|Pramod Yadav said: (Mar 19, 2018)|
|Crash time is the least time for construction. So it’s B.|
- 1 Is that time beyond which the activity Cannot be shortened by any amount of increase in resource?
- 2 What are the types of time estimate?
- 3 What is float time in critical path?
- 4 Why do we estimate time?
- 5 What are the two types of estimation?
- 6 What is minimum time in critical path?
- 7 What is free float or slack time?
- 8 When estimating time for activities a PM should?
What is the standard time that an estimator would usually allow for an activity?
Normal time : (i) Normal time is the standard time that an estimator would usually allow for an activity.
Is that time beyond which the activity Cannot be shortened by any amount of increase in resource?
Crash time is that time, beyond which the activity cannot be shortened by any amount of increase in resources.
What are the types of time estimate?
The Three Chances – There are three estimation times involved in PERT; Optimistic Time Estimate (TOPT), Most Likely Time Estimate (TLIKELY), and Pessimistic Time Estimate (TPESS). In PERT, these three estimate times are derived for each activity. This way, a range of time is given for each activity with the most probable value, TLIKELY. Following are further details on each estimate:
What is the estimation time?
The term ‘time estimation’ refers to the assessment of the number of hours needed to complete a task or a series of tasks. The deeper your understanding of work specifics and nuances is, the more accurate time estimates you can receive.
What is float time in critical path?
Late Start Dates – The next step is to work through the network diagram from right to left beginning with the mandated completion date, which is a milestone that is set in the project plan. Subtract the duration of each activity in each path to determine the latest date the activity could begin and still meet the project completion date.
- Subtract the predecessor activity’s duration from its late finish date.
- Subtract the or add the to the late finish date.
- Refer to the that applies to the people and equipment necessary for the activity, and subtract the number of off days that the activity would span on those calendars.
- Assign the calculated date as the late start date of the predecessor activity.
The difference between the and the late start date for activities on the is usually the same as the, unless the activities are affected by the differently in the forward and backward pass. For example, if a piece of key equipment is only available for a few days, activities that depend on it have the same start and finish dates in the forward and backward passes.
To calculate total project float, begin at the start date and add the duration of each activity in each possible path through the network diagram, including nonworking days from the, to determine the early project end date. The longest path through the network is the, The difference between the early end date and the required completion date of the project is the total project float, and the start date of each activity is the, To calculate the late start dates, begin with the required project completion date and work backward, subtracting the duration of each activity though each possible pathway.
The path through the network that results in the latest completion date of the project. The earliest date the activity can begin. Activities that have predecessor-successor relationships occur sequentially—one after the other. An account of time must go by before a successor activity can begin.
The successor activity can overlap the end of its predecessor activity and begin before the predecessor is finished. A calendar that indicates which days they are available and which are days off to consider the availability of team members, consultants, and vendors. If the critical path takes less time than is allowed by the client to complete the project, the project has a positive total float or project slack.
If the client’s project completion date precedes the calculated critical path end date, the project has negative float. The difference between the finish date of the last activity on the critical path and the project completion date. The calculated completion date of the last activity is later than the targeted completion date established at the beginning of the project.
What is float time?
Float time refers to the amount of time between when an individual writes and submits a check as payment and when the individual’s bank receives the instruction to move funds from the account. Before the implementation of the Check Clearing for the 21st Century Act (Check 21), the average float time was two to four days. Now, most checks clear within a day.
What is crash time in project management?
What is crashing in project management? – In its simplest terms, crashing is a method in project management that helps you speed up the timeline of a project through the addition of resources. Project managers and stakeholders often use this method to either preserve a project’s estimated deadline or expedite it.
- Project crashing provides your team with the additional resources needed in critical moments to meet project deadlines.
- There are many project decisions that could be described as crashing.
- It could mean including more team members to work on a task so it will be completed faster.
- Crashing may also involve paying an additional fee for faster results.
Incentivized third-party contractors could provide additional manpower to help up a work schedule. The goal of crashing in project management is to reduce the length of a project and its time-consuming tasks while also keeping costs minimal to mitigate budget concerns and retain satisfied stakeholders.
What is a three time estimate?
Three-point estimation In this technique, each task receives three estimates: optimistic, most likely, and pessimistic. Each of these three estimates is then associated with the corresponding amount of time that task is expected to take.
What is estimate and its types?
