Fabrizio D'Amico

Analysis of driver speeds under night driving conditions using a driving simulator

PROBLEM Accident statistics demonstrate that there should be a greater focus on nighttime driving to improve our knowledge of driver behavior under poor lighting conditions. However, the current geometric design criteria do not take into account driving at night. Moreover, studies that propose predictive models of operating speed only consider daytime driving conditions. METHOD This study compares driver speed behavior during daytime and nighttime driving and models operating speeds and speed differentials, identifying significant factors that influence speed behavior under different lighting conditions. The research was carried out using a driving simulator for a section of an existing two-lane rural road composed of 39 tangent-curve configurations. Speed profiles were recorded for 40 drivers under simulated daytime and nighttime driving conditions. RESULTS New predictive speed models, differentiated for daytime and nighttime driving, are proposed that highlight the effects of different geometric predictors under different visibility conditions. Specifically, predictive models for operating speed on curves identified the inverse of the radius and the deflection angle of the curve as predictors under both driving conditions. For speed differentials based on the 85th percentile for maximum speed reduction (85 MSR), we found that the inverse of the approaching tangent length and of the curve radius significantly explained the dependent variable in both cases, with a higher dependence of nighttime 85 MSR on the curve geometry than on the tangent length. Tangent length had a significant effect on operating speed for independent tangents only for the daytime model, whereas the inverse of the previous radius was confirmed as a predictor for both visibility conditions. PRACTICAL APPLICATIONS This research may influence design considerations for nighttime driving by providing evidence of the effects of nighttime conditions on driver speed choices and road safety.

Effects of Mobile Telephone Tasks on Driving Performance: A Driving Simulator Study

Mobile phone use while driving is increasing among road users. Although the most of countries made illegal the cell phone use while driving, the drivers still use it both for calling and texting. Several studies investigated the distraction factors related to the use of mobile while driving and the effects on road safety. The main findings of these studies generally demonstrated an increasing of reaction time and decreasing of driving performance especially during not critical driving conditions, while the evaluation of the effects of mobile use during critical driving conditions is not so much investigates. The overall objective of this work is to contribute to the evaluation of the effects of the mobile phone use on driving safety. Specifically the effects of using cellular phone at the same time the driver is faced with making a critical stopping decision are investigated. The experiments are carried out using an interactive driving simulator. Three different road scenarios (urban road, rural road and motorway) are simulated. Thirty subjects take part to the experiments and drive four times each scenario: one time without calling (control scenario) and the other three times answering the calls by hand-held mobile, hands-free mobile and hands-free voice device. The drivers reaction time, the deceleration rate, the speed and the following distance are evaluated. The main effects of driving and calling are observed in the urban scenario, where the decreasing of driving performance is much more evident than in the rural and motorway scenario. Not significant differences on driving performances are found across the three telephone modes. Keywords - mobile phone, hand-held, hands-free, reaction time, driving simulator, driver distraction Language: en

An overview of ground-penetrating radar signal processing techniques for road inspections

Ground-penetrating radar (GPR) was firstly used in traffic infrastructure surveys during the first half of the Seventies for testing in tunnel applications. From that time onwards, such non-destructive testing (NDT) technique has found exactly in the field of road engineering one of the application areas of major interest for its capability in performing accurate continuous profiles of pavement layers and detecting major causes of structural failure at traffic speed. This work provides an overview on the main signal processing techniques employed in road engineering, and theoretical insights and instructions on the proper use of the processing in relation to the quality of the data acquired and the purposes of the surveys. GPR is an increasingly used NDT technique in pavement applicationsProper choice of the signal processing techniques according to the GPR data sourceOverview of signal processing techniques to use prior to any post-processing stepOverview of signal processing techniques to perform after the GPR data collection

A Study of the Effects of Road Tunnel on Driver Behavior and Road Safety Using Driving Simulator

The present paper wants to contribute to the knowledge of the tunnel effects on driving performance and safety using the advanced technology of driving simulator. Specifically this study presents the first results of a wider research aimed at establishing how drivers behave inside road tunnel as well as approaching it and exiting from it. Moreover the study verifies a correlation between accident rates and an advanced indicator of simulation computed inside tunnel sections. A highway scenario with eight existing tunnels is reproduced in CRISS driving simulator and several driving parameters are recorded among a sample of twenty-five drivers. Tunnel scenario (TS) data are processed and compared with those of a control scenario (CS), characterized by the same road geometries and alignment of the first one, but without any tunnels. Results confirm previous findings of naturalistic and simulator driving studies about drivers performance inside road tunnels, with significant differences of longitudinal speeds, acceleration and lateral position recorded along the TS and the CS. Moreover the literature safety indicator of driving simulation Pathologic Discomfort (PD) is computed in order to 1) assess the length of approaching and exiting sections of road tunnel and 2) verify PD correlation with the accident rate recorded inside each tunnel. Simulator limitations and future directions of the research are discussed in order to provide guidelines for practical application to road tunnel design and safety measures, taking in account driving performance.

FDTD simulation of the GPR signal for effective inspection of pavement damages

Ground-penetrating radar (GPR) is a wide ranging non-destructive tool used in many fields of application including effective pavement engineering surveys. Despite the high potential and the consolidated results obtained over the past decades, pavement distress manuals based on visual inspections are still widely used, so that only the effects and not the causes of faults are generally considered. In such context, simulation can represent an effective solution for supporting engineers and decision-makers in understanding the deep responses of both revealed and unrevealed damages. In this study, the use of FDTD simulation of the GPR signal is analyzed by simulating three different types of flexible pavement at two different center frequencies of investigation commonly used for road surveys. Comparisons with the undisturbed modelled pavement sections are carried out showing promising agreements with theoretical expectations, and good chances for detecting the shape of damages are demonstrated.

