Networking And Scheduling

NETWORKING AND SCHEDULING 5

NetworkingAnd Scheduling

Networkingand scheduling

Whenplanning for a project, the project is usually sub-divided into manyinterrelated tasks. The order that these sub-divided tasks willfollow must be planned. If the order is erroneous, the final projectresult will most likely be faulty also. A good plan can schedule sometasks to be performed side by side. All these can be simplified byclearly illustrating the schedule. This is done either manually or byuse of specialized softwares.

Networkdiagram is a flow chart used for project planning. It is designed tocritically analyze and represent the roles involved in a givenprojecttill completion, and how they relate to each other. Network diagramassists to define the project`s path, delineates the sequence ofroles, the interrelations of each activity, assesses the project’selement dependencies, set up simultaneously running tasks, andassists in project monitoring and evaluation.

Thefirst and crucial step in planning the city Green Space project is toknow the required tasks and the sequence they must be completed in.The order for some tasks (e.g.Removal of all garbage typewaste from the site, removal of other wastes such as concrete andbuilding rubble from site, overall grading for site to obtainrequired site profile and drainage, building and preparation offlower beds, plant flowers in beds etc. may be easy and simple torecord and illustrate. However, other tasks may prove difficult torecord and estimate time. This is especially so for tasks whichoverlap or are done concurrently. Estimated time ordinarily reflectsthe normal, non-rushed time. The time scheduled can be reduced tosave costs, but, runs the risk of interfering with the projectquality.

Ina network diagram the information covered is: the name of theactivity undertaken, the normal duration/time, the early start time(ES), the earliest finish time (EF), the late start time (LS), latestfinish time (LF) and slacker.

Thetasks to be covered are labeled using letters. The roles which can beaccomplished together are A and B these tasks in our subject projectinclude the removal of hazardous wastes (e.g. oil, batteries) fromsite, the removal of all garbage type wastes from site, remove wastesuch as concrete and building rubble from site, overall grading forsite to obtain required site profile and drainage. C represents thosetasks which can only be done after the preceding tasks are completed(C, cannot commence until A is finished), in the project Green City these tasks include building and preparation of flower beds,building of brick pathways through green space and installation ofthe required signage throughout green space. Each task also has threeestimates in time optimistic -O, non-rushed time-M, pessimistictime-P. Expected time-TE.After determining the project completion expected time, we will thenascertain the late start and end of each task undertaken. This willassist to show if the scheduled activities have slack.

Activity

Predecessor

Time estimates

Expected time

Opt. (O)

Normal (M)

Pess. (P)

A

2 weeks

4 weeks

6 weeks

4.00

B

3 weeks

6 weeks

9 weeks

6.33

C

A

3 weeks

4 weeks

7 weeks

4.17

D

A

4 weeks

5 weeks

10 weeks

5.33

E

B, C

4 weeks

5 weeks

7 weeks

5.17

F

D

2 weeks

3 weeks

8 weeks

3.50

G

E

2 weeks

4 weeks

8 weeks

4.17

Thisschedule will assist in building up our project network diagram.

ProjectNetwork Diagram

Therequest for speeding up the project will call for inclusion of safetyin the baseline plan in order to cater for unexpected disruptions.Such disruptions are the major cause of delay in most projects. Humanerror can also be avoided by cautiously observing safety duringproject execution. Reactive scheduling should also be incorporated totake care of disruptions that cannot be absorbed in the baselineschedule.

Sinceestimation is an inexact act, the best approach of completing theproject on time and, or even before the estimated time will call intoplay many factors. Experience with similar projects, if the weatheris good/ conducive, if building materials are procured and deliveredon time, the construction workers/crew is on time. However, whenrains disrupt the construction program, materials arrive late crewdelay due to sicknesses (pessimistic estimate) must also be scheduledand planned for.

Sometimesit is possible to reduce the time taken by an individual to completean activity by paying more (over time). If the project is to behastened, will have to spend more money to speed things up. Theactivities that can be sped up are those on the critical path.However, this presents a challenge since some activities on thecritical path are more expensive than the others. Again, if you speedup an activity on the critical path, the critical path may itselfevolve to some other set of activities. All activities must bescrutinized simultaneously using a nifty optimization formulation.

Ina complex project such as the City Green, numerous resource typesare deployed viz bulldozers, graders, mixers, electricians,engineers, dump trucks, excavators etc. A single activity carriedout involves several of these resources. To plan this combinatoriallyproblem effectively and save projects’ time is quite a challenge.This can be tackled by heuristics.

Withall factors planned for the project will definitely run smoothlyaccording to the schedule.