A new earthworks estimating methodology

Earthworks and earthmoving operations are a major part of many civil engineering construction projects. Because of their labour and plant intensity, the planning and estimating of such operations is crucial to both the cost and duration of the project; earthworks are considered by many practitioners to be indicators to the success or failure of the project as a whole. Traditionally, a mixture of manufacturers' data (through published charts or computer databases) and historical company data are used in the estimating of earthworks. This process has two main drawbacks. First, plant haul velocity is dependent on the rolling resistance at the soil-wheel interface, which is notoriously difficult to determine; second, the stochastic interface between types of plant provides a non-deterministic system, resulting in estimates of output which may be unrealistically high. An alternative system of earthworks estimating is presented based on a combination of work undertaken in both the soil/vehicle and stochastic estimating fields. This system is demonstrated via a case study based on an actual highway project. The main conclusion to be drawn is that the traditional estimating approach results in a scheme costed well below realistic values.     

Estimation of earthworks execution time cost by means of artificial neural networks

The paper presents a methodology for determining earthworks execution time and cost. The accurate determination of the productivity of machines working in sets is a major problem in earthworks execution planning. Earthworks are conducted in random condition and so the parameter values achieved during their realization have a random character. Using an existing database based on measurements carried out on a construction site, an artificial neural network was built. The latter was used to predict productivity for selected sets of machines and to calculate the task execution time and cost. The obtained set of results allows one to select the machinery set optimum with regard to earthworks execution cost or time.     

A study of preproject planning and project success using ANNs and regression models

It has long been recognized by the industry practitioners that how well preproject planning is conducted has a great impact on project outcome. Through industry project data collection and model analysis, this research intends to investigate the relationship between preproject planning and project success. Preproject planning and project performance information from 62 industrial projects and 78 building projects, representing approximately $5 billion U.S.D. in total construction cost, is collected and used for this research analysis. Based on the information obtained, preproject planning is identified as having direct impact on the project success (cost and schedule performance). Two techniques were then used to develop models for predicting cost and schedule performance: statistical regression analysis, and artificial neural networks (ANNs). The research results provide a valuable source of information that supports better planning in the early stage of the project life cycle and have positive impact on the final project outcome.     

Stratégies et méthodes de prévention

The various preventive methods concerning the hazards linked to underground quarries are presented: assessment of the hazard in planning procedures (information of population and decision-makers, control of land use), techniques of active prevention (reinforcement of the cavity, stabilization by filling), techniques of passive prevention (deep foundations, reinforcement of structures on the surface), techniques used for getting rid of the empty space (caving, earthworks), surveying. The lines used to select the best solution are then reviewed: what are the existing and planned land use? the aims of the prevention (people safety, damage control)? the technical data available (geology, type of exploitation)? Are there limitations to carry out the engineering works? what is the amount of the budget? Finally, simplified decision trees are proposed, in order to select a solution suited to the problem.     

Heuristic methods in resource allocation

Since the introduction of resource allocation techniques to the field of project planning and control by networks, many attempts have been made to improve the effectiveness of the heuristic methods used. Reference has been made to the problem of defining the characteristics of the networks used in the experiments in a few cases. The major results are presented of an investigation into the effects of a range of heuristic methods related to a system for categorizing networks. Two alternative allocation procedures have been tested, and the results are considered separately.     

Structural equation model of project planning effectiveness

Previous research studies investigating the impact of situational variables on project planning effectiveness have not examined how the situational variables work together to influence planning effectiveness. A structural equation model (SEM) has been developed for describing and quantifying the influence of situational factors in project environments and organizational characteristics of performing organizations on project planning effectiveness. The individual effects of directly‐observable variables on the project planning process were evaluated using regression analysis. The SEM approach enables the modelling of multiple factors as latent not‐directly‐measurable variable sets, thus providing a theoretical insight into how individual influence factors work together to determine the effectiveness of project planning efforts. The project environment has a dominant significant influence on the potential effectiveness of project planning efforts. In contrast, the influence of organizational characteristics is relatively insignificant.     

An integrated construction planning system using object-oriented product and process modelling

An interactive planning system approach poses challenges to the efficient integration of the design and construction planning process. Current research is focused on organizational knowledge processing in building design and construction, such as the representation of object-oriented planning models and constraint management incorporating design, engineering and construction planning through several planning stages. Since building construction involves cooperation among designers, engineers and project managers, comprehensive organizational planning and management tools are relevant. The integrated construction planning system (ICPS) aims to cover a wide range of knowledge processing based on formalization and representation of building and construction systems. To realize the integrated construction planning system, appropriate modelling techniques need to be introduced. This paper presents the results of research on several issues such as formalization and representation of interactive design and construction planning processes, methods for incorporating project information, knowledge and constraints and the concept of applying an object-oriented paradigm to interactive building and construction system planning. A prototype system is also presented which integrates building space planning, building system planning, construction system planning, construction activity planning and construction site layout planning.     

