overall project scheduling

8/13/2019 Overall Project Scheduling

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Chapter 8

OVERALL PROJECT SCHEDULINGRoger G. Haga and Richard P . Campbell

Project Controls Divisio n Stearns Ca ta ly ti c Corp.Denver, Colorado

IntroductionProject scheduling

. What i s i t ?Why i s t done?

. Who does i t ?How i s t done?

. When i s t done?These are some o f th e que sti onsth a t w i l l be addressed i n t h i s

paper. I t i s intended th at byexploring these questions, anunderstanding o f project schedul in g,i t s purpose and b en ef it s can beachieved. The purpose o f t h i sa r t i c l e i s n ot t o de sc ribe i n d e ta i lhow t o schedule , but rather t ogive an overview of the schedulingfunction on a project.

A success fu l schedul ing e f f o r ti s dependent upon th e peoplerespons ibl e for developing,implement ing and mon itor ing thesch edu le, and th e to o ls andprocedures t ha t are used. Thesethr ee elements are in tegra lcomponents o f projec t schedu ling.What is i t ?

A schedule i s the in tegra tion o fnetwork relationships, resourceco ns tra in ts and th e calendar. The

schedule i d e n t i f i e s when thea c t i v i t i e s w i l l be done, while thenetwork st a te s when th ey must bedone. Networking tech niq ues are th emost widely accepted scheduling toolfo r complex projec ts. The be ne fi to f the network i s the s imp l ic i t y inil lu st ra ti n g, presenting andanalyzing the dependencyrelati onsh ips o f a project. Thelogic network i s the foundation o fth e schedule . When calendar da te sare applied t o th e lo gic network, tbecomes a schedule which providesthe basis for evaluat ion o f projectsta tus , forecasting the occurrenceo f events and c ontr oll in g th eproject.

The sequence o f ac t i v i t i es tha trequires the longest time t ocomplete determines the overallduration o f the schedule. Thislongest sequence o f a c t iv i t ie s i scalled th e cr it ic a l path . Thecritical path method C P M ) i s usedt o describe t h is par t icu lar schedulenetwork methodology. The two commonconventions o f CPM networks are thearrow diagram met hod (ADM) and theprecedence diagram method P I M ) .There are arguments i n favor o f each

o f thes e two methods, and u su al lythe one that i s used i s a mat ter o fpersonal pr efer enc e, projectdirective or corporate procedure.

7 7


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CONCENTRATION AND DEWATERING CIRCUITSA comparison of the two i s shown

i n F i g u re 1. The ADM ne tw ork showst h e a c t i v i t y a s an ar ro w w i t h n od es

i - j ) a t ea c h end t o i d e n t i f y i twh il e t h e PDM network shows t h e worki t em i n a box w i t h a s i n g l ei . d e n t i f i e r t o d e s c r i b e i t . In PDM,networks a re de scr ibe d by twosepar a te componen ts : a c t i v i t i e s andre l a t i ons h ip s . The t ime e lement o fa n a c t i v i t y i s i t s durat ion. Theti.me el~emento f a r e l a t i o n s h i p i sr e f e r r e d t o a s a l a g . I n ADMhowever , th e a c t i v i t y embodiesc h a r a c t e r i s t i c s o f t ime a s w e ll a s1.ogic. I n ad d i t i o n t o t h ef i n i s h - to - s t a r t r e l ~ a t i o n s h i p n ADMPDM re1 a t i o n s h i . p ~ n c l u d e s t a r t - t o -s t a r t , f i ni s h -t o - fi n is h , e t c .

T h ere a r e o t h e r s ch ed u l in gtechn iques t ha t can be used ,howeve r, t h e CPM i s probab ly themost comnon i n t he co ns t r uc t i onindus t ry .

T he fo rma ts av a i l ab l e fo rp re s e n t a t i o n o f s ch ed u l e i n fo rma t i ona r e v a r i e d a nd i n c l u de p r i n t e d o r

format should be s el ec te d which be s ts u i t s t h e p u rp os e. Bar c h a r t s a r egood f o r upper management review .They a re c onc i s e and a l low a b r i e fo v e r a l l p i c t u r e o f p r o j e c t p r o gr e s s.For pro je ct management revi ews , at ime-scaled bar ch ar t or 1ogi.c d iagramo f s p e c i f i c p r o j e c t a r e a s mi gh t bemore su i t ab le . Se lec ted d i sc i.p l ine ,p ro j e c t a r ea o r acco un t s ch ed u l esegments or break-outs a r e gooddocuments fo r schedu le a na ly s i s andco n t r o l . A l ~ l f t h e s e fo rma t s can b eaccomnodated f or t h e same sch edu les i nc e th e inf ormat i on comes from acomnon da ta bas e. Fi gu re showsexamples of v ar io us formats o r 1evel.so f d e t a i l av a i l - ab le . Ch a r t s g en e ra tedf rom schedu le da ta o f f e r a weal th o finf orm ati on on a sing1 e page and canmake a complex r e l at io ns hi p muchcl ea re r than f i .gures o r words , andp re s en t i t with l e s s ambigu i ty . Amanager can quick1.y v i s u a l i z e at r en d . A ls o, t h e co n t en t o f t h ev a r i o u s fo rma ts can be ea s i l ycustomized t o meet exc ep t ion re por t in grequ i rements by se le c t in g o rsummarizing the schedule informat ion.

p l o t t e d re por t s and g raph ics . TheDM / PDM ONVENTIONS 1

RELATIONSHIPc ADYc PDYcACT pJ jy

rm m TO n A AK @

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OVER LL PROJECTSCHEDULING

t h e ad ven t o f s o p h i s t i c a t ed p ro j ec tP R O J E C T C O N T R O L S G R P H I C S management sof twa re programs and t h emicro computer, computer based

L ;_LOGIC DI GR M B RCH RT

LOGIC B RCH RT CUMUL TIVE

ISTOGR M

Fi g u reWhy i s i t done?Why prepare a schedu le?

rOMBIN TION

Almost every thing we do req ui re st ime, and s i nce t ime in t he bus inessworld is a valuable comnodi ty , i t suse needs t o be we ll planned. Wea l l p lan o ur t ime , o r s ch ed u leev en ts which conc ern us. Byd e f i n i t i o n a p r o j e c t i s a p l an ; ascheme; a proposal; a plannedunder tak ing . P lanning i s animportant par t of any project ands i n ce t h e p lan n in g p ro ces s d e f i n e st h e e v e nt s and a c t i v i t i e s r e q u ir e dt o c a u p l e t e t h e p r o j e c t , t h o seeve nts must be sequenced i n th eproper t ime f rame o r schedu led fo ra suc ces s fu l p ro je c t complet ion.The amount o f d e t a i l i n th e schedu ler e l a t e s d i r e c t l y t o t h e s i z e o rcomplex i ty o f t he p r o je c t i n t ermso f t h e number of a c t i v i t i e s t o b eaccompl ished and th e in te r f ac esb e t w e e n a c t i v i t i e s .

