks simultaneously, making urban driving a complex task. An advanced driver assistance system may support drivers in this specific driving task, but the design details of such a system need to be determined before they can be fully deployed. A driving simulator experiment was conducted to determine the relationship between different subtasks of driving at urban intersections. Participants completed four drives, each comprising 20 comparable intersections with different traffic situations and encountered one unexpected braking event during the experiment. The effects of varying levels of event urgency on the relationship between different driving subtasks were studied. Furthermore, the influence of workload on this relationship was determined by giving half of the subjects an additional cognitive task. After the lead car braked unexpectedly, participants reduced speed and increased headway depending on the urgency of the braking event. Depending on the workload, participants returned to the normal speed and headway again after a number of intersections. Participants experiencing a high-workload drove more smoothly, except for those who had experienced the most urgent unexpected event. High workload additionally affected the length of the adjustments to the unexpected event.
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      Subjective strain estimation depending on driving manoeuvres and traffic situation
      • Author(s): C. Schießl
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 258 –265
      • DOI:  10.1049/iet-its:20080024
      • Type: Article
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      • p. 258 –265 (8)
        Access to current workload is regarded as crucial for new driver assistance systems that aim at optimising drivers' workload in addition to their specific functionalities (e.g. coordinate, prioritise information). As stress factors change dynamically within the driving context, workload assessment should be dynamic and continuous rather than discrete. Here, the effects of two dynamically changing stress factors (traffic density and different demands within the manoeuvre ‘entering the motorway’) on workload are examined. The aim of the study is to analyse whether the influence of these stress factors on workload can be measured using a continuous subjective rating method. The results demonstrate that the use of the subjective rating method allowed the assessment of detailed information on the influence of varying stress factors on subjective strain. Furthermore, the significant interaction between the stress factors demonstrated the importance of precise description of the relations among different dynamically changing stress factors and resulting subjective driver strain. By integrating the current findings with results from the previous studies, the wider aim of the research, the development of a qualitative and quantitative model of stress and strain, is discussed.
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      User strategies for the interaction with in-vehicle devices while driving
      • Author(s): N. Rauch ; B. Gradenegger ; H.-P. Krüger
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 266 –275
      • DOI:  10.1049/iet-its:20080025
      • Type: Article
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      • p. 266 –275 (10)
        In this study, the efficiency of different strategies for the interaction with in-vehicle devices was analysed. Twenty-four drivers completed a test course in a motion-based driving simulator containing different critical situations. At predetermined points of the route, an additional menu navigation task was offered to the driver. The driver could decide whether the actual situation was suitable to execute a task and when to interrupt it. The results show that drivers are able to adapt their secondary task behaviour to the situational demands. The anticipation of potential conflicts could be shown in secondary task behaviour (complete task rejection or task delay in critical situations). These strategies were successful to maintain driving safety. Adequate situational assessment prior to the start of the task and adequate monitoring of situational development during secondary task execution are identified as relevant processes for situation awareness in this context.
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      Applying the RESPONSE Code of Practice for evaluation of driver assistance systems: driver age and perception of steering torque signals
      • Author(s): G. Schmidt
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 276 –284
      • DOI:  10.1049/iet-its:20080026
      • Type: Article
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      • p. 276 –284 (9)
        An assessment of additional steering torque as a haptic signal to give drivers feedback from the vehicle in order to give lane-departure alerts or to support lane keeping is described. In two studies, driver performance and vehicle response were assessed in a practical study of haptic feedback conducted on a test track in a specially equipped vehicle. The first study was conducted on a total of 30 drivers and examined variations on the amplitude of the haptic signals. In a second study, with another group of 30 drivers, the focus was on the gradient of the signal. The RESPONSE Code of Practice requires that the signals used in driver assistance systems should be tested on driver groups which might perform less well than the average driver. Hence, both younger drivers and older drivers have been included in these studies. The analyses compared the results of these subpopulations with those from a group of experienced middle-aged drivers. The results do not indicate that age and experience influence the reactions times or perceptions of the signals. This finding was replicated in the second study. Furthermore, the results of the two studies show clear effects of amplitude and gradient of the haptic signal on drivers' perception and reactions.
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      ReflektAS: lane departure prevention system based on behavioural control
      • Author(s): A. Kullack ; I. Ehrenpfordt ; K. Lemmer ; F. Eggert
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 285 –293
      • DOI:  10.1049/iet-its:20080031
      • Type: Article
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      • p. 285 –293 (9)
        As a great portion of fatal accidents is caused by road departures, numerous systems for lateral control have been developed. These systems possess different functionalities, like warning the driver if he tends to depart from the lane or adding a steering torque to reduce the necessity for small steering corrections. To overcome some disadvantages of the classical systems and to develop a system for emergency situations, the knowledge of behavioural principles was utilised. A system based on reflexes has the potential of eliciting reactions reliably and quickly. In a simulator study, the principle was examined and different adjustments of the stimulus used to elicit target behaviour were tested. Subjective and objective data were collected. Results show that the participants trusted the system and perceived it as a valuable contribution to traffic safety. Objective data, like steering angle and measures of lateral position, were analysed and three different types of elicited reactions could be identified. Reaction time, reaction strength and a number of other measures were calculated for each type of reaction. The results confirmed that the system elicits reflexive reactions with very short delays, thus showing its potential for avoiding severe accidents.
