PERT/CPM

Activity list for the Rehabilitation of Warehouse ProjectActivityActivity DescriptionImmediate PredecessorsEstimated Duration

APurchase of Construction Materials-------1 day

BDismantling of Front Wall and GateA2 days

CDemolition of FloorB3 days

DLaying of reinforcement barsC4 days

EFilling of CementD8 days

FFabrication of Web Member and trussesC3 days

GInstallation of Web members and trussesF5 days

HRepair and installation of front wall and gateE,G2 days

Scheduling of the Warehouse Rehabilitation Project with PERT/CPMFigure 1. The project network for the Rehabilitation of WarehouseSTARTABCCC

DCC

FCC

ECC

HCC

GCC

FINISH0823352104

Path and path lengths through the Warehouse Rehabilitation Project

PathLength

START A B C D E H FINISH 0 + 1 + 2 + 3 +4 + 8 + 2 + 0 = 20 days

START A B C F G H FINISH 0 + 1 + 2 + 3 + 3 + 5 + 2 + 0 = 16 days

The critical part for the rehabilitation of warehouse: START A B C D E H FINISH Estimated project duration = 20 days

Scheduling Individual Activities

Such procedure can determine when can the individual activities start and finish (at the earliest) if no delays occur. The starting and finishing times of each activity if no delays occur anywhere in the project are called the earliest start time and the earliest finish time of the activity.

ES = earliest start time for a particular activityEF = earliest finish time for a particular activityWhere:EF = ES + (estimated) duration of the activity

The latest start time for an activity is the latest possible time that it can start without delaying the completion of the rehabilitation, assuming no subsequent delays in the project. The latest finish time has the corresponding definition with respect to finishing the activityLS = latest start time for a particular activityLF = latest finish time for a particular activityWhere:LS = LS (estimated) duration of the activity

Figure 2. Earliest start time (ES) and earliest finish time (EF) values for the activities in Figure 1.

STARTABCCC

DCC

FCC

ECC

HCC

GCC

FINISH0823352104ES = 0EF = 1

ES = 1EF = 3

ES = 3EF = 6

ES = 6EF = 9

ES = 9EF = 14

ES = 6EF = 10

ES = 10EF = 18

ES = 14EF = 16

ES = 16EF = 16

ES = 0EF = 0

ES = 18EF = 20

ES = 20EF = 20

Figure 2. Latest start time (LS) and latest finish time (LF) values for the activities in Figure 1.

STARTABCCC

DCC

FCC

ECC

HCC

GCC

FINISH0823352104LS = 0LF = 1

LS = 1LF = 3

LS = 3LF = 6

LS = 6LF = 9

LS = 9LF = 14

LS = 6LF = 10

LS = 10LF = 18

LS = 14LF = 16

LS = 16LF = 16

LS = 0LF = 0

LS = 18LF = 20

LS = 20LF = 20

Identification Slack in the Schedule

The slack for an activity is the difference between its latest finish time and its earliest finish time. In symbols,Slack = LF - EF

ActivitySlack (LF EF)On Critical Path

A0Yes

B0Yes

C0Yes

D0Yes

E0Yes

F0Yes

G0Yes

H0Yes

Each activity with zero slack is on critical path through the rehabilitation of warehouse network such that any delay along its path will delay project completion.