projmgmt-1/14 depaul university project management i - realistic scheduling instructor: david a....

Projmgmt-1/14

DePaul University

Project Management I - Realistic Scheduling

Instructor: David A. Lash

Projmgmt-2/14

From Project Definition

Project

Rules

ScopeDeliverables

PrePlanningRisk Management

- Develop Approach- Risk Management

Step 1Develop a WBS

All

Project

TasksStep 2

Sequence thetasks

Step 3Estimate the

work packages

Duration

Estimates

Step 4:Calculate an

initialschedule

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estim

ates

Step 5:Assign & level

resources

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Step 6DevelopBudget

Realistic schedule& forecast

No

n-l

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sts

Realistic schedule

& forecast

Project Plan- all project task s

- schedule- responsibilities

- budgetResource forecase

All

Pro

ject

Tas

ks

Net

wd

iag

ram

s

Projmgmt-3/14

Sequencing Tasks

No Task Pred Res Dur

1 Acquire Lawnmaterial

Homeowner

2D

2 Remove Debris Teens& YthGroup

4D

3 Prepare Soil 1,2 Teens 4D4 Plaint lawn seed 3 Teens 1D5 Plant Shrubs 2 Teens 12D

•Either Task 1 or 2 can go first (Can be concurrent)•Task 5 can't start until 2•Task 3 needs 1 & 2•Task 4 needs 3 (therefore needs 1 & 2 too!)

Projmgmt-4/14

Finish

4

5

Start

1

2

3

Correct Network Diagram

•How get from network diagram to schedule?

Projmgmt-5/14

Step 4 - Calculate Initial Schedule

PERT Charts - Program, Evaluation & Review Technique - Calculate 4 variables:

– Early Start (ES) - The earliest date a task can BEGIN

– Early Finish (EF) - The earliest date a task can END

– Late Start (LS) - The latest date a task can BEGIN

– Late Finish (LF) - The latest date a task can END ID DUR

ES EF

LS LF

FL

Early Start

Early Finish

Late Finish

Late Start Float Days

Projmgmt-6/14

Step 4 - Diagram ES,EF, LS, LF, FL

ID DUR

ES EF

LS LF

FL

Early Start

Early Finish

Late Finish

Late Start Float Days

EarlyStart

DurationEarlyFinish

Late Start SlackLate

Finish

Task Name

Projmgmt-7/14


There are 3 major steps– Step 1 - Forward Pass - Determine the Early

Start (ES) and Early Finish (EF) for each task Works through tasks from start to finish

– Step 2 - Backward Pass - Determine the late start (LS) and late finish (LF) dates.

Works backward through tasks from end to start

– Step 3 - Calculate Float - Determine the schedule flexibility for each task.

Calculated by subtracting the ES from LS.

Projmgmt-8/14


Step 1 - Forward Pass - Work forward from the start to calculate ES and EF

Task 1 & 2 is assumed to be the first day of the project.



Homeowner

2D


4D


ID DUR

ES EF

LS LF

FL

1 2D

1 2

LS LF

FL

2 4D

1 4

LS LF

FL

Projmgmt-9/14


Step 1 - Forward Pass - Calculate ES and EF

Task 5 finishes after task 2.



Homeowner

2D


4D


ID DUR

ES EF

LS LF

FL

5 1`2D

5 16

LS LF

FL

2 4D

1 4

LS LF

FL

Projmgmt-10/14

Step 4 - Calculate Initial Schedule Step 1 - Forward Pass - Calculate ES and EF

Task 3 finishes after task 1 & 2. (4 after 3)



Homeowner

2D


4D


ID DUR

ES EF

LS LF

FL

3 4d

5 8

LS LF

FL

2 4D

1 4

LS LF

FL

1 2D

1 2

LS LF

FL

4 1d

9 9

LS LF

FL

Projmgmt-11/14


3 4d

5 8

LS LF

FL

2 4D

1 4

LS LF

FL

1 2D

1 2

LS LF

FL

4 1d

9 9

LS LF

FL

Start

5 1`2D

5 16

LS LF

FL

Finish

Projmgmt-12/14








Projmgmt-13/14

Step 4 - Calculate Initial Schedule Backward Pass -

– Set Project Finish Date - Calculate the LS and LF dates

– Determine The Last Start for the last CP task (5)

Last finish is the minimal time = 16 The finish day = 16 therefore LS = 5

(16+1-12) = 5 if task 5 not start by day 5 the project

will be late

5 1`2D

5 16

5 16

FL

Finish

LSLF

Finishday is finish day ofproject(17)

Projmgmt-14/14


Backward Pass - – Take the next CP date (task 2). Find LS

The finish day = 4 therefore LS is 1 (4+1-4).

