Crashing and updation

PROJECTPROJECTCRASHING,UPDATING,CRASHING,UPDATING, RESOURCE ALLOCATION RESOURCE ALLOCATION

Project CrashingProject CrashingThe process of accelerating a project is referred as crashing.Crashing a project relates to resource commitment; the more resources expended, the faster the project will finish.There are several reasons to crash a project:

Initial schedule was too optimistic Market needs change and the project is in demand earlier than anticipatedThe project has slipped considerably behind scheduleThere are contractual late penalties

Project CrashingProject CrashingPrincipal methods for crashing are:

Improving existing resources’ productivityChanging work methodsIncreasing the quantity of resources

Increasing the quantity of resources is the most commonly used method for project crashing. There are 2 approaches:

Working current resources for longer hours (overtime, weekend work, etc.)Adding more personnel

Project CrashingA

ctiv

ity c

ost

Activity time

Crashing activity

Crash time

Crash cost

Normal Activity

Normal time

Normal cost

Slope = crash cost per unit time

Fully expedited (no expense is spared

Time-Cost RelationshipTime-Cost Relationship Crashing costs increase as project duration decreases Indirect costs increase as project duration increases Reduce project length as long as crashing costs are less than indirect

costs

Time-Cost Tradeoff

cost

time

Direct cost

Indirect cost

Total project costMin total cost = optimal project time

Project CrashingProject CrashingIn analyzing crash options, the goal is to find the point at which time and cost trade-offs are optimized.

Various combinations of time-cost trade-offs for crash options can be determined by using the following formula:Slope = crash cost – normal cost

normal time – crash time

Project Crashing ExampleProject Crashing ExampleSUPPOSE:

NORMAL ACTIVITY DURATION = 8 WEEKSNORMAL COST = $14,000CRASHED ACTIVITY DURATION = 5 WEEKSCRASHED COST = $23,000

THE ACTIVITY COST SLOPE = 23,000 – 14,000 OR $9,000 = $3,000 per week 8 – 5 3

Cease crashing when

the target completion time is reachedthe crash cost exceeds the penalty cost

Project Crashing ExampleProject Crashing Example Normal Crashed

Activity Duration Cost Duration CostA 5 days $1000 3 days $1500B 7 days $700 6 days $1000C 3 days $2500 2 days $4000D 5 days $1500 5 days $1500E 9 days $3750 6 day $9000F 4 days $1600 3 days $2500G 6 days $2400 4 days $3000H 8 days $9000 5 days $15000Total costs = $22,450a) Calculate the per day costs for crashing each activity

b) Which are the most attractive candidates for crashing?

Project Crashing Example Project Crashing Example

Activity Per Day Cost(in $)A 250B 300C 1500D -E 1750F 900G 300H 2000

Project costs by durationProject costs by duration

Duration Total costs

27 days 22,450

26 days 22,700

25 days 22,950

24 days 24,700

23 days 26,450

22 days 28,200

21 days 30,200

20 days 32,200

19 days 34,200

UPDATING PROJECTUPDATING PROJECT

• Can be done in 2 ways– Use the revised time estimate of incomplete activities

and calculate from initial event the earliest completion time and the latest completion time of each event in the usual manner to know the Project completion time.

– Change the complete work to zero duration and represent all the activities already finished by an arrow called the Elapsed time arrow. Events in the revised network are renumbered.

• The network for a project is shown below. A review of the project after 15 days reveals that – Activities 1-2, 1-3, 2-3, 2-4 and 3-4 are completed.– Activities 3-5 and 4-6 are in progress and need 2 and 4 days more

resp.– The revised estimate shows that activity 8-9 will take only 8 days but

activity 7-9 will need 10 days.

• Draw the new network after updating the Project and determine the Critical path.

10

0

23

3

37

7

413

13

514

15

616

16

719

26

824

249

34

34

2

3

46

7

7

5

9

3

12

810

8

Network at the start of the Project

10

0

23

3

37

7

413

13

514

15

616

16

719

26

824

249

34

34

2

3

46

7

7

5

9

3

12

810

8


1

0

0

2

3

3

3

7

7

4

13

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27

27

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35

35

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12

8

8

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Updated Network after day 15 of the Project

14

15

15

13

15

15

(Finished 4-6) 2

(Finished 3-5) 8

Review at the end of 15th day

Activity Time reqd. (Days)

