Time Planning and Control

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Arthur Davis
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1 Time Planning and ontrol Precedence iagram G44 NGINRING MNGMNT 1

2 Precedence iagramming S ctivity I LS T L n important extension to the original activity-on-node concept appeared around 14. The sole relationship used in PRT/PM network is finish to start type of dependency, with s i =. Precedence diagramming includes precedence relationships among the activities. In ddition, one may specify a lag time associated with any of the precedence relationships, which can be used to account for overlapping times among activities. The computation of activity times (published in 173) is more complex than ON. G44 NGINRING MNGMNT 2

3 Lag / Lead Times In many cases, there is a delay between the completion of one activity and the start of another following or there is a need to show that one activity will overlap another in some fashion. successor "lags" a predecessor, but a predecessor "leads" a successor. Lag time can be designated on a dependency line with a positive, negative, or zero value. Limitations and isadvantages of Lag: Lag would complicate the scheduling process. Lags are not extensively used except where the time effects are substantial for special proect type. S ctivity I LS T L G44 NGINRING MNGMNT 3

4 Precedence iagramming Relationships Types and constraint 1. Start-to-Start (SS i ) i [() cannot start till (i) starts] SS IJ SS i is equal to the minimum number of time units that must be completed on the preceding activity (i) prior to the start of the successor (). Lag is always applied to SS relation. 2. inish-to-inish ( i ) [() cannot finish till (i) finishes] i IJ i is equal to the minimum number of time units that must remain to be completed on the successor () after the completion of the predecessor (i). G44 NGINRING MNGMNT 4

5 Precedence iagramming Relationships Types and constraint 3. inish-to-start (S i ) [() cannot start till (i) finishes] S i is equal to the minimum number of time units that must transpire from the completion of the predecessor (i) prior to the start of the successor (). 4. Start-to-inish (S i ) [() cannot finish till (i) starts (rare)] i S IJ S IJ ' S i is equal to the minimum number of time units that must transpire from the start of the predecessor (i) to the completion of the successor (). i S IJ '' G44 NGINRING MNGMNT

6 Precedence iagramming Relationships Types and constraint. Start-to-Start and inish-to-inish (ZZ i ): ZZ i is a combination of two constraints, i.e., a start-to-start and finish-to-finish relationship. It is written with the SS i time units first, followed by the i time units. S uration ctivity (i) LS Total loat L Types of constraints with lag/lead urations SS S S ZZ i i i i SS i( i i) S uration ctivity () LS Total loat L G44 NGINRING MNGMNT

7 Precedence iagram omputation S ctivity I LS T L orward Pass omputations Initial Time i + S i [1] S = Max. all i S i + SS i i + i S i + S i - [2] = S + G44 NGINRING MNGMNT 7

8 Precedence iagram omputation S ctivity I LS T L ackward Pass omputations Terminal Time LS -S i [3] L i = Min. all L - i LS -SS i + i L -S i + i [4] LS i =L i i G44 NGINRING MNGMNT

9 Precedence iagramming alculations XMPL or the given precedence diagram, complete the forward and backward pass calculations. ssume the proect starts at T=, and no splitting on activities is allowed. lso assume that the proect latest allowable completion time (proect duration) is scheduled for 3 working days. evelop system spec. (=) SS 3 4 Write comp. program (=12) S SS Test & debug program (=) S 12 ecument program (=12) ollect system data (=4) S Run program (=) G44 NGINRING MNGMNT

10 Precedence iagramming alculations ON diagram evelop system spec. (=) SS 3 4 Write comp. program (=12) S SS Test & debug program (=) ollect system data (=4) S 12 S ecument program (=12) Run program (=) N G44 NGINRING MNGMNT 1

11 Precedence iagramming alculations xample omputation ctivity ctivity ctivity S S Initial Time S Initial Time Max( ) S SS S Initial Time S Max ( ) S SS 3 S 4 13 SS 3 S 4 SS 4 13 S 12 S orward Pass omputations 12 [1] S [2] Initial Time i S i Max( all S i ) i SSi i i Si Si S N G44 NGINRING MNGMNT 11

