Abstract
As it was found steep slope and sharp curve sections account for 14% of the accident-prone sections according to the accidents data in Chongqing. Regular design indices with certain thresholds are found not enough for this kind of mountain highways. The goal of this paper is to find an optimization design method for combination of steep slope and sharp curve sections based on the analysis of vehicle driving stability. The overall safety model of steep slope and sharp curve combined section is established, and the relevant coordination relationship between design indices of the front and rear alignment unit is established by using the operating speed estimation model. Taking the maximum slope length corresponding to the specified design speed as the design condition of the front segment, the threshold values and variation rules of the design indices of the rear segment under different design speeds are calculated ensuring driving safety. The safety model is simulated by CarSim software, the trajectory offset and lateral acceleration are used to indirectly reflect the degree of lateral instability, and the results are compared to verify the effectiveness of the simplified safety model established in this paper.
Highlights
According to the statistical analysis of 1448 traffic accidents on the highways in Chongqing mountainous area [1], 45% of the accidents were caused by overturning, and combination of steep slope and sharp curve (SSSC) sections accounts for 14% of the accident-prone sections
The goal of this paper is to find an optimization design method for combination of steep slope and sharp curve sections based on the analysis of vehicle driving stability
The safety model is simulated by CarSim software, the trajectory offset and lateral acceleration are used to indirectly reflect the degree of lateral instability, and the results are compared to verify the effectiveness of the simplified safety model established in this paper
Summary
According to the statistical analysis of 1448 traffic accidents on the highways in Chongqing mountainous area [1], 45% of the accidents were caused by overturning, and combination of steep slope and sharp curve (SSSC) sections accounts for 14% of the accident-prone sections. The design standard has not given enough consideration of this condition (SSSC) [2]. The safety evaluation standard provides the minimum radius from another perspective [3], which is not adaptable to be used directly for design. Researchers have found that single vehicle to roadside protective facility crash is significant to affect the probability of injury crashes, through the entire freeway sections with horizontal and vertical curve combinations [5]. The 85th percentile vehicle speed had been adopted as part of geometric design consistency evaluation criteria [8]
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