Optimized real options-based approach for government guarantees in PPP toll road projects

The uncertainty associated with future traffic levels in Build–Operate–Transfer toll road projects lead to difficulties in obtaining finance and thus to unsuccessful bids. In order to increase the attractiveness of projects for investors, governments usually provide several types of guarantees such as Minimum Revenue Guarantees (MRGs). In many cases, challenges associated with the valuation of this uncertainty force governments to provide excessive guarantees, placing an increased burden on the public budget. Based on this problem, a real-option-based model is presented for the identification of optimum upper and lower boundaries of compound MRG and Maximum Revenue Cap (MRC) options which establish a fair risk allocation structure. The proposed model uses an optimization approach in which high levels of guarantees in initial years are compensated by the transfer of excess revenues obtained by the private investor in late years. The optimum upper and lower boundaries of compound MRG and MRC options are identified using the proposed model. Results reveal that the emerging net guarantee amount generated by using any pair values of the MRG and MRC that remain in the identified interval not only maintains the attractiveness of project for private investors but also restrains government contingent liabilities. Thus, the identified interval of MRG and MRC enables the structuring of a flexible bargaining environment for both parties.     

Assessment of the attributes based life cycle assessment framework for road projects

A number of life cycle assessment (LCA) tools have been suggested for pavements. However, very few have been adopted by the road authorities. The key reasons for this lack of implementation have been the tendency for very broad LCA analyses that include system boundaries considerably beyond the more natural system boundaries associated with road design, construction and maintenance as well as the lack of available LCA tools that have attributes that reflect key road properties. In this paper, a new attribute based pavement LCA framework is evaluated for use on real road materials. Aggregates from two different sources and the effect of using a warm mix asphalt additive (WMAA) in asphalt mixtures were investigated in the laboratory. Different pavement design alternatives were generated using the laboratory data and analysed using the road LCA framework. Asphalt production and material transportation were found to be the most energy-consuming processes. The results presented show that having actual pavement material properties as the key attributes in LCA enables a pavement-focused assessment of environmental impacts associated with different design options, and LCA can help in decision support by evaluating environmental impacts of different design alternatives in a project planning/design stage.     

Estimating general threshold traffic levels of typical build,operate, and transfer toll road projects in Indonesia

Applying the adjusted present value method enables the estimation of the general minimum traffic levels for the first year of operation required to make typical Indonesia's build, operate and transfer (BOT) toll road projects financially feasible. To determine the level, both average business risk as reflected by the opportunity cost of capital in the country's toll road industry, and project‐specific risk as reflected by traffic risk in terms of ramp‐up scale, ramp‐up duration and catch‐up extent are taken into consideration. Pessimistic and optimistic estimates reveal, respectively, that 18?000 vehicles per day (vhd) and 18?100?vhd are the minimum traffic levels under a low traffic risk scenario. This level increases particularly for optimistic estimate if traffic risk rises. To relax these high traffic requirements, the government should attempt to minimize traffic risk and average business risk or to provide financial supports. Sensitivity analysis results demonstrate that the threshold traffic levels are very sensitive to base tolls and construction cost.     

Dynamic modeling of the quantitative risk allocation in construction projects

Allocation of construction risks between owners and their contractors has a significant impact on the total construction costs. This research presents an integrated fuzzy-system dynamics approach for quantitative risk allocation. All the factors affecting the risk allocation process are modeled using system dynamics approach. Fuzzy logic is integrated into system dynamics modeling structure to account for the existing uncertainties. The values of different factors that have an uncertain nature are determined by fuzzy numbers. The application of Zadeh's extension principle and interval arithmetic is proposed for the system dynamics to enable the system outcomes to be presented considering uncertainties in the input variables. Using the proposed integrated fuzzy-SD model, the project cost is simulated at different percentages of risk allocation. The optimum percentage of risk allocation is determined as a point in which the project cost is minimized. The performance of the proposed method is assessed by employing the method in a tunneling project.     