Although PM t echn iques can beimplemented manually, a lo gi cn e t w o rk g rea t e r t h an 200 a c t i v i t i e scan be main ta ined more e f f i c i e n t lywi th th e ai d of a computer. With

s ch edu l i ng i s w e l l w i t h i n t h e r eachof a lmos t any s i z e p ro jec t . Theadvantages of computer basednetworking go beyond hand1 ing la rg evolumes of da ta and crun chin gthrough complex ca lc ul at io ns . Thecomputer can a l s o make i t a ne f f i c i e n t o p e r a ti o n t o p r ov id e t h efollowing:

Inc rea ses accuracy and da tai n t e g r i t y i n c a l c u l a t i n g t im ereq u i r ed t o co mp le t e a p ro j ec tQ ui ck ly p r i o r i t i z e s r emai ni nga c t i v i t i e s a t any p o i nt a lo ngt h e p r o j e ct l i f e c yc l eId en t i f i e s where t h e s ch edu l ecan b e acce l e r a t edForms th b a s i s f o r e va l u a ti o no f r e s o ur c e u t i l i z a t i o n andeff icient resource managementP r ov i de s t h e b a s i s f o reva lua t ing th e phas ing o f mejorp ro j ec t e l ement s ( en g i n ee r i n g ,p rocurement , mater i a ld e l i v e r i e s , and co n s t ru c t i o n )Mechanism fo r perfor mancerep or t i ng and record ing as wel la s a cc um ul at in g h i s t o r i c a l d a t aPermit s rap id eva lu a t io n ofa l t e rn a t iv e p lans /methods( what i f sce nari os)Forms bas i s fo r eva lua t ing t het i m e impact of changes and delaysL eas t co s t s ch ed u l e an a l y s i sPermits f requent updat ing andrap i d t u rn a ro u n d o f r ep o r t sThe s ch ed ul e e s t ab l i s h e s a b a s i s

from which t h e p r o j e c t a c t i v i t i e scan be c ont ro l le d o r managed. ta ll ow s v i s i b i l i t y a s t o w hic ha c t i v i t i e s a r e c r i t i c a l and whicha c t i v i t i e s h av e enoug h f l o a t t o b escheduled for optimum use of


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CONCENTR TION ND DEW TERING CIRCUITS

re sou rc es. Resources may be def ine das manpower, equipment or c ap it al .

Manpower resources should bepla nne d f o r e f f i c i e n t u t i l i z a t i o n .Under id ea l cond i t io ns i t i sreasonab le t o expec t a s t eady bu i ldup of manpower e f f e c te d by t h ere l ea s e of work ac t i v i t i e s . I t i snot adv i sab le t o r e lea se worka c t i v i t y i n a f as hi on t h a t r e s u l t sin f l uc tu at io ns of the manpowerl ev e l . T hi s r e s u l t s i nin ef f i c i en c i es caused by th eposs ib le as signment of d i f f e r en tpersonnel during t he peak periodsand the unstea dy flow of work, thu sincreas i ng c os t s due t o poorproduct iv i ty . I f the same personnela r e r e t a i n e d on t h e p r o j e c tthroughout t he peaks and va ll ey s ofth e work load to main ta in co n t in u i tyand f am i l i a r i ty wi th the work, thei n e f f i c i en cy en co un te red i s i n t h eform of increased co st due t omain ta in ing the same payro l l dur ingsl ac k per iod s of work. Resourcemanagement can be acco mp lis hedth rough the use of the computer f i l eso t h a t a c t i v i t i e s w l l be scheduledb as ed o n r e s o u rce c r i t e r i a .Purpose o f resource a l l oc a t ion :O A llows fo r r e a l i s i c o p t i mi za t i o n

of p lanO T i e s p r o j e c t e s t im a t e t o p l a nO Allows f or inco rpor at io n of

manpower and equipmentl i m i t a t i o n s i n t o p l an .D et ermi nes f ea s i b i l i t l y o fcomple t ing wi th in a s pec i f i e dtimef rame

a A l l o c a t e s f l o a tTypes o f resource l imi ta t ion s :

Labor poolEquipment ava i l ab i l i tya Conet r u c t ion menpower dens i t e s

Financ ia l resourcesThe schedu le p rov ides th e bas i s

fo r p r ed i c t i n g o r fo r ecas t i n g ca shflow and t he to ol fo r managing i tI t may be de s i r ab le t o de lay the

commitment of c a pi ta l u n t i l thel a t e s t p o i nt i n t im e t h a t a ll ow s t h epr oj ec t to be completed on t ime, o ri t may be adv ant age ous t o makece rt ai n commitments ea r l y due t od i s co u n ts , e s c a l a t i o n c l a us e s , e t c .The s ched ul e pro v id es t h e v i s i b i l i t yt h a t management needs t o make c ashflow management dec is io ns . Figu re 3i s an example of a Cash Flow Curveshowing one curve fo r an ea r l y s t a r tand a no th er f o r a l a t e s t a r tschedule. The optimized curve i sbased on the most e f f i c i e n tu t i l i z a t i o n of r e s o urces . F i gu re 4i s an example of manpower cur ve s byperiod and to-date.

T l M EFigure

So, i t i s concluded th a t p lann ingand schedul ing should be done t osome ex te nt on any pr oj ec t t o manager e so u rc e s and c o n t r o l t h e p r o j e c t t oa c hi e ve t h e de s i r ed r e s u l t ,recognizin g th a t t he amount ofd e t a i l and t h e p r e s e n t a t i o n forma ti s determined by t he p ro je c t s needsWho Does I t ?

Development of th e pro je cts ch ed ul e i s a p a r t i c i p a t o r y e f f o r t .Everyone on th e p ro je ct team fromt h e p ro j ec t manager t o t h e end u s e ris responsible for the developmentand maintenance of the schedulemaking t h i s a team e f fo r t .Depending on the s i z e of th e pro jec t


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OVER LL PROJECTSCHEDLlLlNG 74

SCHEDULEDEVIATION

CHEDULED CTUAL SCHED ULED PHYSICA L COMPLETION

Figureand t he complexi ty of th e schedul ingtoo l s t o be used, a p l anner /s c h e d u l e r s p e c i a l s t may be assignedto th e pr o j ec t team. Ihe p lanne r /s ched u l e r s p rimary r e s pon s ib i l i t yi s t o h e l p c o o r d in a t e t h e s c he d ul edevelopment e f fo r t a s we l l a s da t amanagement and t h e imple men tatio n ofschedul ing t oo ls and procedures .The sc hed ule go al s and majorm i l es tones a re u sua l l y desc r i bed andprovided by t h e owner. Major ev en tsand a c t i v i t i e s a r e d es cr ib ed o rimpl ied by th e scop e of work.A d d it i on a l a c t i v i t i e s a r e d es c ri b edby t he p ro je c t ex ecut ion p lan andth e p roduc ts r equ i red t o achi eve t hep r o j e c t g o a l s and o t h e r d e l i v e r a b l e 8requi red by con t ra c t . We can seet h a t b ec au se o f t h e v a r i e t y ofi n fo rm at ion r equ i red , t he re a re anumber of people i nvolved i n t h eplanning and schedu l ing e f f o r t . Thec l i e n t , t h e p r o j e c t manager, t h eco ns tr uc t ion manager, th eengine ering manager, th e procurement

manager and pr oj ec t co nt ro ls managera r e a l l key members o f t h e p r o j e c tteam and a r e a l l c o n t r i b u t o r s t o t h ep ro j e c t s chedul e de f i n i t i o n . Notonly i s t h e ~ a r t i c i p a t i o n f t he s eteam members i n de fin in g t h es c he d ul e r e q u i r e d , b u t t h e i rcommitment t o t h e sc hed ule i s whatmakes th e pr oj ec t a success . Ihep r o j e c t s c h e d u le r i n t e r f a c e s w i t ha l l t h e se pe op le o r t h e i rr e p r e s e n t a t i v e s when h e e s t a b l i s h e st h e s c h ed u le a c t i v i t i e s and l o g i c .t i s a l s o t h e r e s p o n s i b i l i t y o f

t h e s e pe rs on ne l t o p a r t i c i p a t e i ns t a tu s ing and upda t ing t h eschedule . Ihe pro jec t sched ulerf a c i l i t a t e s and p ro v id e s s c h e du l in gexp er t i s e t o accom pl ish t h eprocess . F igure 5 graphical ly showsthe se schedule in te rac t io ns . Thep r o j e c t s c h e d u le r a n a ly z e s t h eschedul e da t a and i s sues r ou t i nerep or t s t o pr o j ec t management a longwi t h recommendations t o r e c t i fy anyadver se t re nds t h a t may be detec ted .


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SCHEDULE MlTER CTNMlS How i s t Done?Schedule development u su al ly

begins with somewhat limitedM N QEMENT i nf or ma ti on . Q ui te o f t e n a l l t h a ts known ar e a few s ig ni fi c an t

milesto nes e st ab li sh ed by the ownero r cl ie nt . The amount ofin fo rma t ion av a i l ab l e s u su a l lyco n s i s t en t w i th t h e s t ag e t o whichth e pro je ct has developed fromproposa l th rough s t a r tu p . Sosch edu le s b egin a t a s imp le l ev e land develop wi th th e p ro je c t t o ade ta i l ed l ev e l a s more in format ionabout th e ta sk s t o be performed

COST CONTROL becomes av a i l ab le . The number ofschedule a c t i v i t i e s might range f romt e n t o f i f t y a c t i v i t i e s p r es en te d i na s imple bar cha r t fo r a p roposa l

Figure 5 sched ule whereas a t t h e d e t a i l edengineering phase of th e p ro j ec t

WBS EX MPLEF CILITIES EMPH SIS

LEVEL I F CI L I TY 117 F CI L I TY arLEVEL77 F CI L I TY 3rLEVEL 5 ~ l i ? e ? J ? S ? . . m . 3 . > q a . l . B . 8 . J 7 1 1 m 1 ~ 1 . I . . . l . J l 6 1 1 1 >Sx

Figure 6


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OVER LL PROJECTSCHEDULING 743the schedule could con tain a s manya s f i v e t o s ev en t ho us an d a c t i v i t i e so r more. Of cour se, t he a ct ua lnumber o f ac t iv i t i e s s r e l a t e d t othe s i z e and complexity of t hep r o j e c t .

The subjec t of the le ve l ofd e t a i l s i z e of netw ork) o f t e ng e n e ra t e s a g r e a t d e a l o fd iscuss ion. The le ve l of de t a i l i sgenera l ly de temi ned by th ei n fo r ma t io n r eq u i re d f o r R o j e c tManagement t o moni tor and c o n t r o lth e pro je ct These requirementss ho ul d b e c l e a r l y o u t l i n e d i n t h eproject scheduling procedures .Ac t iv i t i e s s hou ld be p roduc to r i e n t e d a n d a c t i v i t i e s i n s i g n i f i -can t to t ime o r r e s ou rce con s t r a in t smay be omitted.

of a WBS fo r a la rg e, complexp r o je c t. Ih e WBS s a s ys temat icmethod of sub div idi ng a complexpr oj ec t i n t o manageable workpackages while maintaining ano r d er l y s t r u c t u r e f o r r e po r t in g t oa l l pr oj ec t management leve ls. TheWBS becomes t h e fou ndati on f o res t ima t ing budgeting and schedulingt h e work See Figu re 7 . Zhe nexts t e p s t o l s t a c t i v i t i e si d e n t i f i e d by t h e WBS. Not everyele men t of t h e WBS s schedules i gni f ic an t and should not bei d e n t i f i e d a s a s e p a r a t e a c t i v i t y .A s re f l ec te d by th e WBS, an a c t i v i t y

s a ls o product or ien te d .

