1,721,107 research outputs found
La simulazione di guida per l'analisi della sicurezza dell'esercizio viario
No full textLa sicurezza stradale rappresenta una delle principali problematiche sociali in tutto il mondo. L’attuale approccio progettuale delle infrastrutture stradali è basato sul rispetto delle equazioni cinematiche e dinamiche del veicolo isolato che impongono standard geometrici per ogni singolo elemento e non considerano in maniera adeguata il comportamento dell’utente significativamente influenzato dalle scelte progettuali. La continua crescita dei carichi di traffico ha comportato un abbassamento significativo dell’offerta funzionale delle reti stradali. Inoltre sulle stesse infrastrutture congestionate è presente una commistione di flussi diversamente motivati con differenti esigenze e aspettative di servizio.
Le tecnologie emergenti della simulazione di guida in realtà virtuale permettono di interpretare le complesse interazioni esistenti tra l’uomo, l’ambiente stradale e i veicoli attraverso un approccio interdisciplinare.
Nell’ambito di questa breve relazione sono presentati i risultati più interessanti di alcune sperimentazioni condotte nel laboratorio di simulazione di guida in realtà virtuale del CRISS (Centro Interuniversitario di Ricerca per gli Studi sulla Sicurezza Stradale), che dimostrano come il comportamento dell’utente, ed in particolare la sua soglia di percezione ed accettazione del rischio, sia indiscutibilmente influenzata dalle caratteristiche geometriche della strada (per basse densità veicolari, quando prevale il ruolo delle geometrie d’asse e di piattaforma) e dalle interferenze veicolari (per alte densità di flusso, quando prevale il comportamento dell’utente in funzione del disagio). I risultati ottenuti hanno importanti ricadute sulle procedure di simulazione per la verifica della qualità dei progetti in ordine alla sicurezza dell’esercizio viario per la viabilità extraurbana.
Nella prospettiva di un approccio di verifica sistemica della funzionalità e sicurezza dell’infrastruttura, sulla base dei risultati di simulazione, è stata proposta una nuova teoria, la “teoria del disagio” subito dall’utente nel percorrere un certo itinerario stradale causato dalle differenze esistenti tra le aspettative e necessità della domanda di mobilità e la reale offerta dell’infrastruttura. L’applicazione della teoria a numerosi casi di studio reali ne ha ampiamente validato le ipotesi di base rivelando che le scelte progettuali non possono prescindere da una dettagliata analisi dei flussi veicolari (in termini di entità, composizione, variabilità, motivazione degli spostamenti), della funzionalità sistemica dell’infrastruttura, delle aspettative e desideri degli utenti e del loro comportamento indotto dalla strada
A Study on Driving Performance Along Horizontal Curves of Rural Roads
Full text linkSeveral studies have indicated that road crashes are more likely to occur on horizontal curves than on straight roadway segments for a good number of reasons, the most important of which is associated with the driver's behaviour along the curve depending on his perception of the road geometry. However, the evaluation of the effects of curve features on driving performance still remains a critical issue for road safety and design.
The main objective of this study is to investigate driver's behaviour and his perception of road curves, which is directly related to road safety. Specifically, the effects of some curve features (radius, transition curve, visibility, cross section) on driving performance are investigated through a multi-factorial experiment based on driving simulation. The driving speeds and trajectories of a sample of 34 drivers were statistically processed over 72 different curves distributed along three test scenarios. The main and interaction effects of the independent variables are described and discussed in the results section of this paper providing a significant improvement of the actual knowledge on in this field of research.
In general, the results confirm that driving simulation can disclose the relationships between road design features and driver behavioural aspects that are crucial issues in creating a safer road infrastructure
Analysis of Driver’s Behaviour in Road Tunnels: a Driving Simulation Study
No full textThe subject of safety in road tunnels has always been one of the topics most discussed in literature, especially in applying the risk theories to the design of new galleries or measures for adaptation of existing tunnels. In this paper the author presents the main results of a preliminary study, developed in virtual reality environment with a driving simulator, on the dynamic and cinematic effects of road tunnels in driving behaviour: a sample of drivers has driven along the same stretches of an existing highway implemented on CRISS driving simulator, but in two different cases: in presence and in absence of road tunnels along the same scenario. The outcomes have been elaborated for comparing driving behaviours. Results show significant differences in terms of speed and trajectory adopted by drivers along the road sections with tunnels and along the same path in the absence of the galleries.
Moreover it is presented the enlargement of the database of a previous research developed on other highways stretches, to verify the correlation between an experimental indicator able to interpret driver’s behaviour and the actual accident rate recorded in each kilometre of the road stretches implemented on driving simulation
Does Roadside Vegetation Affect Driving Performance? Driving Simulator Study on the Effects of Trees on Driver’s Speed and Lateral Position
Full text linkThis study investigated the effects of roadside vegetation on driving performance on a two-lane rural road. Forty-four participants drove along seven different roadside tree configurations implemented in a driving simulator. Configurations were characterized by two offsets of trees from the road edge (1.5 m and 4.0 m) and three spacings between trees (10.0 m, 17.5 m and 25.0 m) located on the roadside of a 6.0 m wide two-lane rural road. One additional configuration, without trees, was used as the baseline condition. The investigation was developed over five geometric elements: sharp/gentle, left/right curves and tangent. The driver’s lateral position and speed were subsequently collected.
