Critical Path Method Schedule

Development, Review and

Analysis Guidelines
Mike Lehmann, P.E.
Texas Department of Transportation
District Construction Engineer
San Antonio District
 Presentation Overview
Background Information
CPM Guide History
Highlights of the Guide
Where to get the Guide
Future developments

August 2005 AASHTO SOC, Mike Lehmann, P.E. 2

 Background Information
(1)
TxDOT workload as of June 2005

1,372 Active Construction Projects

$12.4 billion under contract
SAT district workload

108 Active Construction Projects

$994 million under contract

(1) Includes some “active” projects that have yet to start and some that
have been completed and have yet to be removed from active status.
August 2005 AASHTO SOC, Mike Lehmann, P.E. 3
Counties of San Antonio District

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 History and Background
Development of Expertise
Used CPM since 1988
Used CPM for the resolution of 50+ claims
and disputes
Developed and delivered 40+ in-house
training classes
Co-authored 1993 CPM spec
Primary author of 2004 CPM spec

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August 2005 AASHTO SOC, Mike Lehmann, P.E. 6
 History and Background
Development of the Guide
Guidelines were
developed and
finalized on
December 7, 2001
Guidelines were
posted to TxDOT
Website,
December 2001

August 2005 AASHTO SOC, Mike Lehmann, P.E. 7

 CONSTRUCTION CLAIMS ADVISOR
December 13, 2004 issue
“We recently
stumbled
stum on
one of the
more practical
treatments of
this approach
at the Texas
DOT website.”

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 CONSTRUCTION CLAIMS
ADVISOR
“To the extent that unfamiliarity with the software is an
impediment to use of CPM scheduling, these guidelines are
a must-read for the project manager or scheduler who
wishes to enhance project performance with better
schedules. The TIA guidelines also contain valuable tips,
even for the experienced scheduler. We strongly suggest
downloading the Guidelines (also available at our website)
and printing them out on a color printer.”

www.constructionclaims.com

August 2005 AASHTO SOC, Mike Lehmann, P.E. 9

 Highlights of the Guide
Chapter 1 - Development Of Critical Path
Method Schedules For Contract Time
Determination
Chapter 2 - Review Process For Original
Schedules
Chapter 3 - Review Process For Updated or
Revised Schedules
Chapter 4 - Time Impact Analysis Process
For CPM Schedules

August 2005 AASHTO SOC, Mike Lehmann, P.E. 10

 Chapter 1
Primavera Basics (P3 version 3.1)

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 Chapter 1
Time Determination Basics
Understand The Sequence Of Work And
Traffic Control Plan In The PS&E
Calculate/Estimate Quantities Of Work By
Phase
Determine Attainable Production Rates

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 Chapter 1
Schedule Development Steps
1. Break Down The Work Into Distinct Activities
2. Create The New Schedule
3. Set Up The Calendars
4. Set Up Coding
5. Enter Basic Activity Information
6. Add Relationships
7. Run The Schedule Calculations And Trouble-
Shoot

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 Chapter 1
Schedule Development Steps
Set Up The Calendars
Work Week
Holidays
Bad Weather Days

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 Chapter 1
Schedule Development Steps
Enter Basic Activity Information
Activity ID Number
Description
Duration
Assign Calendar
Assign Coding

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 Chapter 1
Schedule Development Steps
Enter Relationships
Finish to Start (F-S)
Start to Start (S-S)
Finish to Finish (F-F)
Start to Finish (S-F)

August 2005 AASHTO SOC, Mike Lehmann, P.E. 16

 Highlights of the Guide
Chapter 1 - Development Of Critical Path
Method Schedules For Contract Time
Determination
Chapter 2 - Review Process For Original
Schedules
Chapter 3 - Review Process For Updated or
Revised Schedules
Chapter 4 - Time Impact Analysis Process
For CPM Schedules

August 2005 AASHTO SOC, Mike Lehmann, P.E. 17

 Chapter 2
Schedule Review Steps
1. Restore The Schedule
2. Open The File
3. Review The Calendars
4. Review Activity Coding Structure
5. Review Resource Loading, If Required
6. Defining The Critical Path
7. Organizing The Schedule (Layouts)
8. Calculate The Schedule
9. Review Constraints
10. Prepare Plots And Prints
11. Complete The Schedule Review

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 Chapter 2
Schedule Review Steps
Defining The Critical Path
“Total Float Less than” option allows:

Making all activities show as critical

Making selected activities show as critical

Making no activities show as critical

Using constraints to force float calculations
and drive the critical path
Recommend using “Longest Path”

August 2005 AASHTO SOC, Mike Lehmann, P.E. 19

August 2005 AASHTO SOC, Mike Lehmann, P.E. 20
 Highlights of the Guide
Chapter 1 - Development Of Critical Path
Method Schedules For Contract Time
Determination
Chapter 2 - Review Process For Original
Schedules
Chapter 3 - Review Process For Updated or
Revised Schedules
Chapter 4 - Time Impact Analysis Process
For CPM Schedules

