time mgmt slides

8/12/2019 Time Mgmt Slides

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Network Information



Koll Business Center —Partial

Network



Network Information



Koll Business Center —Complete

Network



Network Information



Activity-on-Node Network



Forward Pass Computation

• Forward pass starts with the first activity andtrace each path (sequential activities)

• Longest path denotes completion time for the

plan and is called ‘Critical Path’

• Example

– A has an activity duration of 5 days

–Forward pass begins with project start time (Earliest

start (ES)), usually 0 (upper left corner of node) – (calendar times can be computed later)



–Early finish activity of A is 5 (Es + Duration) = (0 +5)

–For B,C,D ES is 5 and EFs are 20,15 and 10

–For E ES is 20 ( because before we start this activityeach of preceding activities must be completed

–Hence we take largest of EFs among the preceding

activities – For F, 30 is carried to next G

–For H (Merge activity with preceding EFs 35 and 200)Es is 200

–EF of H is 235• Forward pass gives us ES, EF and Project

duration




Activity-on-Node Network Forward Pass



• For computation of forward pass the followingthree things are important

– Add activity times along each path in the network (ES

+ Duration = EF).

–Carry the early finish (EF) to the next activity where it

becomes its early start (ES) unless…

–The next succeeding activity is a merge activity, in

which case the largest EF of all preceding activities isselected.




•Starts from last project activity

• Each path is traced backwards by subtracting activity

duration for finding latest start (LS) and latest finish (LF)

for each activity.

• Before one can start the Backward pass the latest finishtime for last activity must be determined

• Selecting latest finish for last activity

– In early stages of project – EF time is used

– In case of multiple last activities activity with largest EF is

used

– If project dead line exists that date is used.

Activity-on-Node Network Backward Pass



Backward Pass Computation

• Three things to remember• Subtract activity times along each path in the

network (LF - Duration = LS).

• Carry the late start (LS) to the next activitywhere it becomes its late finish (LF) unless

• The next succeeding activity is a burst activity,

in which case the smallest LF of all precedingactivities is selected.



• Example –Begin with last activity (H). Let us presume EF = LF

–LS for H = 235 – Duration = 200

–LS for H becomes LF for E, G (200), LS for E (200-15) = 185 and G (200 -30) = 170

–LS for G becomes LF for F, its LS 20

– Activity B, C are burst activities to E and F

–Late finish for activity B is controlled by LS of E and F

– follow the arrow backward. LS for ES of E and F havebeen placed on the right hand side of arrow.

–Select the smallest of the values ((WHY?)

–Similarly for activity A, take smallest of LSs for B,C, D

Backward Pass Computation



Activity-on-Node Network Backward Pass

time mgmt slides

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