建设项目管理的研究长期聚焦在正式的合同和组织管理层面。对动态非正式沟通和决策的研究，尤其是Time Buffer的形成机制及社会性对其影响，在国内外基本处于空白。Time Buffer是计划的任务时间和在最有利情况下最短完成任务所需时间的差值。它在施工计划中普遍存在，层层叠加,导致浪费，延误工期。我们提出的研究目标为1）测量Time Buffer出现频度和程度,并跟踪其原因；2）用Structural Equation Modeling方法确认并建立Time Buffer产生机制模型；3）建立动态的以Specialty Trade为单位的Social Network; 4)从Social Network的中心度和可信度的角度分析社会性与Time Buffer的相互影响。研究结果将有助于项目管理者策略性地减少和分配Time Buffer，在不增加成本的前提下，有效地提高劳动生产率，缩短工期。

In the past decades, construction engineering management research has focused on the formal contract management or organizational level management. Little quantitative research effort was devoted in the informal and dynamic decision process at site management level, especially in the field of the factors causing Time Buffer in task duration estimation or the mechanism of Time Buffer estimation and allocation, which causes low productivity and schedule overrun. This research proposes to investigate the Time Buffer estimation and allocation mechanism from a special and unique perspective, Social Network. The research objectives are: 1) quantitatively measure the frequency and severity of Time Buffer and track the causes; 2) using Structural Equation Method to identify the forming mechanism; 3) build dynamic Social Network based on production data; and 4) explore the relationship between Time Buffer and Social Network Centrality and Norm. The result will not only fill in the gap of knowledge in the field of Time Buffer study, it will also be able to help project managers effectively reduce Time Buffer and strategically allocate it where needed most. It will also aid contractors to address the problems of shortage of skilled labors, increased labor cost, and extended project duration, which will have significant impact in the construction industry planning practice nationally and internationally.