Estimates is defined as the process of calculating the probable quantities and costs of various items required in connection with work. Estimate is prepared by calculating the quantities from the dimension on the drawings for various items required to complete the project and multiplied by the unit cost of items concerned. Purpose of Estimates:
- To know the amount of money required to complete the proposed work.
- Estimates know the quantities of materials required in order to program their timely procurement.
- This assess the requirement tools, plants and equipment required to complete the work according to the program.
- To draw up the construction, schedule and program and also to arrange funds required according to the programming.
- To fix up the completion period from the volume of works involved in the estimate.
- For inviting tender and prepared bills for payment.
- To justify the investment from the benefit cost ratio.
Types of Estimates:
- Preliminary approximate estimate
- Plinth area estimate
- Cubic contents method
- Approximate quantity method
- Item rate estimate
- Revised estimate
- Supplementary estimate
- Annual repairs
It gives the approximate cost of work and is prepared the basis of cost of similar works carried out in past
It is prepared after its complete set of drawings are ready This is the accurate method of estimating. Interested in learning about similar topics? Here are a few hand-picked blogs for you!
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Why do we estimate time?
You need to estimate time accurately if you’re going to deliver your project on time and on budget. Without this skill, you won’t know how long your project will take, and you won’t be able to get commitment from the people required to help you achieve your objective.
What are the two types of estimation?
It is often of interest to learn about the characteristics of a large group of elements such as individuals, households, buildings, products, parts, customers, and so on. All the elements of interest in a particular study form the population. Because of time, cost, and other considerations, data often cannot be collected from every element of the population.
- In such cases, a subset of the population, called a sample, is used to provide the data.
- Data from the sample are then used to develop estimates of the characteristics of the larger population.
- The process of using a sample to make inferences about a population is called statistical inference,
- Characteristics such as the population mean, the population variance, and the population proportion are called parameters of the population.
Characteristics of the sample such as the sample mean, the sample variance, and the sample proportion are called sample statistics. There are two types of estimates: point and interval. A point estimate is a value of a sample statistic that is used as a single estimate of a population parameter,
What is project time estimation?
What is project estimation? – Project estimation is the process of forecasting the time, cost, and resources needed to deliver a project. It typically happens during project initiation and/or planning and takes the project’s scope, deadlines, and potential risks into account.
What is float and lag?
How is float time calculated in critical path analysis? And what is total float in the critical path method? Is total float a slack? – The Total Float and slack are synonymous. The Total Float is the difference between the project completion date and the total duration of critical path activities. In summary, Find the second-longest sequence of activities in the network diagram. Subtract its total duration from the duration of the critical path sequence. The difference between the two durations will give you the float for each activity in the second sequence.
What is float construction?
Who Owns The Float Experienced contractors and construction attorneys know that practically time always is of the essence on a construction project, regardless of what the contract says. This is particularly true on today’s complex construction projects where almost every line item or specified scope of work is governed by an ever evolving Critical Path Schedule (“CPS”).
A typical CPS dictates the start date of key work, its duration, and when it must be finished to maintain the ultimate completion date. However, a CPS also typically includes certain non-critical work items that have an element of “float” or “slack” that can be utilized before the completion of those items impacts the overall critical path or completion date.
Given that time and associated delay claims can lead to some of the largest issues on a construction project, an interesting question arises concerning “float” or “slack” in the schedule; namely, who owns it? As a general matter, float can be defined as an amount of time that a project activity can be delayed without affecting the project completion date.
If a project activity is said to have zero float, any delay to that activity will result in a corresponding delay to the project completion date (this is a critical path activity) unless recovery measures are taken. If a project activity has positive float, that activity can be delayed until the float reaches zero, without delaying the project completion date.
Thus, float can be a valuable asset to the extent it can be used to absorb or offset a delay in a zero float activity and can serve to recover the CPS completion date. Understanding that float is a valuable asset, the question becomes, which party to the construction project is entitled to control or use the float? As will be discussed further below, the answer to this question can, and should, be answered by looking to the language of the contract between the Owner and Contractor.
In the absence of controlling contract language, however, there generally are three competing arguments concerning who owns the float. The three arguments are: 1) the Contractor owns the float; 2) the Owner owns the float; and 3) the project owns the float. The merits of each argument are discussed in turn below.
The Contractor Owns the Float The most common argument, and perhaps the general rule, is that the Contractor owns the float. The logical basis for this argument is that the Contractor typically creates the CPS, determines the sequence of construction activities, and thereby creates the float.