The f i r s t s te p in t he developmentof a pro jec t schedule s t odemonstrate an unders tanding of thescope of work by de sc ri bi ng t h e waythe work s t o be accomplished.This s e f f ec t ive ly donethrough the use of thework breakdovnstructure WBS).F igure i san example

W T ACCOUNT------J

Figure 7


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T h e b a s i c p r o j e c t o r g a n i z a t i o n a ls t r u c t u r e may be obvious. However,t h e o r g a n i z a t io n s t r u c t u r e ( 0 s ) i sfo rmal ized by ass ig n ing respons ib i l i t y f o r p e rf o rming t h e w ork byi nt e gr a t in g t h e OS with t h e WBS.When t h e pr o j e c t award i s made,a l l t h a t i s in hand i s t h e p r o p o s a lschedule . Th is schedule i s veryg e n e r a l and may b e o f l i t t l e u s e i nd e t e r min in g t h e d e t a i l s . Thep r o p o sa l s ch ed u le s e r v es i t s purposeby e s t ab l i s h in g major mi l e s to n es andt h e d e s i r e d o v e r a l l p r o j e c tdura t ion . The nex t s ta ge o f

schedule development i s t h e i n i t i a lp r o j e c t e x e c u t i o n p l a n f o r t h e n e xtn i n e t y d ay s. T h is p l a nn i ng e f f o r tr e q u i r e s i n p u t f rom t h e e n t i r epr o j ec t t eam, inc lu d ing the owner.I t i s d ev el op ed i n d e t a i l t o i n c l u d ea l l ma jor e ve n ts , a c t i v i t i e s ,i n t e r f a c e s , and du r a t i o n s f o r t h esp ec i f i ed p e r io d . I t sh o u ld i n c lu d ea l l a c t i v i t i e s t o be s t a r t e d wi th inth e per iod even though they may notbe scheduled to be completed. Th iss c he d ul e s e r v e s t h e p r o j e c t w h i l et h e c o n t r o l l e v e l s c h e du l e is beingdeveloped and preven ts a scheduleblack-out period.

One of t h e a c t i v i t i e s t h a t s h o ul dbe included i n th e 90-day schedu leis t h e d ev e lo p men t o f t h e P r o j ec tMaster Schedule or Level Ischedu le. The Maste r Schedule i sth e pr es en ta t i on format recommendedf o r re p or t in g t h e t o t a l p r o j ec t t othe owner. I t should be updatede ac h r e p o r t c y c l e t o show a c t u a lp r o g r es s ag a in s t s ch ed u led . I t i sp r e s e n t ed a s a t im e- sc al e d b a r c h a r tand sh o u ld b e l im i t ed t o ma jo r ev en ta c t i v i t i e s a nd ma jo r m i l es t on e s w i t ha p p r o p ri a t e r e s t r a i n t s a ndi n t e r f a c e s . F i g u r e i s an exampleof a Mas ter Schedule. The Maste rSchedule rep re se nt s a summary le v e lof t h e more d e t a i l e d c o n t r o l l e v e lschedule .

F ig u r eOnce th e WBS an d OS have b eendef in ed , we can proceed wi th t h edevelopment of th e network lo gi c,conc ur ren t wi t h t he development o fth e mas ter schedule . The in te r f ac esbetween Owner, EngineeringCo n t r ac to r , Co n s t r u c t i o n Co n t r ac to r ,Subcont rac tor , Vendor , Engineer ingD i s c i p l i n e s, e t c . a r e e s t a b l i s h e d by

agr eement among p a r t i c ip an t s a s t oth e r e l a t i o n sh ip s o f eac h p ackage o fwork t o a l l o th e r work p ack ag es.Handdrawn network diagram sketchesa r e us ed t o g r a p h i c a l l y show t h i sl o g i c a l s e qu en ce of a c t i v i t i e s a nde v e n t s a n d b e c o m e t h e i n i t i a lcomputer inp ut documents. From t h i spoint forward, computer-plot tedn etwo rk d i agr ams a r e u su a l l yp ro du ced f o r r ev i s i n g t h e n e two rklo g i c . The n ex t s t e p i s t o d e f in ea c t i v i t y d u r a t i o n s . By c o r r e l a t i n ga s s um p ti o ns t h a t a r e b e i n g us ed i ndevelop ing th e es t ima te t o t he WBS,p e r f o r m a n c e c r i t e r i a i s e s t a b l i s h e da nd d u r a t i o n s a r e c a l c u l a t e d a nda p p li e d t o e ac h a c t i v i t y .H i s t o r i c a l u n i t m a n h o u r v a l u e s p e rp r o d uc t , c r ew s i z e an d co mp os i t i o ne s t i m a t e s , as w e l l a s q u a n t i tyt a k eo f fs a i d i n e s ti m a ti n g a c t i v i t yd u r a t i o n s .An eva lu at io n may be perfonnect t op r e d i c t t h e o cc u rr e nc e o f t h ed e f i n e d a c t i v i t i e s o r e ve n ts . T hi si s us ua l l y accompl i shed by prepar i ng


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OVERALL PROJECTSCHEDULING

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. A

LEVEL

Figurea s e r i e s o f h i e r a r c h i c a l s c he d u le sof s ucces s ive ly inc reasing de ta i l .F igure 9 i s a ch a r t of t h i shierar chy. The le ve ls of schedulemay or may not c or re la te di re c tl y tothe W S le ve ls . However t h ed e t a i l s should summarize t o the W Slev els as wel l as t he per formingorganization information needs.

Due t o th e volume of a ri th me ti ccombinations t ha t may ex is t in avery de ta il ed o r complex networkt h e ne x t s t e p a f t e r t he l o g i cnetwork i s developed i s u s u a l l y t oinput the data in the computeru t i l i z i n g one of t he many schedulingso ware packages ava il ab le on themarket. The calen dar i s app lie d ands chedule da te s a r e ca lcu la ted fo reach o f the ac t i v i t i e s . Calendarscan be used which account forweekends hol id ays e t c . i fdes i r ed s o th a t the s chedule da te sar e ca lc ul at ed based on working daysonl y. Many of th e sof tw ar e packagesprovide the capabil i ty for a number

Figure 10of dat a manipulation func tions sucha s s o r t s e l e c t i o n s r es ou rc ea l l o c a t i o n and l e v e l i ng f l o a ta n a l y s i s e a r l y and l a t e d a t e sa c t i v i t y i d e n t i f i c a t i o n andc l a s s i f i c a t i o n e t c . F ig ur e 1 0dem onst rat es how da ta i s i np u t t o acomputer based schedule ma st er f i leand the p roduc t s t ha t a r e ava i l ab l efrom i tA t t h i s p o i n t i t i s impor tant t ove r i fy the ne twork l og ic p r io r t or esou rce load ing the ac t i v i t i e s .Resource loading and an al ys is i s oneof th e more di f f i c u l t and importants teps in the schedule developmentprocess. Through th e proc ess ofresourc e a ll o c at io n we confirm andenhance our understa nding of th e CPMmodel by assign ing res our ces t o thea c t i v i t i e s . R es ou rc e a l l o c a t i o na ll ow s f o r a r e a l i s t i c e v a lu a ti o n oft h e p r o j e c t p l an o n t h e b a s i s o fmanpower and equipment limitations.The schedul e th en becomes th e ba si sf o r manpower pr oj ec ti on s. Once th eresourc es have been loaded th e nexts t e p i s t o o pt im iz e t h e e f f i c i e n tuse of a vai lab le resources and leve lthe peaks and val le ys of no nc r i t i ca lresource requirements . This e f f o r tproduces the optimum schedule orbasel ine t o which a c t ua l per formanceand fo re ca st s ar e compared scheduleimpacts due t o changes and del ay s


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ar e assessed , upda t ing and ana lys i sr ep o r t i n g is per fo rmed , co r rec t iveac t i o n s a r e ev a l u a t ed , anda1 e rn a t ive p la ns a re compared .

