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1、反思前瞻規(guī)劃優(yōu)化施工流程 Farook Hamzeh Glenn Ballard Iris D. Tommelein 摘要 研究的問題：如何改善前瞻規(guī)劃在建設(shè)行業(yè)的做法來提高生產(chǎn)方案的可靠性？ 目的：為了評估前瞻規(guī)劃的性能，尋找一個標(biāo)準(zhǔn)化的做法，使前瞻規(guī)劃與活動執(zhí)行有緊密的聯(lián)系，來提高生產(chǎn)方案的可靠性。 研究設(shè)計/方法：本研究采用案例分析，行業(yè)訪談，和行業(yè)調(diào)查，以評估目前在北美、南美和歐洲的建設(shè)工程執(zhí)行的前瞻規(guī)劃。 研究結(jié)果：研究結(jié)果顯示存在與去年規(guī)劃系統(tǒng)規(guī)那么的不符合，前瞻規(guī)劃與標(biāo)準(zhǔn)化做法的缺乏，識別和去除限制的緩慢，而且沒有對方案失敗的分析。 關(guān)

2、鍵詞：前瞻規(guī)劃，生產(chǎn)方案，生產(chǎn)控制，精益建設(shè)，最后的規(guī)劃系統(tǒng)，規(guī)劃建設(shè)。 簡介 建筑、工程與施工是受變化問題的困擾的，即破壞工程績效和擾亂施工流程導(dǎo)致對工程時間、本錢和質(zhì)量造成的不利影響〔Hamzeh等，2007年，霍普和Spearman2021年，薩利姆等。 2006年，克萊頓1966年〕。組織使用許多種不同的方法來維持生產(chǎn)流程的一致性和屏蔽產(chǎn)量內(nèi)部業(yè)務(wù)流程以及外部環(huán)境的變化。湯普森〔1967〕著重介紹了這些方法，其中包括： ?預(yù)測 ?緩沖 ?平滑 各種預(yù)測方法是用于預(yù)測在內(nèi)部流程和生產(chǎn)原料中的變化。然而，預(yù)測不能滿足所有的變化，并且有許多限制： 越詳細(xì)的預(yù)測越不準(zhǔn)確，越遙遠(yuǎn)的預(yù)

3、測越容易出錯?！布{米亞斯2021年〕。 緩沖用于減輕同時在輸入側(cè)和輸出側(cè)的工藝變化。輸入通常需要成功執(zhí)行的任務(wù)包括：信息，先決條件工作，人力資源，空間，材料，設(shè)備，外部條件和資金〔巴拉德＆Howell公司1994年，科斯基拉2000年〕。 緩沖區(qū)可以采取的三種主要形式：時間，庫存和產(chǎn)能。時間緩沖 是分配松弛的活動，利用額外的庫存緩沖庫存以應(yīng)對供給的變化，以及用容量緩存，保存額外的容量，如加班或只在需要的時候維持機(jī)器工作，以適應(yīng)激增的負(fù)荷。 平滑的供給和需求的變化是另一種方法，組織申請由于緩沖可能的缺乏，以滿足所有的變化，是昂貴的，并可能導(dǎo)致滿荷。平滑需求的一個例子在豐田生產(chǎn)系統(tǒng)中平穩(wěn)的

4、工作負(fù)荷或平準(zhǔn)化的倡導(dǎo)〔萊克2004年〕。 雖然變化破壞了工程的績效，生產(chǎn)系統(tǒng)可以通過設(shè)計減少這種變化，并且可以通過上述提到的方法的組合來管理這種殘差。 一個生產(chǎn)系統(tǒng)可以被定義為人員和資源的集合?！怖?，機(jī)械，設(shè)備，信息〕，被安排設(shè)計和制造產(chǎn)品〔“貨物〞或“效勞〞〕的價值給客戶〔Ballard等人，2007年〕。一個生產(chǎn)系統(tǒng)的基石是生產(chǎn)管理，例如最近的一個規(guī)劃系統(tǒng)已成功實施建設(shè)工程〔2004年巴拉德和Howell〕，以提高規(guī)劃的可靠性，提高生產(chǎn)性能，在設(shè)計和施工作業(yè)中創(chuàng)立可以預(yù)測的工作流程。 在任何工程中，規(guī)劃過程中可能遇到各種問題的困擾。規(guī)劃涉及到的越遠(yuǎn)的工程可能越不準(zhǔn)確〔納米亞斯20