Integrated road pavement survey using GPR and LFWD

Ground Penetrating Radar is frequently used for inspection the road pavement. Many applications are carried out: from pavements layer thickness estimation, to damage detection and diagnosis, from the evaluation of geotextile effectiveness to the assessment of the bridge decks. Here we propose to integrate GPR survey with the Light Falling Weight Deflectometer. LFWD is a portable instrument that is used for measuring the Young Modulus through the analysis of the propagation of elastic waves in the pavement structure. The point of strength of this approach is that it is possible to correlate geometrical and some physical characteristics, in this case dielectric constant, of pavement layers, extracted from the GPR maps, to the mechanical properties, such as young modulus, measured using LFWD. It is well known that from a GPR stand alone survey is not possible to have directly any information about the mechanical characteristics of the structure. Otherwise, following this integrated method it is possible to reach a more comprehensive description of the road pavement. This diagnostic tool for pavement damage investigations seems absolutely very promising, cost effective and efficient in its implementation. Finally two case studies are presented: the first over about 3000 m of a real pavement the second over an unpaved airport strip.

GPR Applications Across Engineering and Geosciences Disciplines in Italy: A Review

In this paper, a review of the main ground-penetrating radar (GPR) applications, technologies, and methodologies used in Italy is given. The discussion has been organized in accordance with the field of application, and the use of this technology has been contextualized with cultural and territorial peculiarities, as well as with social, economic, and infrastructure requirements, which make the Italian territory a comprehensive large-scale study case to analyze. First, an overview on the use of GPR worldwide compared to its usage in Italy over the history is provided. Subsequently, the state of the art about the main GPR activities in Italy is deepened and divided according to the field of application. Notwithstanding a slight delay in delivering recognized literature studies with respect to other forefront countries, it has been shown how the Italian contribution is now aligned with the highest world standards of research and innovation in the field of GPR. Finally, possible research perspectives on the usage of GPR in Italy are briefly discussed.

An empirical study on traffic safety indicators for the analysis of car-following conditions

The likelihood that a car-following driving condition can lead to a rear-end collision is usually assessed through the Time Headway (TH) and Time To Collision (TTC), considered as safety indicators of traffic conditions. The present study computed and compared TH and TTC on the basis of data recorded by means of a traffic control system of an Italian highway. Specifically four measurements sites were investigated for two days and almost 200000 travelling vehicles were collected. About 50% of vehicles were travelling in car-following conditions. The overall objectives of this paper consisted in verifying if, on highways, TH and TTC are independent of each other and, therefore, do not provide the same information on the driver behaviour in car-following situation but could be used for evaluating different conditions. Moreover the effects of different visibility conditions (day or night driving), the type of lead vehicle (passenger car or heavy vehicle) and the type of travelling lane (left or right) on TH and TTC were evaluated in order to increase the knowledge of drivers behavior in car-following conditions. The results demonstrated that TH and TTC provide different information on driver behaviour in carfollowing conditions as they can be considered practically independent of each other. Moreover it was found that shorter THs are used by the following driver during daytime, behind passenger vehicle and driving on the passing lane. On the contrary only few cases with critical TTC values were recorded, demonstrating that TTC is more effective for detecting impending dangerous situations. Language: en

Evaluating the effects of the number of exit lanes on the diverging driver performance

ABSTRACT This study investigated the driving performance of drivers exiting from the highway under various geometric deceleration lane conditions. Specifically, the effects of different deceleration lanes on the speeds, trajectories, and decelerations of diverging drivers were investigated to increase the knowledge of driver behavior while approaching a highway exit, during the lane-change maneuver, and along the deceleration lane. Thirty-one drivers took part in the experiments. Two different tapered deceleration lanes (with a single-lane exit ramp and with a two-lane exit ramp, respectively) were implemented using a driving simulator to observe how exiting drivers performed, by analyzing their speeds, decelerations, and trajectories. The main results demonstrated that, for the geometric and operating conditions investigated in this study, a single-lane exit ramp resulted in a poorer performance from the exiting drivers with regard to the operating and safe driving conditions. In fact, it was found that, when a single-lane exit ramp was available, drivers adopted lower exiting speeds and higher decelerations than those using a two-lane exit ramp. Therefore, the latter seemed to provide improved performance, by limiting the interferences of the diverging drivers with through traffic.

Investigating driver reaction time and speed during mobile phone conversations with a lead vehicle in front: A driving simulator comprehensive study

ABSTRACT This study analyzed driving performance while using different mobile devices in different road configurations and geometries during a critical driving situation. Three different road environments were implemented in a driving simulator: an urban road, a two-lane rural road, and a highway. Thirty drivers with an average age of 26.8 years were asked to answer a phone call while driving, using different mobile devices: hand-held, hands-free, and hands-free voice-activated cellular phone. The effects of using the mobile phones were also compared to the BC (no phone conversation). Driving performance, under car-following conditions, were collected and statistically analyzed when a sudden braking of the leading vehicle occurred. The main results demonstrated that the drivers speed generally reduced during the phone call whereas the reaction time generally increased, especially under certain driving conditions (urban road, along tangent, using hand-held mobile device). This study analyzed the effects of using a mobile phone while driving, highlighted the worst combinations of the variables investigated, and demonstrated that some reductions in driving performance were revealed, especially in the urban environment, even when using mobile equipment permitted by the regulations of several countries.