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Project float vs total float

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Haresh Jayanth
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What is the difference between Project Float vs total float an also Value Engineering & constructability ?? Pls any one explain.



Haresh Jayanth




Zoltan Palffy
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total float is the difference between the late finish date and the early finish date this is on an activity by activity basis.

project float represents how much float time there is for the total project which is through the critical path of the project.

Value engineering is where you have a better way to do something than speficied and there is a cost savings associated with the better way and that cost savings ot VALUE is split btween the owner and the contractor.

Constructability is the review of the contract drawings prior to startng the project to determine how you are going to constrcut the project to see if you missed naything in your original bid and is there are any road blocks in your way. This is a project management technique used to reduce cost, avoid errors and avoid potential delays. 

Rafael Davila
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> Total Float – time period of potential activity delay that does not cause a delay of the project finish or any target date set in the project schedule.

> Terminal float – the duration between planned completion and the current contract Completion Date. This is also ‘owned’ by the Contractor and cannot be used to mitigate the effect of a compensation event.

Total Float – Free Float & Terminal Float

> Negative Float – the amount of time that must be saved to bring the project to completion on time.

> Free Float – time period of potential activity delay that does not cause a delay of any other activity in the project schedule.

  Both total and free floats may be applied to activity start and activity finish.

Occurrence of Two Total Floats in One Activity

> Interfering Float - is that part of the total float which causes a reduction in the float of the successor activities.

Interfering Float

Interfering and free float video

> Independent Float - the amount of delay which can be assigned to any one activity without delaying subsequent activities or restricting the scheduling of preceding activities.

10.4 Activity Float and Schedules

Independent Float video

> Relationship Slack [Slack] - the amount of ‘unused’ time difference between the predecessor and the successor activities or relative float in relationships. This slack value has nothing to do with the float values or either of the two activities that it relates. It merely indicates how close each predecessor is to becoming the driving relationship for the successor activity.

Relationship Slack [Slack]

> Start Flex shows if Activity start may happen earlier with the same activity finish without changing any other dates in the current schedule.

> Finish Flex shows the potential delay of the activity finish without the moving activity start date and that does not delay any other schedule activity.

> Super Float – the time period of potential activity finish delay without delaying the activity’s start and that does not delay the project finish date.  Super Float shows what maximum deceleration of activity execution is acceptable.

> DRAG shows an impact of the project activity on project duration.

> Assignment Float - Activity floats do not provide all the data necessary for project control. In the projects with the complicated resource assignments there may be situations when an activity has different start and finish floats. Its start cannot be postponed without delaying project finish date, although its finish can be delayed without serious consequences.  Resources are often separately assigned on an activity.  There are several types of independent assignments.  Thus, a team of resources can be assigned on an activity to do a certain amount of work, or for a certain period of time, while other resource teams perform the rest of activity work independently - earlier, simultaneously or later.

RCP and Assignment Floats

> Buffer - CCPM is based on the assumption that the critical chain can be protected by using excessively large buffers something that is impractical in most construction schedules. Too much buffer and frequently a continuously changing Critical Chain/Path It make no sense to manage buffers no longer feeding into the critical chain. Managing Student Syndrome, Parkinson law and buffers can be done without the need of specialized software if you understand CPM and Project Risk Analysis. CCPM

Resource Critical Path Approach to Project Management by Vladimir Liberzon

Five Behaviors That Can Reduce Schedule Risk

An analysis of Critical Chain concepts

All these parameters are useful for project schedule analysis and decision making.

Patrick Weaver
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Total float is an activity by activity calculation and done properly is the result from (LF - ES) - Duration: see:  Every activity has TF, the value may be positive, 0 or negative.

Project float is usually the difference between the scheduled completion date and the required/contracted completion date. I the schedule shows completion 10 days before the contract date the project float is +10.  This is usually (but not always) the float value on the project critical path.