Nonlinear pricing on private roads with congestion and toll collection costs

Nonlinear pricing (a form of second-degree price discrimination) is widely used in transportation and other industries but it has been largely overlooked in the road-pricing literature. This paper explores the incentives for a profit-maximizing toll-road operator to adopt some simple nonlinear pricing schemes when there is congestion and collecting tolls is costly. Users are assumed to differ in their demands to use the road. Regardless of the severity of congestion, an access fee is always profitable to implement either as part of a two-part tariff or as an alternative to paying a toll. Use of access fees for profit maximization can increase or decrease welfare relative to usage-only pricing for profit maximization. Hence a ban on access fees could reduce welfare.     

江汉湾桥两种钢拱安装方案的建安费对比

随着国民经济的发展,对于桥梁的形式,人们在安全实用的基础上,增加了对美的追求。近年来,拱桥因造型优美受到了人们的广泛青睐。然而,目前的市政定额体系对大跨度钢桁拱桥的费用测算实例较少,因此通过结合江汉湾桥实际情况,运用造价软件对大跨度钢桁拱桥的工法进行分析,对比架梁吊机施工和缆索吊机施工两种不同工法的建筑安装工程费用,分析两种工法在缆索吊、码头、栈桥、平台等方面的差异,为今后大跨度钢桁拱施工方案的选择提供参考。     

To competitively tender or to negotiate - Weighing up the choices in a mature market

A key attribute of competitive tendering for the periodic selection of operators of subsidised public transport services is to secure the provision of specified services at efficient cost levels. This has proved particularly effective where services were previously provided by an inefficient monopoly operator. The arguments for the adoption of competitive tendering in preference to negotiation with the incumbent operator may be less clear-cut in other cases.Consideration is given to both theoretical and practical insights into the relative merits of competitive tendering and negotiation approaches in such situations. The limited literature on the topic is reviewed and insights and lessons identified. Influencing issues include prior conditions, the nature of the supplier market, features of contracts, negotiating and competitive tendering strategies and practice, accountability and transparency, and long-term market implications. The evidence suggests that ‘one size does not fit all’, and the choice will depend on specific circumstances.The relative merits of the two approaches for renewal of bus contracts are considered with regard to Adelaide, for contracts which have previously been awarded through competitive tendering. The paper draws out the main factors that could influence the authority’s choice between the options, and discusses the relevance of the findings to other situations.     

Efficiency measurement in public transport: Are findings specification sensitive?

The need to measure transit system performance along with its various dimensions such as efficiency and effectiveness has led to the development of a wide array of approaches and vast literature. However, depending upon the specific approach used to examine performance, different conclusions are oftentimes reached. Using data from 15 European transit systems for a ten year time period (1990-2000), this paper discusses three important transit performance questions; (i) Do different efficiency assessment methodologies produce similar results? (ii) How are the two basic dimensions of transit performance, namely efficiency and effectiveness, related? and (iii) Are findings regarding organizational regimes (public operations, contracting and so on) sensitive to the methodological specifications employed? Results clearly indicate that efficiency scores and associated recommendations are sensitive to the models used, while efficiency and effectiveness are - albeit weakly - negatively related; these two findings can have far reaching policy implications.     

基于支持向量机的舰船维修费用组合预测研究

在费用预测中,利用单一模型往往存在着信息不足的缺陷。为了提高舰船维修费用的预测精度和稳定性,采用支持向量机（SVM）回归算法,把几种单一预测模型结果作为输入,实际值作为输出,然后用足够多的预测案例训练学习机器,在各组合的模型预测结果与实际之间得到一种非线性映射关系,从而建立了非线性组合预测模型。最后,以某型舰船维修费用为例,对指数平滑法、灰色预测和参数法3种方法的预测结果进行仿真,结果表明此法较传统的单一模型预测法具有更高的预测精度。     

工程量清单计价中若干问题的分析与思考

列举了建设工程工程量清单计价中常出现的工程量准确计算、措施项目费用调整和报价合理性评审三大问题,分析了问题产生的原因,并提出了解决这些问题的几点建议.