Critical Traffic Situations Research Articles

A machine consciousness approach to urban traffic control

Abstract In this work, we present a distributed cognitive architecture used to control the traffic in an urban network. This architecture relies on a machine consciousness approach – Global Workspace Theory – in order to use competition and broadcast, allowing a group of local traffic controllers to interact, resulting in a better group performance. The main idea is that the local controllers usually perform a purely reactive behavior, defining the times of red and green lights, according just to local information. These local controllers compete in order to define which of them is experiencing the most critical traffic situation. The controller in the worst condition gains access to the global workspace, further broadcasting its condition (and its location) to all other controllers, asking for their help in dealing with its situation. This call from the controller accessing the global workspace will cause an interference in the reactive local behavior, for those local controllers with some chance in helping the controller in a critical condition, by containing traffic in its direction. This group behavior, coordinated by the global workspace strategy, turns the once reactive behavior into a kind of deliberative one. We show that this strategy is capable of improving the overall mean travel time of vehicles flowing through the urban network. A consistent gain in performance with the “Artificial Consciousness” traffic signal controller during all simulation time, throughout different simulated scenarios, could be observed, ranging from around 13.8% to more than 21%.

ANALYSIS OF THE PROCESS OF DOUBLE-DECK BUS ROLLOVER AT THE AVOIDANCE OF AN OBSTACLE HAVING SUDDENLY SPRUNG UP

A critical traffic situation has been explored where a double-deck bus may roll over. The factors that may cause critical situations during a bus drive have been analysed. Based on this, they may be categorised as being related to vehicle construction, vehicle operation, and road infrastructure. A situation has been chosen for the analysis where the bus without passengers avoids an obstacle having suddenly sprung up in front of the bus at a distance within which the bus cannot be stopped. A similar problem occurring in the case of a passenger car drive was analysed in study [6]; it was indicated there that the manoeuvre of avoiding an obstacle is definitely more favourable in comparison with the braking process. A model of the bus motion dynamics with 12 degrees of freedom was adopted. The vehicle trajectory was given in the form of a predefined input generated by a driver model. The course of the rollover process depends to a significant extent on the interaction between the tyres and the road surface. A semi-empirical non-linear TMeasy tyre model was chosen. The calculations were carried out with the use of a computing program specially built for this purpose, where a double-deck bus model and a driver model were applied to investigate the traffic situation as described above. The calculation results obtained have shown that the process of rollover of a bus without passengers emerges at the final stage of the obstacle avoidance manoeuvre at a speed exceeding 108 km/h. This has been confirmed by the course of changes in the pressure of wheels on the road. Based on the simulation calculations carried out, an attempt was made to determine, from the observed courses of changes in physical quantities, the values that might warn the driver about a situation of imminent danger of rollover of the double-deck bus and thus might affect driver’s actions.

Development of a test rig for the precise positioning of a pedestrian dummy in driving tests

Preventive pedestrian protection systems are validated by means of driving tests reproducing safety–critical traffic situations with pedestrian involvement on a testing ground. Hence, a test rig is needed to position the dummy which replicates the pedestrian during the manoeuvre. This paper presents the development of a new test rig ensuring a precise and reproducible positioning of the pedestrian dummy according to the tolerances defined in the corresponding test specifications. The test rig is designed for the use in outdoor environment and features a high flexibility achieved by a modular design, which enables also an easy assembly. Furthermore, a special dummy mounting is developed preventing damage due to collisions between the Vehicle Under Test (VUT) and the pedestrian dummy. Finally, based on measurement results of an appropriate test scenario the high positioning accuracy of the new test rig is presented.

Planning of Optimal Collision Avoidance Trajectories with Timed Elastic Bands

This paper is concerned with the planning of optimal trajectories for vehicle collision avoidance with a Timed Elastic Band (TEB) framework. The avoidance trajectory is represented by a TEB which is optimized with respect to multiple partially conflicting objectives. The resulting trajectory constitutes the optimal compromise between a mere braking and a lane change maneuver that avoids the collision with the smoothest feasible path. The approach is applicable to general critical traffic situations as the TEB considers the constraints imposed by the vehicle dynamics, road boundaries, static obstacles and moving vehicles.

