Mountainous freeways always suffer from accidents due to special terrain, weather conditions, driving environment, and so on. Based on the records of 898 accidents that occurred on mountainous freeways in Chongqing during the past 6 years, the partial proportional odds model is used to identify the factors affecting the accident severity. The time of the accident, season, involvement of trucks, accident characteristics, speeding, maximum driving experience of involved drivers, and weather and road conditions are found to be important for the levels of accident severity. Zero to 6 a.m. and 19 to 24 p.m. are the times prone to serious traffic accidents. The probability of serious traffic accidents in summer and autumn is greater than that in spring and winter. Once a truck is involved in an accident, the consequence is often more severe. Turnover and speeding will result in a grave accident. When there is an experienced driver, the probability of serious traffic accidents is low. The fog is extremely unfavorable weather conditions. The probability of serious accident happening in the downgrade, ramp, curve, bridge, and tunnel sections is greater than the others. The results aim to provide valuable reference for traffic safety on mountainous freeways.

This study investigates the skid resistance performance of asphalt mixtures containing composite aggregates of basalt and limestone. The research aimed to predict the service life of the asphalt mixtures and identify the optimal basalt content for enhanced performance. Using an accelerated friction tester, friction indices such as the British pendulum number (BPN), mean texture depth (MTD), and dynamic friction coefficient (Dµ) were measured. The study conducted accelerated wear tests on mixtures with varying basalt contents under different water flow rates and loads. Results indicate that anti-skid performance decreased with increasing water flow, load, and wear cycles, initially showing a sharp decline followed by a gradual stabilization. Orthogonal experiments determined that basalt content had the most significant impact on skid resistance, followed by load and water flow rate. By converting skid resistance and MTD values into IFI values, a four-area diagram was created to illustrate skid resistance deterioration. The four-area IFI diagram also demonstrated that higher basalt content significantly enhances the skid resistance and service life of asphalt mixtures. Cost analysis based on life prediction showed that a 40% basalt content mixture is cost effective while maintaining excellent skid resistance. A test section study further validated that a 40% basalt content ensures good skid resistance, with indoor test predictions aligning closely with field data. Although the test section has been operational for only two years, ongoing monitoring will provide further insights into long-term skid resistance performance.

The content and density of traffic signs directly affect the operation of urban road traffic and drivers. To overcome the limitations of quantitative research on the density threshold of traffic signs on urban roads, a real vehicle experiment was conducted to record the psychological characteristics of drivers. Four psychological parameters of drivers-pupil area, fixation intensity, heart rate change rate, and heart rate variability-were explored. Subsequently, principal component analysis was used to present a new index, S, divided into 5 grade scales, to represent the driving visual comfort level. The information entropy theory was applied to quantify the amount of information on road traffic signs that are included in driving tests, and a regression relationship between the traffic sign information and comfort index S was established. The visual psychological load thresholds for different comfort levels were -2.289≤S < -1.526 for very comfortable, 1.526≤S < -0.763 for relatively comfortable, -0.763≤S ≤ 0.763 for comfortable, 0.763<S ≤ 1.526 for uncomfortable, and 1.526<S ≤ 2.289 for very uncomfortable. To maintain the visual comfort of drivers, the information density of traffic signs should be less than 0.373 bits/m and the maximum information density of traffic signs should not exceed 0.507 bits/m. This conclusion provides a reference for the rational layout of traffic signs on urban roads.

Excessive or insufficient driving load disrupts driving comfort and highway coordination, increasing accident risk. This study examines the relationship between highway alignment and driving comfort, analyzing its effects on drivers’ physiological responses and driving load. A naturalistic driving experiment collected eye movement and heart rate data from 28 drivers. Heart rate increase rate and pupil area change rate were selected as driving load indicators, and an entropy weight method was applied to establish a model. Using k-means clustering, driving load thresholds (0.34, 0.64) were determined, classifying comfort levels as “comfortable”, “moderately comfortable”, and “uncomfortable”. Results show that steep slopes, small curve radii, and complex curved-slope sections increase driving load and reduce comfort. Alignment indices exhibit a “threshold effect”, where exceeding comfort limits intensifies stress responses and lowers comfort. This study provides theoretical support for mountainous highway reconstruction and management.

Guide signs are a primary source of driving information in urban roads. By conveying route and decision-making cues through text and symbols, they help drivers plan maneuvers in advance and reduce ...