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An Introduction Into Understanding Time Impact Analysis for Construction Delays

Time Impact Analysis

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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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The Importance of Knowing Time Impact Analysis for Construction Delays

“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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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


Method 3

Retrospective Modeled Addit ive Single Base Stepped InsertionMethod

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

7

Prospective Modeled Addit ive Single Base Global Insertion | Stepped Insertion

Method 8

Prospective 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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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


Uses schedule updates that were prepared contemporaneously during the project – aka Window Analysis or Contemporaneous Period Analysis.

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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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



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 aka Window Analysis or Contemporaneous Period Analysis.

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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This method allows for an objective evaluation of impacts to contemporaneous schedule updates without the need for “what-if” modeling.

Prospective

Observational



Method 3


Uses schedule updates that were prepared contemporaneously during the project aka Window Analysis or Contemporaneous Period Analysis.

BASIC SPECIFIC

METHOD

BASIC

IMPLEMENTATION

Not Applicable

BASIC SPECIFIC

METHOD

BASIC SPECIFIC

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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

Stepped Insertion

Stepped Insertion: Delays are added individually into a CPM network for analysis

Method 4

BASIC SPECIFIC

METHOD

BASIC SPECIFIC

IMPLEMENTATION

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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.

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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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 –aka Collapsed As-built or But-for.

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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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


Multi Simulation

Single Simulation: Delay activities are removed from a single CPM network- aka Collapsed As-built or But-for.

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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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 added to 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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The concept of this method is easy to understand and can be implemented without the use of a baseline or updated schedules.

Prospective

Modeled

Subtractive


Single Base

Single Base: Delay activities are removed from a single CPM network– aka But-for.

Global Collapse / Stepped Collapse

Global Collapse: Delays are removed from a CPM Network all at once for analysis.

Stepped Collapse: Delays are removed from a CPM Network individually for analysis.

Method 9

BASIC SPECIFIC

METHOD

BASIC SPECIFIC

IMPLEMENTATION

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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

The Vertex Companies400 Libbey Industrial ParkwayWeymouth, Massachusetts 02189 USA tel: +1 888.298.5162

For further information: Diana Minchella, Vice President of Construction Claims117 N. Jefferson St. #304 | Chicago, IL 60661 | USAtel: +1 [email protected]

For general media inquiries: [email protected]

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