If task 2 not start by day 1 the project will be late!

5 1`2D

5 16

5 16

FL

Finish

LSLF

Finishday is start date of next task.

2 4D

1 4

1 4

FL

Projmgmt-15/14


Backward Pass - (Repeat for non - CP items)– Start with last non-CP task (task42).

Find LF - For task 4 with dur=1 LF=16 Find LS = 12 (15+1-1). If task 4 not started on day 16 will be late! If task 3 not start on day 12 will be late!

Finish

LS

LF

Finishday is start date of next task.

3 4d

5 8

12 15

FL

1 2D

1 2

10 11

FL

4 1d

9 9

16 16

FL

LF = 15 latest it can finishLS = 15+1 -5 = 11 - latest it can start

Projmgmt-16/14


3 4d

5 8

12 15

FL

2 4D

1 4

1 4

FL

1 2D

1 2

10 11

FL

4 1d

9 9

16 16

FL

Start

5 1`2D

5 16

5 16

FL

Finish

Projmgmt-17/14








Projmgmt-18/14

Step 3 - Calculate Float

Float? - Some tasks have schedule flexibility

– others have none - E.g, those in the Critical Path– it is a measure of schedule flexibility of a task

Float = ES - LS - duration

Projmgmt-19/14


3 4d

5 8

12 15

FL=7

2 4D

1 4

1 4

FL=0

1 2D

1 2

10 11

FL=9

4 1d

9 9

16 16

FL=7

Start

5 1`2D

5 16

5 16

FL=0

Finish

FL=(16+1)-5-12FL=(4+1)-1-4

FL=(16+1)-9-1

FL=(11+1)-1-2 FL=(15+1)-5-4

Projmgmt-20/14

Time-Scaled View

Figure 7-5 page 136 shows a time scaled view of above diagram

– wider boxes show the task duration– float is shown indirectly

Figure 7.6 shows network diagram for entire home landscape project

Projmgmt-21/14

From Project Definition

Project

Rules

ScopeDeliverables

PrePlanningRisk Management

- Develop Approach- Risk Management

Step 1Develop a WBS

All

Project

TasksStep 2

Sequence thetasks

Step 3Estimate the

work packages

Duration

Estimates

Step 4:Calculate an

initialschedule

Equi

pmen

t

requ

irem

ents

& la

bor &

ski

ll

estim

ates

Step 5:Assign & level

resources

Cr i

tica

lP

ath

, f l

oat

,m

iles

ton

es

Step 6DevelopBudget

Realistic schedule& forecast

No

n-l

abo

rco

sts

Realistic schedule

& forecast

Project Plan- all project task s

- schedule- responsibilities

- budgetResource forecase

All

Pro

ject

Tas

ks

Net

wd

iag

ram

s

Projmgmt-22/14

Step 5: Assign & Level Resources

Goal: Optimize the use of resources– continuos use of fewest resources possible– avoid repeatedly adding a reusing resources– that is, limited people and resources affect the

schedule Figure 7.6 network diagram shows can build fence

and put in lawn at the same time.– Not take into consideration over allocation of teens– Figure 7.11 shows the resource shreadsheet.

Note teens heavily overallocated– Figure 7.13 shows same project with resources

leveled (3 teens @ 8 hrs per day with no more than 24 total hours per day).

Projmgmt-23/14

Step 5: Assign & Level Resources: The Process

Resources: People, equipment, and raw materials – Resource leveling - focus only on people and

equipment 4 steps to level resources

1. Forecast resources throughout project. Use resource spreadsheet such as figure 7.11 Creates an early start schedule - usually with

lots of uneconomical resource peaks and valleys (e.g., teen overallocation)

2. Identify resource peaks Use resource spreadsheet (figure 7.11) &

resource histogram (figure 7.12)

Projmgmt-24/14

Step 5: Assign & Level Resources: The Process (steps 3

& 4) 4 steps to level resources

1. Forecast resources throughout project.

2. Identify resource peaks

3. Delay non-critical tasks within their float. Use the float to fill in the resource valleys (I.e., spreading

resources out over time when schedule permits) See figure 7.13 compare to figure 7.12- task 5 was

delayed within float to balance resources.

4. Re-examine resource peaks - Look again at peaks, can redistribute schedule affecting

resource? Task 12 on 7.13 changed from 2 teens for 1 day to 1

teen for 3 days

Projmgmt-25/14

Step 5: Assign & Level Resources: Now what?

What happens if new schedule still unexceptable?

– The project date might now be pushed out longer than acceptable

You could accept the new date Work additional resources likely need to involve sponsor &/or

customer to make decision(s)

projmgmt-1/14 depaul university project management i - realistic scheduling instructor: david a....

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