The team review of th e sch edu lees ta bl is he s a commitment on th e par to f t h e u s e r s t o fo ll o w and ma i n t a i nt h e p r o j e c t s c he du le a s t h e c e n t r a lcontrol mechanism.When i s i t Done?

In ad d re s s i ng t h i s q u es t i o n , weneed t o l o ok a t t h e co n v ent i o n a lphases o f a p ro jec t Proposa l ,Prel i minar y Design, De ta i l Designand Procurement, Constr uct ion ,Mechanical Completion and Sta rt- up.T he re a r e v ar y in g l e v e l s o f d e t a i lf o r s ch ed u le s a s s o c i a t ed w i t h eacho f t h e s e p r o j ec t p h as e s w hi ch a r eu s u a l l y c o n s i s t e n t w i t h t h ec l a s s i f i c a t i o n o f e s ti m at es . Ihees t i ma t e of p ro j e c t co s t i sco n s i s t en t i n co n t en t w i t h t h e s co p eof work. t t r a n s l a t e s t h e w r i t t e ns co pe i n t o c o s t s a s s o c i a t e d w i t h t h ework breakdown s tr u ct ur e and accountc l a s s i f i c a t i o n . B ec au se c e r t a i ni t ems o f cos t a re schedu ledependent , i t would be veryd i f f i c u l t t o e s t im a t e th e c os t of ap r o j e c t a c c u r a t e l y w i t h ou t a n

DEVELOP M K A K D O W N l T R U C N R E R U

ap p ro p r i a t e l ev e l o f s ch ed u ledevelopment . L ikewise , th e de ta i ls ched ul e ac t i v i t y d u ra t i o n s d ependupon t h e i n p u t o f e s t i m a t e d a t a s u cha s manhours r eq u i r ed t o i n s t a l l anitem.

I f t h e e st i m a t e i s based onl i t t l e i nf or ma ti on , i t may b e te rmedo r c l a s s i f i e d a s C on ce pt ua l o r O rd erof Magnitude and w l l co n t a i n v e ryl i t t l e de ta i l . By th e same token ,th e schedu le fo r the same p ro je c tw l l be ver y surmnary, p er ha ps as imple barc har t which con ta ins themaj or mi l e s to n es o r p ro j e c t g o a l sand e s t a b l i s h e s t h e o v e r a l l d u r a t io n .

As informat ion i s developedt h ro u gh t h e s t u d y ph ase o rp re l i min a ry d es i gn , t h e e s t i ma t e canbe done i n more d e t a i l and may bec l as s i f i ed now a s a Pre l iminaryes t i ma te . I h e l o g i c o f t h e s ch ed u leexp an ds co n s i s t en t w i t h t h einfor mat io n lev el . Ihe number ofa c t i v i t i e s c an b e i nc r ea se d t oacco moda te th e knowledge o f th escope of work. The impact a t t h i sp o i n t i s p r i ma r i ly i n t h eengineering and procurementcomponents of t h e pr oj ec t . Thes ch ed ul e s u pp o r ts t h e i n i t i a lp ro jec t mi les tones and goa l s .

DEVELOP DETAILED NETWORK LOGIC

..DEVELOPILESTONES

MILESTONES

tYEAR TERM DETAILED SUPPORT SCHEDULES

t i

1 REPORTING LEVEL C O Y R O L L EV EL

PROPOSALSCHEDULE

Figure 11

SCHEDULE LEVEL 1 SCHEDULE LEVEL LEVEL 4LEVELt t .


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s t he p ro j e c t p rogre s se s i n t ot h e d e t a i l d e si g n p ha se i t i scus tomary t o perform a Def in i t ive orD e ta i le d e s ti m at e . f i e d e t a i l o fthe schedule can then be expandedfo r t he c ons t ruc t ion pha se of t h ep r o j e c t . I t should be noted tha tthe schedule base l ine remainsunchanged un les s th e scope of t hep r o j e c t i s changed su f f i c i e n t ly t oimpac t t he sc he du le c r i t i c a l path ,e i th e r through logic change o r byexceeding the l i m i t s of there sourc e s a va i l a b l e .

In summary, sch edu le developmentand updating is performed a t va r iou sphases of th e pro jec t in inc reas in gd e t a i l c o n s i s t e n t w i t h t h edevelopment of infor mation. Only a smuch d e t a i l a s i s re qu i re d t oc on t ro l t h e p ro j e c t need bedeveloped. The sche dule is adynamic tool and must be updated ands ta t use d throughout the pro jec tw it ho ut s a c r i f i c i n g t h e p r o j e c tgoal s. The schedule updatingp r oc e ss a l lo ws t h e p r o j e c t s t a t u s t obe known a t any poi nt in timeFigure 11 o u t l i n e s t h e v a r i o usl e v e l s of s c he du le s and r e l a t e s t h ele ve ls t o pr ojec t development.Summary

Define project scopeEstabl i sh projec t mi les tones andgoa l sDetermine project execut ionplan /work breakdown s t r u c t u r eDetermine projecti n t e r fa c e s r e s t r a i n t sDraf t logica l sequence ofa c t v i i e s even tsC a l c ul a t e a c t i v i t y s ch ed ul e d a t e s

Resource limitedTime limitedE ar ly s t a r tL a t e s t a r tE a r l y f i n i s hLa te F in ishF l o a tI de nt if y c r i t i c a l

a c t i v i t i e s / c r i t i c a l p athSummarize area/discipl ine/c r a f t i t a s k s c he d ul e s

E s t a b l i s h b a s e l i n esc he du le s / c he c k l i s t sU p da te le ta tu s a c t i v i t i e sAnalyze schedule t re nd s /variancePubl i sh schedule repor t s

