copyright © 2009 t.l. martin & associates inc. chapter 6 practical methods to reveal cpm covert...

Copyright © 2009Copyright © 2009T.L. Martin & Associates Inc.T.L. Martin & Associates Inc.

Chapter 6Chapter 6Practical Methods to Practical Methods to Reveal CPM Covert Reveal CPM Covert

ActivitiesActivities


A. Schedule comparison A. Schedule comparison softwaresoftware


Schedule comparison softwareSchedule comparison software

• The comparison software notes changes between updates or between an update and the baseline schedule.

• One such system, which compares Primavera CPM schedules, is called “Primaplan Project Investigator.”

• Another system that compares Primavera schedules is called “Claim Digger.”


Schedule comparison softwareSchedule comparison software• These systems note the differences between the two

compared schedules. – Activities added and deleted, – revised activity durations, – start and finish dates, – calendars, constraints, – changes in float, – changes in critical paths, – resources, – quantities, and – changes in relationships.


B. Physical versus B. Physical versus metaphysical metaphysical dependenciesdependencies


Physical versus metaphysical Physical versus metaphysical dependenciesdependencies

• Physical relationships are those which are required based on the nature of the work. – A footing must be excavated prior to concrete

placement, formwork must be completed to a certain extent prior to rebar placement, rebar must be completed to a joint prior to concrete

• Contractor sequence preference sometimes is just mere metaphysical dependency. – Logic between activities becomes that of abstract

and speculative reasoning.



• Very good examples of metaphysical relationships occur within industrial plant projects, which are more controlled by labor resources than by physical dependencies. (With thousands of feet of pipe work to be installed, work location timing is scheduled primarily by preference not due to physical dependencies.)

• In this case the critical path goes through resources and the sequencing of activities, for the most part, becomes physically unrestricted.



• The productive work can be performed out-of-sequence requiring the next schedule update to include the revised logic.

• Since the change affected non-physical activity dependencies, the update should indicate that the revised logic did not delay project completion, since the critical path is driven by resource use which was simply shifted to a new location.



• However, if the contractor does not have sufficient resources during the period, the project will be critically delayed.

• The contractor will argue that the directed change stopped work on the critical path, and thus it is entitled to a compensable time extension.

• Depending on the wording of the project contract, the contractor may be correct.

• One of the owner’s defenses is that the contractor has a duty to mitigate delay and damages by, among other things, re-sequencing work.



• A CPM schedule, if it is to be a viable tool to determine delay cause and resulting damage, must include work quantities and key resources.

• Otherwise, the CPM schedule becomes a meaningless magic trick, producing wildly conflicting results depending which side produces it, to the bewilderment of the audience.


C. Standard delay C. Standard delay evaluation techniquesevaluation techniques


Standard delay evaluation Standard delay evaluation techniquestechniques

• Delay may result from contractor responsible issues, subcontractor failure to perform and/or supplier problems.

• Generally, the contractor is not entitled to time for its causes of delay and, if critical, may have to accelerate the work at its own cost to ensure timely completion.

• These delays are inexcusable and non-compensable.



• Delay can also result from “neutral events” or from causes outside the control of both the contractor and the owner.

• Delays associated with extraordinary weather and “Acts of God” fall under this category.

• Under most contracts, this type of delay entitles the contractor to an extension of time but no compensation.

• This type of delay is considered excusable but non-compensable.



• The third group of delays fall under the responsibility of the owner and is defined by the contract.

• Generally, owner directed changes, differing site conditions, owner furnished materials and/or equipment, owner responsible approvals and designs, are a few of the areas an owner may cause delay that would result in a compensable time extension for a contractor.

• The owner responsible delay is considered excusable and compensable.



• Only excusable delays that fall along the projects CPM critical path or paths are to be considered with respect to contract time extensions.

• A CPM schedule is a dynamic tool, as a project progresses and the schedule is updated, the critical path or paths shift.

• A delay to a prior update path may use all available float plus require additional time, thus shifting the critical path through the delay event.

• Additionally, actual and potential re-sequencing of work activities mitigating delay events should be analyzed.


Standard delay evaluation Standard delay evaluation

techniquestechniques “As-planned vs. As-built”“As-planned vs. As-built”

• The first delay analysis method compares the original baseline or as planned schedule with the completed as built schedule.

• Delay events and delay mitigation are determined supported by contemporaneous project documents (daily reports, meeting minutes, memos, letters, etc.)

• The credibility of the analysis rests in the accuracy of the as planned and as built schedules and the extent to which delay can be tied to project factual events.


