A study of relationships between traffic noise and annoyance for different urban site typologies

The paper intends to analyse the different attitudes of residents in urban areas in regard to annoyance induced by traffic noise, account taken of the effects of the street configuration and of the presence of specific public transport modes in the definition of the dose-response curves.People’s annoyance was investigated through a campaign of noise and traffic measurements and an epidemiological survey, administered to a sample of 830 residents in the buildings close to the measurement points.An ordinal regression model taking into account environmental and urban characteristics was used to identify a dose-response relationship. The cumulative probabilities allowed to define two cut points on the dose-response curves (60 and 75 dB(A)), grouping people in three classes and making the representation of the dose-response relationships different from those traditionally defined that use only the percentage of highly annoyed people.The results show different people’s attitudes towards the annoyance in the urban sites while the dose-response relationship shows that the correlation between annoyance and noise is low. For the same value of day equivalent level, 10% more people are annoyed in L sections (broad streets) than in U sections (narrow streets). Furthermore, all the dose-response curves show a higher sensitivity of people living in L sections; this difference can be measured as a shift of about 4 dB(A). Noise levels are, arguably, a useful indicator, but they are not reliable enough to define the discomfort of the residents, while the site characteristics could shed light on annoyance variability.     

Analysis of a proposed mechanism for carbon-neutral growth in international aviation

In October 2013, the International Civil Aviation Organization (ICAO) announced that it would put in place a market-based mechanism to cap net greenhouse gas emissions from international civil aviation at 2020 levels. This paper analyses the obligations that would be placed on real airlines under an initial draft “Strawman” proposal that was originally formulated as a starting point for discussions within ICAO, and the extent to which such a proposal would succeed in keeping emissions at or below the desired level. The provisions of the ICAO proposal were then applied to more than 100 existing airlines. In order to protect commercial sensitivities, we used hierarchical cluster analysis to identify groups of different types of airlines. We report the results for these groups rather than for individual airlines. While ambiguities in the Strawman proposal complicated the analysis, we found that, depending on their size and rate of growth, airlines will be required to offset very different proportions of their emissions from international flights. A system of de minimis exemptions, as currently proposed, would benefit some rich countries as well as poor ones. Targeting such exemptions more narrowly would raise practical difficulties, which we describe. We conclude by recommending that ICAO design and implement a much simpler system; and propose one alternative.     

深圳地铁2222标施工成本分析与风险防范

地铁施工已经进入了微利时代,亏损项目比比皆是。深圳地铁2222标段隧道施工出现了巨额亏损,充分说明了地铁施工也是成本高风险专业施工,并非"金隧银桥"。文章通过全面、系统地分析深圳地铁2222标段施工成本,计算出各项施工成本指标,总结出施工过程中成本风险控制方法,提出了地铁隧道施工成本风险的防范措施。     

Airport ground transportation management: moving towards the turn of the century

Over the last fifty years ground transportation management (GTM) has slowly evolved into a major function at most larger airports. However, during this time there has been relatively little written discussing the idea, organization structures or duties included within this functional activity. This paper reviews and updates the limited, earlier research. This study replicates initial work done in 1989 and thus provides a short longitudinal view of the airport GTM function. The final results demonstrate the current position of GTM and suggest trends for the future.     

全球民航事故调查数据统计与分析

为探索全球民航事故的发生及调查规律,从航空安全网(ASN)采集626起事故调查数据,对事故发生季度、类型、机型等特征进行统计分析,同时对事故调查的实施机构、调查时长、各类事故调查时长等特征展开分析。结果发现:全球民航事故随运行时间的增加呈现波浪形缓慢下降;事故数量最多的前两位为冲偏出跑道和飞机失去控制,并多集中在第三季度(7-9月);波音公司各机型事故曲线整体类似,同时与空客公司各机型飞机事故曲线存在差异。民航事故调查从开始到发布报告的平均周期为26.1个月;各调查机构针对冲偏出跑道、失去控制、可控飞行撞地事故的平均调查周期分别为22.2、40.4、12.4个月。研究结果为民航事故预防政策制定及事故调查提供参考依据。     

Cost overruns and demand shortfalls – Deception or selection?

A number of highly cited papers by Flyvbjerg and associates have shown that ex ante infrastructure appraisals tend to be overly optimistic. Ex post evaluations indicate a bias where investment costs are higher and benefits lower on average than predicted ex ante. These authors argue that the bias must be attributed to intentional misrepresentation by project developers. This paper shows that the bias may arise simply as a selection bias, without there being any bias at all in predictions ex ante, and that such a bias is bound to arise whenever ex ante predictions are related to the decisions whether to implement projects. Using a database of projects we present examples indicating that the selection bias may be substantial. The examples also indicate that benefit–cost ratios remain a useful selection criterion even when cost and benefits are highly uncertain, gainsaying the argument that such uncertainties render cost-benefit analyses useless.     

