The role of volume-delay functions in forecasting and evaluating congestion charging schemes: the Stockholm case

This paper uses observations from before and during the Stockkholm congestion charging trial in order to validate and improve a transportation model for Stockholm. The model overestimates the impact of the charges on traffic volumes while at the same time it substantially underestimates the impact on travel times. These forecast errors lead to considerable underestimation of economic benefits which are dominated by travel time savings. The source of error lies in the static assignment that is used in the model. Making the volume-delay functions (VDFs) steeper only marginally improves the quality of forecast but strongly impacts the result of benefit calculations. We therefore conclude that the dynamic assignment is crucial for an informed decision on introducing measures aimed at relieving congestion. However, in the absence of such a calibrated dynamic model for a city, we recommend that at least a sensitivity analysis with respect to the slope of VDFs is performed.     

实施物流目标成本事前管理的方法探讨

物流目标成本事前管理是物流企业施行物流目标成本管理的最重要环节,然而在实施过程中却存在着各种问题。本文将站在另外一个角度,对物流企业如何有效实施目标成本事前管理进行尝试性的探索。     

BOM在成本核算与控制中的常见问题与对策

BOM作为重要的经营管理手段已被越来越多的制造业所采用,其在成本核算与成本控制中的作用也日趋明显。尤其是ERP系统和财务软件应用较好,物流管理程序化的企业。本文是围绕BOM在成本核算和成本控制实务中常见的几个问题及相应的解决对策等进行的讨论。     

关于完善公路养护投资管理的探讨

针对我国目前公路养护投资管理工作中存在的投资管理不科学、投资效益不高等问题,探讨了如何完善公路养护工程投资管理的基本思路和对策,即在养护投资管理中实行定额管理、推行养护工程费制,对养护资金的分配和安排应进行费用-效益分析和优化研究,完善养护工程造价管理体系,加强养护费用审批制和监督机制,还建立了基于路况综合评价指标和交通量因素的养护费用预测模型,为推进养护市场化提供理论支持.     

效用函数在工程成本风险预测中的构建

分析风险预测准确程度进行评价的意义,提出了将风险可预测性作为风险预测准确程度的评价指标,并以效应理论为基础构造风险可预测性效用函数,实现了风险预测结果的评价,验证了风险预测的准确性和可靠性.     

施工企业成本管理存在的问题及对策

随着我国市场经济的不断发展,竞争机制已渗透到公路行业,如何降低施工企业工程成本,提高企业经济效益成为当务之急。文中结合施工企业的实际,就成本管理的问题及对策进行分析与探讨。     

铁路隧道使用凿岩台车与风钻钻爆的比较研究

为进一步分析研究高铁隧道凿岩台车与风钻钻爆的优劣及适用性问题,以郑万高铁小三峡隧道工程为依托,介绍风钻钻爆 的施工应用情况及凿岩台车钻爆在施工应用方面的制约因素,并从施工工效、人员配置、安全性、超欠挖控制、成本投入等方面对比 分析。 主要研究结论如下: 1)采用凿岩台车钻爆,在硬岩条件下钻爆速度较快,Ⅲ、Ⅳ级围岩可通过工法调整来提高凿岩台车的施 工效率,遇软弱围岩时应慎重选用; 2)凿岩台车钻爆与风钻钻爆相比,劳动强度低、节省劳动力、安全风险小等方面具有突出成效; 3)理论分析凿岩台车钻爆较风钻钻爆平均线性超挖小,但实际施工过程中却反之,可通过加强管理来缩小与人工钻爆之间的超挖 差距; 4)凿岩台车对风钻钻爆的优势显而易见,随着隧道施工机械化进程不断地发展,将来一段时间凿岩台车钻爆替代风钻钻爆 施工是未来地下工程开挖的发展方向之一。     

多方式多类型交通分配模型(MMA)在收费型公路网中的应用研究

在对收费型公路运营模式进行研究的基础上,利用交通规划软件建立了基于广义费用的交通流量分配模型即多方式多类型交通分配模型,通过对模型参数的科学标定和网络的合理设置,得到各类车型在特定网络上的流量分配、路段饱和率以及通行费用,并对此模型的应用效果进行分析,最终为区域高速公路网规划、路段交通量预测提供依据。     

Multi‐objective highway alignment optimization using a genetic algorithm

The available highway alignment optimization algorithms use the total cost as the objective function. This is a single objective optimization process. In this process, travel‐time, vehicle operation accident earthwork land acquisition and pavement construction costs are the basic components of the total cost. This single objective highway alignment optimization process has limited capability in handling the cost components separately. Moreover, this process cannot yield a set of alternative solutions from a single run. This paper presents a multi‐objective approach to overcome these shortcomings. Some of the cost components of highway alignments are conflicting in nature. Minimizing some of them will yield a straighter alignment; whereas, minimizing others would make the alignment circuitous. Therefore, the goal of the multiobjective optimization approach is to handle the trade‐off amongst the highway alignment design objectives and present a set of near optimal solutions. The highway alignment objectives, i.e., cost functions, are not continuous in nature. Hence, a special genetic algorithm based multi‐objective optimization algorithm is suggested The proposed methodology is demonstrated via a case study at the end.     

公路基本建设项目设计阶段工程造价控制

公路工程造价控制,是工程项目管理的重要内容。文章分析了在公路基本建设项目设计阶段控制工程造价的重要性,阐述了设计阶段工程造价控制的必要条件,提出了对公路基本建设项目工程造价进行有效控制的措施。