基于LCA的轮轨与磁悬浮方案比选研究

本文基于LCA对京沪高铁的轮轨与磁悬浮方案进行比选研究,在材料、设备、运输与施工阶段对轮轨与磁悬浮的能源消耗进行计算分析,最后对两者进行综合比选评价。从能源消耗的全生命周期评价角度为铁路在轮轨与磁悬浮两个方案的比选评价提供科学可靠的参考思路。     

高速公路路线比选方案安全性评价分析

为对高速公路路线比选方案的安全性评价进行研究,文章以隆林委乐至革步高速公路二期工程为研究对象,从地形地质、危险路段、重要结构物、不利气象等主要危害因素出发,选取五大安全评分指标,对路线各比选方案的安全性进行评价分析,选出最佳路线,为后续类似项目比选方案安全性评价提供借鉴。     

隧道工程施工技术方案经济比选方法的探讨

文章从隧道工程的特点出发,提出了在隧道工程施工技术经济方案比选中,采用增额投资收益率和等期值费用两个经济评价指标进行技术方案的经济比选,供在隧道施工方案比选时参考.     

共和新路高架工程一体化高架结构桥墩方案比选

从交通功能，结构合理性，景观与环境和工程造价四个方面，论术共和新路高架工程一体化高架结构桥墩方案比选。     

蒙三铁路选线方案研究

蒙三铁路是鄂尔多斯西部及周边地区对外运输的大能力货运通道。为保障线路方案的安全、经济和社会效益最大化,依据路网及城市规划、园区规划,结合蒙三铁路功能定位、沿线企矿经济据点位置、环境敏感区分布等因素,从线路走向、工程地质、环境保护等三个角度进行线路方案比选,分析蒙三铁路的选线理念。期望能够为类似工程提供参考。     

上海外滩通道工程福州路工作井结构设计实践

在上海外滩通道工程福州路工作井设计中遇到了周边建筑物保护要求高以及既有人行地道处理等难题。从设计角度出发，结合施工方法，论述和分析了两种工作井支撑围护方案，并对其进行了技术比选。     

基于客流通行服务水平的轨道交通车站方案比选

随着轨道交通网络密度的增大,新建线与既有线换乘站受到越来越多边界条件的限制,客流通行服务水平的方案比选难以通过简单公式计算及常识分析进行判断。介绍和分析了上海轨道交通静安寺站客流通行的现状及方案,采用行人仿真手段对各方案客流通行服务水平进行评价及对比,提出了基于客流通行服务水平的轨道交通车站方案比选建议。     

上海外滩观光隧道浦西竖井超深基坑支护结构设计方案优化

详细介绍了处于险恶中的外滩观光隧道浦西亍的工程概况。通过对在周边工程环境的深入调研，从满足基坑工种的保护等级着手，同时考虑业主方的施工工期要求及降低工程造价，对不同的支护结构设计方案进行了优化比选。     

山区高速公路走廊带方案比选思路探讨

基于山区高速公路走廊带方案选择的重要性,结合工程实例探讨了山区高速公路走廊带方案比选时需要考虑的相关因素和注意事项,提出了走廊带方案的比选思路,以期对山区高速公路走廊带方案的比选论证提供参考。     

怒江沿江公路路线方案综合比选评价

以怒江沿江公路泸水县境内腊子庙至维拉坝段路线方案比选为例,通过建立综合评价指标体系,量化分析各备选方案,构建多因素综合评价模型,采用德菲尔法进行多方案比选,最终确定最优方案。     

Who switches to hybrids? A study of a fuel conversion program in Colombia

Air pollution from mobile sources is an important environmental problem in larger cities. In 2001, a program was implemented to encourage the use of natural gas in vehicles in the Aburrá Valley in Colombia, with incentives to convert small cars from gasoline and diesel to hybrid engines with natural gas, most notably a cash subsidy. Using a survey administered to both commercial and private car owners we study the determinants of conversion under this fuel conversion program. We thus obtain information about the reasons for adoption of new technologies in vehicles. This allows us to discuss the possible outcomes of this type of policy. Results show that a large part of owners who switched would have done it anyway without the subsidy. Based on the findings, commercial vehicles are most likely to be converted to natural gas vehicles.     

Telecommuting and environmental policy: Lessons from the ecommute program

In 1999 the National Air Quality and Telecommuting Act established pilot telecommuting programs (ecommute) in five major US metropolitan areas. The major goal of the ecommute program was to examine whether a particular type of economic incentive, tradable emissions credits from telecommuting, represents a viable strategy for reducing vehicle miles traveled and improving air quality. A context is established for evaluating whether the envisioned trading scheme represents a feasible approach to reducing mobile source emissions and promoting telecommuting and a review of the limited experience with mobile source emissions trading programs is provided. Using two-and-one-half years of data collected in the ecommute program, telecommuting frequency, mode choice, and emissions reductions are examined. It is found that from a regulatory perspective, the most substantial drawback to such a program is its questionable environmental integrity, resulting from difficulties in designing sufficiently rigorous quantification protocols to accurately measure the emissions reductions from telecommuting. Such a program is not likely to be cost-effective because the emissions reductions from a single telecommuter are very small.     

A comparative study of the emissions by road maintenance works and the disrupted traffic using life cycle assessment and micro-simulation

Life cycle assessment is being accepted by the road industry to measure such key environmental impacts as the energy consumption and carbon footprint of its materials and laying processes. Previous life cycle studies have indicated that the traffic vehicles account for the majority of fuel consumption and emissions from a road. Contractors and road agencies are looking for road maintenance works that have the least overall environmental impact considering both the roadwork itself and the disrupted traffic. We review life cycle assessment studies and describe the development of a model for pavement construction and maintenance, detailing the methodology and data sources. The model is applied to an asphalt pavement rehabilitation project in the UK, and the micro-simulation program VISSIM is used to model the traffic on that road section. The simulation results are fed into a traffic emissions model and emissions from the roadwork and the traffic are compared. The additional fuel consumption and emissions by the traffic during the roadwork are significant. This indicates that traffic management at road maintenance projects should be included in the life cycle assessment analysis of such work.     

Modeling taxi drivers’ decisions for improving airport ground access: John F. Kennedy airport case

Taxi service is an important component of airport ground access, which affects the economic competitiveness of an airport and its potential positive impact on the surrounding region. Airports across the globe experience both taxi shortages and excesses due to various factors such as the airport’s proximity to the city center, timing and frequency of flights, and the fare structure. Since taxi drivers are independent entities whose decisions affect the taxi supply at airports, it is important to understand taxi drivers’ decision mechanisms in order to suggest policies and to maintain taxi demand and supply equilibrium at the airports. In this paper, New York City (NYC) taxi drivers’ decisions about airport pick-ups or cruising for customers at the end of each trip is modeled using logistic regression based on a large taxi GPS dataset. The presented approach helps to quantify the potential impacts of parameters and to rank their influence for policy recommendations. The results reveal that spatial variables (mainly related to proximity) have the highest impact on taxi drivers’ airport pickup decisions, followed by temporal, environmental and driver-shift related variables. Along with supplementary information from unstructured taxi driver interviews, the model results are used to suggest policies for the improvement of John F. Kennedy (JFK) airport’s ground access and passenger satisfaction, i.e. the implementation of taxi driver frequent airport server punch cards and a time-specific ride share program.     

Optimal fleet conversion policy from a life cycle perspective

Vehicles typically deteriorate with accumulating mileage and emit more tailpipe air pollutants per mile. Although incentive programs for scrapping old, high-emitting vehicles have been implemented to reduce urban air pollutants and greenhouse gases, these policies may create additional sales of new vehicles as well. From a life cycle perspective, the emissions from both the additional vehicle production and scrapping need to be addressed when evaluating the benefits of scrapping older vehicles. This study explores an optimal fleet conversion policy based on mid-sized internal combustion engine vehicles in the US, defined as one that minimizes total life cycle emissions from the entire fleet of new and used vehicles. To describe vehicles' lifetime emission profiles as functions of accumulated mileage, a series of life cycle inventories characterizing environmental performance for vehicle production, use, and retirement was developed for each model year between 1981 and 2020. A simulation program is developed to investigate ideal and practical fleet conversion policies separately for three regulated pollutants (CO, NMHC, and NO_x) and for CO₂. According to the simulation results, accelerated scrapping policies are generally recommended to reduce regulated emissions, but they may increase greenhouse gases. Multi-objective analysis based on economic valuation methods was used to investigate trade-offs among emissions of different pollutants for optimal fleet conversion policies.     