工程项目风险性费用的预测与管理

结合工程造价的风险管理理论与计算机模拟技术进行了风险性费用的预测,并提出了基于风险概率分析为基础,应用蒙特卡罗方法对风险性费用进行动态监管,最后以实例阐述了应用过程。     

Exposure and risk assessment for aluminium and heavy metals in Puerh tea

As the consumption of Puerh tea is booming because of its multiple health-promoting effects, the possible health risks resulting from long-term exposure to metals contained in this tea need to be evaluated. To assess the human risk associated with drinking Puerh tea, concentrations of aluminium, lead, cadmium, mercury, zinc, copper and arsenic were determined in samples of Puerh tea, tea leaves from the plants, and planted soil collected from the Yunnan province, China. Site-specific exposure parameters such as body weight and consumption rate of Puerh tea were investigated in Kunming and Puer cities using face-to-face surveys. Health risks were evaluated for the inhabitants of Kunming and Puer cities by gender and by age groups. Although the Puerh tea plant easily absorbs aluminium from soil, the concentrations of Al and six other elements in Puerh tea were all far below the safety concentration limits of China. Both the HQ (Hazard Quotient) values for single elements and the HI (Hazard Index) value for all seven elements were far below one, indicating no non-carcinogenic risks from these seven elements for inhabitants of Kunming and Puer under the current consumption rates of Puerh tea. However, probabilistic estimation of carcinogenic risk shows that the 95th percentile carcinogenic rate of arsenic in Puerh tea approaches the accepted risk level of 10^− 4 for the highest exposure group. Therefore, the arsenic in Puerh tea is of concern.     

公路工程施工项目风险分析与控制

结合公路施工实际体会,在分析公路工程施工常见风险的基础上,提出了控制风险的对策,并给出加强风险管理的措施,以期为公路工程项目管理提供指导。     

公路工程施工期风险评价

结合某高速公路改扩建工程,以施工期为研究对象,初步探讨了公路工程建设项目风险的特点和施工期风险评价的基本方法,为今后更深入的研究奠定了基础。     

浅析房地产项目风险评估

通过分析房地产开发活动中存在的风险因素及特点,从不同角度、不同出发点介绍项目风险评估的方法,为项目决策者采用何种方法能进行风险评估提供依据,从而有效控制风险的产生。     

高速公路联网收费网络安全管理

介绍了高速公路联网收费系统的网络结构和特点,分析了收费网络和办公网络互联存在的安全问题,提出了相应的安全防范方案。     

Proposal of a probabilistic model for multi-hazard risk assessment of structures in seismic zones subjected to blast for the limit state of collapse

It is desirable to verify the structural performance based on a multi-hazard approach, taking into account the critical actions the structure in question could be subjected to during its lifetime. This study presents a proposal for a probabilistic model for multi-hazard risk associated with the limit state of collapse for a reinforced concrete (RC) structure subjected to blast threats in the presence of seismic risk. The annual risk of structural collapse is calculated taking into account both the collapse caused by an earthquake event and the blast-induced progressive collapse. The blast fragility is calculated using a simulation procedure for generating possible blast configurations, and verifying the structural stability under gravity loading of the damaged structure, using a kinematic plastic limit analysis. As a case study, the blast and seismic fragilities of a generic four-storey RC building located in seismic zone are calculated and implemented in the framework of a multi-hazard procedure, leading to the evaluation of the annual risk of collapse.     

Mercury concentration in meconium and risk assessment of fish consumption among pregnant women in Taiwan

Meconium is a matrix that can be obtained easily and noninvasively and is useful for detecting antenatal fetal exposure to environmental toxins. Taiwan is an island with high fish consumption, and many pregnant women would like to enjoy the benefits of fish without jeopardizing their health or that of their child. The aim of this study is to assess the mercury concentration in meconium in relation to the health risk of mercury exposure. A total of 198 mother-infant pairs residing in the city of HsinChu were recruited for the study between January 2007 and June 2007. The average mean concentration of mercury in meconium was 79.2 ± 7.3 ng g^− 1 dry wt We use the Monte Carlo technique to assess the uncertainty in risk assessment and the impact of these uncertainties on the estimation of expected risk of mercury intake from fish in mothers. Based on the FAO/WHO's tolerable daily intake of methylmercury (0.23 μg kg^− 1 d^− 1), we found that 17.3% and 14.0% of the daily mercury exposure estimated exceeded the reference dose for foreign-born and Taiwan-born mothers, respectively. We found that the mercury concentration in meconium was much higher than in other studies, except for one study done in Tagum in the Philippines where mercury is used in gold mining. This may be because Asia is the largest emitter of anthropogenic mercury, accounting for 53% of worldwide emissions. Sensitivity analysis suggests that mercury concentration in fish and the rate of ingesting fish may be the key parameters for governments offering risk management guidance to protect the health of mothers and unborn babies.     

