The Effects of an Eco-Driving Interface on Driver Safety and Fuel Efficiency

Real-time, in-vehicle guidance on eco-driving is likely to produce substantial improvements in vehicle fuel economy. However, the benefits of such in-vehicle systems should be achieved without impairing driver safety. A simulator study evaluated both visual and haptic eco-driving feedback systems, which provided advice on gas pedal usage. Hill driving scenarios with variable traffic density were used to test drivers’ prioritization of safe and fuel-efficient driving. A visual, second-order display and a haptic force feedback gas pedal created the smallest errors in gas pedal usage and so maximized fuel efficiency. The visual display increased time spent looking away from the road, implying reduced driver safety. Participants were worse at eco-driving in more demanding, high traffic conditions. Drivers appeared to prioritize safety over eco-driving, however safety margins were shorter in the high density traffic condition, despite the degradation in eco-driving performance. The findings suggest which modality could be most appropriate for presenting in-vehicle eco-driving guidance, and hint that these systems should advise drivers based on the prevailing traffic conditions

Lessons learnt from OS operations

This report focuses on the specific lessons learnt from the data collection in UDRIVE, derived from the difficulties encountered by the operation sites and the solutions applied to mitigate the problems where possible. These lessons learnt concern all aspects of the data collection. Such lessons learnt will provide useful insights for any future naturalistic driving study or field operational test. During the project, the operation sites provided three feedbacks related to their lessons learnt. These reports covered the pilot phase, the first six months of data collection and the last one at the end of the data collection. This iterative process gathered 71 lessons learnt. After the data collection, the final questionnaire was filled in by the participants and they provided with some interesting feedback. Most important lesssons learned were: Selecting only one or two vehicle types contributed to easier instrumentation of the Data Acquisaition System to the vehicles. However, this decision put some constraints in the recruitment of participants due the different fleet of vehicles across the European countries, especially some models were not very common in certain countries. One of the common problems across the Operation Sites (OS) was the participants’ drop-outs. The main lesson learnt was that it is important to maintain a set of replacement participants until the end of the project to cover any eventual drop out. Data protection was one of the most challenging aspects of the project. Dealing with images and personal data create some difficulties between the partners and their country data protection agencies. From the participants’ questionnaires, it was noted that even if they felt comfortable, their driving behaviour was somehow affected. Hide the equipment, and especially the cameras, the best it can be will help the participants drive normally. They also were pleased to have all the information beforehand and happy when dates, deadlines, incentives, etc., were respected as explained to them. When involving any external supplier (e.g. rental vehicle company, garage, equipment supplier, etc.). the role, responsibilities, response time, liability, etc., of every supplier have to be defined in more detail to avoid misunderstandings, delays or ambiguities. Developing as early as possible a very detailed and realistic plan of action allows to avoid delays, overspending, save resources and to achieve the project objectives

Interface design considerations for an in-vehicle eco-driving assistance system

This high-fidelity driving simulator study used a paired comparison design to investigate the effectiveness of 12 potential eco-driving interfaces. Previous work has demonstrated fuel economy improvements through the provision of in-vehicle eco-driving guidance using a visual or haptic interface. This study uses an eco-driving assistance system that advises the driver of the most fuel efficient accelerator pedal angle, in real time. Assistance was provided to drivers through a visual dashboard display, a multimodal visual dashboard and auditory tone combination, or a haptic accelerator pedal. The style of advice delivery was varied within each modality. The effectiveness of the eco-driving guidance was assessed via subjective feedback, and objectively through the pedal angle error between system-requested and participant-selected accelerator pedal angle. Comparisons amongst the six haptic systems suggest that drivers are guided best by a force feedback system, where a driver experiences a step change in force applied against their foot when they accelerate inefficiently. Subjective impressions also identified this system as more effective than a stiffness feedback system involving a more gradual change in pedal feedback. For interfaces with a visual component, drivers produced smaller pedal errors with an in-vehicle visual display containing second order information on the required rate of change of pedal angle, in addition to current fuel economy information. This was supported by subjective feedback. The presence of complementary audio alerts improved eco-driving performance and reduced visual distraction from the roadway. The results of this study can inform the further development of an in-vehicle assistance system that supports ‘green’ driving

Exploring the relationship between risk perception, speed limit credibility and speed limit compliance

Driving speed is an important factor in road safety. Speed limit compliance is not only affected by the speed limit credibility, but is also related to driver’s risk perception. This study investigates the relationship between the factors of risk perception, speed limit credibility and speed limit compliance for a given rural single carriageway road and roadside environment. Speed limit credibility, subjective risk perception and compliance with the speed limit were measured separately. To be specific, speed limit credibility was measured by speed limit rating score using a picture questionnaire. Subjective risk perception was measured by risk rating in an automated car driving simulator for a given speed and road environment. Speed limit compliance was measured by percentage of driving time spent below the speed limit in a simulated manual driving task with a given speed limit and road environment. Multilevel regression and logistic regression analysis demonstrate that risk perception has a positive influence on compliance with the speed limit. Credibility of speed limit has a positive influence on speed limit compliance. Risk perception has a negative influence on speed limit credibility. The research results can be used for guiding speed limit design and speed management

How I reduce fuel consumption: An experimental study on mental models of eco-driving

