采用千斤顶顶升桥梁梁体调整横坡的施工技术

本文简要介绍了常张高速公路K127 475分离式立交桥施工中采用千斤顶顶升梁体调整横坡的施工方法。     

预应力现浇箱梁施工工艺

文章结合三江至柳州高速公路施工实例,对分离式立交桥预应力现浇箱梁施工工艺进行了系统性论述,可为类似工程施工提供参考。     

预应力混凝土箱梁静力有限元分析与参数研究

文章结合水源分离式立交桥实际工程,采用Midas Civil软件对实桥进行运营段静力分析,研究了温度作用和基础沉降对水源分离式立交桥的影响,以及不同边跨比对主梁各受力性能的影响规律,得到适合的边中跨比在0.6～0.8之间。     

广西山区高速公路分离式路基设计实践

分离式路基在山区高速公路设计中具有很好的灵活性和适应性。文章结合广西山区高速公路分离式路基设计实际情况,从平面、纵断面、横断面设计等方面对山区高速公路分离式路基设计的要点进行了介绍,对设计中需注意的问题进行了探讨。     

中承式梁拱组合桥梁空间静力计算分析

文章以某绕城高速公路上跨分离式立交桥为工程背景,采用空间有限元分析法,对中承式连续梁拱组合桥进行施工阶段及运营阶段静力计算,分析钢管混凝土拱肋与预应力混凝土连续梁及吊杆内力、应力及位移随工序进程的变化规律。计算结果表明,该梁拱组合桥型能够充分利用各自构件的受力特性形成互补,同时拱梁的组合呈现美观的造型又兼具较好的技术经济指标。     

泰山大街分离式立交桥的设计与施工

城市桥梁须注重建筑造型,做到轻巧、简洁、桥下视野开阔.介绍了泰安市泰山大街分离式立交桥采用薄壁固接墩预应力连续刚构在设计施工上的一些特点.     

张店互通立交桥上跨济青高速公路支架的设计与施工

在对滨州至博山高速公路淄博段张店互通立交跨济青高速工程实践的基础上,提出了张店互通立交桥上跨济南-青岛高速公路支架的设计方法与施工方案.     

高速公路分离式立交设计

论述了在高速公路分离式立交设计中,应该遵循的设计原则和标准,并就设计中关于结构选型和接线问题进行了阐述.     

津石高速公路上跨京九铁路立交桥不平衡称重及试转研究

文章以津石高速公路上跨京九铁路立交桥转体施工为例,分析了该立交桥的实际结构设计情况,确定了主要转体参数,并根据转体前不平衡称重结果,提出了配重建议。同时进行了试转测试,结果表明转体过程平稳,可进行正式转体施工。     

我国首条大规模风积沙填筑公路10月完工

##正##日前,三岔口至莎车高速公路(以下简称"三莎高速公路")项目进展顺利,将于10月底完工。三莎高速公路是新疆迄今投资规模最大的高速公路之一,也是我国首条大规模利用风积沙填筑的高速公路项目。三莎高速公路北起正在建设的阿克苏至喀什高速公路三岔口互通式立交桥,南至莎车县乌达力克乡北铂穿越巴楚、麦盖提、莎车,跨越G315线以及喀什至和田铁路,与喀什至叶城高速公路相连,主线为双向四车道高速公路,     

Discrete mode-choice analysis of urban travel demand by the Analytic Hierarchy Process

This paper develops a new procedure for the problem of multimodal urban corridor travel demand estimation by using the Analytic Hierarchy Process (AHP). Certain conceptual and operational features of the AHP are common to the discrete choice theory-based modeling approach. Whereas the computational and data requirements of standard discrete choice models are immense, the proposed AHP approach deals efficiently with multidimensionality, nested demand structure and discrete travel decision making behavior. The paper concludes by summarizing the AHP-aided, step-by-step procedure for metropolitan travel demand (modal split) estimation.     

Development of an indicator to assess the spatial fit of discrete choice models

Discrete choice models are increasingly implemented using geographical data. When this is the case, it may not be sufficient to project market shares accurately, but also to correctly replicate the spatial pattern of choices. Analysts might then be interested in assessing the results of a model’s fit relative to the spatial distribution of the observed responses. While canonical approaches exist for the exploratory spatial analysis of continuous variables, similar tools have not been widely implemented for discrete choice models, where the variable of interest is categorical. For this reason, despite recent progress with spatial models for discrete outcomes, there is still not a simple and intuitive tool to assess the quality of the spatial fit of a discrete choice model. The objective of this paper is to introduce a new indicator of spatial fit that can be applied to the results of discrete choice models. Utility of the indicator is explored by means of numerical experiments and then demonstrated by means of a case study of vehicle ownership in Montreal, Canada.     