August 2005 AASHTO SOC, Mike Lehmann, P.E. 21

 Chapter 3
Updated Schedule Review Process
1. Restore The Schedule
2. Open The File
3. Review The Schedule For Conformance To The
Specifications
4. Set Up Target Schedules
5. Review Status Of Updated Schedule
6. Recalculate The Schedule
7. Prepare Plots And Prints
8. Decide If The Schedule Has Been Updated Or
Revised
9. Document The Schedule Update Status
10. Prepare Look-ahead Schedule Plot
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 Chapter 3
Updated Schedule Review Process
Update or Revision?
A schedule update is defined as the addition of
actual start dates and/or actual finish dates to
activities that have been started and/or
completed, and revising the percent complete
figure or the remaining duration figure for started
activities.
A schedule revision is defined as adding or
deleting activities, relationships, resources, or
any other component of the schedule, or
changing durations.
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 Project Schedule Status Report
Project: STP 2005(01) County: Anywhere
CSJ: 0001-01-001 Contractor: Construction Company, Inc.

Calendar Days Working Days TxDOT Loss

Schedule Completion Working
Data Date Period Cumulative Period Cumulative Calendar Working Explanation for Loss/Gain
Name Date Days
Gain/Loss Gain/Loss Gain/Loss Gain/Loss Days Days
GUOR 5/1/2000 11/30/2000 120
GU01 6/1/2000 11/15/2000 109 15 15 11 11 Good production on subgrade widening
GU02 7/1/2000 12/14/2000 112 -29 -14 -3 8 14 0 4 working day delay, Time Suspension
already granted - compare GU02 to GUOR
GU03 8/1/2000 1/26/2001 131 -43 -57 -19 -11
GU3R 8/1/2000 1/30/2001 131 -4 -61 0 -11
GU3D 8/1/2000 2/22/2001 147 -23 -84 -16 -27
GU04 9/5/2000 2/14/2001 145 8 -76 2 -25
GU4A 9/15/2000 3/8/2001 144 -22 -98 1 -24
GU05 10/1/2000 3/8/2001 155 0 -98 -11 -35
GU06 11/1/2000 3/22/2001 163 -14 -112 -8 -43
GU6R 11/1/2000 3/16/2001 163 6 -106 0 -43
GU07 12/9/2000 3/30/2001 169 -14 -120 -6 -49 22 19 ROW Impact - Compare GU07 to GU4A
GU08 1/1/2001 3/30/2001 169 0 -120 0 -49
GU8E 1/10/2001 4/9/2001 159 -10 -130 10 -39
GU09 2/1/2001 5/22/2001 175 -43 -173 -16 -55
GU10 3/1/2001 5/22/2001 167 0 -173 8 -47
GU11 4/1/2001 6/5/2001 174 -14 -187 -7 -54 57 15 Tree CO and Drainage COs, ongoing, may
be until next update before finalized,
compare GU11 to GU8E

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 Highlights of the Guide
Chapter 1 - Development Of Critical Path
Method Schedules For Contract Time
Determination
Chapter 2 - Review Process For Original
Schedules
Chapter 3 - Review Process For Updated or
Revised Schedules
Chapter 4 - Time Impact Analysis Process
For CPM Schedules

August 2005 AASHTO SOC, Mike Lehmann, P.E. 25

 Chapter 4
Time Impact Analysis
Types of Time Impact Analyses
The As-Planned Impacted Schedule
Analysis
The As-Built But-For Schedule Analysis
The Contemporaneous Schedule
Analysis

August 2005 AASHTO SOC, Mike Lehmann, P.E. 26

 Chapter 4
Time Impact Analysis
Time Impact Analysis Steps – Contemporaneous
Approach
1. Determine the status of the project
immediately before the impact begins.
2. Predict the effect of the impact on the project
completion date.
3. Track the status of the project during the
impact.
4. After the impact is over, determine the status
of the project and compare it to the status
before the impact began.

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 Chapter 4
Time Impact Analysis
Time Impact Analysis Steps – Two Different
Approaches
1. Pre-Impact TIA

Includes Steps 1 and 2 only
2. Post-Impact TIA

Includes Steps 1, 2, 4 and possibly 3 if
impact is long duration

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 Where to get the Guide
http://www.dot.state.tx.us/cst/construction_strategies.htm

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 Future Developments
Planned Revision for 2004 Spec Book
Possible conversion to P3 e/c
Addition to SAT District Construction
Office Intranet Website, along with other
tools

August 2005 AASHTO SOC, Mike Lehmann, P.E. 30

Questions?
 Thank You!

Mike Lehmann
(210) 615-6100
mlehman@dot.state.tx.us