B a r c h a r t sLogic char t sNetwork reportsManpower schedulesCash flowRecommend c o r r ec ti v e a c t on where

neededTake a c t i o n t o c on t ro l p ro j e c t

GLOSSARY OFSCHEDULING TERMS

ACTIVITY - a basic e lement ofwork. An a c t i v i t y occu rs over agiven period of timeACTIVITY DUBATION - t he e s t ima teo f a u n i t o f t ime ne c essa ry fo r t heaccomplishment of t h e work de scr ibe dby an a c t i v i t y , c ons ide ring t hena tur e of th e work and the reso urce sneeded for i tPBOY - t he g ra ph ic p re se n t a t i on

o f an a c t i v i t y i n ADM notat ion whichembodies cha ra c t e r i s t i c s of time a swe l l a s l og i c .ERCU DIAGBlllPiING METHOD ADl4) - a

method of construct ing a logicalnetwork of a c t v i i e s us ing a rrowst o r e p r es e nt t h e a c t i v i t i e s andconnect ing them head t o t a i l throughth e use of nodes, i . e . I andB R CEL4RT - a g ra ph ic p re se n t a t i onof work ac t i v i t i e s shown by atime-scaled ba r l i n e sometimesr e f e r r e d t o a s a G an tt c h a r t ) .BEGINNING NODE OF ~ T Y O W S T ~ IAnn ) a node a t which no a c t i v i t i e send, but one or more ac t i v i t ie s

begin.C LEND R - th e calendar used i nsc he du l ing a p ro j e c t p l a n ; i e ,hours, s h i f t s , days, weeks, months,year s or any combinat ions the reo f.Th is c a l e nda r c a n o f t e n be a l t e r e d


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so weekends, ho lid ays , weath er days,e t c . , a r e i nc lu de d o r e xc lu de d a sworking days.CODE OF ACCOlWS/CMRT OF ACCOWIS

sys te mat i c method of ide n t i fy i ng(number ing) co s t s incur red i n t h epr og re ss of the job. This methodal lows es t ima tes t o be compared t oa c t u a l c o s t s i n c u rr e d .COlIPLETED ACTIVITY an a c t i v i t yw i t h an a c t u a l f i n i s h d a te .COHCIWTUAL SCHEWLB a conceptualschedule i s s i m i l a r t o a p r o po s alschedu le excep t t i s u s u a l l ytime-scaled and s developed fromt h e a b s t r a c t d e s ig n o f t h e p r o j e c t .This schedule i s u sed p r i mar i l y t og i ve t h e c l i e n t a g e n e r a l i d e a ofth e p r o j ec t scope and an overv iew ofa c t iv i t i e s . Most concep tua lsched ules co nta in between 30 and 200a c t i v i t i e s .COST ESTIMATION Thedetermina t ion o f qua n t i ty and thep r e d i c t i n g o r f o r e c a s t in g , w i t h i n ad e f i n e d sc op e, o f t h e c o s t s r e q u i r e dt o c o n s t r u c t a nd e q ui p a f a c i l i t y ,t o manu fact ure g oo ds , o r t o fu rn i s ha se rv ice . Cost s a r e de te rminedu t i l i z i n g p a s t e x pe r i en c e a ndca l cu l a t i n g an d fo recas t i n g t h efu t u re co s t o f resour ces , methods,and management within a scheduledt ime f rame. Included in the se co s t sa r e assessments and an eva lua t ion ofr i s k s and u n ce r t a i n t i e s . Cos te s t i ma t i o n p rov i des t h e b a s i s f o rproject management , businessp lann ing , budget p repara t ion , andcos t and schedu le con t ro l .CRITICAL ACTIVITY a n y a c t i v i t yon a c r i t i c a l pa th .CRITICAL PATE sequence of jobso r a c t i v i t i e s i n a n etwork a n a l y s i sp r o j e c t such t h a t t h e t o t a l d u r a t i o nequ als t he sum of the du ra t i on s oft h e i n d i v i d u a l j ob s i n t h esequence. There i s no time leewayo r s l a c k ( f l o a t ) i n a c t i v i t y a lo ngc r i t i c a l pa th ( i e , i f t h e time t o

complete one o r more jobs in th ec r i t i c a l p at h i nc r ea s es , t h e t o t a lp roduct ion t ime increases )CRITICAL P TE SCHEDULING ORCRITICAL PATH METHOD CM) anetwork planni ng techn ique used f orp lann ing and con t ro l l i ng e lements ina pr oj ec t . By showing each of th e see lements and assoc ia ted l ead t ime,t h e c r i t i c a l p at h c an b ed et ermin ed . The c r i t i c a l p a t hi d e n t i f i e s t h os e el em en ts t h a ta c t u a l l y c o n t r o l t h e l e a d t im e o fth e p ro je c t . CPM uses vec t o rdiagrams. It i s eas i l y ru n o n acomputer.DATA DATE t h e c a l e nd a r d a t e t h a ts e p ar a t es a c t u a l ( h i s t o r i c a l ) d a t afrom scheduled data .DELIVERABLE a r e p o r t o r p rod u cto f o ne o r more t a s k s t h a t s a t i s f yone or more ob je ct iv es and must bed e l iv e r ed t o s a t i s f y c o nt r a c t u a lrequirements .DETAILED SCHKDULE t h i s s ch ed u l ed i s p l a y s t h e l ow es t l e v e l o f d e t a i ln ec e ss ar y t o c o n t r o l t h e p r o j e c tthrough job completion. The in te nto f t h i s s ch ed u l e i s t o f i n a l i z er ema in in g r eq u ir emen t s fo r t h e t o t a lp r o j e c t .ENDING NODE OF NETWORK ADM) anode wh ere no a c t i v i t i e s b eg i n , b u to ne o r more a c t i v i t i e s end .EVENT a n e v e nt i s a ni d e n t i f i a b l e s i n g l e p o i n t i n ti me ona p ro j ec t .FUYLT t h e t o t a l c us hi on o r s l a c ki n a network pla nni ng system. Syn:bank.FORECAST an es t imate andp red i c t i o n o f fu t u r e co n d i t i o n s andeve nts based on informat ion andknowledge a va i l ab le a t th e t ime o ft h e f o r e c a s t .P EE FUYLT FF) t h e amount oft ime ( i n work u n i t s ) an ac t i v i t y may


