Drivers’ Visual Characteristics when Merging onto or Exiting an Urban Expressway

<div><p>The aim of this study is to examine drivers’ visual and driving behavior while merging onto or exiting an urban expressway with low and high traffic densities. The analysis was conducted according to three periods (approaching, merging or exiting, and accelerating or decelerating). A total of 10 subjects (8 males and 2 females) with ages ranging from 25 to 52 years old (M = 30.0 years old) participated in the study. The research was conducted in a natural driving situation, and the drivers’ eye movements were monitored and recorded using an eye tracking system. The results show that the influence of traffic density on the glance duration and scan duration is more significant when merging than when exiting. The results also demonstrate that the number of glances and the mean glance duration are mainly related to the driving task (e.g., the merging period). Therefore, drivers’ visual search strategies mainly depend on the current driving task. With regard to driving behavior, the variation tendencies of the duration and the velocity of each period are similar. These results support building an automated driving assistant system that can automatically identify gaps and accelerate or decelerate the car accordingly or provide suggestions to the driver to do so.</p></div

Experimental regression model.

<p>Experimental regression model.</p

The duration of the merging or exiting process with high and low traffic densities.

<p>The duration of the merging or exiting process with high and low traffic densities.</p

The relationship between glanceTPerc and scanTPerc at different traffic densities when entering (%).

<p>Drivers’ cognitive resources or cognitive energy consists of glanceTPerc and scanTPerc, glanceTPerc consists of 5 DIRs’ glanceTPerc during the merging task and glanceTPerc is further analysed for 5 directions (DIRs).</p

The velocity of the merging or exiting behavior with high and low traffic densities.

<p>The velocity of the merging or exiting behavior with high and low traffic densities.</p

Mean glance duration of each <i>DIR</i> with high and low traffic densities at the entrance or exit.

<p>Mean glance duration of each <i>DIR</i> with high and low traffic densities at the entrance or exit.</p

Entering or exiting an urban expressway and the three analysis periods.

<p>Red line traces the route that the subjects drove. The gray car is driven by the subject according to the planned route. White cars are traveling around the experiment car.</p

Percentage of glance numbers for each <i>DIR</i> at the entrance or exit, subdivided into the two periods.

<p>Percentage of glance numbers for each <i>DIR</i> at the entrance or exit, subdivided into the two periods.</p

Experimental preparations and calibrating the eye tracking system.

<p>Calibration site at the university campus was used to check the accuracy of the eye tracker in between series of experiments. Beginning of experiment was selected to start near the calibration point.</p

DataSheet1_Spatial patterns and drivers of soil total nitrogen in anthropogenic shrub encroachment in desert steppe.CSV

Nitrogen is the most important driving factor in primary production and decomposition in arid and semi-arid ecosystems. The effects of shrub encroachment on nitrogen cycling have been investigated at the site scale but seldomly conducted at the landscape scale. Here, we selected 43 shrubland sites distributing across 3000 km2 area in temperate desert grassland in eastern Yanchi County of Ningxia Hui Autonomous. We investigated the spatial heterogeneity and driving factors of soil total nitrogen (STN) at the landscape scale by using geostatistical analysis and the geographical detector method. Our results showed that the average soil total nitrogen decreased in the order of 0–5 cm (0.21 g kg−1) > 5–15 cm (0.19 g kg−1) > 15–40 cm (0.18 g kg−1). Geostatistical analysis showed that soil total nitrogen exhibited the strong spatial autocorrelation in the 0–5 and 5–15 cm soil layers and the moderate spatial autocorrelation in the 15–40 cm soil layer. Furthermore, the geographic detector method indicated that soil physicochemical properties exhibited the stronger effects than these of topographic and vegetation biomass in determining the spatial distribution of soil total nitrogen. Specifically, soil water content in the 0–20 cm soil layer explained 35% of variation in soil total nitrogen spatial pattern in the 0–5 cm soil layer, while soil organic carbon content in the 15–40 cm soil layer explained 64% and 45% of variation in soil total nitrogen spatial patterns in the 5–15 cm and 15–40 cm soil layers, respectively. It was concluded that soil water content and organic carbon content primarily drove the formation of soil total nitrogen spatial heterogeneity in shrubland at the landscape scale, indicating that anthropogenic shrub encroachment evidently affected soil water content and redistribution in dryland.</p