Life-cycle CO2 emissions and influential factors for asphalt highway construction and maintenance activities in China

This study tried to clarify the magnitude of CO₂ emissions from highway construction and maintenance in China through life cycle assessment (LCA) method. For this, 227 real highway projects constructed from the year 2000 to 2011 in Zhejiang Province, China are classified into six types by two categories of N road (62 projects without grand bridge, great bridge and tunnel) and Y road (165 projects with the same road structures) and three sub-categories of (i) newly constructed road, (ii) replacing pavement road and (iii) full rehabilitated road. Significant influential factors of LCA results were revealed through multivariate linear regression models, combined with data quality assessment and sensitivity analysis. Numerical interval of assessment results indicate that the construction emissions of N highway project are more centralized to no more than 2900 t/lane-km, while Y project have a normal upper boundary of construction CO₂ emissions, about 5000 t/lane-km. The contribution of maintenance to CO₂ emissions probably could exceed that of newly construction both for Y project and N project. In addition, the pavement replacing and rehabilitation could bring about large amount of CO₂ emissions which even match with the CO₂ emissions from cumulative traffic volume during highway's life cycle. There are common factors for six categories. Cement and steel are the top largest CO₂ emissions contributors and sensitive factors for N road and Y road. The LCA results are not sensitive to the local construction materials but sensitive to the emission factor of diesel used in transportation and on-site construction.     

Preventive maintenance of road pavement with microsurfacing—an economic and sustainable strategy

To ensure a good quality level of road pavements, it is essential to perform preventive maintenance before they are irreparably damaged. Treatments for preventive maintenance are a solution that is recognized but still in the acceptance phase; effective models covering different combinations of techniques and intervention times and assessing economic and environmental benefits are lacking. The present study aimed to respond to the abovementioned issues, using microsurfacing as the subject of analysis. Several structures and different interventions were evaluated, conducting an economic analysis over their life cycles and an environmental study evaluation using emission factors. The most advantageous solution included the maximum possible number of treatments of preventive maintenance with microsurfacing applied consecutively. This scenario ensures economic and environmental benefits. Additionally, it became clear that it is economically advantageous to design pavements for longer lifetimes.     

基于谱系聚类分析的集装箱装箱方案优化研究

围绕集装箱装箱优化问题,在聚类分析中利用谱系聚类分析原理,提取包装箱的长、宽、高作为3行1列矩阵,对包装箱进行聚类分析后,得到聚类的个数和各类的长、宽、高尺寸。然后,选取聚类中的任意4种作为方案生成的输入,利用层叠原理、边际方法、递归原理对选取的包装箱进行装箱,以达到占有率较高的目的。同时通过图形显示,对方案生成结果进行简单的一维和二维示意。     

关于新时期铁路编组站设计

铁路编组站设计是站场设计的重要内容之一,从编组站的站型、驼峰类型,到自动化管理,正在逐步走向成熟,并形成符合中国国情的自动化编组作业体系。随着路网的建设,有的编组站在路网中的作用逐渐减弱;而有些在路网中起着重要作用的编组站,由于衔接线路的增加,作业量增加幅度较大。随着枢纽客内货外布局的优化,对编组站的站位及规模将会作出新的调整。结合新的发展要求,探讨新时期铁路编组站设计。     

我国铁路快捷货运产品设计及组织优化的探讨

快运产品设计是铁路快捷货运普遍关注的问题.针对铁路快捷货运产品现状和存在的问题,提出铁路快捷货运业务流程再造的目的、内容和机理.基于流程再造,对快捷货运产品进行完善设计,提出细分和强化既有快运产品,开发诸如多式联运、高速、客车化、运输组织创新的快运新产品.以特快、快速、普快三类快运产品划分为标准,设计运输组织优化步骤,实现以市场为导向的铁路快捷货运产品设计和组织.     

Adding a freight network to a national interstate input–output model: a TransNIEMO application for California

The state of the nation’s infrastructure is the subject of widespread discussion and comment because it is thought to include many deteriorating and unsafe bridges. Ever since the terrorist attacks of 9/11, there has been increasing concern over the extent to which an attack on infrastructure could result in serious economic disruption. This research develops a model to analyze the economic consequences of an attack on a major element of the highway network. We add a freight network to a national multiregional economic impact model and make freight traffic flows endogenous. The use of a sub-national interstate model recognizes that most infrastructure planning is at the state level and most political leaders’ interest is local. We base our approach on the National Interstate Economic Model (NIEMO) and refer to an elaboration that we name Transportation network and the National Interstate Economic Model (TransNIEMO). The new model enables us to study the state-specific and industry-specific economic impacts of some significant changes in the nature of highway freight movements. We tested the model for selected freight movements in and out of California. The results are entirely plausible and encourage us to elaborate and test the model for hypothetical disruptions of freight traffic throughout the US.     

关于铁路枢纽联络线与疏解线的设计分析

铁路联络线和疏解线是铁路路网不可缺少的组成部分,线路不长但用途很大,在新线设计尤其是枢纽设计中经常遇到。联络线的标准一般应与相邻线的标准一致;疏解线的标准由于其特殊性．在设计规范中规定了最小曲线半径和最大纵坡。站场设计手册对枢纽的疏解方式做了一些归类与分析,但设计者只知道这些还远远不够。随着枢纽引入线路的增多,联络线与疏解线会越来越复杂,既涉及到如何节省工程投资,更涉及到运输安全、质量与效率。分析铁路枢纽联络线与疏解线的设计方法,以便更好地设计这类线路。     

列车编组计划车流分析系统设计

为实现铁路车流分析的现代化,建立列车编组计划车流分析系统十分必要。为此进行了系统的总体方案设计,提出了系统设计目标和系统总体结构,根据实际需求设计了系统功能模块,并探讨了最短径路算法问题。     

对铁路中小站站坪平纵断面设计的细节问题分析

铁路车站站坪就是按规汜范要求能布置下车站咽喉区及配线的正线平纵断面范围。站坪平纵断面既涉及土建工程量,又涉及运营条件。从中小站站坪平纵断面设计源头进行分析,论述中小站站坪范围内正线平纵断面的选择,以及站坪范围外与区间线路平纵断面的衔接关系．提出处理不同类型车站站坪的具体方法,以达到设计最优。     

Optimizing EV-based P&R subsidy policies for commuting corridor based on cross-nested logit model

The promotion of electric vehicles (EVs) is restricted by cruising range limitation and charging station deficiency. Given the mature development of Park and Ride (P&R) mode, which is used in many cities worldwide to attract more travelers to use public transit, a new travel mode, i.e., EV-based P&R is introduced as an alternative for commuters’ daily travel. This seems quite attractive to expand the use of EVs and further increase their market share. This paper aims to investigate the impact of EV-based P&R introduction on travel mode choice along commuting corridor, and further aid in the optimal subsidy policies decision for the government. A bi-level model is proposed to model the presented problem. The lower level describes commuters’ joint mode and transfer choice behavior through a cross-nested logit (CNL) model, while the upper level minimizes the system cost. A genetic algorithm is developed to solve the formulated model with a partial linearization algorithm for solving the lower level model. And a numerical example is then used to demonstrate the effectiveness of the methodology and illustrate how the network flow pattern reshapes due to the introduction of EVs into the P&R mode and the change of corresponding subsidy policies. As the results show, improving the EV hardware, applying the intelligent supporting service system, developing new technologies for EV fast charging, appropriately improving the parking space capacity, and increasing the parking fee of transfer stations near the central business district (CBD) are all helpful to save the social cost and promote the usage of EVs.