Air transportation in a carbon constrained world: Long-term dynamics of policies and strategies for mitigating the carbon footprint of commercial aviation

With increasing demand for air transportation worldwide and decreasing marginal fuel efficiency improvements, the contribution of aviation to climate change relative to other sectors is projected to increase in the future. As a result, growing public and political pressures are likely to further target air transportation to reduce its greenhouse gas emissions. The key challenges faced by policy makers and air transportation industry stakeholders is to reduce aviation greenhouse gas emissions while sustaining mobility for passengers and time-sensitive cargo as well as meeting future demand for air transportation in developing and emerging countries. This paper examines five generic policies for reducing the emissions of commercial aviation; (1) technological efficiency improvements, (2) operational efficiency improvements, (3) use of alternative fuels, (4) demand shift and (5) carbon pricing (i.e. market-based incentives). In order to evaluate the impacts of these policies on total emissions, air transport mobility, airfares and airline profitability, a system dynamics modeling approach was used. The Global Aviation Industry Dynamics (GAID) model captures the systemic interactions and the delayed feedbacks in the air transportation system and allows scenarios testing through simulations. For this analysis, a set of 34 scenarios with various levels of aggressiveness along the five generic policies were simulated and tested. It was found that no single policy can maintain emissions levels steady while increasing projected demand for air transportation. Simulation results suggest that a combination of the proposed policies does produce results that are close to a “weak” sustainability definition of increasing supply to meet new demand needs while maintaining constant or increasing slightly emissions levels. A combination of policies that includes aggressive levels of technological and operations efficiency improvements, use of biofuels along with moderate levels of carbon pricing and short-haul demand shifts efforts achieves a 140% increase in capacity in 2024 over 2004 while only increasing emissions by 20% over 2004. In addition, airline profitability is moderately impacted (10% reduction) compared to other scenarios where profitability is reduced by over 50% which pose a threat to necessary investments and the implementation of mitigating measures to reduce CO2 emissions. This study has shown that an approach based on a portfolio of mitigating measures and policies spanning across technology and operational improvements, use of biofuels, demand shift and carbon pricing is required to transition the air transportation industry close to an operating point of environmental and mobility sustainability.     

Global carbon dioxide emissions scenarios for aviation derived from IPCC storylines: A meta-analysis

This research summarises the aviation CO₂ emissions studies that use the Intergovernmental Panel on Climate Change IS92 and Special Report on Emissions Scenarios storylines as GDP growth assumptions to estimate future global carbon dioxide emissions from the aviation sector. The inter-quartile mean and the first and third quartiles are calculated to enable researches studying climate change policies for aviation to use an average global baseline scenario with lower and upper boundaries. We also perform a simple meta-analysis to analyse the assumptions used to derive the baseline scenario and conclude, as expected, that change in revenue-tonne-kilometres and fuel-efficiency are the main drivers behind the baseline scenarios.     

加强成本控制 实施低成本战略的方法探讨

文章以施工项目的成本管理工作为主线,阐述了加强成本管理对企业实施低成本战略的意义和必要性,分析了实施项目成本管理中存在的问题,重点论述了项目成本管理过程中需要采取的各种成本控制措施。     

Using DEA models to jointly estimate service quality perception and profitability – Evidence from international airports

With increasing competition between airports and a growing share of non-aeronautical revenues, particularly at large international hubs, perceived quality and consumer satisfaction have not only become a key focus of management but potentially the most important tool to achieve or maintain a competitive advantage. However, in the long run stakeholders aim for profit maximisation and it has been shown for other parts of the aviation supply chain that quality does significantly impact on profitability. In this paper we aim to investigate whether perceived airport quality has an impact on airport profit margins. We further apply two-stage Data Envelopment Analysis (DEA) models to estimate a single efficiency measure that combines the potentially conflicting indicators of perceived service quality and profitability for the airport context. We also identify determinants of the jointly estimated single quality/profitability measure.     

高速公路噪声污染及其治理措施探讨

文章通过对高速公路交通噪声污染源特性的分析,结合降低噪声源的功率以及破坏和隔断噪声能量的传输路径等两个噪声治理防护的原则,提出采用低噪声路面、隔声屏障、防噪堤以及绿墙技术和降噪绿化林带等防护技术措施进行高速公路噪声污染治理。     

The Effectiveness of Conceptual Airport Terminal Designs

Abstract

Aviation passenger traffic is forecast to grow significantly over the next decade and beyond. To accommodate this growth will require investment in airport infrastructure, including terminals. These buildings represent large, lumpy investments, so it is important to provide the capacity to accommodate the forecast traffic. However, this depends on at least two factors: the accuracy of the forecast of future demand, and the process of translating these forecasts into designs. Error in either factor can be potentially catastrophic financially. Translating forecasts into designs depends on ‘rules of thumb’ formulae that convert design hour flows into area requirements for each terminal facility. This paper examines the process of translating demand forecasts into conceptual terminal designs. The basic methods used are outlined, and how they affect the conceptual terminal design process are revealed. A model for conceptual terminal design is derived, presented and validated based on a sample of UK airports. It is shown that even if demand forecasts can be taken to be completely accurate, there can still be errors in terminal design and size resulting from the use of these ‘rules of thumb’.     

岩沥青改性沥青混合料应用技术和效益分析

岩沥青改性剂是天然的改性剂,加工合成不会造成环境污染,而且岩沥青改性剂与普通的沥青改性剂相比造价低,因此岩沥青改性剂具有良好的经济和社会效益。本文详细介绍了岩沥青改性剂优点,并通过路面实体工程的分析,证明了岩沥青改性沥青混合料的技术性能和效益优越,是一种值得推广的路面改性剂。     

上市航空类企业现金持有水平研究

新冠肺炎疫情重新使人们认识到现金对企业的重要性。航空业运营成本巨大,持有一定量现金对维持航空企业运营具有重要意义。本文利用1998~2019年间沪深两市航空类上市公司的数据,研究了我国航空业现金持有水平。研究发现:航空业现金持有水平较低,航空公司更是呈逐年下降的趋势,低现金持有水平可能是投资挤压导致的;近几年,航空类企业持有的现金最多仅能维持5个月;企业债务融资与固定资产投资等密切相关;航空公司和机场利用商业信用的程度较弱。对此,我国民航企业应改变单一的投融资方式,加大对商业信用的利用。