An innovative approach for generation of a time location plan in road construction projects

Existing linear scheduling methods for earthwork activities lack accurate scheduling locations in road construction projects. Project planners and construction managers largely depend on subjective decisions for the allocation of resources at correct locations. This has caused uncertainties in planning and scheduling, and consequently delays and cost overruns of projects. Accurate information of working locations is vital for efficient resource planning, scheduling and equipment mobilisation. A theoretical framework for a virtual construction prototype model is developed using the theory of location‐based planning and this is used as the basis of sensitivity analysis to identify critical factors affecting road construction. An arithmetic algorithm is developed by incorporating road design data, sectional quantities, variable productivity data, unit cost, site access points and haulage distance. The model generates a time location plan automatically with the aim to provide location‐based scheduling information of earthwork activities. Weekly progress profiles, terrain surfaces, cost profiles and S‐curve are the other outputs of the model. Data and information collected from the case studies are used to demonstrate functionalities of the model. Critical factors controlling the productivity of earthwork activities such as different types of equipment, soil characteristics and site access points were used to display the sensitivity effect by means of ‘what‐if scenarios’. The model is a valuable tool in analysing impacts of different factors associated with productivity data and resource planning from location aspects in the earthwork construction projects.     

多维作业空间下的装配式建筑工程资源调度

装配式建筑促进传统建造方式向现代工业化建造方式的转变,但其现场装配、构件生产、运输物流等多维作业空间的异地域与非同步特点,常导致建造资源调度性质各异、相互牵制,并成为其推广应用的重要瓶颈问题。该文以装配式建筑工程为对象,深入分析其建造方式的特性,研究其建造过程中分布于各作业空间的建造资源协同机理|在多空间信息共享前提下,以人工、设备等建造资源协调配置为核心,提出基于时间轴多维作业调度空间降维处理技术、信息共享下多维作业空间资源调度协同技术、现场装配作业空间最优资源线确定技术|建立了装配式建筑工程资源调度方法并进行实证分析。结果表明,该调度方法能有效确定各作业空间的排产进度计划并提供额外决策支持信息。     

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.     

Resource Leveling in Line‐of‐Balance Scheduling

Resource leveling involves minimizing resource fluctuations without changing the completion time of a project. A smooth distribution of resources minimizes logistical problems and results in cost savings. Line‐of‐balance (LOB) is a resource‐based scheduling system that is used in projects that exhibit repetitive characteristics, performs resource allocation as a matter of course, but does not deal with resource leveling. In the past, researchers experienced declines in productivity whenever they leveled resources in different linear scheduling models by adjusting activities’ production rates. The objective of this research is to develop a genetic algorithm‐based resource leveling model for LOB schedules that does not impact productivity negatively. This model is based on the “natural rhythm” principle, according to which a crew of optimum size will be able to complete an activity in the most productive way. The “natural rhythm” principle allows shifting the start time of an activity at different units by adjusting the number of crews without changing the duration of the activity in any one unit and without violating the precedence relationships between activities. An LOB schedule is established for a pipeline project and is used to illustrate the proposed resource leveling model. It was observed that the model provides a smoother resource utilization histogram. Performing resource leveling in LOB scheduling without sacrificing productivity is the major contribution of the proposed model.     

现场施工组织设计优化要点

介绍了现场施工组织的定义,从人员优化、方案优化、进度计划优化、管理技术优化等方面综合论述了现场施工组织设计优化的要点,以满足新型施工组织设计科学指导施工活动、提高生产效率、降低资源能耗,保证工程质量与安全的新要求。     

Resource scheduling and planning for tunneling with a new resource model of the Decision Aids for Tunneling (DAT)