- If the Contractor created the float through its own scheduling/sequencing, and can directly impact the float based on the performance of its work, the Contractor should own the float.
- Furthermore, it is often assumed that the Contractor is the party with the most risk relative to any delays and is therefore in the best position to responsibly utilize the float.
In essence, if the Contractor created float through its scheduling/sequencing activities, the Contractor should be permitted to utilize that float to offset any delays experienced in zero float activities. A Board of Contract Appeals recognized a contractor’s interest consistent with this argument.
- The Court stated, allows the manager latitude in the scheduling of non-critical activities that originate or terminate at that event, and to effect trade-offs of resources to shorten or control his project. Joseph E.
- Bennett Co,, 72-1 BCA ¶9364(GSBCA 1972) at 43, 467 n.7.
- The general rule there is that a contractor cannot recover delay damages where he and the owner are jointly responsible for the delay.
In other words, any contractor-caused delay will bar his claim. However, the courts have refused to apply this rule where the contractor caused delays occurred on items which did not lie on the critical path. The necessary implication is that the contractor had the right to delay those items to the extent of their “float:’ and thus that the float was his” The Owner Owns the Float While the general view is that the Contractor owns the float, there is an argument that the Owner should own/control the float.
This argument is based on the assumption that the Owner has paid for the Contractor’s services, the CPS, and any resulting float as part of the cost of the project. Since it theoretically has paid for the project sequencing and management, the Owner argues that it should be entitled to control float generated as a byproduct of those efforts to reduce the Owner’s costs and control the progress of the project.
Similar to the Contractor, an Owner can incur significant additional costs if its project is delayed and thus the Owner has an interest in making sure any float is used to its benefit. Even further, proponents of this argument take the position that by allowing the Contractor to use float, the Owner is granting the Contractor an extension of time when the Contractor has not actually been delayed or otherwise entitled to such an extension.
Of course, this argument ignores the fact that using float does not actually extend the Contractor’s time for completion of the project. Regardless, there is an argument that the Owner should be entitled to the most efficient performance of the work possible by controlling the Contractor’s use of float.
The Project Owns the Float The third argument for ownership of the float is that neither party should exclusively control the float. Under this theory, the project should be the beneficiary of the float and it should be used on a first-come, first-serve basis by whoever needs the float.
If the Contractor needs to use the float to recover the schedule due to a delay in a critical activity, the Contractor can use the float. If the Owner needs to use the float to ensure the efficient completion of a non-critical work item to obtain a financial benefit to the project, the Owner can use the float.
However, the key to this argument is that the parties use the float in good faith, for the benefit of the project. For instance, the Contractor should not claim a time related change order for an item when float time exists to compensate for the time that otherwise would be needed.
- Such allocations of float do not advance the interests of the project and therefore are not legitimate under this view of float allocation.
- Conclusion Given that there is not a significant amount of case law on the three arguments discussed above, and respective jurisdictions may treat the issue differently, the best way to address ownership of float is through specific language in the contract between the Contractor and Owner.
Obviously, you can minimize the risk of dispute by drafting in a provision that specifically provides that one or the other party specifically owns the float. Alternatively, some common clauses addressing the issue of float are so called “joint ownership” and “non-sequestering” clauses.
A generalized example of such clauses is as follows: Float, slack time, or contingency within the schedule (i.e., the difference in time between the project’s early completion date and the required contract completion date), and total float within the overall schedule, is not for the exclusive use of either the Owner or the Contractor, but is jointly owned by both and is a resource available to and shared by both parties as needed to meet contract milestones and the contract completion date.
The Contractor shall not sequester shared float through such strategies as extending activity duration estimates to consume available float, using preferential logic, or using extensive crew/resource sequencing, etc. Since float time within the schedule is jointly owned, no time extensions will be granted nor delay damages paid until a delay occurs which extends the work beyond the contract completion date.
Since float time within the construction schedule is jointly owned, it is acknowledged that Owner caused delays on the Project may be offset by Owner caused timesaving (i.e., critical path submittals returned in less time than allowed by the contract, approval of substitution requests and credit changes which result in a savings of time to the Contractor, etc.).
In such an event, the Contractor shall not be entitled to receive a time extension or delay damages until all Owner caused timesaving are exceeded and the contract completion date is also exceeded. Obviously the clauses provided above are complementary by indicating that float can be used by either party to meet contractual milestones or completion dates (joint ownership clause), but neither party may consume all of the available float by extending activity durations or employing resource loading/sequencing strategies (non-sequestration clause).