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OVERALL PROJECTSCHEDUI ING

be de la yed without a f fe c t i ng t hes t a r t of a ny o th e r a c t i v i t yinmedia te ly fo l lowing.INTBBPACE ACTIVITY a n a c t i v i t yconne ct ion from one subnet t o ana c t i v i t y i n a n o t h e r s u b ne t ,represent ing logica l in te rdependence .LAG t h e l o g i c a l r e l a t i o n s h i pbetween th e s t a r t a nd /o r f i n i sh o fone a c t i v i t y a nd t h e s t a r t a nd / o rf i n i s h of a n o th e r a c t i v i t y .HBCBAAICAL COMPLETION a f i xe dasset becomes mechanically completeupon t s ins e rv ice da te . Mechanica lcomplet ion s an event .HIIESfONE an important o rc r i t i c a l e v en t an d/ or a c t i v i t y t h a tmust oc c ur i n t h e p ro j e c t c yc l e i no r d e r t o a ch i ev e t h e p r o j e c tobjec t ive ( 8) .UIIESrONE SCHEDULE a schedulecomprised of key events orm i l es t on e s s e l e c t e d a s a r e s u l t o fc oord ina t ion be twe e n the c l i e n t sand t h e c o n t r a c t o r s p r o j e c tmanagement. These ev en ts a r ege ne ra l l y c r i t i c a l a cc ompl ishmen tsp la nned a t t ime in t e rv a l s t h roughou tt h e p r o j e c t and use d a s a b a s i s t omoni to r ove ra l l p ro j e c tperf orm ance . The fo rm at may bee i t h e r network or b ar c ha rt and mayc o n t a i n minim al d e t a i l a t a h i g h l ysummerized level.IIDNITORING pe r iod i c ga the r ing ,va l ida t ing and ana lyz ing var iousda t a on c on t ra c t s t a tu s t o det e rminea ny e x i s t i ng o r po t e n t i a l p rob le ms .Usua l ly one accompl ishes th i sthrough use of t he data provided i nc on t ra c to r r e por t s on sc he du le ,manpower, co s t and technic al. st a t u sto mea sure p rogre s s a ga i ns t t hee s t a b l i she d ba s e l i ne s f o r e a ch ofth es e re po rt ar ea s. However, whendeemed necess ary, on-s i t e ins pec t ionand va l i da t i on and othe r methods canbe employed.

NETWORK a g ra ph ic p re se n t a t i ono f a p r o j e c t d e p i c t i n g a l l s el e c t e da c t i v i t i e s o r su b ne ts and t h e i rp hye ic a l in te dependence andindependence.NETWORK ANALYSIS technique ueedi n p l an n in g a p r o j e c t c o n s i s t i n g o fa s eq uen ce of a c t i v i t i e s and t h e i ri n t e r r e l a t i o n s h i p w i t h in a n e tv o r kof a c t i v i t i e s making up a pro jec t .(See CRITICAL PATH).NETWORK PLANNING a broad gener ict erm f o r t e c hn ique s used t o p l a ncomplex projects . wo of th e mostpopula r t e c hn ique s a r e PERT and CPM.W E the symbol on a logicd iag ram a t t h e i n t e r s e c t i o n o fa rrows (a c t i v i t i e s ) . Nodes i de n t i fyc omple tion a nd /o r s t a r t o fa c t i v i t i e s .PDM FI NI SH TO FI NI SH BBLATIONSEIPFF) t h i s r e la t i on e hi p r e s t r i c t sthe f i n i s h of t he work i t em u n t i lsome spe c i f ied d ura t io n fo l lowingth e f in i sh of ano the r work i tem.PDM FINISE TO STAPT BBLATIONSHIPF S ) th e s tan dard node type ofr e l a t i o n s h i p a s used i n DM wherethe a c t i v i t y o f work i t em may s t a r tj u s t a s soon a s a no the r work i t em i sf i n i she d .PDM START TO FINISH BELATIONSEIP

S F ) t h e r e l a t i o n sh i p r e s t r i c t sthe f i n i s h of t he work i t e m u n t i lsome dura t i on fo ll owing th e s t a r t o fan ot he r work item.PDM STAPT TO STAPT BBLATIONSEIPS S ) t h i s r e la t i o ns h ip r e s t r i c t st h e s t a r t of t h e work i t em u n t i lsome sp ec i f ie d du ra t ion fo l lowingth e s t a r t of t he preceding work i tem.PrtaCENT CONPLETE a comparison ofvork completed t o th e cur ren tpro jec t io n of t o t a l work.PEMOBHANCB MEASUBLVIgNT BAggLINEthe t ime-phased budge t p lan aga ins twhich co nt ra ct performance i s


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measured. t is formed by thebudgets assign ed t o scheduled worke l ement s and t he app l i cab l e i nd i re c tb ud ge ts . F or f u t u r e e f f o r t n o tp lanned i n de ta i l , th e performancemeasurement basel ine a l so includesbudge ts a s s igned t o h igher l eve lCW S e l emen t s and und i s t r i bu t edbudget. t w i l l r e c on c il e t o t h econt ract budget base . t e q u a l s t h et o t a l a l l o c a t e d bu dg et l e s smanagement reserve.PLAN a pre det ermi ned co ur se o fac t i o n over a spec i f i ed pe r i od o ft ime which represents a pro jectedr e s po n se t o a n a n t i c i p a t e denvironment in o rde r t o accompl i sh as p e c i f i c s e t of a d a p t i v e ob j e c t i v es .PLANNIBG Ih e de te rm in at io n o f ap r o j e c t s o b j e c t i v e s a ndi d e nt i f ic a t i on o f t h e a c t i v i t i e s t obe performed, methods and resourcesto be used fo r accompl ish ing t h et asks , a s s i gnmen t o f r e spons ib i l i t yand accountabi l i ty , andes t ab l i shmen t o f an i n t eg ra t ed p l anto ach i eve comple t i on as r equ i red .PBBCEDEACB DUGBlUI HETBOD PDW)a method of l o g i c networking whichuses nodes t o r ep resen t t hea c t i v i t i e s and ar ro ws t o d es c r i b el o g i c r e l a t o ns hi ps .PBEDECZSSOB ACTIVITY anya c t i v i t v t h a t ex i s t s on commonp a th w i t h t h e a c t i v i t y i n q u e st i onand o c cu r s b e f or e t h e a c t i v i t y i nques t ion.PBOJBCT DUBATION t h e e l a pse dd u r a t i o n from p r o j e c t s t a r t d a t et hr ou gh p r o j e c t f i n i s h d a t e .PBOJECT P U i t is t h e p r imarydocument fo r p ro j ec t a c t i v i t ee . tc o ve r s t h e p r o j e c t from i n i t i a t i o nthrough completion.PROPOSAL SCHEDULE u s u a l l y t h ef i r s t s c h e d u l e i s s u e d o n a p r o j e c tand acctmpanies either t h e c l i e n t sreques t or the proposal . tcon a n s key engineer ing

