131 research outputs found
Comparison of Collisions of Rigid Trucks and Articulated Trucks Against Road Safety Barriers
No full text
Lettres philosophiques, sur les physionomies.
No full textAscribed to Jacques Pernetti, and also to Guillaume Hyacinthe Bougeant. cf. A. de Backer, Bibl. de la Comp. de Jésus, nouv. éd., 1890.Mode of access: Internet
A new approach to assess the influence of road roughness on driver speed behavior based on driving simulator tests
No full textVehicle speed is one of main parameters describing driver behavior and it is of paramount importance as it affects the travel safety level. Speed is, in turn, affected by several factors among which in-vehicle vibration may play a significant role. Most of speed reducing traffic calming countermeasures adopted nowadays rely on vertical vibration level perceived by drivers that is based on the dynamic interaction between the vehicle and the road roughness. On the other hand, this latter has to be carefully monitored and controlled as it is a key parameter in pavement managements systems since it influences riding comfort, pavement damage and Vehicle Operating Costs. There is therefore the need to analyse the trade-off between safety requirements and maintenance issues related to road roughness level. In this connection, experimental studies aimed at evaluating the potential of using road roughness in mitigating drivers’ speed in a controlled environment may provide added value in dealing with this issue. In this paper a new research methodology making use of a dynamic driver simulator operating at the TEST Laboratory in Naples is presented in order to investigate the relationship between the driver speed behavior on one hand, and the road roughness level, road alignment and environment, vehicle characteristics on the other. Following an initial calibration phase, preliminary results seem fairly promising since they comply with the published data derived from scientific literature
An exploratory analysis of curve trajectories on two-lane rural highways
No full textThis paper is aimed at obtaining a better understanding of driving behavior on horizontal curves of two-lane rural highways in terms of trajectories in relation to the different curve radii and directions by a driving simulator experiment. The driving simulator experiment involved 50 drivers and eight classes of curve radii, ranging from 125 m to 800 m. Overall, 2000 curve trajectories were analyzed and classified. Six major classes were defined: (1) ideal behavior, (2) normal behavior, (3) driving close to the centerline, (4) driving outside in curve approach, (5) cutting, and (6) correcting. Furthermore, 21 sub-classes were introduced to consider both lane departures and location of the corrective actions. The CATANOVA tests and Bhapkar's tests showed that both the curve radius and the curve direction had a significant effect on the classification results. To get a clearer understanding of the effect of the curve radius and direction on curve negotiation, three macro-classes corresponding to safe, intermediate, and dangerous behavior were introduced. The safest behaviors significantly increased with the curve radius while the most dangerous behaviors significantly decreased with the curve radius. Furthermore, left curves showed a higher proportion of dangerous trajectories. Overall, it seems that the driving trajectories are a promising surrogate measure of safety as highlighted by the correlation between the trajectories identified as dangerous and the radii of the curves
HEAVY-GOODS VEHICLE COLLISIONS WITH STEEL ROAD SAFETY BARRIERS: COMBINED INFLUENCES OF POSITION OF CENTER OF MASS AND TIRE-PAVEMENT FRICTION
No full textVehicles that collide with highway safety features do not always produce the same effects. The outcome for each vehicle that collides with a feature will be different, depending greatly not only on its mass, velocity, and impact angle but also on the position of its center of mass and on the tire-pavement friction. The ways in which barrier and striking vehicle behaviors are affected by changes in the position of the center of mass and in the tire-pavement side friction were analyzed to identify the most dangerous loading systems. Toward this aim numerous simulations of a collision of a truck against a steel road safety barrier were carried out through nonlinear, dynamic finite-element analysis. The results obtained demonstrate that the position of the center of mass is of greater consequence in collisions in which the impact energy is close to the maximum barrier containment capacity and under conditions that favor friction. The longitudinal position of the center of mass has a large impact on the risk that the vehicle will pass over the barrier or roll over. If it is in the back, the most common loading system, the risk of passing over the barrier is rather limited compared with the risk of rolling over. As the position of the center of mass is pushed forward, the risk of rolling over is reduced but the risk of passing over the barrier increases. If the height of the center of mass increases, the rollover risk is higher, but a higher center of mass does not significantly influence displacement and the risk of passing over the barrier
L'influenza dei criteri di dimensionamento sul comportamento sismico dei telai in acciaio.
No full text4° Convegno Nazionale A.N.I.D.I.S. "L'Ingegneria Sismica in Italia", Milano, 4-6 October 198
alysis of the influence of the clothoids on curve negotiation on two-lane rural highways
No full textMost geometric design standards recommend the use of clothoids when connecting tangents and circular curves to produce a smooth, pleasing alignment. Despite the advantages of using clothoids, there are also possible adverse effects and literature results do not yet provide definitive results on clothoids effectiveness. Since the effect of clothoids is still an open issue, this paper provides a contribution in the evaluation of the effect of clothoids on curve negotiation on two-lane rural highways by a driving simulator experiment. The study is carried out evaluating the combined effect of different curve radii, deflection angles, and curve directions. Sixty-eight participants were involved in the study. The experiment was conducted in the VERA (Virtual Environment for Road sAfety) dynamic-driving simulator, operating at the Road Safety Laboratory of University of Naples Federico II in Italy. The variables are: clothoid (2 levels: with and without), curve radius (four radii: 125, 200, 400 and 800 meters), deflection angle (three angles: 20, 40 and 60 degrees), and curve direction (left direction in the outer lane and right direction in the inner lane). Trajectory dispersion and lateral position were used as measures of driving behaviour. Study results show that the clothoids produce significant advantages, reducing the lateral position variability, the maximum and minimum lateral positions, and the number of departures in the opposite lane and in the shoulder. The greatest effectiveness is shown in the curve approach. Clothoids are effective on all curves tested but the effect on the curves with radius equal to 800 m is quite smaller than on curves with radii of 125, 200, and 400 m
L'influenza dei criteri di dimensionamento sul comportamento sismico dei telai in acciaio.
No full text4° Convegno Nazionale A.N.I.D.I.S. "L'Ingegneria Sismica in Italia", Milano, 4-6 October 198
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