The objective of this research was the analysis of the driving performance of drivers with Mild Cognitive Impairment (MCI) or Alzheimer’s disease (AD), in different road and traffic conditions, on the basis of a driving simulator experiment. In this experiment, healthy “control” drivers, patients with MCI, and patients with AD, drove at several scenarios at the simulator, after a thorough neurological and neuropsychological assessment. The scenarios include driving in rural and urban areas in low and high traffic volumes. The driving performance of healthy and impaired drivers was analysed and compared by means of Repeated Measures General Linear Modelling techniques. A sample of 75 participants was analysed, out of which 23 were MCI patients and 14 were AD patients. Various driving performance measures were examined, including longitudinal and lateral control measures. The results suggest that the two examined cerebral diseases do affect driving performance, and there were common driving patterns for both cerebral diseases, as well as particular characteristics of specific pathologies. More specifically, cognitively impaired drivers drive at lower speeds and with larger headway compared to healthy drivers. Moreover, they appear to have difficulties in positioning the vehicle on the lane. The group of patients had difficulties in all road and traffic environments, and especially when traffic volume was high. Most importantly, both cerebral diseases appear to significantly impair reaction times at incidents. The results of this research suggest that compensatory behaviours developed by impaired drivers are not adequate to counterbalance the direct effects of these cerebral diseases on driving skills. They also demonstrate that driving impairments increase as cognitive impairments become more severe (from MCI to AD).@en

Although driver distraction can be considered as part of everyday driving it constitutes a basic contributory factor for increased risk for road accidents internationally. Within this content, cell-phone use and conversation with passenger are two critical in-vehicle distraction conditions with respect to driver behavior and safety. The objective of this research is the investigation of the effect of area and traffic conditions on driving performance of drivers while talking on the mobile phone or conversing with the passenger. For this purpose, a large driving simulator experiment is carried out, in which 95 drivers from all different age groups (young, middle aged and older) were asked to drive under different types of distraction (no distraction, conversation with passenger, cell phone use) in rural and urban road environment, in low and high traffic. In the next step, an appropriate modelling methodology has been developed, including first descriptive analysis in order to explore the large database. Then generalized linear models as well as generalized linear mixed models regarding average speed and reaction time were implemented in order to estimate the effect of the examined distraction sources as well as area and traffic characteristics on driving behaviour and road safety. Results indicate that female drivers, especially in rural areas, were found to have the worst reaction times, while being distracted (either conversing with a passenger or talking on the cell phone). This is probably explained by the fact that in urban area, the complex road environment alerts the drivers in order to self-regulate their driving to compensate for any decrease in attention to the driving task. Furthermore, regarding average speed, it is observed that in rural areas drivers reduce the speed while distracted either by talking on the mobile phone (older drivers) or by conversing with the passenger (young and middle aged drivers), especially at high traffic volume while in urban areas suggesting a driver's compensatory behaviour. The next steps of the present research could focus on the investigation of the impact of mobile phone use, not only when the drivers talk on mobile phone using a hand-held device, but also when they use a hands-free device, a Bluetooth, or when they type messages.@en

The objective of this research is the analysis of pedestrians behaviour along entire trips in urban road networks, with focus on their interaction with the traffic and the road environment while crossing roads. For this purpose, a special field survey was designed and carried out, which involved the recording of pedestrians road crossing behaviour along entire trips in real time by means of camera in motion at the centre of Athens, Greece. Based on the results of the field survey, an analysis of road crossing behaviour of pedestrians is presented, concerning characteristics of the trips, the pedestrians, the road environment and the traffic conditions. The results indicate that basic parameters of pedestrian trips (i.e. trip length, walking speed, number of crossings) can be described by appropriate probability distributions. They also reveal a tendency of pedestrians to cross either in the beginning or in the end of the trip, an increased probability of crossing at signalized junctions when these are available, and increased probability of crossing at mid-block in low traffic volume and on one-way roads. Furthermore, there is an overall tendency of pedestrians cross to at mid-block when the road and traffic conditions are favourable. On the contrary, more traffic lanes and increased traffic volume appear to discourage pedestrians from accepting important interaction with the vehicles and to lead them towards the choice of protected crossing locations. The proposed data collection method and the results of the analysis can be exploited in further research for the development of models of pedestrian crossing behaviour along entire trips in urban areas.@en