5、21〕。 當(dāng)規(guī)劃師把方案推向前線專家而不涉及他們的方案開展時是很難執(zhí)行??的工作日程。在一廂情愿的想法的根底上開發(fā)的短期工作方案，貿(mào)易專家沒有可靠的承諾，這種短期方案就會變得更短。如果方案失敗的原因并不在識別和處理不及時，進(jìn)一步的失敗是必然要發(fā)生的〔哈姆澤2021年〕。此外，可靠的規(guī)劃依賴于有效的約束分析與排除。約束是一個活動啟動前必須存在的先決條件〔例如，以前的工作，信息，勞動力，材料，設(shè)備，工具，空間，天氣等〕。管理約束條件可以通過識別資源沖突和提前解決這些問題幫助優(yōu)化工作方案使工作開始。如果沒有約束，是難以管理和減少工作流程不確定性的，這往往導(dǎo)致過程的變化〔蔡等，2003〕。 考慮到

6、上述挑戰(zhàn)，最后規(guī)劃系統(tǒng)主張工程規(guī)劃中的以下步驟： ?方案越詳細(xì)情，執(zhí)行工作越細(xì)致〔科恩，2006年〕 ?制定工作方案要執(zhí)行工作的人制定工作方案 ?提前識別和消除工作的限制，作為一個團(tuán)隊，做好工作準(zhǔn)備，提高工作方案的可靠性 ?在與工程參與方協(xié)調(diào)和積極談判的根底上，做出可靠的承諾和工作執(zhí)行 ?從失敗的方案中學(xué)習(xí)經(jīng)驗，找出錯誤的根源，并采取預(yù)防措施〔巴拉德，等。 2021年〕 盡管該系統(tǒng)的優(yōu)點〔阿拉爾孔和克魯茲1997年，岡薩雷斯等人，2021〕，在許多建設(shè)工程目前的做法顯示了執(zhí)行不力前瞻規(guī)劃，在較大差距長期規(guī)劃〔主階段附表〕和短期規(guī)劃〔承諾/每周的工作方案〕，降低了可靠性規(guī)劃系統(tǒng)，并能

7、夠建立先見之明。 本文提出了一種前瞻規(guī)劃實施的一種評估，為最新規(guī)劃系統(tǒng)的一個過程，其重點介紹了統(tǒng)營規(guī)劃系統(tǒng)一些缺乏之處，強(qiáng)調(diào)的前瞻規(guī)劃每周工作規(guī)劃成功的一個主要驅(qū)動力的作用，并建議進(jìn)行前瞻規(guī)劃的指導(dǎo)方針有關(guān)的活動故障，操作設(shè)計，及制約因素分析。 最新的規(guī)劃系統(tǒng) 最新規(guī)劃系統(tǒng)開發(fā)者是格倫·巴拉德和格雷格·豪威爾，其是一生產(chǎn)方案和控制建設(shè)工作的系統(tǒng)，以協(xié)助平滑的變化流，開展規(guī)劃先見之明，并減少施工作業(yè)中的不確定性。 系統(tǒng)最初是每周的工作方案水平，但很快就把處理工作流程中的變化擴(kuò)大到覆蓋整個方案和進(jìn)度開發(fā)過程中，從主調(diào)度，通過??前瞻規(guī)劃，逐步調(diào)度到達(dá)每周工作規(guī)劃中。 方案完成百分比〔PPC

8、〕是一個度量，用于跟蹤每周的工作方案水平的性能可靠性，通過測量相對于那些方案完成任務(wù)的百分比。 因此，它有助于評估的可靠性工作方案，并開始準(zhǔn)備工作，以執(zhí)行工作方案。 PPC并不是直接衡量工程的進(jìn)展，而是承諾保持在何種程度上的措施，因此在何種程度上未來的工作負(fù)載可能是可預(yù)測的。以前的研究發(fā)現(xiàn)PPC和勞動生產(chǎn)率之間的相關(guān)性〔2021年劉和巴拉德〕。 PPC上提高可能產(chǎn)生的二次沖擊工作平安和質(zhì)量需要進(jìn)一步的研究〔1998年，巴拉德和Howell Ballard等。2007〕。有研究說明，盡管在LPS的優(yōu)勢，許多企業(yè)實施系統(tǒng)時都面臨重大障礙?！睟allard等人，2007;哈姆澤，2021年維亞納等

