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Preconstruction
Published in Len Holm, John E. Schaufelberger, Construction Cost Estimating, 2021
Len Holm, John E. Schaufelberger
One important contribution contractors make during the preconstruction phase is to review progress drawings from the design team and comment and make suggestions regarding their ‘constructability’. This is not to say that the design team’s documents are not constructible, but rather, can they become more constructible or easier to build? Constructability analysis involves reviewing the proposed design for its impact on the cost and ease of construction. These proposals are often as simple as changing a welded structural steel connection to bolted, which can be assembled in the field faster and safer, or having steel gusset plates welded on to the columns in the fabrication shop rather than in the field, which is also safer and ensures better quality control. An example with wood framing is to change dimensional lumber to engineered lumber, which will be straighter and not shrink. A popular change with wood-framed mixed-use development apartment buildings today is to have the wall and floor systems ‘panelized’ and built in a fabrication shop, which improves quality and enhances the schedule. These prefab panels are then flown in with a tower crane and connected with fewer field connections. Many of these types of changes save cost but not all. Some constructability changes may actually increase cost, but improve the schedule, quality, safety, energy efficiency, and/or long-term building maintainability.
An Overview of Constructability Practices
Published in Sharmin Khan, Constructability, 2018
Various researchers have focused on the concept of constructability, after its worldwide importance was recognized. Glavinich (1995) describes constructability of a design as “the ease with which the raw materials of the construction process (labour, production, equipment, tools, materials and installed equipment) can be brought together by a builder to complete the project in a timely and economic manner.” Fischer and Tatum (1997) have quoted in their paper the definitions of Buildability and Constructability according to the United Kingdom. Buildability is defined as “the extent to which the design of building facilitates ease of construction, subject to overall requirement for the completed building.” U.K. definition for Constructability is “it is the extent to which the design of building facilitates ease of construction, subject to the requirements of construction methods.” Buildability focusses on design whereas constructability takes into consideration both, the design and management issues. Constructability incorporates project management systems in the construction project and the benefits are perceptible when constructability is introduced at an early stage (Wong et al., 2006).
BIM & Engineering 9
Published in Jonathan Ingram, Understanding BIM, 2020
BIM is now used for infrastructure design around the world. It brings efficiency to the production of integrated and complete design documentation, allowing multiple alternatives to be considered. The refinement and the production of coordinated construction documents is achieved more rapidly. Projects are shorter together with more predictable construction timetables. Other benefits include integrated project planning and improvements in highway and road design from visualization, simulation and analysis. Designing for constructability helps reduce these issues and can significantly reduce construction costs.
Influence of briefing clarity on construction projects: a fuzzy hybrid simulation approach
Published in Construction Management and Economics, 2022
Ali Vahabi, Farnad Nasirzadeh, Anthony Mills
Clearly defining the project brief also assists designers/builders to thoroughly understand the real project requirements. This impacts the quality of their design solution proposals, which eventually improves the design constructability in construction projects. The high quality of design solutions improves the constructability of the project design, which can accelerate the construction process and ultimately decrease the project duration. The P3 arrows in Figure 3 show this process. However, clearly defining the project brief requires clients to spend more time and effort during briefing. This increases the required time and budget for the briefing process, which consequently increases the project cost and duration. The N4 and N5 arrows in Figure 3 show these two causal relationships, respectively.
Benchmarking project performance: a guideline for assessing vulnerability of mechanical and electrical projects to productivity loss
Published in Construction Management and Economics, 2019
Awad S. Hanna, Karim A. Iskandar, Wafik Lotfallah
The RPL score has several practical uses. First, RPL can be used to track the performance of projects and provide warning signs. Contractors can set a goal/threshold for a project so that the RPL does not exceed 30% (i.e. the approximate average value for unimpacted projects) at any point in the project timeline. If the RPL exceeds 30%, this is a warning sign. The factor(s) contributing to this high value can then be identified. For example, if the project is overmanned (ratio to peak to average manpower >1.6), contractors can adjust their manpower loading requirement, level their resources, and shift some of the non-critical field activities in order get back on track and reduce RPL below 30%. The factors included in the RPL score can be forecasted from a similar previous project and a redline can be set for a new project. It should be noted that owners/owner representatives and engineers also play a role in contractors achieving their RPL threshold/goal. They should adequately define the scope of their projects through early constructability reviews in order to decrease the amount of change and variations during construction. Expeditious change order approval process and faster responses to Requests for Information (RFIs) should be also ensured throughout the course of the project.
Unpacking the ambiguity of rework in construction: making sense of the literature
Published in Civil Engineering and Environmental Systems, 2018
While an array of strategies, techniques and tools are available to mitigate rework seldom are they integrated and appropriately implemented. Improving constructability is a robust strategy for reducing errors as it focuses on the ease and efficiency with which structures can be built. In part, constructability reflects the quality of the design documents. If the design documents are difficult to understand and interpret, the project will be difficult to build. Seldom, however, is construction knowledge wholly integrated and relied upon during the design process, even when non-traditional procurement methods are utilised. Furthermore, design audits and reviews of documentation can iron-out design issues and ensure redundant items are identified prior to construction. While this is the responsibility of designers, such practices tend to be undertaken on a piecemeal basis and whether they can be accommodated within the competitive fees that are charged is another matter. Design practices that can be used to reduce and contain rework cost by constructors are disregarded as they have a cost associated with them. Designers rarely take responsibility for their errors, and once works commence on-site there is a perception that if they are identified they become the contractor’s problem (Love, Smith, et al. 2018).