A pedestrian trip is a spatiotemporal process going through different states and related to different decisions made at certain times and locations on the urban network. The analysis of pedestrian trips in terms of crossing patterns is a complex task, which is often further limited by a lack of appropriate and detailed data. The objective of this research is the development and testing of appropriate indicators of pedestrian crossing behavior along urban trips, and a methodology for collecting and processing the data required for the analysis of this behavior. First, a comprehensive set of indicators for the assessment of pedestrian behavior in urban areas is proposed (i.e. average trip length, number, type and location of crossings). Then, a GIS tool is developed for the storage and integration of information on pedestrian trips, and the crossings made during the trips, with other geographical information (e.g. road network function and geometry, traffic control and pedestrian facilities). The proposed approach is then tested at network level on a sample of pedestrian trips collected by a field survey. The results suggest specific patterns of pedestrian crossing behavior, such as the tendency to cross at the beginning of the trip and the tendency to cross at mid-block locations when signalized junctions are not available. The results are further discussed in terms of urban planning and management implications. It is concluded that the proposed approach is very efficient for the analysis of pedestrian crossing behavior in urban areas.@en

The objective of this research was to analyze pedestrian exposure to risk along urban trips in relation to pedestrian crossing behavior. First, an appropriate microscopic indicator was selected for the estimation of pedestrian exposure to risk while a person crossed a road at isolated locations. This indicator expressed exposure as the number of vehicles encountered by pedestrians during the crossing of a single uncontrolled road lane and could be further adapted and applied for various road design and traffic control features. Moreover, the number and type of crossings along a pedestrian trip could be identified on the basis of the trip length and topology, whereas the set of choices of alternative crossing locations for each crossing decision could also be defined. The crossing probability associated with each alternative location along the trip could then be estimated by means of a sequential logit model. A method is presented for the estimation of exposure to risk for pedestrians along a trip in relation to their crossing behavior. The proposed approach was demonstrated in a pilot implementation for a typical pedestrian trip in the center of Athens, Greece, for four scenarios combining different traffic conditions and pedestrian walking speed. The results showed that exposure to risk for pedestrians along a trip was significantly affected by the pedestrians' crossing choices, as well as by road and traffic characteristics. Results also revealed that pedestrians with increased walking speed might have partly compensated for their exposure to risk so that the risk was not significantly affected by traffic volume. Moreover, specific locations with increased pedestrian exposure to risk could be identified for each trip. The proposed microscopic analysis of exposure to risk proved advantageous compared with existing macroscopic ones. This microscopic analysis revealed the different possible definitions and aspects of pedestrian exposure, with useful implications for road safety analysis.@en

The objective of this research is the analysis of perceived highway level of service in relation to drivers’ personal characteristics and traffic conditions. A field survey was carried out for that purpose, in which drivers were asked to assess the traffic conditions experienced on a freeway segment, just after having actually driven along this segment. At the same time, traffic counts were taking place. Exploratory analysis revealed a large dispersion in drivers’ assessment of level of service for each volume-to-capacity (v/c) value, especially at moderate traffic conditions. Furthermore, the effect of driver’s age, gender, driving experience, familiarity with the road, vehicle capacity, and v/c on perceived level of service was examined by means of nonparametric statistical tests. It was found that, in this sample, only traffic conditions affected drivers’ assessment of level of service. Perceived level of service was then modeled against v/c by means of a piecewise linear regression technique for three scenarios, covering different types of drivers with respect to their tolerance of congestion. The results confirm that the relationship between perceived level of service and traffic conditions has a piecewise linear form with significant differences in slopes and breakpoints. Moreover, they suggest that drivers perceive no more than two or three levels of traffic conditions. More specifically, only low-tolerance drivers appear to distinguish level of service A from B and only high-tolerance drivers appear to distinguish level of service D from E. On the contrary, an impressive reduction of perceived level of service occurs within the v/c interval of 0.55–0.70 in all scenarios. These findings are further discussed in relation to their accordance with the highway capacity manual approach for level of service and its possible adjustments.@en