It also is key to note that such clauses typically do not allow for extensions of time, delay claims, or the assertion of liquidated damages until a delay occurs that extends the work beyond the contract completion date. Thus, this type of language follows the “project owns the float” argument where the goal is to complete the project on time without additional costs.
To the extent a client has specific questions about the issue of float, they should follow-up with counsel to review this issue. : Who Owns The Float
What is minimum time in critical path?
What is the Method? – The concept of CPM is quite simple and may best be illustrated in terms of a project graph. The graph is not an essential part of CPM; computer programs have been written which permit necessary calculations to be made without reference to a graph.
- Nevertheless, the project graph is valuable as a means of depicting, visually and clearly, the complex of jobs in a project and their interrelations.
- First of all, each job necessary for the completion of a project is listed with a unique identifying symbol (such as a letter or number), the time required to complete the job, and its immediate prerequisite jobs.
For convenience in graphing, and as a check on certain kinds of data errors, the jobs may be arranged in “technological order,” which means that no job appears on the list until all of its predecessors have been listed. Technological ordering is impossible if a cycle error exists in the job data (e.g., job a precedes b, b precedes c, and c precedes a ).
- Then each job is drawn on the graph as a circle, with its identifying symbol and time appearing within the circle.
- Sequence relationships are indicated by arrows connecting each circle (job) with its immediate successors, with the arrows pointing to the latter.
- For convenience, all circles with no predecessors are connected to a circle marked “Start”; likewise, all circles with no successors are connected to a circle marked “Finish.” (The “Start” and “Finish” circles may be considered pseudo jobs of zero time length.) Typically, the graph then depicts a number of different “arrow paths” from Start to Finish.
The time required to traverse each path is the sum of the times associated with all jobs on the path. The critical path (or paths) is the longest path (in time) from Start to Finish; it indicates the minimum time necessary to complete the entire project.
- This method of depicting a project graph differs in some respects from that used by James E.
- Elley, Jr., and Morgan R.
- Walker, who, perhaps more than anyone else, were responsible for the initial development of CPM.
- For an interesting account of its early history see their paper, “Critical-Path Planning and Scheduling.” 1 ) In the widely used Kelley-Walker form, a project graph is just the opposite of that described above: jobs are shown as arrows, and the arrows are connected by means of circles (or dots) that indicate sequence relationships.
Thus all immediate predecessors of a given job connect to a circle at the tail of the job arrow, and all immediate successor jobs emanate from the circle at the head of the job arrow. In essence, then, a circle marks an event—the completion of all jobs leading into the circle.
Since these jobs are the immediate prerequisites for all jobs leading out of the circle, they must all be completed before any of the succeeding jobs can begin. In order to accurately portray all predecessor relationships, “dummy jobs” must often be added to the project graph in the Kelley-Walker form.
The method described in this article avoids the necessity and complexity of dummy jobs, is easier to program for a computer, and also seems more straightforward in explanation and application. In essence, the critical path is the bottleneck route. Only by finding ways to shorten jobs along the critical path can the over-all project time be reduced; the time required to perform noncritical jobs is irrelevant from the viewpoint of total project time.
Why is it called a float?
A floating point number, is a positive or negative whole number with a decimal point. For example, 5.5, 0.25, and -103.342 are all floating point numbers, while 91, and 0 are not. Floating point numbers get their name from the way the decimal point can “float” to any position necessary.
- Due to this, in computer science, floating point numbers are often referred to as floats.
- Other common types of numbers in computer science are integers, short, and long.
- While some programming languages define these different types of numbers, others don’t.
- For example, in C you need to store the number 18 as an integer ( int ), and 50.3233 as a float ( float ).
Integer Definition Rational Number Definition Irrational Number Definition Natural Number Definition
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What is free float or slack time?
What Is Float in Project Management? – In project management, float, sometimes also referred to as “slack,” is a number that indicates the amount of time a task can be delayed without impacting subsequent tasks or the project’s overall completion. It’s important to track when you are maintaining your project schedule,
- Free float is the amount of time that a task can be delayed without impacting the subsequent task.
- Total float is the amount of time a task or a project can be delayed without impacting the overall project completion time.
Float is a key piece of the critical path method (CPM), a system used by project managers to efficiently schedule project activities.
How you will estimate the expected time for an activity?
