| Přispěvatelé: |
Montella, A, Galante, F, Liani Imbriani, L, Mauriello, F, Pernetti, Mariano, Ranieri, V. |
| Popis: |
Horizontal curves of two-lane rural highways are among the most dangerous elements of the road network. Despite this obvious and well safety issue, several geometric design standards are based on hypotheses which are often violated, such as: design speed different from the operating speed, constant speed through the curve, and driving at the center of the lane. In the experiment, the VERA (Virtual Environment for Road sAfety) high-fidelity dynamicdriving simulator, operating at the TEST (Technology Environment Safety Transport) Road Safety Laboratory located in Naples (Italy), was used. To validate the VERA driving simulator speed data, comparison between real-world and driving simulator speed data was performed in a previous study. The comparison showed that there were not significant differences between the real and the simulated speed samples. A two-lane rural highway with lane width equal to 3.50 m and shoulder width equal to 1.25 m was simulated. The experimental route consisted of the succession of 20 tangents with length equal to 1,000 m and curves with radius equal to 400 m and deflection angle equal to 35 degrees (L = 190 m). The tangent-to-curve transition was carried out by spiral curves with length equal to 55 m (A = 150 m), which corresponds to 2.0 s at 100 km/h. Thirty participants were recruited for the experiment. Seven subjects, 5 women and 2 men, exhibited simulator sickness and did not complete the experiment. Twenty-tree participants, 13 men and 10 women with age ranging between 23 and 55 years (mean = 35,2 years; s.d. = 9,3 years) and valid Italian driving licenses from more than four years (mean = 15,5 years; s.d. = 10,0 years), completed the experiment. Driving speed in the first two curves were significantly different from the speeds in the other curves, because of the adaptation phase. These curves were removed from the analysis and only the remaining eighteen curves were used in the analyses. Operating speeds were compared with operated speeds obtained through speed prediction models calibrated in world experiments in Italy in roads with similar alignments and the differences were less than 10 km/h. Speeds in left curves and right curves were compared. Statistically significant differences were not observed. Average decelerations were equal to 0.64 m/s2 whilst average acceleration were equal to 0.47 m/s2. The minimum speed of the operating speed profile was close to the beginning of the curve. Analysis of lateral positions showed that before the spiral drivers move away from the curve whilst in the circular portion of the curve they drive closer to the inside of the curve. In the exiting spiral drivers tend to move toward the outside of the curve. Overall, drivers tend to cut the curve (+ 0.25 m at the beginning of the spiral transition, - 0.5 m at the center of the curve). Lateral positions (relative to the axis of the lane) were significantly different ( < 0.05) in left and right curves, with a greater shift towards the inside of the curve for right curves |