Semiparametric specification of the utility function in a travel mode choice model

We propose a semiparametric approach that can capture the nonlinearity of deterministic components of the utility functions in discrete choice models and demonstrate it by analyzing travel mode choice behaviour for an interregional trip. The proposed smoothing spline-based specification method can be used to make ex ante evaluations regarding the parametric specifications of the deterministic utility functions in discrete choice models.     

Statistical models of discrete choice processes

A number of problems studied in the transportation literature, such as automobile choice, motorist route choice, and transportation mode choice, involve an agent who makes a series of discrete choices over time. This paper presents statistical models and estimation methods for such discrete choice processes, and illustrates potential applications of these methods to the transportation literature.     

On the relationship between the discrete and continuous models for combined distribution and assignment

The relationship between the discrete and continuous models for the combined distribution and assignment problem is presented. In particular, it is shown that, under certain conditions, the classic continuous flow formulation of the combined distribution and assignment problems can be viewed as the continuous approximation of the discrete model formulated in terms of the Efficiency Principle.     

The evaluation of high occupancy vehicle lanes on sun yat‐sen freeway in Taiwan

This study proposes a methodological framework to incorporate latent factors, including direct and indirect perceptions, as the explanatory variables in a discrete choice models using revealed preference and stated preference data sets. The methodology requires the estimation of a model system comprising of a discrete choice model and the structural and measurement equations of a latent variable model. The application involves the evaluation of responses to the new high occupancy vehicle (HOV) lanes on the Sun Yat‐Sen Freeway in Taiwan. The results obtained from this study provide valuable insights into the planning and assessment of HOV lanes.     

A nonparametric approach to the incorporation of heterogeneity into repeated polytomous choice models of urban shopping behaviour

Longitudinal discrete choice models which use a mixing distribution to control for unobserved heterogeneity, and which are estimated by a nonparametric maximum likelihood mass point procedure, have so far been restricted to the analysis of dichotomous choices. This paper extends mass point methods to the case of polytomous choice problems and in so doing makes an important contribution to the analysis of longitudinal data and dynamic discrete choice models. The paper concludes with an empirical assessment of the performance of mass point methods in the analysis of urban shopping behaviour, using short-term panel data from the Cardiff Consumer Panel.     

Optimal allocation of limited and random network resources to discrete stochastic demands for standardized cargo transportation networks

We consider the resource allocation problem with discrete random demands and discrete random resource capacities for standardized cargo transportation networks, in which a freight operator needs to determine the integral quantity of booking requests to be accepted for each product to maximize the expected profit. We formulate the problem as a stochastic integer programming model and provide theoretical results that completely characterize the optimal solution to the stochastic model under a special case. We present a progressive augmentation algorithm and a sampling based method for solving the stochastic model under a general case. We also offer numerical experiments to test the two methods and shed light on their performances.     

Modeling and solving discrete network design problem with stochastic user equilibrium

In this paper, we address the discrete network design problem, which determines the addition of new roads to existing transportation network to optimize the transportation system performance. Road users are assumed to follow the traffic assignment principle of stochastic user equilibrium. A mixed‐integer nonlinear nonconvex problem is developed to model this discrete network design problem with stochastic user equilibrium. The original problem is relaxed into a convex mixed‐integer nonlinear program, whose solution provides a lower bound of the original problem. The relaxed problem is then embedded into two proposed global optimization solution algorithms to obtain the global optimal solution of the problem. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of task complexity and time pressure on activity-travel choices: heteroscedastic logit model and activity-travel simulator experiment

This paper derives, estimates and applies a discrete choice model of activity-travel behaviour that accommodates potential effects of task complexity and time pressure on decision-making. To the best of our knowledge, this is the first time that both factors (task complexity and time pressure) are jointly captured in a discrete choice model. More specifically, our heteroscedastic logit model captures potential impacts of task complexity and time pressure through the scale of the utility of activity-travel options. We collect data using a novel activity-travel simulator experiment that has been specifically designed with the aim of testing our model. Results are in line with expectations, in that higher levels of task complexity and time pressure are found to result in a smaller scale of utility. In other words, higher levels of task complexity and time pressure lead to more random choice behaviour and as a consequence to less pronounced differences in choice probabilities between alternatives. An empirical illustration suggests that choice probability-differences between models that do and those that do not capture these effects, can be very substantial; this in turn suggests that failing to capture the effects of task complexity and time pressure in discrete choice models of activity travel decision-making might lead to serious bias in forecasts of the effects of transport policies.