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An Overview of Various Forensic Schedule Analysis Methods for Construction Delay Claims Including Time Impact Analysis
Forensic Schedule Analyses For Construction
Delays
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“Nowhere is the confusion between moral and legal ideas more manifest than in the law of contract…The duty to keep a contract at common law means a prediction that you must pay damages if you do not keep it – and nothing else.”
Justice Oliver Wendell HolmesThe Path of the Law, Harvard Law Review, March 25, 1897
“Although figures do not lie, liars figure.”
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Specific Delay Claims Provisions Exist
“Provide a justification of delay to the Contracting Officer in accordance with the contract provisions and clauses for approval within 10 days of a delay occurring. Also prepare a time impact analysis for each Government request for proposal (RFP) to justify time extensions.”
- UNIFIED FACILITIES GUIDE SPECIFICATIONS (USACE / NAVFAC / AFCESA / NASA)
“When changes or delays are experienced and a Notice of Direction (NOD) is executed by the Authority, the Contractor must submit a Time Impact Analysis. This analysis must include a written narrative and supporting schedule fragnet detailing the anticipated schedule impact of the change(s), if any.”
- NEW YORK CITY SCHOOL CONSTRUCTION AUTHORITY
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Delay Analysis Process
There are several industry standard methodologies used to perform time impact analyses for construction delay claims. Determining which is the best method to use is dependent on several factors.
1BASIC Method
• Retrospective
• Prospective
2SPECIFIC
Method
Observational:• Static Logic
Observation• Dynamic Logic
Observation
Modeled• Additive Modeling• Subtractive Modeling
3BASIC
Implementation
• Gross or Periodic Mode
• Contemporaneous: As-is or Contemporaneous: Split
• Modified or Recreated
• Single Base Simulation or Multi Base Simulation
4SPECIFIC
Implementation
• Fixed Periods vs. Variable/Grouped Periods
• Global (Insertion or Extraction) vs. Stepped (Insertion or Extraction)
METHOD IMPLEMENTATION
4 Steps
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The MethodologiesAn overview of the methodologies covered.
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Time Impact Analysis
The below is a snapshot of nine methodologies, commonly referred to as Time Impact Analysis, which are routinely used to evaluate construction delay claims. Following are more details on each method and the scenarios for which they are most useful.
Methodologies overview
Retrospective Observational Dynamic LogicObservation
ContemporaneousUpdates
All Periods /Grouped Periods
Method 1
Retrospective Observational Dynamic LogicObservation
Modified/Reconstructed Logic
Fixed Periods /Variable Windows
Method 2
Prospective Observational Dynamic LogicObservation
ContemporaneousUpdates
Method 3
Retrospective Modeled Addit ive Single Base Stepped CollapseMethod
4
Retrospective Modeled Addit ive Multi Base Fixed Periods Method
5
Retrospective Modeled Subtractive Single Simulation Stepped CollapseMethod
6
Retrospective Modeled Subtractive Multi Simulation Fixed Periods Method
6
Prospective Modeled Addit ive Single Base Global Insertion | Stepped Insertion
Method 8
Retrospective Modeled Subtractive Single Base Global Collapse | Stepped Collapse
Method 9
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
IMPLEMENTATION
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Retrospective or ProspectiveCan be either
• Can be performed during the project or after completion.
• Performed after the impact of the event is known
• Performed while Project is ongoing.
• Performed contemporaneously with delay event.
• Estimate of Schedule Impact due to event – not a forensic analysis
Retrospective Analysis
Prospective Analysis
VS
Depending on whether you are in the midst of construction or after the fact, when a construction delay claim is identified, analysis falls into one of two categories.
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Time Impact Analysis
This method allows for an objective evaluation of impacts to contemporaneous schedule updates without the need for “after-the-fact” modeling.
Retrospective
Observational
Dynamic LogicObservation
Uses schedule updates whose logic network may differ to varying degrees from the baseline and from each other
ContemporaneousUpdates
Uses schedule updates that were prepared contemporaneously during the project.
All Periods /Grouped Periods
All Periods: The analysis is performed for each and all contemporaneous updates. Whether the periods are of fixed or variable width is dictated by the frequency of the contemporaneous updates, not by the forensic analyst
Grouped Periods: The analysis is performed for grouped periods where each group may contain updates between two or more updates with the same planned critical path being compared for variance calculation.
Method 1
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
IMPLEMENTATION
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Time Impact Analysis
This method considers the dynamic nature of the critical path by taking into account and identifying the changes to the network logic that affect the critical path, even when contemporaneous updates do not exist.
Retrospective
Observational
Dynamic LogicObservation
Uses schedule updates whose logic network may differ to varying degrees from the baseline and from each other
Modified / Reconstructed
Logic
Modified / Reconstructed Logic:This involves extensive modification of the contemporaneous updates, or the recreation of entire updates where no contemporaneous updates exist, as in the recreated implementation.
Fixed Periods /Variable Windows
Fixed Periods: The analysis periods are of virtually identical widths (duration) and may coincide with regular schedule update periods
Variable Windows: The analysis periods are of varying widths (duration) and are characterized by their different natures such as the type of work being performed, the types of delaying influences or the operative contractual schedule under which the work was being performed.