Explaining pedestrians’ crossing behavior along entire trips may contribute toward more efficient and targeted planning of pedestrian facilities in urban areas and more accurate consideration of pedestrian safety. Although existing research on pedestrians’ crossing behavior is extensive, most related studies examine pedestrians’ crossing decisions at local level and focus on a particular set of determinants (roadway environment, traffic conditions, or human factors). On the contrary, crossing behavior along entire trips is seldom explored. This paper presents a theoretical framework for modeling pedestrians’ crossing behavior along a trip, addressing a large part of the difficulties involved in collecting the necessary data and setting up a modeling framework. First, a topological approach of pedestrian trip characteristics and crossing decisions is proposed, allowing consideration of distinct patterns of crossing behavior along a trip. Moreover, specific techniques from the family of discrete choice models are proposed for determining the number and location of pedestrians’ crossings, accounting for the hierarchical and dynamic nature of pedestrians’ decisions along a trip. Finally, a field survey method is presented, allowing collection of detailed information about pedestrians’ crossing decisions along urban trips, including data on roadway, traffic, and individual characteristics, as well as the interactions between pedestrians and motorists. Preliminary results from a pilot implementation of the proposed framework are promising, and a full-scale application for testing and validation is in progress.@en

This paper concerns a review and critical assessment of the existing research on pedestrian behaviour in urban areas, focusing on two separate yet complementary aspects: route choice and crossing behaviour. First, an exhaustive review of the existing route choice models for pedestrians is presented. It is shown that the existing models are mainly more stochastic and more macroscopic than required and seldom incorporate the interactions between pedestrians and traffic. Second, the existing models on pedestrians crossing behaviour are presented and assessed. It is shown that, although their approach is usually detailed, deterministic and traffic-oriented, they are mainly devoted to a local level behaviour and focus on only one type of all the potential determinants. Most importantly, these two complementary and possibly interdependent aspects of pedestrian behaviour are always examined separately. The results of this review reveal a lack of an overall and detailed consideration of pedestrian behaviour along an entire trip in urban areas. Moreover, the need for an integrated approach based on flexibility, disaggregation and more determinism is identified. Accordingly, a set of modelling techniques are discussed as a general framework for further research in the field.@en

Pedestrians are mainly exposed to the risk of road accident when crossing a road in urban areas. Traditionally in the road safety field, the risk of accident for pedestrian is estimated as a rate of accident involvement per unit of time spent on the road network. The objective of this research is to develop an approach of accident risk based on the concept of risk exposure used in environmental epidemiology, such as in the case of exposure to pollutants. This type of indicator would be useful for comparing the effects of urban transportation policy scenarios on pedestrian safety. The first step is to create an indicator of pedestrians’ exposure, which is based on motorised vehicles’ “concentration” by lane and also takes account of traffic speed and time spent to cross. This is applied to two specific micro-environments: junctions and mid-block locations. A model of pedestrians’ crossing behaviour along a trip is then developed, based on a hierarchical choice between junctions and mid-block locations and taking account of origin and destination, traffic characteristics and pedestrian facilities. Finally, a complete framework is produced for modelling pedestrians’ exposure in the light of their crossing behaviour. The feasibility of this approach is demonstrated on an artificial network and a first set of results is obtained from the validation of the models in observational studies.@en

Within this research the travel patterns of passenger car drivers are investigated in relation to their age, as recorded from a national travel survey conducted in Greece. For the needs of this research drivers are classified into three mutually exclusive age groups: young (18–24), adult (25–64) and elderly (65+). The mobility of these three driver groups—expressed in terms of average annual distance driven—is then investigated with respect to parameters involving driver characteristics (experience, gender), vehicle characteristics (engine size) and the nature of the trip (time of trip and road type). Several patterns are analysed, and the dependence of the various travel patterns on driver age is tested through analysis of variance (ANOVA), mainly by the use of the Welch test. The results show that driver experience is not an influencing factor for driver mobility, whereas driver gender and vehicle characteristics, such as engine size, are. Furthermore, the results illustrate dependences between driver age and driving at night and during the weekends, highlighting the relationship between driver age and trip purpose. The distribution of mobility across the different road types does not reveal any interactions with driver age; however, specific trends are detected when distance driven is also segregated into weekday and weekend categories, indicating a relationship between driver age and mobility in relation to type of day.@en

Introduction This paper reports on the accident risk of foreign and native drivers in various road environments in Greece. In particular, the analysis aims to determine the combined effect of driver nationality, area type (inside/outside urban area), junction (yes/no), and lighting conditions (day/night) on accident fault risk. Methods Data from the national accident database of Greece are used in a hierarchical log-linear analysis. The induced exposure technique is applied due to the lack of exposure data. Estimated and observed odds ratios are then examined for the quantification of the various effects in terms of relative risk. Results The initial examination of a saturated model leads to the rejection of all three- and higher-order effects within variables, without providing an adequate fit to the data. On the contrary, a non-saturated second-order model presents a very satisfactory overall fit. The examination of single and combined effects indicates that the most significant effect on accident risk rises from the presence of foreign drivers at junctions. Conclusions Results confirm that foreign drivers in Greece are at increased risk. However, immigrant permanent residents appear to have a lower risk compared to tourists, regardless of the road environment.@en

This paper investigates the combined effect of driver nationality and several road characteristics (area type, at or not at junction, lighting conditions) on accident fault risk. Data from the national accident database of Greece are used to calculate accident relative fault risk rates under induced exposure assumptions. A log-linear analysis is then used to examine first- and higher-order effects within three or more variable groups. The examination of the second-order interaction among the accident fault risks of various driver nationalities at or not at junction was found to be significant. On the contrary, the respective combined effects of area type and lighting conditions were found to be non-significant. It was also shown that roadway features do not affect accident fault risk in a combined way. Results clearly indicate that foreign drivers in Greece are at increased risk. Moreover, foreign nationalities corresponding to permanent residents (i.e. Greeks and Albanians) appear to be at lower fault risk compared to foreign nationalities corresponding to tourists and visitors (e.g. EU Nationals). The effects of the various road characteristics do not modify these general trends.@en

This paper presents a methodology for modeling pedestrians’ crossing behavior along an urban trip, as well as an algorithm for the estimation of accident risk along the trip. For that purpose, existing models are exploited and further developed. In particular, a nested logit model and a linear regression model are merged and adapted to develop a hierarchical crossing behavior model, allowing for the estimation of a distribution of crossing probabilities on an urban road link among junctions and various midblock locations. The explanatory variables concern a set of directly measurable geometric and traffic characteristics. A second model is then developed for the estimation of the distribution of crossing probabilities along a trip in relation to the distance from the trip origin. Both models were sufficiently validated by means of appropriate surveys. On the basis of these models, a complete framework for the assessment of pedestrians’ crossing behavior in urban areas is developed. Moreover, a set of formulas for the calculation of accident risk along a trip in relation to the estimated crossing behavior of pedestrians is proposed.@en

This paper investigates the mobility patterns of powered two-wheeler riders in comparison with those of passenger car drivers in Greece, a country in which an increased rate of two-wheeler ownership and related traffic is observed. A nationwide travel survey targeted at active two-wheeler and passenger car drivers was carried out for that purpose. The results of the survey were exploited in two ways. First, the use of the vehicle types examined in Greece was investigated in relation to driver characteristics by calculation of the respective sample distributions. The results demonstrated a clear difference between vehicle ownership rates and vehicle use rates by vehicle type. Moreover, the mobility patterns of each vehicle type were compared on the basis of the average yearly mileage traveled in relation to driver (age, gender, experience), vehicle (engine size), type of trip (weekday or weekend), and road environment (area type, lighting conditions, road type). The findings indicated that driver gender, age, and experience appeared to be a stronger determinant of mobility patterns than vehicle type. But different mobility patterns among vehicle types in different road environments were identified; this suggests that mopeds and motorcycles are preferred for particular types of trips (e.g., traveling in residential areas and weekdays during the daytime), whereas passenger cars may be used in all cases.@en

This paper reports a study of the combined effect of driver age and engine size on accident severity and at-fault risk of young riders of two-wheelers. Data from the national accident database of Greece are used to calculate accident severity and relative fault risk rates. The induced exposure technique is applied due to the lack of exposure data. A log-linear analysis is then used to examine first- and second-order effects within three-variable groups. Accident severity modelling revealed a significant second-order interaction between severity, driver age and two-wheeler engine size. On the contrary, no second-order effects were identified in fault risk modelling. Moreover, a significant effect of driver age on accident fault risk was identified. The effect of engine size was not significant.@en