基于设计面为曲面的土方计算工程的数据处理

对于土方计算工程,为保证土方量计算精度,可采用三角网法。具体的计算,可引入参考面,对于设计面为曲面时,可引入填挖方平衡面。     

Energy-sensitive land-use planning

The Department of Landscape Planning (part of the Environmental Agency) in Hamburg, Germany, is undertaking a project to address the existing disparity between energy and land-use planning. This project involves the integration of energy-relevant parameters in new land-use plans currently being developed for the entire Hamburg area. In order to facilitate this integration, a comprehensive cartographic process has been developed that is compatible with the existing mapping and planning techniques used by the Department. This mapping process consists of a series of overlay maps designed to produce a composite picture of existing energy use, conservation and renewable resource potential, and environmental impacts associated with existing energy production.     

Active biomass in activated sludge mixed liquor

The engineering and technology of the activated sludge system are reasonably well established, with systems implemented worldwide for the biological removal of C, N and/or P. Parallel to this development, significant advances have been made in the microbiological and biochemical areas of activated sludge. These advances have been driven by the development of new analytical techniques that allow microorganisms to be studied in situ in the activated sludge environment. However, there has been little cross-linking and overlap between the engineering and technology and microbiology and biochemistry paradigms. In particular, the information from the microbiology and biochemistry has not been integrated into the engineering and technology paradigm, to enable improved system design and optimization. One area that can form a starting point to build bridges between the two paradigm sets, is measurement of active biomass. The current design and simulation models invariably include active biomass for each organism group as fundamental parameters which define quantitatively the kinetic rates of the relevant biological processes. However, these parameters remain purely hypothetical because to date they have not been quantitatively measured; their acceptance is based on the consistency of model predicted results over a wide range of application. This paper describes developments in quantitative measurement of the heterotrophic and autotrophic active biomass concentrations within the engineering and technology paradigm, and the formulation of a multinational project which will attempt to link these measurements and the defined engineering environment to the new microbiological and biochemical analytical techniques. It is hoped that this project will facilitate integration of the two paradigms sets.     

A new approach for automation of location-based earthwork scheduling in road construction projects

Accurate information of working locations is vital for efficient resource planning, safety of the construction site and monitoring the weekly progress of earthworks, which is missing in the existing linear scheduling methods. Construction managers have to depend on the subjective decisions for resources allocation and progress monitoring from location aspects. This has caused uncertainties in planning and scheduling, and consequently delays and cost overruns of projects. In this context, a prototype computer-based model was developed using the theory of the location-based planning. An arithmetic algorithm was designed by incorporating road design data, sectional quantities, variable productivity rates and haulage distance. This paper focuses on the improvement and demonstration of the model functions through a case study experiment, which include the automatic generation of location-based earthwork schedules and the optimisation of the weekly resource allocation when and where necessary from the location aspects, considering different options such as construction sequences of the cut/fill sections, site access points and the equipment sets with known productivity rates. The study concluded that the model is a decision supporting tool that assists in the resources planning, identifying time–space congestion, monitoring the activities progress on a weekly basis from the location aspects, and reducing the gap when communicating the scheduling information amongst the construction site teams.     

System development for non-unit based repetitive project scheduling

Repetitive activities are commonly found in construction projects. It is stated in many literatures that repetitive scheduling methods are more effective than traditional CPM methods in the planning and scheduling of repetitive construction projects. Nevertheless, almost all the repetitive scheduling methods developed so far have been based on the premise that a repetitive project is comprised of many identical production units. In this research a non-unit based algorithm and a prototype system are developed for the planning and scheduling of repetitive projects. Instead of repetitive production units, repetitive or similar activity groups are identified and employed for scheduling. The developed system takes into consideration (1) the logical relationship of activity groups in a repetitive project, (2) the usage of various resource crews in an activity group, (3) the maintaining of resource continuity, and (4) the time and cost for the routing of resource crews. A sample case study is conducted for system validation, as well as for demonstration. Application of repetitive scheduling methods can be facilitated with the developed system.     

Application of 4D for dynamic site layout and management of construction projects

Construction schedules and site space arrangement are essential to project management, as they directly influence security, machine running, material deployment, power distribution as well as construction progress and cost. There has been a strong need for more effective planning and management of site space and facilities. This paper introduces a 4D Integrated Site Planning System (4D-ISPS) which integrates schedules, 3D models, resources and site spaces together with 4D CAD technology to provide 4D graphical visualization capability for construction site planning. The features of 4D-ISPS are described in detail. The implementation techniques of this system are also discussed and a real life case is presented.     

Challenges and opportunities for productivity improvement studies in linear,repetitive, and location-based scheduling

Despite theoretical advancements in alternative project planning methods the extent of their practical implementation varies strongly; it has been limited especially in the US construction industry. The family of linear, repetitive, and location-based scheduling techniques holds significant but barely substantiated promise by containing multiple variables of interest for integrated analysis and optimization. Yet it is necessary to provide empirical evidence that using such techniques can improve productivity to increase credibility and acceptance by practitioners, because claims of conceptual superiority are only sporadically supported with detailed measures. An analysis is performed to identify relevant decision-making variables, extract challenges that currently limit the corpus of quantitative productivity studies on alternative scheduling to its insufficient size, and reveal opportunities to expand it in breadth and depth. Variables are categorized by their relevance to time, activity, resource and location, as well as the managerial approach. Challenges include the diverse definitions of productivity itself, issues related to achieving generalizability, and the detailed steps of data collection, preparation, and analysis. Opportunities include the guidance from existing but rare studies and well-established research methods such as case studies that can be applied. This is illustrated with a sample project of a high-rise apartment building in Brazil. If alternative methods can be proven to be measurably better for specific applications, there might be a paradigm shift from merely defaulting to traditional but problematic network-based scheduling toward consciously choosing the planning method based on its potential benefits for a project.     