9、〕。為建設(shè)工程的最新規(guī)劃系統(tǒng)的成功實施提出了一個框架。 然而，當(dāng)整個規(guī)劃系統(tǒng)〔主生產(chǎn)方案，階段調(diào)度，前瞻的規(guī)劃，每周工作規(guī)劃〕執(zhí)行和更新設(shè)計，PPC 工程進(jìn)展情況的指標(biāo)，PPC和進(jìn)步應(yīng)隨對方。 這可以表示為如權(quán)利要求一個復(fù)雜的假設(shè)，即： H1：如果前瞻任務(wù)是從一個階段方案結(jié)構(gòu)實現(xiàn)到工程的結(jié)束日期和中間里程碑，如果前瞻規(guī)劃是準(zhǔn)備應(yīng)該怎樣做，如果每周選擇什么，可以做什么工作方案由應(yīng)該做在臨界的順序沒有游戲的系統(tǒng)，PPC將隨工程的進(jìn)展情況而不同。 如果我們接受這個假設(shè)，那么，如果不隨PPC工程的進(jìn)展情況，在虛擬鏈的某個地方就有一個破碎的鏈接。 圖1顯示了活動打破階段的規(guī)劃系統(tǒng)〔礫石〕的過程〔

10、巖石〕，然后在四個規(guī)劃過程中的操作〔卵石〕不同的按時間跨度：主生產(chǎn)方案，階段調(diào)度，前瞻規(guī)劃和每周工作規(guī)劃。 主生產(chǎn)方案是一個前端的規(guī)劃過程中產(chǎn)生的時間表描述工作在進(jìn)行整個工程的持續(xù)時間。它涉及到工程級活動，并確定重要的里程碑日期主要集中在有關(guān)合同文件和擁有者的價值主張〔Tommelein和Ballard，1997〕。 相調(diào)度產(chǎn)生的時間表，覆蓋工程的每個階段，如地基，結(jié)構(gòu)框架，或完成。在協(xié)作規(guī)劃設(shè)置工程團(tuán)隊：〔1〕定義工程階段或里程碑，〔2〕將其分解成組成活動，〔3〕時間表向后的里程碑。合并后從不同的工程方輸入和在重要的階段識別專家和團(tuán)隊執(zhí)行之間逆相調(diào)度的平衡，從重要的階段里程碑〔哈姆澤20

11、21年，巴拉德和豪威爾2004〕。 前瞻規(guī)劃是在生產(chǎn)控制〔執(zhí)行時間表〕的第一步，通常包括一個為期6周的時間。前瞻時段隨正在執(zhí)行的工作類型和上下文的不同而不同?！怖?，因為這種現(xiàn)象的出現(xiàn)，在概念設(shè)計，任務(wù)可以不在詳細(xì)的預(yù)見水平很遠(yuǎn)的水平。在工廠停工時，前瞻期延伸到年底關(guān)機(jī)。在這項研究中，重點是正常的建設(shè)工程，并在這些4至6周的時間框架是常用的前瞻規(guī)劃〕。 在此階段，活動被分解成水平的生產(chǎn)過程/操作，約束被識別，操作的設(shè)計，和準(zhǔn)備作業(yè)就緒〔巴拉德1997年，哈姆澤2021年〕。 每周工作規(guī)劃〔WWP〕也被稱為承諾方案是最系統(tǒng)的詳細(xì)方案，展現(xiàn)了工作的各專業(yè)組織之間的相互依存，和直接驅(qū)動的生產(chǎn)過

12、程。方案在這個級別的可靠性促進(jìn)了質(zhì)量分配和可靠的承諾，使生產(chǎn)單元從上游業(yè)務(wù)中的不確定性被屏蔽。這個工作任務(wù)是一個詳細(xì)的測量完成可的方案。每個方案期結(jié)束時，作業(yè)被評論，評估它們是否是完整的，從測量規(guī)劃中的可靠性。對于不完整的任務(wù)，對方案失敗的原因進(jìn)行分析，并采取行動，這些原因是學(xué)習(xí)和持續(xù)改良的根底〔巴拉德2000年〕。 Farook Hamzeh, Glenn Ballard & Iris D. Tommelein (2021) Rethinking Lookahead Planning to Optimize Construction Workflow. Lean Constru

13、ction Journal 2021 pp 15-34 leanconstructionjournal.org Lean Construction Journal 2021 ://creativecommons.org/licenses/by-nc-nd/3.0/ 15 leanconstructionjournal.org Rethinking Lookahead Planning to Optimize Construction Workflow Farook Hamzeh1; Glenn Ballard2; Iris D. Tommelein3 A

14、bstract Research Question: How to improve lookahead planning practices in the construction industry to increase the reliability of production planning? Purpose: To assess the performance of lookahead planning, advise a standardized practice to support a strong linkage between Lookahead planning

15、and activity execution, and improve the reliability of production planning. Research Design/Method: This study employs case study analysis, industry interviews, and an industry survey to assess the current implementation of lookahead planning on construction projects in North America, South Amer

16、ica, and Europe. Findings: The study findings indicate the existence of non-compliance with Last Planner? System rules, inadequate lookahead planning and standardized practices, sluggish identification and removal of constraints, and absence of analysis for plan failures. Limitations: The author

17、s’ active role on the projects used as case studies may constitute a limitation to the research methods and tools used. The industry survey may have not covered all companies applying the Last Planner System. The suggested framework should be custom tailored to different projects to cater for siz

18、e, culture, etc. Implications: This research provides a framework for applying the Last Planner System rules during lookahead planning. It aims at increasing the success of the making activities ready, designing operations, and ultimately improving PPC. Value for practitioners: The study present

19、s to industry practitioners applying the Last Planner System a standardized framework for implementing lookahead planning on construction projects. The paper also highlights the use of two metrics to assess the performance of lookahead planning at a given point in time and to monitor performance

20、 over a period of time or between projects. Keywords: Lookahead planning, production planning, production control, lean construction, the Last Planner System, construction planning. 1 Corresponding Author- Assistant Professor, Department of Civil and Environmental Engineering, 406E Bechtel, Amer

21、ican University of Beirut, Riad El Solh, Beirut 1107 2021, Lebanon, Farook.Hamzeh@aub.edu.lb 2 Research Director, Project Production Systems Laboratory ://p2sl.berkeley.edu and Associate-Adjunct Professor, Civil and Environmental Engineering Department, 215 McLaughlin Hall, University. of Cali

22、fornia, Berkeley, CA 94720-1712,USA, ballard@ce.berkeley.edu 3 Professor, Dept. of Civil and Environmental Engineering, and Director, Project Production Systems Laboratory ://p2sl.berkeley.edu, 215-A McLaughlin Hall, University of California, Berkeley, CA 94720-1712, USA , tommelein@ce.berke

23、ley.edu Hamzeh, Ballard, & Tommelein: Rethinking Lookahead Planning to Optimize Construction Workflow Lean Construction Journal 2021 ://creativecommons.org/licenses/by-nc-nd/3.0/ page 16 leanconstructionjournal.org Paper type: Full Paper Introduction Architecture, Engineering, and Con

24、struction (AEC) processes are plagued with problems associated with variations that undermine project performance and disrupt workflow leading to detrimental impacts on project’s duration, cost, and quality (Hamzeh et al. 2007, Hopp and Spearman 2021, Salem et al. 2006, and Crichton 1966). Organi

25、zations use a number of different methods to maintain consistency in production flow and to shield production from variations in internal business processes as well as the external environment. Thompson (1967) highlighted some of these methods including: ? Forecasting ? Buffering ? Smoothing

26、Various forecasting methods are used to anticipate variations in internal processes and in inputs to production. However, forecasts cannot cater for all variations and have many limitations: the more detailed a forecast is the more off it will be, the farther a forecast looks into the future the

27、less accurate it becomes, and forecasts are always wrong (Nahmias 2021). Buffering is used to mitigate process variations on both the input and output sides. Inputs typically needed for successful execution of tasks include: information, prerequisite work, human resources, space, material, equip

28、ment, external conditions, and funds (Ballard & Howell 1994, Koskela 2000). Buffers can take on one of three main forms: time, inventory and capacity. Time buffers allocate slack to an activity, inventory buffers utilize extra stock to account for supply variations, and capacity buffers reserve

29、extra capacity such as using overtime or maintaining machinery used only when needed to accommodate surges in load. Smoothing variations in supply and demand is another method that organizations apply since buffering may not be enough to cater for all variations, is costly to apply, and may lead

30、 to complacency. An example of smoothing demand is leveling the work load or heijunka as advocated in the Toyota Production System (Liker 2004). Although variation undermines project performance, production systems can be designed to reduce them and to manage residuals utilizing a combination of