Method 2
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
IMPLEMENTATION
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Time Impact Analysis
This method allows for an objective evaluation of impacts to contemporaneous schedule updates without the need for “what-if” modeling.
Prospective
Observational
Dynamic LogicObservation
Uses schedule updates whose logic network may differ to varying degrees from the baseline and from each other
Method 3
ContemporaneousUpdates
Uses schedule updates that were prepared contemporaneously during the project.
BASIC SPECIFIC
METHOD
BASIC
IMPLEMENTATION
Not Applicable
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
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Time Impact Analysis
This method can be quickly implemented and does not require the use of an “as-built” schedule as a base. However, this method cannot account for the impact of any concurrent delays.
Retrospective
Modeled
Additive
The additive modeling method consists of comparing a schedule with another schedule that the analyst has created by adding schedule elements (i.e. delays) to the first schedule for the purpose of modeling a certain scenario
Single Base
Single Base: Delay activities are added to a single CPM network – aka impacted as-planned
Fixed Periods /Variable Windows
Fixed Periods: The analysis periods are of virtually identical widths (duration) and may coincide with regular schedule update periods
Variable Windows: The analysis periods are of varying widths (duration) and are characterized by their different natures such as the type of work being performed, the types of delaying influences or the operative contractual schedule under which the work was being performed.
Method 4
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
IMPLEMENTATION
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Time Impact Analysis
This method can be quickly implemented and does not require the use of an “as-built” schedule as a base. However, this method cannot account for the impact of any concurrent delays.
Retrospective
Modeled
Additive
The additive modeling method consists of comparing a schedule with another schedule that the analyst has created by adding schedule elements (i.e. delays) to the first schedule for the purpose of modeling a certain scenario
Multi Base
Multi Base: Delay activities are added to multiple CPM networks – aka window analysis.
Fixed Periods
Fixed Periods: Analysis periods are fixed in date and duration by the data dates used for the contemporaneous schedule updates, usually in regular periods such as monthly. Each update period is analyzed.
Method 5
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
IMPLEMENTATION
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Time Impact Analysis
The concept of this method is easy to understand and can be implemented without the use of a baseline or updated schedules.
Retrospective
Modeled
Subtractive
The subtractive modeling method consists of comparing a CPM schedule with another schedule that the analyst has created by subtracting schedule elements (i.e. delays) from the first schedule for the purpose of modeling a certain scenario.
Single Simulation
Single Simulation: Delay activities are removed from a single CPM network
Stepped Collapse
Stepped Collapse: Delays are removed individually from a CPM network for analysis.
Method 6
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
IMPLEMENTATION
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Time Impact Analysis
This method allows for a limited quantification of any schedule mitigation and/or acceleration as well as accounting for changes in the prospective critical path of the schedule updates reviewed.
Retrospective
Modeled
Subtractive
The subtractive modeling method consists of comparing a CPM schedule with another schedule that the analyst has created by subtracting schedule elements (i.e. delays) from the first schedule for the purpose of modeling a certain scenario.
Multi Simulation
Single Simulation: Delay activities are removed from a single CPM network
Fixed Periods
Fixed Periods: Analysis periods are fixed in date and duration by the data dates used for the contemporaneous schedule updates, usually in regular periods such as monthly. Each update period is analyzed.
Method 7
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
IMPLEMENTATION
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Time Impact Analysis
This method can be quickly implemented and does not require the use of an “as-built” schedule as a base. However, this method cannot account for the impact of any concurrent delays.
Prospective
Modeled
Additive
The additive modeling method consists of comparing a schedule with another schedule that the analyst has created by adding schedule elements (i.e. delays) to the first schedule for the purpose of modeling a certain scenario.
Single Base
Single Base: Delay activities are removed from a single CPM network– aka impacted as-planned.
Global Insertion / Stepped Insertion
Global Insertion: Global InsertionDelays are inserted into a CPM Network all at once for analysis.
Stepped Insertion: Delays are inserted into a CPM Network individually for analysis.
Method 8
BASIC SPECIFIC
METHOD
BASIC SPECIFIC
IMPLEMENTATION
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Time Impact Analysis
For further information about this topic or to contact VERTEX directly, CLICK HERE.
Contact
AUTHORED BY:David M. Ponte, P.E.Division Manager – Contract Claims
The Vertex Companies400 Libbey Industrial ParkwayWeymouth, Massachusetts 02189USA
tel: +1 781.952.6012fax: +1 781.952.6060email: dponte@vertexeng.com
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1. Recommended Practice No. 29R-03 “Forensic Schedule Analysis”, AACE International, June 23, 2009
2. Recommended Practice No. 52R-06 “Time Impact Analysis – AS Applied in Construction”, AACE International, October 19, 2006
3. Zack, Jr., James G., Delay and Delay Analysis: Isn’t it Simple? 1st ICEC & IPMA Global Congress on Project Management, Ljubljana, Slovenia April 26, 2006.
Time Impact Analysis References
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