*Article* **Application Issues of Impacted As-Planned Schedule for Delay Analysis**

**Kyong Ju Kim 1, Bonghee Han 2,\*, Min Seo Park 1, Kyoungmin Kim <sup>3</sup> and Eu Wang Kim <sup>1</sup>**


**Abstract:** Most construction projects are delayed, and many are subject to claims or disputes. Therefore, delay analysis is a critical component of any construction project to determine who is responsible for delays. This research examines four different techniques for estimating delay impacts using the impacted as-planned (IAP) method. A sample network was introduced as an example to discuss several concerns. The advantages and limitations of each approach were identified, and recommendations were given for each approach. When inserting an activity or activities representing delay events in IAP, it is necessary to use both constraints and logical relations among delay events, their logical predecessors, and successors. Constraints representing the actual date of delay events are the simplest and easiest. However, constraints should not be used in "single insertion" and "inserting only owner- or contractor-caused delay" approach. In addition, in the case of using constraints, it is critical to ensure that the impact of delay events is less than the duration of those delay events. Constraints should be avoided in this scenario, and delay events should be logically connected to their logical predecessors and successors without constraints. This study also identified through an example that inserting delay events only by logic can cause wrong analysis results. The results of this study will be helpful for delay analysts in identifying what kinds of problems occur in IAP methods and how to prevent those problems.

**Keywords:** delay analysis; delay impact; impacted as-planned; claims; dispute resolution
