SCHEDULE DELAY ANALYSIS

Schedule Delay Analysis



Abstract

Assessing schedule delay's impact on total project duration to distribute delay liability remains a controversy. None of existing delay analysis methods is perfect because including an element of assumptions, subjective assessment and theoretical projection. Windows-based delay analysis methods are excellent in identifying and measuring construction schedule delays. Based on a previous study identifying potential problems in available windows-based delay analysis methods, this study proposes an innovative windows-based delay analysis method, called the effect-based delay analysis method (the EDAM method). The EDAM method performs delay analysis using extracted windows and determines delay impacts by considering the effects of delays on the critical path(s). According to its application to hypothetical cases and comparisons with other methods, the EDAM method is efficient in delay analysis and effective in solving concurrent delays and determining schedule shortened. The proposed EDAM method is a good alternative for schedule delay analysis for construction projects.

Table of Contents

Abstract1

1. Introduction3

2. Available windows-based delay analysis methods4

3. Problems in windows-based delay analysis methods5

3.1. Unable to identify critical path changes5

3.2. Incapable of dealing with complicated delay situations5

3.3. Inefficient delay analysis5

3.4. Unclear liability allocation6

4. Methodology development7

4.1. Innovative concept7

4.2. Analytical procedures8

4.3. Baseline schedule development approach10

4.4. Approach for determining analysis timing10

4.5. Algorithms for liability identification and calculation10

5. Hypothetical Case Study13

5.1. Case description13

5.2. Summary analytical procedures15

5.3. Final results16

6. Discussion19

6.1. Efficiency for delay analysis19

6.2. Ability to identify critical path changes19

6.3. Ability to deal with concurrent delays and project acceleration20

6.4. Liability allocation approach22

6.5. Comparison to other windows-based delay analysis methods22

6.6. Advantages and limitations23

7. Conclusions23

References26

Schedule Delay Analysis

1. Introduction

Construction projects generally have highly complicated situations during execution, involve many project stakeholders and interfaces, and are influenced by many external factors. Therefore, schedule delays in construction projects are common and affect total project duration in unpredictable ways. Delay information and evidence are usually recorded and represented in different records, documents and schedules during the construction phase. Selecting a suitable delay analysis method and analyzing delay information accurately are essential tasks in any delayed construction project. Current delay analysis methods analyze delay liabilities based on delay information and evidence. Various analysis methods have been developed, such as global impact, as-planned, impacted as-planned, net impact, time impact, collapsing, isolated delay type, snapshot, window analysis and isolated collapsed but-for ( [Bordoli and Baldwin, 1998], [Gothand, 2003], [Hegazy and Zhang, 2005], [Kim et al., 2005], [Mbabazi et al., 2005], [Ng et al., 2004], [Yang and Yin, 2009] and [Zack, 2001]). Farrow (2007) had clearly claimed that none of the delay analysis methodologies is perfect because they all include an element of assumptions, subjective assessment, and theoretical projection.

Generally, a delay analysis method attempts to discover delay information derived from as-planned and as-built schedules, those are the bases for resolving delay disputes and claims. However, existing delay analysis methods still have the following shortcomings: (1) concurrent delays cannot be recognized or calculated by some of existing methods; (2) the critical path method cannot be executed in analysis and critical path changes cannot be considered; (3) the relative cost of float consumption is not considered; (4) analysis ...