Resource scheduling and planning are the strategies required to determine the sequence of activities and resource allocation during tunnel construction. Resource scheduling and planning have been implemented in a new resource model of the Decision Aids for Tunneling (DAT), which are a computer based tool used to simulate tunnel construction. Tunneling plans obtained with the new resource model of the DAT take into account the technical precedence of activities, the resource/space availability, the dynamic status of the process, and the work continuity. In particular, the new resource model of the DAT can provide the optimal tunneling plan, which produces the shortest construction time and the smallest construction cost, and satisfies the special characteristics of tunnel construction such as excavation methods, distance requirements between the headings, and preempting activities (e.g., blasting).The paper attempts to contribute to both theory and practice: Optimization of the construction process considering time, cost and resources is particularly complicated in tunneling where activities and resource availability have to be appropriately sequenced and interference has to be avoided. The paper addresses this fundamental problem with the development of different schematic tunneling plans that consider the relevant activities and optimizes them with regard to overall cost and time, also considering uncertainties. Equally important is to make the theoretical development practically useable. This is done through implementation of the resource optimization in the DAT and, very importantly, by demonstrating the practical use with an application to a real tunnel case.     

Framework for an intelligent earthwork system: Part II. Task identification/scheduling and resource allocation methodology

This paper is focused on developing (1) automated task identification and scheduling method and (2) resource allocation method for intelligent earthwork system (IES) described in Part I. The task identification and planning in IES involve the translation of input data to tasks for earthwork operations and explanation of what will happen with the scheduled time zone, where it will happen, and how it will happen. After scheduling earthwork tasks, the available resources, which refer to construction equipment, are allocated for task execution. Resource allocation is essential to achieve successful earthwork operations and is carried out using the resource allocation policy, which is based on the contract net algorithm proposed by Smith and Davis.     

4D dynamic construction management and visualization software: 1. Development

With the increasing complexity of modern construction projects, there is a pressing need on higher degree of assistance from computer in order to accomplish effective planning and management. This paper delineates the previous development and implementation of a prototype four-dimensional site management model (4DSMM), with the objectives to address the requirement for linking scheduling data to a three-dimensional computer graphics building model and to furnish the capability for planners to view graphic simulations of the construction process at any prospective specified date. Through the development and various real site trials in these few years, this prototype model extends 4D technology into areas of resource management and site space utilization, in addition to planning of building construction solely. In this study, a new information system platform, graphics for construction and site utilization (GCPSU), has been developed to implement the model 4DSMM. The characteristics of the prototype system, including the integration of dynamic resource management at the project level and decision-making support, and the underlying techniques, employed in the model to facilitate and tailor the construction management practice, are presented.     

A simulation-based method for effective workface planning of industrial construction projects

The generation of well-defined and moderately sized field installation work packages for the construction workforce, referred to as workface planning, has been recently employed to plan large-scale industrial construction projects under tight schedules. However, traditional CPM-based scheduling of several thousand work packages (e.g. 5000 activities multiply by 10 work packages per activity on average) is a tedious, error prone process. Defining proper logics and controlling congestion among work packages crossing several work areas, and also effective resource allocation over time are other major challenges in workface planning. This paper presents a novel simulation-based framework to implement workface planning for large-scale industrial construction projects. This framework proposes a time-stepped discrete event simulation-based modelling for dynamic resource allocation based on congestion and other constraints on the job site. The proposed method is demonstrated and tested against traditional CPM-based solutions based on an actual case study.     

Integrating resource production and construction using BIM

This paper presents the outcomes of a research and development project carried out at the University of Maribor, Construction IT Centre, with regard to the introduction of a building information model (BIM) and a model based construction process into the operational environment of a construction company. The initiative for the project came from the industry and was performed as a joined effort of the research organization and the construction company. Work was performed in the scope of an industrialized construction environment, with the main aim to integrate mass production prefabrication processes with construction site activities. BIM was used as a link between an enterprise resource planning (ERP) information system that supports manufacturing process and construction object related information, mainly handled by CAD tools. The benefits of this link are presented with regard to project progress monitoring and material flow management.     

Simulation-based methodology for project scheduling

This paper describes a discrete-event simulation that incorporates the critical path method (CPM) in generating comprehensive information for construction project scheduling or planning. An activity-based graphical model able to consider complexities in construction, for example, unbalanced logical dependencies, unbalanced resource involvements and repetitive activity operation is proposed. An activity scanning (AS)-based forward pass algorithm for early-time information and a backward search algorithm for late-time information are developed. The simulation results that include both resource utilization statistics and late-time information (i.e. latest start or finish time and total float (TF)) of every activity for each cycle of operation cannot be easily achieved through traditional simulation or CPM. Illustrations demonstrate the advantages of the activity-based graphical model and the impacts of resource allocation policies on the schedule. The proposed methodology aims at widening the application of construction simulation by providing float time information and enhanced modelling capability.     