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      LIVES (LenkerInnenInteraktion mit VErkehrstelematischen Systemen) – driver interaction with transport-telematic systems
      • Author(s): C. Kaufmann ; R. Risser ; A. Geven ; R. Sefelin ; M. Tscheligi
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 294 –305
      • DOI:  10.1049/iet-its:20070017
      • Type: Article
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      • p. 294 –305 (12)
        It is expected that the number of in-vehicle telematic systems will increase over the next few years, leading to an increased amount of information that a driver has to deal with besides the primary task of driving. In the project LIVES (Driver Interaction with Transport-telematic Systems), the organisations CURE (Center for Usability Research & Engineering) and FACTUM (Transport- and Social Analyses) investigated how these systems could be used in an optimum way in order to improve safety on the road. The main research questions, namely ‘How does information given simultaneously from different sources affect the driver?’ and ‘What is the best sensory modality for which type of information?’ were answered with the help of a driving simulator. This simulator made it possible to investigate the effects of different modalities for information on the driving behaviour. The outcomes consist of, firstly, a matrix in which different modalities (acoustic, visual, haptic) were combined with the priority level of a given information. The aim of this matrix is to provide better understanding which modalities should be used in which type of situation. Secondly, recommendations were formulated that would enhance safety in connection with the transmission of different types of information.
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      Consistency and sensitivity of lane change test according to driving simulator characteristics
      • Author(s): M.-P. Bruyas ; C. Brusque ; H. Tattegrain ; A. Auriault ; I. Aillerie ; M. Duraz
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 306 –314
      • DOI:  10.1049/iet-its:20080041
      • Type: Article
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      • p. 306 –314 (9)
        The aim, here, is to evaluate consistency and sensitivity of the lane change test (LCT), which is the subject of a proposed ISO standard. The method is intended to estimate driver distraction while a secondary task is being performed, by measuring performance degradation on a primary driving-like task. An experiment was conducted in two experimental contexts: a fixed-base driving simulator and a personal computer (PC) (including pedals and steering wheel), and with two auditory and two visual–manual secondary tasks. Three performance measures were calculated: adapted mean deviation, correct lane change (LC) ratio and mean delay in LC initiation. The effect of experimental context was significant. The trajectory, measured by the adapted mean deviation, was significantly better on the simulator and the percentage of correct LC higher. This difference might be explained by the greater immersion of the driver in the driving scene, which led to easier control of the trajectory in the simulator. Conversely, participants initiated quicker responses to signs when using the PC, to the detriment of trajectory control. The LCT was also proved to be sensitive enough to evaluate driving performance impairment because of the simultaneous performance of secondary tasks, even if it failed to differentiate all of them.
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      A method to assess the driver mental workload: The driving activity load index (DALI)
      • Author(s): A. Pauzié
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 315 –322
      • DOI:  10.1049/iet-its:20080023
      • Type: Article
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      • p. 315 –322 (8)
        Intelligent transport system (ITS) can induce improvement in road safety, as long as acceptability by user's population and adequacy with driving task demands have been checked. The Human-Centred Design process allows taking into account the diversified driver's population needs and functional abilities in addition to the complexity of the driving context, for setting up design recommendations and for the development of methodologies for safety assessment. Evaluation of the driver's mental workload is an important parameter, complementary to objective ones such as control of the vehicle and driver's visual strategies. This paper describes experiments conducted in the framework of the European project AIDE aiming at validating the DALI (Driving Activity Load Index), a tool set up to allow the evaluation of driver's mental workload while driving, with or without the support of in-vehicle systems. The main results and conclusion from the conducted analysis are presented.
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      Improving speed behaviour: the potential of in-car speed assistance and speed limit credibility
      • Author(s): N. Van Nes ; M. Houtenbos ; I. Van Schagen
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 323 –330
      • DOI:  10.1049/iet-its:20080036
      • Type: Article
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      • p. 323 –330 (8)
        Speeding is still a common practice on many roads and it contributes to a significant number of crashes. Two new approaches to solve speeding issues are focused on: intelligent speed assistance systems (ISA) and speed limit credibility. Research has indicated that ISA is promising with respect to improving speed behaviour but has not been widely implemented yet. Another promising approach to reduce speeding involves adjusting the environment to improve the speed limit credibility. The aim here is to investigate the potential of both approaches and particularly the potential of the combination of these measures. A driving simulator study was conducted to investigate the individual and combined effects of the use of an ISA system and the speed limit credibility on drivers' average speed and the amount of time spent speeding. The results indicated that both the informative ISA system used here and the speed limit credibility significantly improved speed behaviour. Drivers not using ISA appeared to be more susceptible to the speed limit credibility than those using ISA. It is concluded that both the measures can be effective to improve speed behaviour. The results obtained suggest that the properties of this particular informing and warning type of ISA could have resulted in the speed limit credibility neither affecting the amount of time speeding nor the average speed.
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      Incorporating intelligent speed adaptation systems into microscopic traffic models
      • Author(s): I. Spyropoulou  and  M.G. Karlaftis
      • Source: IET Intelligent Transport Systems, Volume 2, Issue 4, p. 331 –339
      • DOI:  10.1049/iet-its:20080034
      • Type: Article
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      • p. 331 –339 (9)
        Intelligent speed adaptation (ISA) systems are incorporated here into microscopic traffic models; Gipps' car-following model is discussed and the appropriate model parameters that need to be modified and additional ones that may need to be introduced are investigated. Driver behaviour under three different functionalities of ISA, namely informative, warning and intervening, is investigated through a driver simulator experiment. The impact of ISA systems on driver behaviour is a complex matter because it varies both among drivers and under different scenarios. The main parameters that capture the ‘reaction’ to the system are identified and are quantified through model parameters. These are driver speed, acceleration, deceleration, reaction time and effective size of the vehicle, and are estimated following the analysis of the simulator data. The resulting values confirm the necessity of parameter modification. The analysis performed for the incorporation of ISA into the traffic model indicated that a prerequisite of successful implementation is a deep understanding of the model parameters and dynamics.
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