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191.
水泥混凝土是目前建筑工程中用途最为广泛、用量最大的建筑材料之一,了解新拌水泥混凝土的和易性对控制施工质量具有重要意义。 相似文献
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In the US, the rise in motorized vehicle travel has contributed to serious societal, environmental, economic, and public health
problems. These problems have increased the interest in encouraging non-motorized modes of travel (walking and bicycling).
The current study contributes toward this objective by identifying and evaluating the importance of attributes influencing
bicyclists’ route choice preferences. Specifically, the paper examines a comprehensive set of attributes that influence bicycle
route choice, including: (1) bicyclists’ characteristics, (2) on-street parking, (3) bicycle facility type and amenities,
(4) roadway physical characteristics, (5) roadway functional characteristics, and (6) roadway operational characteristics.
The data used in the analysis is drawn from a web-based stated preference survey of Texas bicyclists. The results of the study
emphasize the importance of a comprehensive evaluation of both route-related attributes and bicyclists’ demographics in bicycle
route choice decisions. The empirical results indicate that travel time (for commuters) and motorized traffic volume are the
most important attributes in bicycle route choice. Other route attributes with a high impact include number of stop signs,
red light, and cross-streets, speed limits, on-street parking characteristics, and whether there exists a continuous bicycle
facility on the route.
Ipek N. Sener is currently a Ph.D. candidate in transportation engineering at The University of Texas at Austin. She received her M.S. degrees in Civil Engineering and in Architecture, and her B.S. degree in Civil Engineering from the Middle East Technical University in Ankara, Turkey. Naveen Eluru is currently a Ph.D. candidate in transportation engineering at The University of Texas at Austin. He received his M.S. degree in Civil Engineering from The University of Texas at Austin, and his Bachelors in Technology Degree from Indian Institute of Technology in Madras, India. Chandra R. Bhat is a Professor in Transportation at The University of Texas at Austin. He has contributed toward the development of advanced econometric techniques for travel behavior analysis, in recognition of which he received the 2004 Walter L. Huber Award and the 2005 James Laurie Prize from the American Society of Civil Engineers (ASCE), and the 2008 Wilbur S. Smith Distinguished Transportation Educator Award from the Institute of Transportation Engineers (ITE). He is the immediate past chair of the Transportation Research Board Committee on Transportation Demand Forecasting and the International Association for Travel Behaviour Research. 相似文献
Chandra R. Bhat (Corresponding author)Email: |
Ipek N. Sener is currently a Ph.D. candidate in transportation engineering at The University of Texas at Austin. She received her M.S. degrees in Civil Engineering and in Architecture, and her B.S. degree in Civil Engineering from the Middle East Technical University in Ankara, Turkey. Naveen Eluru is currently a Ph.D. candidate in transportation engineering at The University of Texas at Austin. He received his M.S. degree in Civil Engineering from The University of Texas at Austin, and his Bachelors in Technology Degree from Indian Institute of Technology in Madras, India. Chandra R. Bhat is a Professor in Transportation at The University of Texas at Austin. He has contributed toward the development of advanced econometric techniques for travel behavior analysis, in recognition of which he received the 2004 Walter L. Huber Award and the 2005 James Laurie Prize from the American Society of Civil Engineers (ASCE), and the 2008 Wilbur S. Smith Distinguished Transportation Educator Award from the Institute of Transportation Engineers (ITE). He is the immediate past chair of the Transportation Research Board Committee on Transportation Demand Forecasting and the International Association for Travel Behaviour Research. 相似文献
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城市机非混行交叉口的管理与控制是交通管理的重要内容.针对信号交叉口设置非机动车等候区的交通组织方式,建立了交叉口元胞自动机模型.对机动车流采用基于经典 NaSch(NS)的改进多车道元胞自动机模型,建立了交叉口换道规则,增加主动减速规则;对非机动车流采用具有侧向运动的扩展多值 CA模型.研究了设置等候区的车流状态特性,以及非机动车密度和等候区纵向长度对信号交叉口的影响.研究结果表明:设置等候区能在一定程度上提高交叉口的通行能力,但长度并非越长越好,当长度过长时在一定条件下会增大对机动车流的阻滞,总体上等候区是一种值得借鉴的方式;非机动车密度对机动车流的基本图具有显著影响. 相似文献
198.
为了研究未来无人驾驶车辆对路网容量的影响,揭示无人驾驶车辆与普通车辆的相互影响特性,假设无人驾驶车辆遵循系统最优路径,普通车辆遵循用户最优路径,构建了无人驾驶环境下的道路网络储备容量模型。上层模型为满足路段容量约束条件下的最大交通需求,各OD之间的交通需求采用不同的增长乘子;下层模型为两类用户的混合路径选择行为模型,无人驾驶车辆以系统总阻抗最小为目标,而普通车辆以个人出行成本最小为目标。采用多种群遗传算法进行求解,并通过算例验证了模型和算法的有效性和可行性,得到非统一增长乘子下的路网容量,比较了统一增长乘子与非统一增长乘子的异同之处。研究结果表明:①两种计算结果所得到的道路网络容量增长趋势类似,但是非统一增长乘子计算结果大于统一增长乘子计算结果,当无人驾驶车辆市场渗透率达到一定比例时,二者计算结果的差异随着市场渗透率的增加而逐渐减小;②不同OD对的增长乘子不一定相同,无人驾驶车辆的加入可以优化不同地区的OD需求分布,从而提升整个道路网络的容量;③非统一乘子的计算方法可以有效避免不同OD对的干扰作用,提高部分OD对在低市场渗透率下的路径利用率,路段流量分布更加均衡;④当无人驾驶市场渗透率达到较高的比例时,道路网络容量可增加的幅度较小。 相似文献
199.
复合地层盾构隧道工程地质勘察方法的研究 总被引:1,自引:0,他引:1
盾构法施工与其它地下工程施工方法相比有其特殊性,反映在相应的地质勘察工作中就会有专门的要求,结合复合地层中盾构施工的特点,对目前的勘察内容、工作量等提出了改进意见,对地质勘察阶段的划分提出了看法。 相似文献
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The empirical valuation of travel time savings is a derivative of the ratio of parameter estimates in a discrete choice model. The most common formulation (multinomial logit) imposes strong restrictions on the profile of the unobserved influences on choice as represented by the random component of a preference function. As we progress our ability to relax these restrictions we open up opportunities to benchmark the values derived from simple (albeit relatively restrictive) models. In this paper we contrast the values of travel time savings derived from multinomial logit and alternative specifications of mixed (or random parameter) logit models. The empirical setting is urban car commuting in six locations in New Zealand. The evidence suggests that less restrictive choice model specifications tend to produce higher estimates of values of time savings compared to the multinomial logit model; however the degree of under-estimation of multinomial logit remains quite variable, depending on the context. 相似文献