31、the above mentioned methods. A production system can be defined as a collection of people and resources (e.g., machinery, equipment, information) arranged to design and make a product (“goods〞 or “services〞) of value to customers (Ballard et al. 2007). A cornerstone of a production system is pr

32、oduction management such as the Last Planner System, which has been successfully implemented on construction projects (Ballard and Howell 2004) to increase the reliability of planning, improve production performance, and create predictable workflow in design and construction operations. On any p

33、roject, the planning process can be plagued by various problems. Planning involves forecasts that can be inaccurate the further they project into the future (Nahmias Hamzeh, Ballard, & Tommelein: Rethinking Lookahead Planning to Optimize Construction Workflow Lean Construction Journal 2021 :

34、//creativecommons.org/licenses/by-nc-nd/3.0/ page 17 leanconstructionjournal.org 2021). It is hard to execute work schedules when Planners push plans to frontline specialists without involving them in plan development. Short-term work plans developed on the basis of wishful thinking and in a

35、bsence of reliable promises from trade experts are more likely to fall short during execution. And if causes of plan failures are not identified and dealt with in a timely fashion, further failures are bound to happen (Hamzeh 2021). Moreover, reliable planning depends on effective constraint anal

36、ysis and removal. Constraints are those prerequisites required to be present before an activity can start (e.g., previous work, information, labor, material, equipment, tools, space, weather, etc.). Managing constraints can help optimize work plans by identifying resource conflicts and resolving

37、them prior to work start. Without constraint removal, it is hard to manage and reduce work flow uncertainties that often cause process variations (Chua et al. 2003). Taking into account the challenges mentioned above, the Last Planner System advocates the following steps in project planning: ?

38、Plan in greater detail as you get closer to performing the work (Cohn 2006) ? Develop the work plan with those who are going to perform the work ? Identify and remove work constraints ahead of time as a team to make work ready and increase reliability of work plans ? Make reliable promises and d

39、rive work execution based on coordination and active negotiation with project participants ? Learn from plan failures by finding root causes and taking preventive actions (Ballard, et al. 2021) Despite the advantages of this system (Alarcón and Cruz 1997, Gonzalez et al. 2021), the current prac

40、tice on many construction projects shows a poor implementation of lookahead planning resulting in a wide gap between long-term planning (master and phase schedules) and short-term planning (commitment/weekly work plans) reducing the reliability of the planning system and the ability to establish

41、foresight. This paper presents an assessment of lookahead planning implementation as one process in the Last Planner System, highlights some inadequacies in operating the planning system, emphasizes the role of lookahead planning as a prime driver to the success of weekly work planning, and sugg

42、ests guidelines for performing lookahead planning pertaining to activity breakdown, operation design, and constraint analysis. The Last Planner System The Last Planner System as developed by Glenn Ballard and Greg Howell is a system for production planning and control used to assist in smoothing

43、 variations in construction work flow, developing planning foresight, and reducing uncertainty in construction operations. The system originally tackled variations in workflow at the weekly work plan level but soon expanded to cover the full planning and schedule development process from master

44、scheduling to phase scheduling through lookahead planning to reach weekly work planning. Percent Plan Complete (PPC) is a metric used to track the performance of reliable promising at the weekly work plan level by measuring the percentage of tasks completed relative to those planned. It thus help

45、s assess the reliability of work plans and initiates Hamzeh, Ballard, & Tommelein: Rethinking Lookahead Planning to Optimize Construction Workflow Lean Construction Journal 2021 ://creativecommons.org/licenses/by-nc-nd/3.0/ page 18 leanconstructionjournal.org preparations to perform wor

46、k as planned. PPC is not a direct measure of project progress, but rather a measure of the extent to which promises are kept, and hence the extent to which future work load may be predictable. Previous research has found a correlation between PPC and labor productivity (Liu and Ballard 2021). Pos

47、sible secondary impacts of PPC on improving work safety and quality require further research (Ballard and Howell 1998, Ballard et al. 2007). Despite the advantages of the LPS, research has shown that many organizations face significant hurdles when implementing the system (Ballard et al. 2007; Ha

48、mzeh, 2021; Viana et al. 2021). Hamzeh (2021) presented a framework for successful implementation of the Last Planner System on construction projects. However, when the entire Last Planner System (master scheduling, phase scheduling, lookahead planning, and weekly work planning) is executed and