procurement , and con s t r uct ionm i le s t on e , h i s t o r i c a l d a t a , and a nyc l en t -suppl ied informat ion .Usua l ly p resen t ed i n ba r ch a r t formor summary level CPM network , th i sschedule i s used fo r inq ui ry andc o n t r a c t n e g o t i at i o n s .RESCBBDULE t h e p ro ce s s ofchang ing t he l og i c du ra t i on , and /o rd a t e s of a n e x i s t i n g s ch ed ul e i nresponse t o ex te rn al imposedcondi t ions .RgSOURCK any f a c t o r s , exceptt ime, req uir ed or consumed t oaccomplish an a c t iv i t y . Somed i e t n c t i on is made between dol larsand o the r r e sou r ces due t o t hefo rmat o f r epo r t i ng and d i f f e rencesin t e rminology ( l i k e budget ve r susp oo l) . T e c h n i c a ll y , d o l l a r s a r e aresource .RSSOIJRCE ALLOCATION PROCESS RAP)- t h e s c he du li ng o f a c t i v i t i e s i n anetwork with the knowledge ofc e r t a i n r e s o u r c e c o n s t r a i n t s a n drequ i remen t s. Ih i s p roces s ad j us t sa c t i v i t y l e v el s t a r t and f i n i s hd a t e s t o c on for m t o r e s o u r c ea v a i l a b i l i t y a n d u s e .RESOURCE-LIMITED SCHEDULING t h es ch ed ul in g o f a c t i v i t i e s s o t h a tp rede t e rmined resou rce ava i l ab i l i t ypoo l s a r e no t exceeded. Ac t i v i t i e sa r e s t a r t e d a s soon a s r e s o u rc e s a r ea v a i l a b l e ( w i th r e s p e c t t o l o g i c a lc o n s t r a i n t s ) , a s r e q u i r e d by t h ea c t i vi ty . When not enough o f ar e so ur c e e x i s t s t o do a l l t a s k s o n ag i ve n d ay , a p r i o r i t y d e c i s io n ismade. R o j e c t f i n i s h may bed el ay ed , i f n e ce ss a ry , t o a l t e rschedules cons t ra ined by resourceusage.BHSPONSIBILI~ or ig in a t e s whenone acc ep t s t he as s ignmen t t operform aeeigned dut ies anda c t i v i t i e s . lhe a c c e p t a n c e c r e a t e sa l i a b i l i t y f o r which t h e as s ig n e eis h e l d a n sw er a bl e f o r a nd t o t h eass ignor . t c o n st i t u t e s a no b l i g a t i on o r a c c o u nt a b i l i t y f o rperformance.


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lgSTBaINT - an e xt er na ll y imposedf a c t o r a f f e c t i n g when a n a c t i v i t ycan be scheduled. The ex te rn alfa ct or may be labor, co st ,equipment, o r oth er such resource.SCIEDmg - the date for complet ionof a pro je ct based on an ordered s e tof a c t i v i t i e s and s e t t o a t im es ca le .SCOPE d e f i ne s t h e work t o bedone and i.s documented by thecon t r ac t parameter s o r a p ro jec t t owhich the company is committed.SCOPE CHMGE - a deviation fromthe p ro jec t s cope o r i g in a l l y agreedt o i n t h e c o n t ra c t . A scope changec a n c o n s i s t of a n a c t i v i t y e i t h e radded to o r de le ted from th eo r ig ina l s cope . A contrac t changeorde r i s needed t o a l t e r t h e p r o j e c tscope.STATUS the cond i t ion o f th ep r o j e c t a t a s p e c i f i e d p o in t i nt i m e . An ins tantaneous snapshot ofthe then cur ren t condi t ions .STATUS LINB a v e r t i c a l l i n e on at ime-scaled schedule indi cat ing th epoin t in time da te ) on which th es t a t u s of t h e p r o j e c t i s repor ted .Of ten ref er re d t o as the t ime now

n e. See DATA DATE.SUUXSSOB ACTIVITY any a c t i v i t yth e e x i s t s on a common pat h with thea c t i v i t y in question and occursa f t e r t he a c t i v i t y i n q ue st io n.TASK any de f in ab le un i t o fwork. I t must have an id en t i f i ab les t a r t and ending and usual lyproduces some recognizable result .TILIE-LMITED SCBEDDLIIC t h es chedul ing of ac t v i t es sop rede te rmined r e s oume av a i l a b i l i typools ar e not exceeded unless t hef u r t h e r d e l a y w i l l caus e the p ro jec tf i n i s h to be delayed . Ac t iv i t i e sca n be d el ay ed o nly u n t i l t h e i r l a t es t a r t da te . However, ac t i v i t i e sw i l l b e gi n when t h e l a t e s t a r t d a t e

i s r eached , even i f r e s ou rce l i m i t sa r e exceeded. Networks wi thnega tive t o ta l f lo a t t ime cannot beprocessed by time-limi ted scheduling.TIIIB-SCALED CPM - a networkdiagram where th e length of th ea c t i v i t i e s i n d i c at e s t h e d u r a ti o n oft h e a c t i v i t y a s drawn t o a c a l e n d a rs ca le .TOT L FLQhT TF) - the amount oft ime in work uni ts ) th a t ana c t i v i t y may be delayed from i t se a r l y s t a r t w i t h ou t de la yi ng t h ep r o j ec t f i n i s h d a te . T o ta l f l o a t i se q ua l t o t h e l a t e f i n i s h minus t h ee a r l y f i n i s h o r t h e l a t e s t a r t minust h e e a r l y s t a r t o f t h e a c t i v i t y .WORK BBZIAKD IWR STRUCTURE UBS) - ap roduc t -o r i ented h ie r a rc h ic a l f ami lyt r e e d i v i s i o n of a p r o j e c t i n t os ucces s ive ly g rea te r l eve l s o fd e t a i l w hich d i s p l a y a l l of the worke lements t o be per fo rmed r e l a t iv e t oeach o the r and the t o ta l p ro jec t .1) Co nt ra ct Work Breakdown

S t r u c t u re CWBS) - t h e c m p l e t eWBS f o r a c on tr ac t developedand used by a contractor inaccordance wi th t he c ontr ac twork statement. It extends thePSWBS t o th e low est l e v e la p p r op r i a t e t o t h e d e f i n i t i o nof the cont rac t work i n termsof account codes and workpackages.

2 ) ~ o j e c t ummary Work BreakdownS t r u c t u r e PSWBS) a summaryWBS ta i l or ed by pro j ec tmanagement t o the s pe c if icp r o j e c t w i t h t h e a d d i t i o n o fthe elements unique to thep ro je ct . ~ e f i n e e h e p r o j e c ts u b d iv i e i on s t o be u t i l i z e d f o rp ro jec t con t ro l .

overall project scheduling

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