Estimating mortality impacts from vehicle emission reduction efforts: The Tune In and Tune Up program in the San Joaquin Valley

As a response to profoundly poor air quality and associated environmental justice concerns in the San Joaquin Valley region in California, the Tune In & Tune Up (TI&TU) program provides residents with free vehicle emissions testing and vouchers for smog repair. We used data on approximately 19,000 repaired TI&TU vehicles from 2012 to 2018, and several estimation techniques, to quantify a range of nitrogen oxides (NO_X) emissions prevented as a result of the program. We then calculated resulting mortality impacts from reduced exposure to fine particulate matter (PM_2.5) in the form of secondary nitrates. After applying a novel smog repair emissions abatement depreciation function, we find that six years of operation of the TI&TU program has reduced NO_X emissions by approximately 53–302 tons by the end of 2018. Using a concentration response function for ambient PM_2.5, we found that between 0.055 and 0.31 premature deaths have also been avoided. We present multiple methods for assessing public health impacts, which can be used as guidance for evaluating similar transportation-based emission reduction programs.     

跨江特大桥径流水收集系统的优化设计探讨

文章以桂林至梧州高速公路马江至梧州段工程浔江特大桥为例,对跨江特大桥桥面径流水收集系统进行研究,提出了适合跨江特大桥的新型桥面水收集方案,为类似跨江特大桥设计和环境保护提供参考。     

An optimization framework for workplace charging strategies

The workplace charging (WPC) has been recently recognized as the most important secondary charging point next to residential charging for plug-in electric vehicles (PEVs). The current WPC practice is spontaneous and grants every PEV a designated charger, which may not be practical or economic when there are a large number of PEVs present at workplace. This study is the first research undertaken that develops an optimization framework for WPC strategies to satisfy all charging demand while explicitly addressing different eligible levels of charging technology and employees’ demographic distributions. The optimization model is to minimize the lifetime cost of equipment, installations, and operations, and is formulated as an integer program. We demonstrate the applicability of the model using numerical examples based on national average data. The results indicate that the proposed optimization model can reduce the total cost of running a WPC system by up to 70% compared to the current practice. The WPC strategies are sensitive to the time windows and installation costs, and dominated by the PEV population size. The WPC has also been identified as an alternative sustainable transportation program to the public transit subsidy programs for both economic and environmental advantages.     

Competitive strategies for original equipment manufacturers considering carbon cap and trade

This paper considers an original equipment manufacturer (OEM) faces competition from an independent remanufacturer (IR) and they both are regulated by carbon cap and trade policy (CTP). We develop models to explore the OEM’s optimal competitive strategy in the face of IR’s competition and environmental regulation. We first investigate the impact of CTP on the OEM and IR. Then, we analyze three competitive strategies that the OEM may choose: remanufacturing, fixed-fee licensing, and royalty licensing. We investigate their optimal decisions under each strategy and identify the conditions under which these strategies can coordinate the OEM and IR. Finally, we explore conditions under which one strategy is superior to another. The results show that the OEM is worse off when competing with the IR under CTP if the carbon cap allocated to the OEM is small. Fixed-fee licensing and royalty licensing can coordinate the OEM and IR not only from an economic perspective but also from an environmental perspective. The OEM’s optimal competitive strategy is determined by thresholds of three critical parameters: the fixed cost of setting up a remanufacturing system, the fixed-fee, and the per-unit royalty. We provide specific guidance on strategy selection for the OEM.     

Evaluating the efficiency of the Essential Air Service program in the United States

Essential Air Service (EAS) is a federally funded program in the United States that provides connecting, commercial air service between rural communities and their nearest large or medium commercial hub airport. During fiscal year 2010, $170 million dollars were spent to provide this service to 107 communities in the US. However, with significant variations in subsidies to each airport (ranging from $427,757 to $3,082,403) and marked differences in passengers served, there are serious concerns regarding the overall efficiency of the EAS program. The purpose of this paper is to use data envelopment analysis integrated in a geographic information system for evaluating service efficiencies at the community level. Policy implications and strategies to improve the EAS program are discussed.