The determinants of the vertical boundaries of the construction firm: comment

A method is presented for allocating resources to construction activities and for scheduling construction projects under resource constraints by considering the effects that such resource limitations may have on the tendency of the activities (and the project in general) to fall into disarray and behind schedule. Resource‐constrained scheduling problems (RCSP) are very common in real‐life construction projects and because of their nature their numerical solution is computationally intensive. The method utilizes a measure of each activity's perceived level of disorder stemming from resource limitations. The proposed technique aims to optimize the number of resources assigned to the activities and to schedule the project so as to minimize the overall project's tendency to fall into disorder. The entropy‐like metric used in the scheduling optimization is related to the ratio of required over‐assigned resource units per activity, and its utilization allows a planner to take into consideration project disorder when planning a project. A case study and its mathematical framework help demonstrate the ‘duration vs. disorder’ trade‐off analysis that planners should perform when considering possible activity resource assignments and the feasibility of these assignments in terms of induced disorder. The entropy optimization method proves to be a powerful project‐planning metric.     

Modelling financial decisions in construction firms

Some contractors predict their corporate cash flow on the basis of individual contracts without considering the relationships between the overall before-tax profit, risks, other crucial qualitative factors, or the allocation of resources within the company. Moreover, some contractors, in predicting their cash flow, focus only on the early-start progress in the project and their predictions of progress are too pessimistic, or result in the overuse of resource in order to make up for delays. In the present research a decision model is established for a contracting firm. It provides a methodical system for construction financial decision-making, and a way of solving a financial decision problem under qualitative and fuzzy circumstances. The model can be applied to the management of corporate cash flow, thereby facilitating the minimal use of resources. The information provided by the model allows the planner to eliminate excess use or idleness of resources during the scheduling of a project. Financial forecasting may also suggest the best time to invest in a new project. Four projects for a medium size construction firm in Hong Kong were employed as case studies in order to evaluate the mathematical model. The cases involve two objectives: maximize profit margin and minimize construction risk (consider in a qualitative factor). The model leads to a compromise optimal schedule that provides the contracting firm with the optimal schedule for achieving optimal profit and construction risk by making optimal use of the contractor's resources.     

Construction resource/method factors influencing productivity for high rise concrete construction

Research among European countries had confirmed variance in productivity rates ascribed by construction planning engineers for identical operations. Similar differences in planned construction resource/method factors also had been identified. It is hypothesized that such variance may be due to differences in contractor preference, resulting from socio-economic and corporate objective impacts. Analysis of variance and correlation tests are used to examine this hypothesis on data obtained from French, German and UK contractors. Numerous construction resource/method factors are tested for their impact on mean productivity rates for principal high rise in situ concrete construction operations. Significant productivity rate variations are identified for reinforcement fixing and formwork erection, while variance in concrete placing productivity rates are not found to be dependent upon construction resource/method factors. Contractors seeking to improve productivity might wish to consider solutions for construction resource/method decisions that have been found herein to be related to higher productivity rates and (in some cases) lower costs.     

A genetic-algorithm-based resource-constrained construction scheduling system

Resources for construction activities are limited in the real construction world. To avoid waste and shortage of resources on a construction jobsite, scheduling must include resource allocation. A new resourceconstrained construction scheduling system is proposed in this paper. A GA-based searching technique is adopted in the system. In this paper, new GA crossover and mutation operators, UX3 and UM3, are presented. These new operators overcome the drawback of traditional GA operators for sequencing problems. The system effectively can provide the optimal combination of construction duration, resource quantities and minimum project duration under the constraint of limited resources.     