公路工程中自锚式悬索桥风险评估关键技术研究

采用概率风险及改进德菲尔法对某一级公路一座自锚式悬索桥运营期间地震作用下结构风险进行了评估,说明了风险评估关键技术在桥梁工程中的应用技术,为工程的设计与施工提供参考。     

基于模糊理论的软件项目风险评估模型构建

为有效控制软件项目风险管理,提出一种新的评估模型,融合模糊理论、风险权重和专家信任度等概念,对软件项目中的风险进行评估.该模型除了计算出通常用于衡量风险程度的风险当量以外,还计算出多种风险对某种风险后果的组合影响,以及单个风险对整体后果的综合影响,使评估者从宏观和微观上充分度量出项目中的风险危害,从而为风险的缓解和控制提供了可靠的依据.     

Simplified site-specific traffic load models for bridge assessment

Traffic load is identified as one of the greatest sources of uncertainty in the assessment of bridges. In recent years, simulation techniques, using measured traffic data, have been used to predict the characteristic traffic load effects on bridges. However, the techniques are complex, sensitive to the assumptions adopted and require specialist statistical expertise. This work presents a simplified site-specific traffic load model that generates comparable load effects to the corresponding results from a full simulation. While the simplified model is still sensitive to the underlying assumptions, these can be carefully reviewed prior to the method being approved. Further, the simplified method can be employed by practising engineers for bridge assessment.     

Numerical estimation and sensitivity analysis of the energy demand for six industrial buildings in France

When it comes to dealing with energy savings in buildings, studies almost systematically focus on the residential and tertiary building stocks while the industrial building stock is ignored. This study comes as a first step to move forward on this topic and its objectives are threefold: first to develop a simple methodology suitable for various industrial activities, then to analyse the distribution of the energy demand by use for six different cases and, finally, to carry out a sensitivity analysis. A first observation was that the energy demands for HVAC and lighting systems and the heat loads were of the same order of magnitude. The energy demand for heating and cooling was normally distributed, and the uncertainty on the results lay between ±20% and ±40% for most cases. The influence of six weather conditions was estimated for all of the six buildings and found to be significant, yet not uniformly.     

沈阳市地下水开采量的确定及风险分析

在考虑城市化进程给水文地质带来影响的基础上建立了地下水开采模型,对沈阳市地下水的开采量进行了粗略的估算.针对模型中的不确定性因素进行蒙特卡罗随机模拟,得出了合理的概率分布,进而得出了每个地下水开采量对应的风险值.     

政府投资项目中社会稳定风险评估方法探析

分析了社会稳定风险评估工作的主要内容和基本流程,结合具体项目的实践经验,提出了政府投资项目进行社会稳定风险评估的定性和定量评估方法,建立了社会稳定风险评估指标体系和参考分值,为政府投资项目社会稳定风险评估提供了参考。     

Sensitivity analysis for failure assessment of concrete pipes subjected to sulphide corrosion

Sulphide corrosion in concrete sewers is the most common form of deterioration and should be investigated in failure assessment of sewage systems. Corrosion parameters are considered as random variables because of data scarcity and uncertainties involved in the corrosion affected concrete sewers. Sensitivity analysis is widely accepted as a necessary part of failure assessment of structures and infrastructure, in which the effect of random variables on the failure can be analysed.

In the current study, the results of sensitivity analysis of a corrosion affected concrete sewer in the UK showed that among eight random variables, alkalinity of concrete and relative depth of the flow have the most effect on the probability of sewer failure. The analysis showed less significant contribution of some variables in failure functions. Therefore, it would not be necessary to consider those parameters as random variables and they can be treated as deterministic constant values for further studies.     

Enhancing life cycle cost analysis with a novel cost classification framework for pavement rehabilitation projects

Life cycle cost analysis (LCCA) procedures have been used over the past decades to justify the choice of one pavement design alternative over the others. However, many ambiguities associated with the life cycle cost input values, such as the discount rate and future cost estimates have questioned the credibility of the analysis results. Another unrecognized source of errors in pavement LCCA is the misunderstanding of pavement treatment costs when historical costs are typically used for estimating those costs. The historical costs of pavement rehabilitation projects typically include a significant amount of non-pavement-related costs, which may result in a wrong LCCA if not treated appropriately. This paper addresses this specific point of error and proposes a solution to eliminating this error by using a novel cost classification framework that successfully differentiates mainline roadway costs from non-pavement cost items. A case study using Monte Carlo simulation is conducted to evaluate the probabilistic LCCA results. The results of the case study indicate that the conventional approach of using total rehabilitation project costs in LCCA may even lead to a wrong investment decision. The findings of this study will help practitioners and researchers better understand the nature of pavement rehabilitation project cost distributions.