Schedule Management

Alaska District AK

Module #4Time Impact Analysis

Reviewing & Analyzing CPM Construction Schedules

Schedule Management

Alaska District AKTime Impact Analysis

“Forward looking schedule analysis technique that adds a modeled delay to an accepted

contract schedule to determine the possible impact of that delay

to the project completion.” (AACE)

Schedule Management

Alaska District AKReferences

Association for the Advancement of Cost Engineers (AACE)

International Recommended Practice No. 52R-06, Time Impact

Analysis - as Applied in Construction

Web site: http://www.aacei.org

Schedule Management

Alaska District AKGoals

Determine the impact of a delay to the project completion date

Give time due to the contractor in the contract modification

Schedule Management

Alaska District AKAssumptions

Acceptable baseline schedule exists

Regular schedule updates

Forward looking

Keep it simple

Schedule Management

Alaska District AKSchedule Terminology

Project Scheduler

Schedule Reviewer

Schedule Management

Alaska District AKSchedule Terminology

Critical and Non-Critical Delays:

Critical delays impact the project completion date

Non-critical delays don’t

Schedule Management

Alaska District AKExample

New Building AdditionApproximately 200 CY of petroleum contaminated soil was discovered on October 27while contractor was excavating the building foundation, and underground water and electrical lines. Excavation cannot continue until the soil is removed. Govt. issued NTP on October 29 to remove soil, haul it away, and backfill with clean fill. Total delay duration is 5 days (2-days stop work and 3-days for excavating and hauling soil to storage yard).

Schedule Management

Alaska District AKTime Impact Analysis

Step 1

Identify affected activity(s)

Model delay impact

Schedule Management

Alaska District AK

Schedule Management

Alaska District AKTime Impact Analysis

Step 1

Affected Activity:

BA650 Excavation

Schedule Management

Alaska District AKTime Impact Analysis

Step 1

Determine delay impact

2 days stop work +

3 days removal/back fill

= 5 Day Delay

Schedule Management

Alaska District AKTime Impact Analysis

Step 1

Model impact with a schedule fragnet

Schedule Management

Alaska District AKTime Impact Analysis

Step 1

Act. 1 Act. 2Delay

Fragnet

Act. 1a Act. 1bDelay Act. 2

Delay

Act. 1 Act. 2

Opt. 1

Opt. 2

Opt. 3

Schedule Management

Alaska District AK

Excavation

7-days

Mod. 1 Remove Contaminated Soil

5-days

Time Impact AnalysisStep 1

Finish Excavation

3-days

Install Underground

Water

Install Underground

Electrical

Excavation

10-days

Install Underground

Water

Install Underground

Electrical

Un-Impacted

Impacted

Schedule Management

Alaska District AKTime Impact Analysis

Step 2

Select the appropriate schedule

Use the last updated schedule prior to the delay start

Progress schedule if time frame between previous schedule update and impact too great

Schedule Management

Alaska District AK

Schedule Management

Alaska District AKTime Impact Analysis

Step 2

Note project completion date

Completion Date August 4, 2000

Schedule Management

Alaska District AK

Schedule Management

Alaska District AKTime Impact Analysis

Step 3

Insert fragnet into the updated schedule (don’t forget calendar, logic, etc.)

Set delay duration to zero

Schedule Management

Alaska District AK

Excavation

7-days

Mod. 1 Remove Contaminated Soil

0-days

Remaining Excavation

3-days

Install Underground

Water

Install Underground

Electrical

Schedule Management

Alaska District AKTime Impact Analysis

Step 3

Re-compute CPM – completion date should not change

Original completion date August 4, 2000

Schedule Management

Alaska District AK

Schedule Management

Alaska District AKTime Impact Schedule

Step 4

Insert delay duration: 5 days

Re-compute CPM

Schedule Management

Alaska District AK

Schedule Management

Alaska District AKTime Impact Analysis

Step 5

Note new completion date

If applicable, note completion date(s) for all other contractual milestones

Schedule Management

Alaska District AK

Schedule Management

Alaska District AKTime Impact Analysis

Step 6

Determine the number of days owed to the contractor:

Old completion date is August 4New completion date is August 11 Total Float = -5 days

5 or 7 days?

Schedule Management

Alaska District AKTime Impact Analysis

Step 7

Determine actual dates for the critical delay

Delay begins on first day of negative float; ends when the number of delay days are exhausted

October 28 – November 3

Schedule Management

Alaska District AK

Schedule Management

Alaska District AKTime Impact Analysis

Step 8

Review Schedule for Concurrent Delays

Contractor delay during same period, then Excusable and non-compensable

No contractor delay, then Excusable and compensable

Schedule Management

Alaska District AKTime Impact Analysis

Step 9

Document TIA

Price Negotiation Memorandum (Act ID, issue, affected trades, date changes, etc.)

Contract Modification

Schedule Management

Alaska District AKTime Impact Analysis

Sample Problem