VR-based planning of construction site activities

This paper presents an approach to the integration of site-related activities into the planning and scheduling of the entire construction project. The paper starts by briefly reviewing some common methods used by construction firms in the planning and scheduling of site activities. Next follows a discussion of current research efforts concerned with the modelling of site-related procedures. Then a virtual-reality-based model is proposed, which uses both knowledge-based simulation of the work progress and visualisation capabilities, to achieve the desired integration. Finally the prototype system is described and its potential is demonstrated through several examples.     

Virtual experiment of innovative construction operations

The planning of construction operations is a complicated activity involving abstraction of construction activities from the drawings, choosing of suitable plants and falseworks, allocation of resources on site, planning of safe working place for labourers, and the scheduling of activities sequence. The increasing competition among contractors demands them to adopt innovative construction methods, which have not been used or tested previously. It is not until the beginning of actual construction that the construction planner can realize the validity of his construction operations planning. The lack of tools for the construction planner to evaluate and validate his planning can result in incorrect construction plans, which cause a lot of rework in the construction phase. Virtual Reality (VR) technology, on the other hand, is very likely to provide a solution to the above problem. VR system generates virtual environment containing objects with real world properties and allows user/planner to interact with the objects. This paper proposes an integrated VR system that generates near to reality construction environment for the construction planner to perform construction activities in a real world manner in order to plan, evaluate and validate the construction operations.     

Proximity hazard indicator for workers-on-foot near miss interactions with construction equipment and geo-referenced hazard areas

Despite the many existing best practices in safety, the construction industry lacks automated safety monitoring and analysis of task-level construction operations. Data to workforce, equipment, and the overall site safety performance are currently observed, measured, and evaluated almost always manually. Such resulting performance information is likely assessed infrequently and due to subjective human interpretation or error. Research in lagging and leading safety indicators shows further that safety knowledge is hardly ever shared among relevant project stakeholders in time to prevent accidents. Since a large number of all construction fatalities are related to struck-by events – for example, workers-on-foot being too close to construction equipment and to other restricted or geo-referenced hazard areas – a novel framework around real-time location tracking technology was designed and tested to collect and study near miss data. The objectives of this article are to automatically identify the areas of static and dynamic hazards on a construction site and to automatically gather and analyze the spatial–temporal conflicts between workers-on-foot and the identified hazards. Automated conversion of raw sensor location data collected to the operation of workers, equipment, and geo-referenced hazard areas into meaningful proximity-related safety information is introduced. Field experiments validate the research based on an a priori created safe site layout information model. Results are in particular useful for practitioners or researchers who would like to enhance their quantitative and visual understanding of operational construction resource activity monitoring and analysis, and in the specific domain of detecting and mapping spatial–temporal proximity relationships of near miss events. Applications of the resulting knowledge are explained in the context of empowering construction safety engineers, managers, and the workforce by enhancing decision making in safe site layout design and planning and providing additional interactive tools in safety education and training.     

高速铁路大量应用连续梁桥的施工管理和技术对策

连续梁(刚构)桥施工技术已经成熟,但大量的连续梁(刚构)桥集中施工时,受工期安排和资源调配的约束,和单一桥梁的施工有着本质的不同。结合杭甬、杭长2个标段100多处连续梁(刚构)桥的施工,从地基处理、合拢施工、跨线防护、管线干扰等方面所采取的不同于单一桥梁施工的管理和技术对策。     

Implementation of visualization as planning and scheduling tool in construction

During the last decade, extensive research efforts have been made on the development of four-dimensional (4D) models (space + time) which integrate computer graphics of three-dimensional geometrical models to scheduling data with a view to generating graphic visualization of construction processes for planning and decision making purposes. Nevertheless, these 4D applications to construction planning are often limited to the component level of a building. Their major drawback is the lack of pragmatic site management features, such as analysis of resource requirements for individual construction activity, generation of site facility layouts, quantification of construction materials and cost evaluation over a specified time period. The objective of this study on 4D graphics for construction planning and site utilization (acronym 4D-GCPSU) is mainly to furnish a solution to the aforementioned problem. In this paper, our works on 4D model in a broader site management context aiming to assist planners to deal with day to day activities are delineated. The prospective requirements for 4D application to support practical use on site management are also highlighted.