Using the PERT Formula – The PERT estimate (E) is based on a formula that includes your optimistic time estimate (O), your most likely time estimate (M) and your pessimistic time estimate (P). The basic equation is this: E = (O + 4M +P) / 6, If you have a hard time with equations, consider using a PERT calculator on the web to simplify things a bit.
When estimating time for activities a PM should?
13. When estimating time for activities, a Project Manager should: –
Use the best guess and estimate all activities since there will be changes as the project progresses and more information becomes available Involve people who will be doing the work to get estimates Estimate for what the cost will allow and include buffers None of the above
What is the most likely time estimate?
Time Estimation in PERT (With Calculation) | Project Management There are three different estimates of activity duration in PERT: 1. Optimistic 2. Pessimistic 3. Most Likely.1. Optimistic time, expressed as ‘t o ‘,represents estimate of minimum possible time by which an activity can be completed assuming that everything is in order according to the plan and there can be only minimum amount of difficulty.2.
- From the above three different estimates, PERT suggests work out of the expected time, expressed as ‘t e ‘ assuming that the probability distribution of the activity duration follows beta-distribution and, thus, t e is the average of t o t p and t m calculated as,
- t e =t o + 4 x t m + t p /6
- This averaging is explained with the assumption that, for every activity, when the t ij is estimated 6 times, the pattern of such estimated time will be once t 0 four times t m and, again, once t p, This can be illustrated in a time scale as follows when t o = 3, t p = 9 and t m = 6 then, as per the formula,
- t e =t o + 4 x t m + t p /6= 3+ 24 + 9/6 = 6; when the three estimates are placed in time scale.
- Three estimates, as above, when placed in time scale, will appear as:
When the probability follows beta distribution (as assumed in PERT), and in the scale of time, time units 12 represents 100 per cent probability, then time units 6 is 0.5 or 50 per cent probability. The most likely estimate is a probability of 0.5. As we have noted in the averaging formula the weightage for t o t m and t p are 1, 4, and 1, respectively.
- PERT considers t e as more probable time estimate for activities and then the network construction and the critical path is drawn considering t e -s for the respective activities.
- The estimate of t e as explained here is more reliable as it takes into account the longest and the shortest possible time estimates also and it provides a probability of 50 per cent.
- Once the t e is worked out for each of the activities the network can be constructed following the same principle discussed earlier and is illustrated below:
- From the three different time estimates, t e is worked out for each activity shown above.
- The network is constructed in PERT as per the t e developed from the three different time estimates as shown below:
All the different estimates of time as well as the worked out t e are shown in the above network diagram against the relevant activity. There is, however, no specific rule for writing such estimates on the network.
- We will now redraft the network (to have a cleaner diagram) with only the t e and work out the Critical Path as per the following steps:
- Step 1. Calculating ESTs and plotting them on the network as detailed below:
- event ① = start with 0;
event ② = EST of tail +t e i.e.0+5=5 days
- event ③= 0+ 14 days;
- event ④ = 5+15=20 days
- event ⑤ = highest of 14 +9, 5+8, and 20+4(as there are different tail events) = 24 days;
- event ⑥ = 24+5=29 days
Step 2. We are to come backward from the end event ⑥. Calculating the LFTs and plotting them on this network as follows: of event ⑥ = EST of event (6) = 29 days, as already found in Step 1; of event ⑤ = LFT of head event minus t e, i.e.29 – 5 = 24 days;
- of event ④ = 24 – 4 = 20 days;
- of event ③ = 24 – 9 = 15 days;
- of event ② = lowest of 24 – 8,20 – 15 and 15-9 (as there are three different head events) = 5 days;
- of event ① = 5-5 = 0 day.
- With the ESTs and LFTs calculated as detailed in Step 1 and Step 2 above we will produce the network diagram as:
- Step 3:
We know the events having same EST and LFT are on the critical path and now we find those are 1, 2, 3, 4, 5 and 6. The critical path is now shown by double-line arrows and the project duration is 29 days. This is subject to the random variation of the actual performance time as against t e (time estimates for PERT) of 5, 15, 4 and 5 time units for activities on the critical path.
What is the good practice in estimating the duration for an activity?
Three-Point Estimates – Under the three-point estimates procedures, the PERT (Program Evaluation and Review Technique) is the most broadly utilized statistical tool to decide the time duration of a project. In Project Management, the PERT technique is the best way to determine the estimated activity durations of a Project.