Eco-driving has the potential to reduce fuel consumption and therefore emissions considerably. Previous research suggests that drivers have a certain level of eco-driving knowledge and skills, which they refrain from practising in their everyday lives. At the same time misconceptions and ambiguous messages from eco-driving support systems can confuse and demotivate. This research aimed to identify the mental models of eco-driving that regular drivers have. A driving simulator experiment with a varied road layout comprising urban and motorway sections was designed. The study used simple driving task instructions to investigate changes in the participants’ behaviour and thoughts in three conditions. Sixteen drivers were asked to ‘Drive normally’, ‘Drive safely’ or ‘Drive fuel-efficiently’. Behavioural measures, think aloud protocols and interviews were compared and analysed. The emphasis of this study was on eco-driving relevant indicators such as accelerating, braking, coasting and car-following. The results show that the participants do have mental models of eco-driving, which they did not use in the Baseline drive, when they were instructed to ‘Drive normally’. Misconceptions about speed and travel time provide the potential for more effective communication with the driver about the momentary efficient speed as well as resulting time losses and fuel savings. In addition, in-vehicle guidance can increase driving safety compared to practicing eco-driving without them

Old habits die hard? The fragility of eco-driving mental models and why green driving behaviour is difficult to sustain

Tangible incentives, training and feedback systems have been shown to reduce drivers’ fuel consumption in several studies. However, the effects of such tools are often short-lived or dependent on continuous cues. Several studies found that many drivers already possess eco-driving mental models, and are able to activate them, for instance when an experimenter asks them to “drive fuel-efficiently”. However, it is unclear how sustainable mental models are. The aim of the current study was to investigate the resilience of drivers’ eco-driving mental models following engagement with a workload task, implemented as a simplified version of the Twenty Questions Task (TQT). Would drivers revert to ‘everyday’ driving behaviours following exposure to heightened workload? A driving simulator experiment was conducted whereby 15 participants first performed a baseline drive, and then in a second session were prompted to drive fuel-efficiently. In each drive, the participants drove with and without completing the TQT. The results of two-way ANOVAs and Wilcoxon signed-rank tests support that they drive more slowly and keep a more stable speed when asked to eco-drive. However, it appears that drivers fell back into ‘everyday’ habits over time, and after the workload task, but these effects cannot be clearly isolated from each other. Driving and the workload task possibly invoked unrelated thoughts, causing eco-driving mental models to be deactivated. Future research is needed to explore ways to activate existing knowledge and skills and to use reminders at regular intervals, so new driver behaviours can be proceduralised and automatised and thus changed sustainably

The activation of eco-driving mental models: can text messages prime drivers to use their existing knowledge and skills?

Eco-driving campaigns have traditionally assumed that drivers lack the necessary knowledge and skills and that this is something that needs rectifying. Therefore, many support systems have been designed to closely guide drivers and fine-tune their proficiency. However, research suggests that drivers already possess a substantial amount of the necessary knowledge and skills regarding eco-driving. In previous studies, participants used these effectively when they were explicitly asked to drive fuel-efficiently. In contrast, they used their safe driving skills when they were instructed to drive as they would normally. Hence, it is assumed that many drivers choose not to engage purposefully in eco-driving in their everyday lives. The aim of the current study was to investigate the effect of simple, periodic text messages (nine messages in 2 weeks) on drivers’ eco- and safe driving performance. It was hypothesised that provision of eco-driving primes and advice would encourage the activation of their eco-driving mental models and that comparable safety primes increase driving safety. For this purpose, a driving simulator experiment was conducted. All participants performed a pre-test drive and were then randomly divided into four groups, which received different interventions. For a period of 2 weeks, one group received text messages with eco-driving primes and another group received safety primes. A third group received advice messages on how to eco-drive. The fourth group were instructed by the experimenter to drive fuel-efficiently, immediately before driving, with no text message intervention. A post-test drive measured behavioural changes in scenarios deemed relevant to eco- and safe driving. The results suggest that the eco-driving prime and advice text messages did not have the desired effect. In comparison, asking drivers to drive fuel-efficiently led to eco-driving behaviours. These outcomes demonstrate the difficulty in changing ingrained habits. Future research is needed to strengthen such messages or activate existing knowledge and skills in other ways, so driver behaviour can be changed in cost-efficient ways

Driver distraction : managing the timing of in-vehicle tasks to improve driver safety

Distracted driving can impair driving performance and increase the likelihood of a collision. Driver interaction with in-vehicle distractions can be highly damaging to driver safety and there is the potential for this threat to increase in future vehicles. The research reported in this thesis considers how to prevent in-vehicle distractions from producing a negative driver safety outcome. This thesis informs on a series of driving simulator studies in which driver responses to lead vehicle braking events are assessed in the presence of surrogate in-vehicle distracter tasks. The design of these studies was informed by previous research using the psychological refractory period paradigm, with each study focusing on a different aspect of in-vehicle task presentation. In summary, the results demonstrate that drivers are slower to respond to a lead vehicle braking event when an in-vehicle task is presented in the period immediately before or after it occurs. The absolute magnitudes of the distracting effects of an in- vehicle task vary with the number of concurrent distracter tasks and the stimulus and response modalities involved in the task. These results were observed with highly expected braking events. The expectancy of a braking effect appears to modulate the impact of a distracter task on braking performance, such that unexpected braking events are less affected by concurrent distractions. This thesis offers a novel and potentially valuable contribution to the management of in-vehicle task presentation so as to reduce the frequency of distracted driving and to mitigate its impacts when it occurs. The results of these studies are used to develop recommendations for an in-vehicle task presentation strategy, which could inform the design of future driver workload management systems. The barriers to implementation of these suggestions are discussed, followed by a summary of further study that could increase the utility of this work.EThOS - Electronic Theses Online ServiceGBUnited Kingdo