Overtaking is one of the most dangerous manoeuvres on two-lane rural highways. The most influential factors are related to drivers, so ITS and assistance systems are not yet common. This research is based on experimental data of overtaking manoeuvres collected using an instrumented passenger car, equipped with four cameras, laser rangefinders and a global positioning service (GPS) tracker. This vehicle was driven along four different road segments in the surroundings of Valencia (Spain) at a speed slightly slower than the operating speed of each segment. Overtaking time and speeds were measured. Unlike previous work, the influence of human factor was also considered. Age and gender of overtaking driver, as well as time spent following were used to characterise this influence. More than 200 manoeuvres were recorded and the influence of driver characteristics and delay on gap acceptance, manoeuvre duration and speed differences have been analysed. Results show differences in behaviour between age and gender groups, since young male overtaking drivers have shown a more aggressive behaviour. Overtaking times were around 1 s lower than other drivers, whereas average speed difference was 4 km/h higher. Collected data and their analysis have provided a basis to review design criteria and to develop future assistance systems.

Methodologies based on naturalistic observation provide the most accurate data for studying drivers’ behaviour. This study presents a new methodology to obtain naturalistic data related to drivers’ behaviour in a road segment. It is based on the combination of using global positioning system data and drivers’ questionnaires. The continuous speed profiles along a road segment and the characteristics of drivers, of their trips and the type of their vehicles can be obtained for a great amount of drivers. It has already been successfully used for several studies, such as the development of models to estimate operating speed profile in two-lane rural road segments; or the characterisation of driving styles. These operating speed models have been the key for the development of a new geometric design consistency model, allowing an easier road safety evaluation. Besides, knowledge on the human factors that influence speed choice may be useful for road safety media campaigns and education programs designers, and also for the improvement of intelligent driver assistance systems.

Naturalistic driving is an experimentation model that allows us to recognise the driving modes observing the driver's behaviour at the wheel of a set of people in natural conditions during long periods of observation. This research methodology aims at increasing the representativeness of the data collected in opposition to data stemming from highly controlled laboratory experiments. However, naturalistic driving research designs produce large volumes of data that are difficult to handle. Thus, it is very important to work with suitable methods for representing and interpreting data, allowing us to observe the variability of the results. The aim of this study is to implement a new methodology adapted to the particularities of the naturalistic method that allows us to retrieve the positioning information through a georeferencing process of the available data. This method is the first step (preprocessing) to achieve a more clear and intuitive representation (cartographic representation) using Geographic Information Systems (GIS).

The methodology of naturalistic driving observation aspires to observe the driver and his environment while driving in natural driving settings. It is of great importance in research on road safety as this method of observing road users eliminates the disadvantages of traditional methods like simulator studies or interviews. However, it produces vast such amounts of data and challenges data reduction and data analysis. Therefore automatic methods for filtering critical incidents based on thresholds for numerical data are often applied to select the data to be analysed. This study reports a small-scale field trial in Valencia, Spain, which was conducted within the promoting real life observation for gaining understanding of road user behaviour in Europe project. The analysis of the numerical data using thresholds resulted in a great number of false alarms and did not identify safety-critical sequences. In contrast, video analysis revealed a number of critical events that had not been previously detected using the numerical parameters. The study conveyed the importance of continuous video recording in these kinds of studies and showed that the methodology of data reduction for naturalistic driving studies requires further development in order to be able to capture all the relevant incidents automatically.

The functionality of an electric vehicle enables to regenerate energy into the battery by using the electric motors for electric braking. By integrating this electric brake into the accelerator pedal, drivers are expected to use more often the electric brake and less often the hydraulic brake. However, the pedal system of a car is a crucial connection between driver and car. Any modification of this part can lead to decreasing acceptance. Two driving simulator studies were conducted to investigate the effect of three different settings of electric braking and the impact of a combined pedal solution (CPS) on acceptance and energy consumption. Participants performed test drives in rural and urban environments, with both the CPS and a conventional pedal solution and different levels of recuperation. The results show that drivers preferred stronger electric braking and the CPS (instead of a conventional pedal solution). With the CPS, drivers used less often the hydraulic brake and drove more efficiently.

In order to reduce CO₂ emissions, the electric vehicle (EV) represents today an alternative to traditionally fuelled vehicles. However, this new eco-friendly mode of transport involves different kinds of constraints to use that are likely to affect mobility. To assess driver acceptability of EVs and to study the impact of electric technology on the mobility behaviours of drivers, the MINI E France project was undertaken by IFSTTAR and carried out in cooperation with the vehicle manufacturer Bavarian Motor Works Germany. Fifty ‘private users’ from Paris drove for 6 months an electric MINI E. This paper presents and describes the mobility, charging and driving behaviours reported by EV users. In particular, the paper focuses on how users organise themselves to deal with the limited range of the EV, what changes are induced in their mobility and what are their requirements in terms of intelligent transport system functions relevant for e-mobility.

Drivers normally elect whether or not to engage with a secondary task while driving. This study aimed to determine whether drivers’ willingness to engage with their mobile phone is affected by demands from the roadway environment and if these effects are more pronounced for some phone functions compared with others. Fifteen video clips were played to 20 participants representing different road scenarios, and therefore demands, such as driving on an empty auto route or turning right on a main arterial road. The participants then used three point Likert scales to rate their willingness to place or answer a call and send or read a text and a five point scale to rate the perceived riskiness of placing and answering a call only. Participants were also asked to think aloud when making their judgements so further insight could be gained. It was found that willingness to engage was affected by both the perceived roadway demands and the phone function under consideration. The perceived riskiness also affected willingness to engage when placing a call only. The think aloud element indicated the participants’ reasoning behind these findings as well as identifying possible future areas of research.