Driving performance in adults with ADHD: Results from a randomized, waiting list controlled trial with atomoxetine

PurposeTo investigate effects of a 12-week treatment with atomoxetine (ATX) on driving performance in real traffic, driving-related neuropsychological performance tests and self-evaluation of driving in adult patients with ADHD compared to an untreated control group with ADHD. MethodsParallel group design with an ATX and a waiting list group. At baseline and endpoint patients were evaluated with a standardized on-road driving test (SDBO), a driving-related neuropsychological test battery (Act and React Test System [ART2020]), and subjective measures of driving performance (one-week driving diary, Driver Coping Questionnaire). ResultsForty-three of the 64 included patients completed the study (n=22 ATX, n=21 controls). Mean intervention period was 11.9±3.0 weeks, mean daily ATX dosage was 71.6±14.9mg. At endpoint, 60.1% of patients treated with ATX and 0% of waiting list group had reduced ADHD symptoms by greater or equal to 30%. In SDBO, ATX group reduced driving errors in three of four driving performance categories (attention, P<0.05; risk-related self-control, P<0.005; driver skills, P<0.001), number of driving errors remained stable in control group. At endpoint, 47.6% of control group and 18.2% of ATX group (P<0.05) did not fulfil the driving fitness criteria according to German Guidelines (percentile rank less or equal to 16 in one or more subtests in ART2020). Total number of self-reported critical traffic situations decreased from 12.0 to 6.8 per week in ATX group (P<0.05) and remained stable in controls by 9.3 and 9.9 at baseline and endpoint (ns). Coping strategies with stressful traffic situations did not change within both groups. ConclusionOur study provides first evidence that treatment with ATX improves driving performance in real traffic in adults with ADHD.

EEG potentials predict upcoming emergency brakings during simulated driving

Emergency braking assistance has the potential to prevent a large number of car crashes. State-of-the-art systems operate in two stages. Basic safety measures are adopted once external sensors indicate a potential upcoming crash. If further activity at the brake pedal is detected, the system automatically performs emergency braking. Here, we present the results of a driving simulator study indicating that the driver's intention to perform emergency braking can be detected based on muscle activation and cerebral activity prior to the behavioural response. Identical levels of predictive accuracy were attained using electroencephalography (EEG), which worked more quickly than electromyography (EMG), and using EMG, which worked more quickly than pedal dynamics. A simulated assistance system using EEG and EMG was found to detect emergency brakings 130 ms earlier than a system relying only on pedal responses. At 100 km h−1 driving speed, this amounts to reducing the braking distance by 3.66 m. This result motivates a neuroergonomic approach to driving assistance. Our EEG analysis yielded a characteristic event-related potential signature that comprised components related to the sensory registration of a critical traffic situation, mental evaluation of the sensory percept and motor preparation. While all these components should occur often during normal driving, we conjecture that it is their characteristic spatio-temporal superposition in emergency braking situations that leads to the considerable prediction performance we observed.

Exploring precrash maneuvers using classification trees and random forests

Taking evasive actions vis-à-vis critical traffic situations impending to motor vehicle crashes endows drivers an opportunity to avoid the crash occurrence or at least diminish its severity. This study explores the drivers, vehicles, and environments’ characteristics associated with crash avoidance maneuvers (i.e., evasive actions or no evasive actions). Rear-end collisions, head-on collisions, and angle collisions are analyzed separately using decision trees and the significance of the variables on the binary response variable (evasive actions or no evasive actions) is determined. Moreover, the random forests method is employed to rank the importance of the drivers/vehicles/environments characteristics on crash avoidance maneuvers. According to the exploratory analyses’ results, drivers’ visibility obstruction, drivers’ physical impairment, drivers’ distraction are associated with crash avoidance maneuvers in all three types of accidents. Moreover, speed limit is associated with rear-end collisions’ avoidance maneuvers and vehicle type is correlated with head-on collisions and angle collisions’ avoidance maneuvers. It is recommended that future research investigates further the explored trends (e.g., physically impaired drivers, visibility obstruction) using driving simulators which may help in legislative initiatives and in-vehicle technology recommendations.

Analyses of Factors of Crash Avoidance Maneuvers Using the General Estimates System

Objective. Taking an effective corrective action to a critical traffic situation provides drivers an opportunity to avoid crash occurrence and minimize crash severity. The objective of this study is to investigate the relationship between the probability of taking corrective actions and the characteristics of drivers, vehicles, and driving environments. Methods. Using the 2004 GES crash database, this study classified drivers who encountered critical traffic events (identified as P_CRASH3 in the GES database) into two pre-crash groups: corrective avoidance actions group and no corrective avoidance actions group. Single and multiple logistic regression analyses were performed to identify potential traffic factors associated with the probability of drivers taking corrective actions. Results. The regression results showed that the driver/vehicle factors associated with the probability of taking corrective actions include: driver age, gender, alcohol use, drug use, physical impairments, distraction, sight obstruction, and vehicle type. In particular, older drivers, female drivers, drug/alcohol use, physical impairment, distraction, or poor visibility may increase the probability of failing to attempt to avoid crashes. Moreover, drivers of larger size vehicles are 42.5% more likely to take corrective avoidance actions than passenger car drivers. On the other hand, the significant environmental factors correlated with the drivers' crash avoidance maneuver include: highway type, number of lanes, divided/undivided highway, speed limit, highway alignment, highway profile, weather condition, and surface condition. Some adverse highway environmental factors, such as horizontal curves, vertical curves, worse weather conditions, and slippery road surface conditions are correlated with a higher probability of crash avoidance maneuvers. These results may seem counterintuitive but they can be explained by the fact that motorists may be more likely to drive cautiously in those adverse driving environments. Conclusions. The analyses revealed that drivers' distraction could be the highest risk factor leading to the failure of attempting to avoid crashes. Further analyses entailing distraction causes (e.g., cellular phone use) and their possible countermeasures need to be conducted. The age and gender factors are overrepresented in the “no avoidance maneuver.” A possible solution could involve the integration of a new function in the current ITS technologies. A personalized system, which could be related to the expected type of maneuver for a driver with certain characteristics, would assist different drivers with different characteristics to avoid crashes. Further crash database studies are recommended to investigate the association of drivers' emergency maneuvers such as braking, steering, or their combination with crash severity.