Near optimal solution for resource-constrained scheduling problems

This paper presents an efficient resource allocation algorithm, and examines its performance against a number of scheduling heuristic rules, aimed at minimizing project durations in a multiple resource-constrained environment. The algorithm has been coded in BASIC and can easily interface with available planning and scheduling software systems. Unlike other heuristic network-based algorithms, resources are allocated simultaneously to sets of activities, rather than to individual activities in a sequential manner. An experiment was conducted to study the performance of the proposed algorithm and compare its results with those generated by four different heuristic scheduling rules, including those found to have the most superior performance such as the widely used least total float rule. Thirty-one network examples adopted from the literature are analysed. The results indicate that the proposed algorithm is superior to the others. The proposed algorithm provides a reasonable trade-off between the best accuracy associated with optimization techniques and the ease of computational effort associated with the simple least total float model. As such, it maximizes the benefits of the two limiting approaches.     

Effect of the Last Planner System® on Social Interactions among Project Participants

Construction is one of the oldest and most established project-based industries, bringing together a diverse collection of professionals for short periods of time. Within the temporary organization of projects, interaction among the participants ensures a smooth transmission of vital information that impacts the process of production planning. While involvement of participants in the planning process increases cohesiveness among them, the Last Planner System® (LPS) identifies detailed specification of the steps to be followed and the constraints to be removed for reliable execution of the project. To accomplish the goal of this study to understand the effect of LPS on the social interactions of the participants, a critical case study method was adopted. In-depth analyses of the interactions among the participants of two projects, one following LPS and another following traditional project planning, have been undertaken to illustrate the role of social interaction in each one of them. Weekly subcontractor coordination meeting was selected as the unit of analysis. Data has been collected using direct observation, and Interaction Process Analysis has been used to analyze the social interaction data. The findings provide a project-level understanding of the role of social interaction among project participants during LPS in comparison to that of traditional project planning. LPS increased the participants’ understanding and control of the work assignments, thereby creating a social system with more information and higher level of trust. Participants using the LPS exhibited more cooperation than those using traditional project planning, working within the social network of the project.     

ON SIMULATION IN PLANNING NETWORKS

Construction activities generally have a non-negligible amount of variability associated with them. This has lead to the consideration of techniques such as PERT, PNET and Monte Carlo simulation in the planning of construction projects. This paper firstly proposes a modification to the PNET procedures and then goes on to examine Monte Carlo simulation in an integrated cost-time formulation under three options relating to the latest finish date of the project final activity. Two of the options lead to the possibility of negative float while the criticality index for the activities is different for all options. The approach is demonstrated on a three-span bridge construction project. A variance reduction technique is used to reduce the number of computations.     

某国际赛车场一级方程式赛道施工及技术要求

结合珠海国际赛车场的工程概况,从土方工程、底基层、粘层油施工、沥青材料的施工等方面介绍了一级方程式赛道的主要施工方法及技术要求,实践证明,该赛道质量如新,为同类工程提供了参考借鉴。     

An integrated approach to electric power system planning and cost of service allocation

Many methods have been proposed to allocate capacity related costs to the various customer classes in an electric power system. These methods are mainly deterministic. Deterministic techniques do not consider the stochastic nature of system components which actually affect the cost behaviour of the system. An important consideration in the process of cost allocation is to ensure that the method used follows the cost behaviour of the system studied. The cost behaviour is basically dependent on the methods and criteria used in system planning and operation. The criteria and planning methods used drives the development of the system which further drives the cost of future investment in the system. It is therefore highly desirable to use similar methods and criteria and to include the same variables which are considered in the system adequacy evaluation. Most large electric power utilities now use probabilistic techniques in their generation system planning. The most commonly used planning techniques are the Loss of Load Expectation (LOLE) and the Loss of Energy Expectation (LOEE) methods. Probabilistic techniques should also be used in the cost of service allocation process as these techniques are capable of incorporating the important factors which actually affect the system cost behaviour.     

建筑工程项目风险与全面风险管理

建筑工程项目的启动需要经过项目立项、可行性研究、设计、项目计划等阶段.所有这些工作都是基于正常的技术、管理和组织以及对将来的情况理想估计等假设上进行的.在建筑项目的实际运行过程中,所有这些假设均有可能发生变化,而这些变化将可能使原定的目标受到干扰甚至不能实现,因此如何识别、分析、应对建筑项目风险成为建筑项目参与各方亟需妥善解决的问题.本文结合大型建筑工程项目的实际,提出了建筑工程项目全面风险管理的模型,并给出了可以在风险管理中运用的工具与方法.