Compared to the baseline condition, it was found that when trees were close to the road edge drivers tended to significantly decrease their speed and moved towards the centerline of the road. On the contrary, when the offset of trees increased, drivers adopted higher speeds, increasing the distance from the road edge but with a lower left lateral displacement. This occurred along all five geometries, especially on sharp curves. Tree spacing did not affect the driver’s speed but significantly influence the lateral position: drivers moved further away from the road edge when tree spacing decreased.
The results demonstrate that drivers balance the useful guidance information that roadside trees provide with the risk associated with their presence: when trees are far, the sense of guidance is predominant and drivers adopt higher speeds; when trees are close, they are seen as a risk by drivers who consequently slow down and move further away from them. Such driving behaviour has direct impacts on the safety implications of roadside trees which are discussed in this paper
Analysis of the Effectiveness of Perceptual Treatments on Crest Vertical Curve: a Driving Simulator Study
No full textNight vs Day Driving: a new Approach to Design Consistency using Driving Simulation
No full text"The paper reports the outcomes of a pilot study aimed at verifying if design consistency measures based on. driver speed profile could provide different evaluation of the road during day and night driving.. Using an interactive fixed-based driving simulator an experimental study was carried out in order to:. a) evaluate the speed differential during night driving for the identification of critical road situations that the. analysis based on speed during day driving is not able to reveal;. b) identify the most efficient road safety measures, that contribute to improve safety during night driving.. A real two-lane rural road, characterized by high accident rate during nighttime, was implemented in the. driving simulator of Inter-University Research Centre of Road Safety (CRISS) and the driver behavior of a. large sample of participants was recorded in daytime and nighttime conditions.. Based on data recorded on 39 tangent-curve configurations, the following main results were obtained. For. several configurations of tangent-curve transitions, the analysis of the speed differential (85MSR) based on. speed during day driving is not able to reveal critical road situations identified during night driving. This result. demonstrates the need for developing design consistency evaluations not only during day driving but also. during night driving conditions. Moreover road safety measures have been proposed to decrease the speed. differential of critical sites identified during night simulation tests, by reducing the speed in the approach. tangent and increasing the driver’s visibility and perception of the curve element.
Quality control of road project: identification and validation of a safety indicator
No full textGeometrical indicators neglect both normal human behavior and driver’s behavior under specific conditions of stress, risk and fatigue. These conditions are frequently induced by the road environment and the way of driving. Repeated dynamic stresses (such as transversal accelerations) during driving can cause abnormal behaviors. This is the reason why a new, advanced and effective indicator is proposed and validated to assess the safety of road infrastructures considering the investigation of the variability of transversal accelerations as an unbiased indicator of discomfort. The main theoretical assumption is: a subject driving on a self-explaining road assumes a correct and safe trajectory and the local transversal accelerations depend only on the curvature of road geometry. If the driver corrects the vehicle’s trajectory more than what road curvature imposes, the road is not self-explaining and, consequently, it can be unsafe. If the local transversal accelerations do not depend only on the actual road curvature, they are biased by the driver’s corrections of trajectory. The proposed indicator takes into account the frequency and the amplitude of anomalous corrections of trajectory. The theoretical hypothesis of high correlation between the proposed indicator and the observed accident rate has been verified using an advanced driving simulator. Moreover an analysis of the correlation between such an indicator and a geometrical parameter has been examined. Two Italian case studies are presented. The numerical results confirmed such a theoretical hypothesis. The values of correlation parameters are much higher than any expectation. These outcomes are extremely promising but validations to other case studies are suggested before model generalization
Effects of simulated day and night driving on the speed differential in tangent-curve transition: a pilot study using driving simulator
No full text"Objective. The pilot study described in this paper is aimed at analyzing the driver speed profile for the evaluation of road design consistency during simulated day and night driving. The research, carried out using a driving simulator, is developed with the overall objectives of evaluating the speed differential during simulated night driving for the identification of critical road situations not detected by design consistency evaluation during simulated day driving.. . Methods. An existing two-lane rural road, where high accident rates were recorded during nighttime, was implemented in the driving simulator of the Inter-University Research Centre of Road Safety (CRISS) and the drivers speed profiles were recorded both in simulated day and night driving conditions over the 39 tangent-curve configurations that composed the road alignment.. . Results. The analysis of the speed differential based on 85MSR indicator during simulated day driving was not able to identify critical road situations that, on the contrary, the same analysis during the simulated night driving revealed. It occurred for the most of tangent-curve configurations.. . Conclusions. The study demonstrate that limiting the speed analysis only to day driving condition can not exclude the possibility that during the night driving some road configurations could become unsafe. The findings of the study highlight the need for carrying out design consistency evaluations also for night driving conditions..
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