路面水膜厚度检验评价方法

降雨在道路表面形成的水膜可显著降低轮胎与路面接触部分的摩阻系数,水膜厚度的增加使得车辆易发生水滑等交通事故.为评价道路表面因降雨形成的水膜对行车安全的影响,研究提出一种路面水膜厚度的检验评价方法.以我国海南省降雨量数据为依据,提出了公路几何设计中检验路面水膜厚度的降雨强度取值.从行车安全角度出发,提出了降雨条件下路面水膜厚度的限值标准,以一条高速公路的设计为例,检验了道路几何线形设计对应的路面水膜厚度,对不满足限值的路段给出了优化设计建议.结果表明,公路几何设计中检验路面排水的降雨强度可取高峰小时降雨量50mm/h;检验路面水膜厚度的限值标准可取一般值2.5 mm,极限值4 mm;水流路径长度最大不超过60 m.     

农村公路建设的社会经济效益分析

农村公路的社会经济效益是评价项目实施效果的重要依据。在分析了农村公路社会经济效益的产生机理的基础上,建立了一套较完善的农村公路社会经济效益评价指标体系。以浙江省"乡村康庄工程"项目为例,对本文建立的体系进行了检验,取得了较好的使用效果。     

在运营高速公路长大下坡段交通安全风险水平评价研究

本文以云南省某典型长大下坡高速公路段为交通安全风险水平评价对象,从具有代表性且可操作性强的角度出发,选取了6大评价指标,采用层次分析法与模糊评价理论相结合的方法对其进行评价。经过实际验证,该评价方法可操作性强,且评价结果较为合理。     

中低速磁浮列车牵引杆设计与分析

设计了一种适合中低速磁浮列车的牵引杆.分析了牵引杆在起动、3 g和5 g冲击等工况下的载荷,采用有限元法分析牵引杆在不同载荷工况下的强度,并对牵引杆强度进行评价.结果表明,所设计的牵引杆是合理的,静强度和疲劳强度均符合要求.     

基于公交站点上下客人数反推OD矩阵的概率论模型研究

基于站点上下客人数,采用简单概率分布模型,可提出反推公交站点间的OD分布矩阵的具体方法.实例表明,在采用此类方法进行反推计算时,应按照土地利用性质对站点进行合并计算,这样方可提高推算的精度.     

基于公交站点上下客人数反推OD矩阵的概率论模型研究

基于站点上下客人数,采用简单概率分布模型,可提出反推公交站点间的OD分布矩阵的具体方法。实例表明,在采用此类方法进行反推计算时,应按照土地利用性质对站点进行合并计算,这样方可提高推算的精度。     

中低速磁浮列车牵引特性分析和计算

磁浮列车牵引特性具有特殊性,直线电机法向力会影响悬浮稳定性。文章对中低速磁浮列车牵引特性进行了分析和计算,并综合了两种情况确定了牵引电机的额定输出功率。     

Analyzing Spatio-Temporal Distribution Pattern and Correlation for Taxi and Metro Ridership in Shanghai

Taxicab is an important mode in urban transportation system, while the role of taxicabs, especially the relationship with metro system has not been fully studied. This study aims at exploring the factors influencing the role played by taxicabs in Shanghai, China. Firstly, taxi trips are categorized into three types, namely metroreplaceable(MR), metro-extending(ME) and metro-supplement(MS) ones. Then, the tendency of travelers towards taxi or metro at a specific metro station is proposed and calculated on the basis of MR taxi trips and metro trips. Factors influencing the tendency are investigated through semi-parametric regression models, with the results indicating that the most significant factors and the influencing radii during the peak and off-peak hours are different. Some built environment factors, such as the number of hospitals and government agencies, have significant positive relationship with the tendency in the time periods. Furthermore, land use related factors, such as the increase of forestry and commercial land, generally promote taxi-hiring in the off-peak hours, while they have a negative impact during the peak hours. Findings of this study can assist governments and policy makers to understand the impact of built environment and land use on trip patterns, and thus may contribute to more reasonable policies and optimized urban planning, which may promote modal switch from taxi to subway.