Standard delay evaluation Standard delay evaluation techniques techniques “But For”“But For”

• The second approach is called the “But For” or collapsing method.

• An as built schedule is developed including all known delay events, regardless of contractual responsibility.

• Owner causes of delay are removed, leaving contractor and non-compensable neutral delay events.

• The difference between the actual completion date including owner, contractor and neutral delay and the forecast completion without owner impacts, represents the period of compensable delay.


Standard delay evaluation Standard delay evaluation techniques techniques “But For”“But For”

• The next step is to remove owner and neutral delay events from the as built schedule.

• The difference between the actual completion date including owner, contractor and neutral delay and the forecast completion without owner and neutral impacts represents the period of inexcusable delay.

• The difference between the completion dates computed based on contractor delay alone and the original contract completion represents the period the contractor may be subject to liquidated damages.


Standard delay evaluation Standard delay evaluation techniques techniques “Window”“Window” analysis analysis

• The third delay determination technique is called a “Snapshot” or “Window” analysis.

• This approach generally starts with a reasonable as planned schedule or baseline and at selected points in time, chronologically includes delay events.

• Once a time impact is identified and founded upon contemporaneous project documents, the original baseline schedule is revised incorporating the delay. This revised schedule is then used as the basis for adjustment with the next identified delay.



• This sequential approach is followed consecutively through the life of the project by identifying a delay event and then revising the previously adjusted schedule, until all impacts are incorporated into the schedule.

• If this approach is chosen, contractor and owner delay mitigation efforts such as activity re-sequencing, reduction in critical activity durations and/or deletion of work tasks, must also be included timely into the various “Windows.”



• This approach can be used during performance to demonstrate delay. A subnet or fragnet is the best way to demonstrate a delay.

• A subnet or fragnet is a sequence of new activities and/or network revisions that are proposed to be added to the existing schedule to illustrate (graphically and mathematically) the method for incorporating changed work that may result in project delay.

• Owners should also prepare independent Time Impact Analyses (“TIA”) using fragnets inserted into the CPM.

– Discuss, negotiate, and timely resolve the question of impact at the earliest opportunity.


Standard delay evaluation Standard delay evaluation techniques techniques “Window”“Window” analysis - How analysis - How

– Determine which activity or activities on the project schedule were affected by the changed work and/or by the delay.

– Review and determine the event timing and duration of all affected activities.

– From the project record keeping systems and key staff, determine impacted activity status.

– Prepare a fragnet analysis showing the sequence of activities necessary to perform the work required, and/or identifying the effects of the delay.


Standard delay evaluation Standard delay evaluation techniques techniques “Window”“Window” analysis – How analysis – How

Example 1Example 1• On February 10, two weeks after the project began,

the project was halted due to a strike. • At the time of the strike, the general contractor was on

schedule and in the process of clearing and grubbing the job site.

• Accordingly, on February 14, the contractor wrote the owner and requested a three (3) day time extension.


Time Extension Analysis - Time Extension Analysis - Example 1Example 1

Clear & Grub SiteStart Excavation for

BuildingComplete Excavation for

Building

Start Building Footings

StartA27 JAN

Finish10 FEB

302301 303

304

Start11 FEB

As-Planned


Example #1Example #1

Clear & Grub Site

Start Excavation for Building

Complete Excavation forBuilding


StartA27 JAN

FinishA12 FEB

302

301

303

304

StartA13 FEB

As-Built

Strike Delay(3 Day Delay)

StartA10 FEB

FinishA12 FEB

TIA01

MF 12 FEB



• Shortly thereafter and during the construction of the building foundation, a field directive was issued by the owner at the start of work on February 19, instructing the contractor to change the fill requirements.

• On March 31 the contractor wrote the owner and requested a seven (7) day time extension.



2/21

Res

tart

Bui

ldin

g Fo

otin

gs

2/19

Cha

nge

Fill

Req

uire

men

ts

302

Start Excavation for Building 304

Start Building FootingsStart

A13 FEBStart

A18 FEB

303

Complete Excavation for Builidng

Start Structural Columns & Walls

Complete Footings

308

306



2/21

Res

tart

Bui

ldin

g Fo

otin

gs

2/19

Cha

nge

Fill

Req

uire

men

ts

302

Start Excavation for Building

304A


StartA13 FEB

StartA18 FEB

TIA02

Changed Fill RequirementsShut Down Fill (2 Day Delay)

304B

Restart Building Footings

303

Complete Excavation for Builidng

StartA19 FEB

FinishA20 FEB

StartA21 FEB



• During the construction of the building structure, a field directive added four columns and a new structural wall. The owner at the start of work on February 26, asked the contractor to determine the impact on completion, if any, for this work, if starting March 1.