49、updated as designed, PPC should be an indicator of project progress; i.e., PPC and progress should vary with each other. This claim can be expressed as a complex hypothesis; namely: H1: If lookahead tasks are drawn from a phase schedule structured to achieve the project end date and intermediate

50、 milestones, and if lookahead planning makes ready what SHOULD be done, and if weekly work plans are formed from what CAN be done selected from what SHOULD be done in the order of criticality without gaming the system, PPC will vary with project progress. If we accept this hypothesis as an assu

51、mption, it follows that if PPC does not vary with project progress, there is a broken link somewhere in the hypothesized chain. Figure 1 shows the Last Planner System where activities are broken down from phases (boulders) to processes (rocks) then to operations (pebbles) across four planning pro

52、cesses with different chronological spans: master scheduling, phase scheduling, lookahead planning, and weekly work planning. Master scheduling is a front-end planning process that produces a schedule describing work to be carried out over the entire duration of a project. It involves project-le

53、vel activities and identifies major milestone dates mostly in relation to contract documents and the owner’s value proposition (Tommelein and Ballard 1997). Phase scheduling generates a schedule covering each project phase such as foundations, structural frame, or finishing. In a collaborative p

54、lanning setup the project team: (1) defines a project phase or milestone, (2) breaks it down into constituent activities, and (3) schedules activities backward from the milestone. After incorporating input from different project parties and identifying hand-offs between specialists, the team perf

55、orms reverse phase scheduling back from important phase milestones (Hamzeh 2021, Ballard and Howell 2004). Lookahead planning is the first step in production control (executing schedules) and usually covers a six week time frame. Lookahead time periods vary with the type of work being performed

56、 and the context. (For example, in conceptual design, tasks cannot be foreseen at a detailed level very far in advance because of the phenomenon of emergence. In plant shutdowns, the lookahead period extends to the end of the shutdown. In this research, the focus is on normal construction project

57、s, and on those 4 to 6 week time frames are commonly used in lookahead planning). At this stage, activities are broken down into the Hamzeh, Ballard, & Tommelein: Rethinking Lookahead Planning to Optimize Construction Workflow Lean Construction Journal 2021 ://creativecommons.org/licenses/by

58、-nc-nd/3.0/ page 19 leanconstructionjournal.org level of production processes/operations, constraints are identified, operations are designed, and assignments are made ready (Ballard 1997, Hamzeh 2021). Weekly work planning (WWP) also known as commitment planning represents the most detaile

59、d plan in the system, shows interdependence between the works of various specialist organizations, and directly drives the production process. Plan reliability at this level is promoted by making quality assignments and reliable promises so that the production unit will be shielded from uncertain

60、ty in upstream operations. The work assignment is a detailed measurable commitment of completion. At the end of each plan period, assignments are reviewed to assess whether they are complete or not, thus measuring the reliability of the planning. For incomplete assignments, analyzing the reasons

61、for plan failures and acting on these reasons is the basis of learning and continuous improvement (Ballard 2000). Figure 1: Planning processes in the Last Planner System. The Last Planner System relates to deliberative and situated action planning as described by Senior (2007) combining aspects

62、of both worlds. On one hand, deliberative planning takes place at the master and phase scheduling level where a premeditated course of action is specified in setting milestones and identifying handoffs. On the other hand, the lookahead and weekly work plans are closer to the situated planning mod

63、el where plans take Hamzeh, Ballard, & Tommelein: Rethinking Lookahead Planning to Optimize Construction Workflow Lean Construction Journal 2021 ://creativecommons.org/licenses/by-nc-nd/3.0/ page 20 leanconstructionjournal.org into account changes in the environment affecting inputs and

64、 outputs of construction activities. However, a question remains unanswered: how can the AEC industry advance the implementation of the lookahead planning within the Last Planner System to improve construction workflow and the reliability of planning? Accordingly, this paper reports an assessme

65、nt of the current implementation of the Last Planner System in construction, presents analytical data, highlights concerns with the current practice, and lays out recommended procedures to perform lookahead planning aiming at producing more reliable production plans. Methodology This paper summ

66、arizes research conducted to study the role of lookahead planning within the Last Planner System in improving construction workflow and increasing the reliability of planning. Research involves results from two construction projects and preliminary results from a survey addressing Last Planner implementation (Hamzeh 2021). Case study research was the methodology adopted in this study because: 1. It is appropriate for answering questions pertaining to ‘how’ and ‘why’ when no control for beh