Adaptive signal system

In contrast to adaptive front lighting a significant leap forward in the quality of rear signal patterns has still to be made as yet. The fact that three of the five rear lamp signal functions still need to be controlled manually and the ongoing discussion about the exceedingly frequent misuse of rear fog lamps are indicative of just two facets of the need for action. The ASIGNIS Adaptive Signal System is a concept developed by Hella. It not only remains fully compatible with today’s signal pattern it also improves the perception of rear lighting under all light and weather conditions as well as in critical traffic situations.

Human-machine interface for a hypovigilance warning system

This paper deals with the human-machine-interface of the AWAKE system, which is designed for the “effective assessment of driver vigilance and warning according to traffic risk etimation”. It shows the development procedure of the AWAKE warning concept based on literature, existing guidelines, analytical steps and usability experiments. The specific contextual conditions of interactions in hypovigilant driver states, low interaction experience, and potentially critical traffic situations are considered. Initial user tests of a mixed virtual and physical prototype in a driving simulator are described, which show high detection rates (99%) for the warnings and good acceptance of the AWAKE system.

Understanding The Relationship between Gross Population and Traffic Accidents in Jordan.(Dept.C)

Jordan has experienced in the last decade a continuous increase in the number of accidents, which has resulted in a high number of fatalities and injuries. There are many reasons behind this critical traffic situation in Jordan, Some of these reasons are the lack of well-defined land use policies that relate the development pattern and density to transportation, the unsafe and unreliable transportation system, and the concentration of jobs and governmental services in the center of the capital and governorates. This paper studies the relationship between the gross population density and the total number of accidents for the different governorates in Jordan. It was concluded that the people of the governorates with high gross population density are involved in more accidents with low severity indices than those of the governorates with less gross p opulation density. On the other hand, the people of the governorates with less gross population densities are involved with fewer accidents but with high severity indices. It was also found that buses are involved in more accidents than their share of total traffic. This paper recommended, among otherthings, a development of land use policy to shape the future transportation system in Jordan and consequently set the goals and objectives to reduce the number of accidents and their severity.

Driver Fatigue and Accidents - Can Visual Sensitivity Predict Drivers Ability to Drive Safely ?

The aim of the study was to investigate whether visual sensitivity, defined as the ability to quickly detect and react to a visual stimulus, could be used to predict drivers ability to drive safely. Ten sleep-deprived and ten alert subjects drove for two hours on a simulation of a motorway, in an advanced driving simulator, and were exposed to a number of critical traffic situations. The results showed that visual sensitivity could predict about 50 % of the subjects' variation in lateral position. Implications for the design of a driver support system, based on measurement of visual sensitivity, are discussed.

Interaction of Automated and Non-Automated Vehicles

Novel car technologies like driver assistance systems may have unforeseen and unintended consequences on overall performance of the vehicle-driver-environment system. As an example the question about the interaction of vehicles with and without automatic support systems is discussed, for further investigations computer simulation of typical and possibly critical traffic situations, where both human conductors and support systems are involved, is recommended. For this purpose a model that accounts for the cognitive capabilities of human drivers is developed.

Measurement of traffic conflicts

Traditionally road accident statistics are used to assess the level of road safety and evaluate road safety programs. In some cases, the lack of good and reliable accident records have hampered proper analyses. A promising approach that overcomes this problem is the traffic conflict technique which relies on observations of critical traffic situations for safety analysis. However, despite the extent of work undertaken in traffic conflict research, there are still a number of issues on conflict measurement and application that have not been well understood by many safety analysts. This has resulted in a general lack of support for the wider application of the technique in safety analysis. This paper shows that one way of using the traffic conflict technique effectively is to ensure that conflicts are quantitatively defined, objectively measured and suitably applied. Before establishing the proposed framework for conflict analysis, the paper first discusses the problems and weaknesses often associated with conflict studies. Considerations for a conflict study based on the proposed approach are then presented and the case of an expressway merging is used to illustrate the method adopted.