• On February 27 the contractor wrote the owner and requested a ten (10) day time extension because of this issue.


Time Extension Analysis - Example 3Time Extension Analysis - Example 3

304B

Restart Building Footing

StartA21 FEB

StartA18 FEB

306

Complete Footings

Install Deck for 1st FloorColumns & Walls Grd Floor

310

FinishA24 FEB

StartA25 FEB

StartA25 FEB

Finish1 MAR

Start2 MAR

As-Planned


Time Extension Analysis - Example 3Time Extension Analysis - Example 3


Columns & Walls Grnd Floor

Wate on NTP Changed FND Work

Construct New FTG'sInstall New Columns

& Wall

Fab & Deliver NewSteel Columns

Install Deck 1st Floor

StartA21 FEB

FinishA24 FEB

StartA25 FEB

Finish1 MAR

StartA26 FEB

Finish28 FEB

Start1 MAR

Finish5 MAR

Start1 MAR

Finish3 MAR

Start6 MAR

Finish7 MAR

Contractor Claimed 10 Day Delay26 FEB through 7 MAR

Start8 MAR

304B

310

Contractor’s Analysis #3



304B


StartA21 FEB

TA03A

Wate on NTP ChangedFND Work

Install Deck for 1st Floor

Columns & Walls Grd Floor

FinishA24 FEB

StartA25 FEB

StartA26 FEB

Finish28 FEB

TA03B

Construct New FTGs

TA03D

Install New Columns

TA03C

Fab & Deliver NewSteel Columns

Start1 MAR

Finish5 MAR

Start1 MAR

Finish3 MAR

Start6 MAR

Finish7 MAR

Actual Delay3/2 through3/5 - 4 days

Start6 MAR

Finish1 MAR Owner’s TIA #3

Deck was planned to start 3/2 and due to the new columns is delayed through 3/5. Deck can actually start prior to completion of new columns.



• There are certain requirements of a credible delay analysis.– The as planned or baseline schedule must be reasonable

and represent an accurate plan to timely build the project. – Delay issues identified must be founded in the

contemporaneous project record. – The CPM schedule must be updated through the life of the

project reflecting actual performance. – The results of the analysis should pass the “common sense”

test. – The foundation of the alleged delay must be physically real

not developed through imaginary scheduling tricks.


D. Performance D. Performance MonitoringMonitoring


The Schedule Update ProcessThe Schedule Update Process

• Review of the final update package:– Verify accuracy of submitted information.– Run comparison software– Review critical path graphic– Review update narrative– Review submitted database calculation settings– Review resource usage


Performance Monitoring and Steps to Performance Monitoring and Steps to Maintain a Proper CPMMaintain a Proper CPM

1. Are all required deliverables submitted?

Compare with General Conditions

2. Is the NTP on the correct day?

Schedule Execution Report or Total Float Report

3. Is the contract duration correct

Schedule Execution Report or Total Float Report

4. Is the contract amount correct

Schedule Resource Report

5. How many activities?

Schedule Execution Report

What to Check on Updated Schedule


Performance Monitoring and Steps to Performance Monitoring and Steps to

Maintain a Proper CPMMaintain a Proper CPM 6. Does the critical path seem reasonable?

Critical Path Bar Chart or Total Float Report

7. Does the cost loading look reasonable?

Cumulative Cost Curve

8. Is there too much float on activities?

Total Float Report

9. How many constraints? Are they reasonable?


10. How many open ends? Are they reasonable?



11. Is there unusual logic, especially on the critical path?

Time Scaled Logic Diagram

Detailed Predecessor/Successor Report

12. Cost loading?

Independent Cost Analysis

Resources Loading Report

13. Manpower loading?

Independent Manpower Analysis

Performance Monitoring and Steps to Performance Monitoring and Steps to Maintain a Proper CPMMaintain a Proper CPM



Maintain a Proper CPMMaintain a Proper CPM 14. Are activity durations appropriate

Bar Chart by Area

Resource Loading Report



Maintain a Proper CPMMaintain a Proper CPM

Within budget and on-time performance are goals.

The simplest means of achieving budget and performance is for each participant in the project execute its duties properly, accept responsibility and to have a good plan for performance of the work, updated and communicated properly among the project team.


Please continue with Chapter 7

Example Development of a Critical Path Schedule