It has already been proved that the use of the mobile phone while driving has a negative impact on the driving performance, increasing the risk of being involved in a car accident. However, in order to plan adequate corrective actions, there is the need to know more about people's usage of mobile phone while driving and what are drivers' opinions about the risk represented by that action. The aim of the present study was three-fold: to investigate the patterns of use of the mobile phone while driving by gender and age, to find out the prevalence of hands-free systems use by gender and age and, finally, to understand the perceived hazard in using the mobile phone while driving by gender and age. A sample of 769 Portuguese drivers answered a web-based survey developed in the frame of the European project INTERACTION. The answers revealed that the rate of mobile phone use among Portuguese drivers is very high. In addition, results showed that drivers perceived talking on a hands-free mobile phone while driving as much less dangerous compared with speaking on a hand-held mobile phone. Based on those results, further research is suggested.

Electronically coupled platoons of vehicles have the potential to increase the efficiency of transport on unmodified motorways. In doing so, the time headway (THW) between participating vehicles will be dramatically reduced. The present study investigated whether drivers are willing to keep a THW smaller than their preferred one to conform to the norm established by the presence of platoons holding short THWs. Firstly, two constructs had to be distinguished to answer this question: the preferred THWs represent a range of THWs drivers feel safe with and the THW that is indeed adopted by drivers in a given situation (adopted THW). Secondly, comparing adopted and preferred THW informs about whether drivers would adopt a THW beyond their preferred one as a result of the influence of platoons. Forty-two participants were asked to follow a lead vehicle (LV) in three different traffic conditions. In two conditions, there was a platoon of vehicles in the inside lane, where the THW between the vehicles was either large (THW = 1.0 s) or short (THW = 0.3 s). In a third baseline drive, the LV was the only vehicle present. Preferred THW was assessed after each traffic conditions with the psychophysical method of limits. Results show a consistency of preferred THW and there is a significant difference in adopted THW values throughout the conditions, which supports the idea of two distinct constructs. Further, participants’ minimum adopted THW did not drop under but was very close to the minimum preferred THW in condition THW03. It can be concluded that platoons could lead drivers to drive closer to their limits. Further studies need to investigate if in other conditions, drivers would go below their limit and in this case, consequences on the drivers (e.g. in terms of safety, workload and performance) will also require further investigations.

Innovative advanced systems have been proposed for improving the safety and efficiency in the mobility of road users in Europe. Particularly for road transport, new ITS-based Cooperative Services for preventing accidents in critical points and situations are emerging where road users, vehicles and a sensorised integrative infrastructure are the main actors. With this motivation, and taking into account the road infrastructure's capability to incorporate new Cooperative Systems technology, this study aims to provide a first set of guidelines for speeding up the convergence process among a broad set of multi-heterogeneous sensor data fusion, high level situation understanding and assessment, and communications capabilities, all of them necessary for the development of advanced ITS safety-related services previously mentioned. Analysis is focused on vulnerable road users (VRUs) and on how this kind of services will contribute to provide more intelligent and safer urban traffic environments. A typical scenario involving VRU is studied as a preliminary analysis of the impact that these systems have on the safety of a specific group of road users. Some of the underlying principles of the proposed architecture will be validated in a field operational test FP7 European project.

Drivers' road perception is an important human factor of comfort and safety on driving. Available sight distance of crest vertical curves superimposed on horizontal curves can be geometrically optimised by applying 3D coordination criteria. However, drivers might not perceive available sight distance improvements. Two approaches were used to investigate the effect of geometrical optimised design on perceived sharpness and visibility of isolated crest vertical curves overlapped with horizontal curves. A survey-based approach was used to evaluate subjective perception of 100 drivers. Three-dimensional renderings were displayed to subjects; who were asked to rank the curves by sharpness and sight distance. Moreover, 50 of those drivers previously participated on a driving simulation experiment involving the same curves, so objective driving data were collected too. Drivers' survey results indicate that driver's curve perception depends on the algebraic difference of grades while coordination of vertical and horizontal curves does not appear to affect this perception. On the other hand, the operating speeds on different curves were not statistically different from each other. Surprisingly, the operating speeds on a flat curve tended to be lower than on the vertical crest curves superimposed on the same horizontal curve. Likely causes are discussed in the paper.

The authors present a new approach to the modelling of human driving behaviour, which describes driving behaviour as the result of an optimisation process within the formal framework of hybrid automata. In contrast to most approaches, the aim is not to construct a (cognitive) model of a human driver, but to directly model driving behaviour. The authors assume human driving to be controlled by the anticipated outcomes of possible behaviours. These positive and negative outcomes are mapped onto a single theoretical variable – the so called reinforcement value. Behaviour is assumed to be chosen in such a way that the reinforcement value is optimised in any given situation. To formalise the authors models they use hybrid automata, which allow for both continuous variables and discrete states. The models are evaluated using simulations of the optimised driving behaviours. A car entering a freeway served as the scenario to demonstrate our approach. First results yield plausible predictions for car trajectories and the chronological sequence of speed, depending on the surrounding traffic, indicating the feasibility of the approach.