Activity Status

1-2 0 completed

1-3 0 completed

2-3 0 completed

2-4 0 completed

3-4 0 completed

3-5(13-15) 2 In Progress


5-7(15-17) 5 Not started






New critical path1-2-3-4-14-16-18-19

Project duration increased by 1 day to 35 days

Review at the end of 15th day

Activity Time reqd. (Days)

Activity Status

1-2 0 completed

1-3 0 completed

2-3 0 completed

2-4 0 completed

3-4 0 completed









New critical path1-10-16-18-19

Project duration increased by 1 day to 35 days

2nd Method

10

0

23

3

37

7

413

13

514

15

616

16

719

26

824

249

34

34

2

3

46

7

7

5

9

3

12

810

8


10

010

15

15

1619

19

1517

1817

22

25

1827

2719

35

3515

4

12

8

9

2

5

10

8

Updated Network after day 15 of the Project

Resource Allocation ProblemResource Allocation ProblemA shortcoming of most scheduling procedures is that they do not address the issues of resource utilization and availability.

Scheduling procedures tend to focus on time rather than physical resources.

Resource Allocation ProblemResource Allocation ProblemSchedules should be evaluated not merely in terms of meeting project milestones, but also in terms of the timing and use of scarce resources.

A fundamental measure of the project manager’s success in project management is the skill with which the trade-offs among performance, time, and cost are managed.

“I can shorten this project by 1 day at a cost of $400. Should I do it?”

Resource Allocation ProblemResource Allocation ProblemThe extreme points of the relationship between time use and resource use are the following:

Time Limited: The project must be finished by a certain time, using as few resources as possible. But it is time, not resource usage, that is criticalResource Limited: The project must be finished as soon as possible, but without exceeding some specific level of resource usage or some general resource constraint

Resource LoadingResource LoadingResource loading describes the amounts of individual resources an existing schedule requires during specific time periods.

The loads (requirements) of each resource type are listed as a function of time period.

Resource loading gives a general understanding of the demands a project or set of projects will make on a firm’s resources.

Resource LoadingResource LoadingThe project manager must be aware of the flows of usage for each input resource throughout the life of the project.

It is the project manager’s responsibility to ensure that the required resources, in the required amounts, are available when and where they are needed.

Resource LoadingResource Loading Table Table

Resource LResource Loading oading ChartChart Another way to create a visual diagram

of resource management problem is to use resource-loading charts.

Resource conflicts can be seen in the resource-loading charts.

They are used to display the amount of resources required as a function of time on a graph.

Each activity’s resource requirements are represented as a block (resource requirement over time).

Resource LResource Leveling eveling (Smooting)(Smooting)

Resource leveling aims to minimize the period-by-period variations in resource loading by shifting tasks within their slack allowances.The purpose is to create a smoother distribution of resource usage.Resource leveling, referred to as resource smoothing, has two objectives:

To determine the resource requirements so that they will be available at the right time,To allow each activity to be scheduled with the smoothest possible transition across usage levels.

Resource LResource Leveling eveling (Smooting)(Smooting)

Resource management is a multivariate, combinatorial problem, i.e. multiple solutions with many variables, the mathematically optimal solution may be difficult or infeasible.

More common approach to analyzing resource leveling problems is to apply some resource leveling heuristics.

Resource LResource Leveling Heuristicseveling HeuristicsPrioritizing resource allocation include applying resources to activities:

with the smallest amount of slackwith the smallest durationthat start earliestwith the most successor tasksrequiring the most resources

Resource LResource Leveling Stepseveling StepsCreate a project activity network diagramCreate a table showing the resources required for each activity, durations, and the total float availableDevelop a time-phased resource loading tableIdentify any resource conflicts and begin to smooth the loading table using one or more heuristics

Resource Leveling ExampleResource Leveling Example

Critical path:A-C-F-H-K


Critical path:A-C-F-H-K

Resource Leveling ExampleResource Leveling ExampleActivity Duration Total Float Resource Hours

Needed Per WeekTotal Resources

Required

A 5 0 6 30

B 4 1 2 8

C 5 0 4 20

D 6 3 3 18

E 6 1 3 18

F 6 0 2 12

G 4 3 4 16

H 7 0 3 21

I 5 3 4 20

J 3 5 2 6

K 5 0 5 25

Total 194


Resource Leveling ExampleResource Leveling ExampleOn day 10 the required resource hours is 10If project is budgetted for up to 10 resource units per day, then it is acceptable.C, D, and E are all scheduled on this day and have require 4, 3, and 3 hours respectively

Which activity should be adjusted?C is on the critical path E has 1 day slack D has 3 days of slack (we can split the activity)


Documents

Crashing and updation