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Based on the symmetric two-lane Nagel–Schreckenberg (STNS) model, a three-lane cellular automaton model between two intersections containing a bus stop with left-turning buses is established in which model the occurrences of vehicle accidents are taken into account. The characteristics of traffic flows with different ratios of left-turn lines are discussed via the simulation experiments. The results indicate that the left-turn lines have more negative effects on capacity, accident rate as well as delay if the stop is located close to the intersections, where the negative effect in a near-side stop is more severe than that in a far-side one. The range of appropriate position for a bus stop without the bottleneck effect becomes more and more narrow with the increase of the ratio of left-turn bus lines. When the inflow is small, a short signal cycle and a reasonable offset are beneficial. When the inflow reaches or exceeds the capacity, a longer signal cycle is helpful. But if the stop position is inappropriate, the increase of cycle fails in reducing the negative effect of left-turning buses and the effectiveness of offset is weakened. [ABSTRACT FROM AUTHOR]

Through field survey and laboratory analysis, we examined the composition and fractal features of soil micro-aggregates in different types of treefall gaps and microsites (pit bottom and mound top) in broad-leaved Korean pine forest and spruce-fir-Korean pine forest. Results showed that the contents of soil microaggregates under the classes of 0.25-2 mm and 0.05-0.25 mm were higher in both forest types, ranging from 25.7% to 50.7% and from 27.0% to 42.8%, respectively, and that of <0.002 mm was the lowest, ranging from 4.4% to 8.9%. In the pit bottom and mound top of gaps, soil bulk density was higher in both forest types. Soil nutrient content in mound top was higher than that in pit bottom and was higher in broad-leaved Korean pine forest than spruce-fir-Korean pine forest. Soil microaggregates of <0.002 mm had no correlation with soil physical and chemical properties, whereas that of 0.25-2 mm and 0.002-0.02 mm had significantly positive and negative correlation with soil non-capillary porosity, total porosity, aeration porosity, organic matter, total phosphorus, total nitrogen and organic carbon, respectively. On the whole, soil fractal dimension (D) and the proportion of characteristic soil micro-aggregates (PCM) in broad-leaved Korean pine forest were larger than those in spruce-fir-Korean pine forest, and the ratio of soil microaggregates diameter (RMD) in mound top and pit bottom was increased in two forest types. Soil D and PCM had no significant correlation with soil physical and chemical properties, while RMD was negatively correlated with capillary porosity, total porosity, soil bulk density and aeration porosity. In two forest types, the formation of mound and pit microsites could decrease the larger size micro-aggregates and the stability of soil micro-aggregate, increase soil D and PCM, and signifi-cantly increase RMD. RMD could be used as a quantitative index of soil physical and chemical properties in pit and mound microsites of forest.