Search

Combined bridge-tunnel scenarios of driving on mountainous city expressways occur when bridges and tunnels frequently alternate during driving. The complex nature of these driving scenarios imposes crucial requirements on the drivers' eye movement characteristics. This paper attempts to clarify these characteristics using descriptive statistics and the box graph method, registering the pupil diameter, blink duration, fixation, saccades, and fixation loci at different tunnel locations, bridges, and ramps. Realistic driving experiments were performed on the road segment spanning from the Nanchang tunnel to the Liujiatai tunnel freeway in Chongqing, China. Eye movement data were collected for 21 drivers. The experimental results showed that, while driving in the tunnel, the maximal pupil diameter of the participating drivers was approximately 4.0mm as the driving mileage and the number of tunnels increased, and the maximal visual load on the drivers in the tunnel tended to be stable. At the second tunnel exit, the ramp, the middle section of the first bridge, and the third tunnel exit, the driving load was the highest, while the fixation duration was shorter for nighttime driving. The fixation duration was the longest for the diversion road of bridge B1 to the ramp during the day, and the fixation times were the longest at the beginning and end of the test road. The drivers more often paid attention to the speed dashboard while entering tunnels during daytime driving (compared with nighttime driving)., Author(s): Jingrong Bai [1]; Qinghai Lin (corresponding author) [2]; Huiyun Bi [1]; Boming Tang [1] 1. Introduction The special geographical environment and geological conditions of mountainous cities necessitate the use [...]

Noise from elevated railway bridges in urban areas has been causing severe environmental issues. To find the peak frequency of sound energy and thus develop targeted countermeasures for noise mitigation, policymakers need a better understanding of the noise characteristics of urban railway bridges during train passage. This study approaches this issue by combining transient dynamic analyses and acoustic finite element simulation. Our frequency characteristic analysis focused on two primary noise sources: wheel-rail noise and bridge-borne noise. We built a spatial noise model that predicts the radiated noise of urban railway bridges in both the active and planning stages. The results show that the wheel-rail noise peaked at 800 Hz, 1600 Hz, and 3150 Hz, while the bridge-borne noise peaked at 40 Hz, 50 Hz, 80 Hz, and 125 Hz. The validation results demonstrated that the developed noise spatial prediction model extended well to similar urban railway bridges. [ABSTRACT FROM AUTHOR]

At present, tuff aggregates as asphalt pavement mixtures have insufficient water damage resistance; hence, modifying and evaluating the related properties of tuff asphalt mixtures are necessary. In this study, cement and a liquid antistripping agent were selected as admixtures, and tuff and limestone mixtures without admixtures were selected as control. The surface energy for the SBS-modified asphalt polymers and aggregates in the mixtures was evaluated by using surface energy theory. The adhesion work and the spalling work of the polymer–aggregate interface was calculated, and a factor k was proposed to predict the water damage resistance of the tuff mixture with admixtures. The prediction values were compared with those of the macroscopic water stability test for the mixture. The results of this research showed that the factor k after adding admixtures was improved, and the increase range was from 7.14% to 47.62%. The admixture scheme with the best improvement was that with 2% cement content, in which the k value increased by 21.57% and 47.62% compared with that of the limestone and tuff mixtures without admixtures, respectively. The tested water stability indexes and the predicted factor k under different admixture schemes exhibited a good positive correlation, and the correlation equations were obtained by linear fitting. Thus, it was feasible to use the factor k characterizing the water damage resistance of tuff mixtures using surface energy theory. [ABSTRACT FROM AUTHOR]

The effect of filler modification on polyurethane (PU) properties was investigated by experimental and molecular dynamics simulation. Ultra-thin wearing course (PUTWC) was prepared using PU composite as a binder. The results indicated that, compared with composite with mineral powder, the tensile strength and elongation at break of PU composite (PUNC) containing CaCO3 increased by 32.7% and 15.8%, also exposed an appropriate viscosity. Stronger interaction energy and smaller free volume distribution existed in PUNC interface, which was obviously related to the PU soft segment. Additionally, prepared PUTWC using the single-layer paving method and PUNC of 1 kg. (m2)−1 showed high-skid resistance. [ABSTRACT FROM AUTHOR]