12 Precedence iagramming alculations xample omputation ctivity ctivity ctivity Initial Ti me S Max() S 1 1 S 1 21 Initial Time S S Max (, ) OR, S S S SS 3 S 4 SS Initial Time Max ( ) S S OR, S S S 12 S orward Pass omputations [1] S [2] Initial Time i S i Max( all S i ) i SSi i i Si Si S N G44 NGINRING MNGMNT 12

13 Precedence iagramming alculations xample omputation L LS Terminal Time 3 ctivity ctivity ctivity L LS L LS L Terminal L Tim e TerminalTime 3 LS S Min(, ) OR L S L 24 1 ackward Pass omputations Terminal Time LS S i [3] Li Min( all L ) i LS SSi i L Si i [4] LS L i i i SS 3 S 4 SS S 12 S N G44 NGINRING MNGMNT 13

14 Precedence iagramming alculations xample omputation ctivity ctivity ctivity L LS L LS 3 Terminal Time 3 LS S Min( ) Or LS 1 1 S L TerminalTim 1 3 e 1 LS S Min( ), OR LS SS L 112 Terminal Tim e 3 L Min ( ) L LS SS LS L 11 3 SS 3 S 4 SS S 12 S 1 3 ackward Pass omputations Terminal Time LS S i [3] Li Min( all L ) i LS SSi i L Si i [4] LS L i 3 3 i i N G44 NGINRING MNGMNT 14

15 Precedence iagramming alculations omputing Slack Time (loat Time) arliest arliest Latest Latest On Start inish Start inish Slack ritical ctivity S LS L LS S Path No No No No No No G44 NGINRING MNGMNT 1

16 xample 2 S ctivity I LS T L Given the precedence network for a small engineering proect with activity durations in working days, it is required to compute the activity times (S,, LS, and L) and total floats (T) and then indicate the critical activities. 3 S 3 I SS S 2 1 ZZ 3,2 J 1 L SS 4 S 13 H S 3,4 7 K S 4 G44 NGINRING MNGMNT 1

17 xample 2 alculate the arly activity times (S and ). S ctivity I LS T L S 3 I SS S 2 ZZ 3,2 J L SS 4 S 13 H 22 S 3,4 7 K 1 S 4 G44 NGINRING MNGMNT 17

18 xample 2 alculate the late activity times (LS and L). S ctivity I LS T L S 3 I SS S 2 ZZ 3,2 J L SS 4 S 13 H 22 S 3,4 7 K 1 S G44 NGINRING MNGMNT 1

19 xample 2 alculate Total loat for an activity. S ctivity I LS T L S 3 I SS S 2 ZZ 3,2 J L S 3,4 S 4 SS S H K 22 1 G44 NGINRING MNGMNT 1

20 xample 2 Indicate the critical activities. S ctivity I LS T L S 3 I SS S 2 ZZ 3,2 J L S 3,4 S 4 SS S H K 22 1 G44 NGINRING MNGMNT 2

21 Notes on Schedule HMMOK TIVITY n activity that extends from one activity to another, but which has no estimated duration of its own. It is time-consuming and requires resources, but its duration is controlled, not by its own nature, but by the two activities between which it spans. Its S and LS times are determined by the activity where it begins and its and L times are dictated by the activity at its conclusion. xamples: ewatering, Haul road maintenance G44 NGINRING MNGMNT 21

22 MILSTONS Notes on Schedule Milestones are points in time that have been identified as being important intermediate reference points during the accomplishment of the work. Milestone events can include dates imposed by the customer for the finishing of certain tasks as well as target dates set by the proect manager for the completion of certain segments of the work. G44 NGINRING MNGMNT 22

23 MILSTONS Notes on Schedule istinctive geometric figure is preferred to represent a milestone (circles, ovals, or other shapes) can be used. ny information pertaining to a milestone and considered to be useful may be entered. G44 NGINRING MNGMNT 23

24 Notes on Schedule Reducing Proect uration How can you shorten the schedule? Via Reducing scope (or quality) dding resources oncurrency (perform tasks in parallel) Substitution of activities G44 NGINRING MNGMNT 24

Time allowed: 1.5 hours

Time allowed: 1.5 hours Student name College of ngineering Civil ngineering Department G 404: NGINRING MNGMNT Second Semester 1438/1439H (MODL NSWR) FIRST MIDTRM XM Monday 24/6/1439H (12/3/2018G) from 7:00 to 8:30 PM Time allowed: