Piling Activity Example, Applicability of different methods to Estimate Activity Duration

Summary

The video script discusses the complexities of piling activity for bridge construction, emphasizing the impact of soil conditions on productivity. It explores parametric estimating, using winch productivity rates for soft soil and soft rock to calculate the duration of piling work. The script also highlights the challenges of estimating activity duration and the importance of considering uncertainties in project planning. It concludes by comparing different estimating techniques, including expert judgment and three-point estimates, and underscores the significance of accurate duration estimation for effective project management.

Takeaways

• 🏗️ The script discusses a construction scenario involving piling activities for a bridge with varying soil conditions on each side.
• 🔍 It highlights the impact of soil conditions—soft soil and soft rock—on production and productivity in piling operations.
• 📏 The script specifies the quantity of work, with 20 piles per abutment and each pile being 15 meters long.
• ⏱️ Productivity rates are given as 1.5 meters per hour for soft soil, implying different rates for soft rock, though not explicitly stated.
• 👷‍♂️ The process involves a winch-operated system for piling, where soil is removed and piles are poured into the ground.
• 🕒 The script emphasizes the importance of understanding the duration of work, which is initially calculated as 10 hours per day.
• 🔢 A calculation error is pointed out regarding the conversion of meters per hour to days, leading to a corrected estimate of 20 days for soft soil.
• 📉 The script suggests adjusting working hours to balance the duration of work between the two different soil conditions.
• 🛠️ It introduces the concept of parametric estimating, which uses factors like productivity and quantity to estimate project duration.
• 🤔 The challenges of estimating duration are discussed, including uncertainties due to variations and lack of concrete data.
• 📚 The script also touches on other estimating techniques such as expert judgment, analogous estimating, and three-point estimating, emphasizing their practicality and limitations.

Q & A

What is the main topic discussed in the script?

The main topic discussed in the script is the process of estimating the duration of piling activities for a bridge construction project, taking into account different factors such as soil conditions and productivity rates.

What are the two different soil conditions mentioned in the script?

The two different soil conditions mentioned are soft soil and soft rock.

How many piles per abutment are mentioned in the script for the bridge piling activity?

The script mentions that there are 20 piles per abutment for the bridge piling activity.

What is the length of each pile mentioned in the script?

The length of each pile mentioned in the script is 15 meters.

What is the normal productivity of a winch-operated system in soft soil as per the script?

The normal productivity of a winch-operated system in soft soil is stated to be 1.5 meters per hour.

What does the script suggest about adjusting the number of working hours based on different soil conditions?

The script suggests that one might decrease the number of working hours for soft soil and increase it for soft rock to balance the durations of piling activities on both sides of the bridge.

What is the concept of 'parametric estimating' as discussed in the script?

Parametric estimating, as discussed in the script, is a method of estimating project duration or cost by using a statistical relationship between historical data and other variables such as quantity or productivity.

What are some of the challenges mentioned in the script regarding parametric estimating?

Some challenges mentioned in the script regarding parametric estimating include uncertainties in productivity and the difficulty in obtaining accurate data for the estimates, which can lead to disruptions in project schedules.

What are the other duration estimating techniques briefly mentioned in the script?

The other duration estimating techniques briefly mentioned in the script are expert judgment, analogous estimating, three-point estimate, and reserve analysis.

Why might expert judgment be used instead of parametric estimating in some cases?

Expert judgment might be used instead of parametric estimating when there is a lack of historical data or when the effort to make a detailed parametric estimate is more than the value it provides, making it a more practical and efficient approach.

What does the script imply about the importance of accurate duration estimating in project management?

The script implies that accurate duration estimating is crucial in project management as it drives the planning process and can significantly impact the project schedule and resource allocation.

Outlines

00:00

🏗️ Piling Activity for Bridge Construction

The script discusses a bridge construction scenario involving piling with varying soil conditions, soft soil and soft rock, affecting production and productivity. It details the piling process using a winch-operated system and the normal productivity rate of 1.5 meters per hour for soft soil. The script also covers the calculation of the total quantity of work, which is 300 meters of piling for each abutment, and the duration of work, initially estimated at 20 days for soft soil and 60 days for soft rock. The speaker encourages questions and seeks to clarify the process of calculation and the factors affecting the duration of the piling activity.

05:01

📉 Adjusting Working Hours and Productivity

This paragraph explores the idea of adjusting working hours based on soil conditions, suggesting a decrease for soft soil and an increase for soft rock to balance the project duration. The speaker discusses the challenges of maintaining the same productivity rate and the impact of working day duration on labor costs. They also consider the use of two crews to expedite the work and the importance of understanding the project's uncertainties and variations. The paragraph concludes with a discussion on parametric estimating, emphasizing the importance of understanding the challenges and uncertainties involved in estimating project durations.

10:05

🤔 Expert Judgment and Heuristic Estimations

The speaker delves into the use of expert judgment and heuristic methods for estimating activity duration when exact productivity values and crew numbers are unknown. They acknowledge the practicality of relying on experienced individuals for reliable estimations, especially when the effort of detailed parametric calculations outweighs their benefit. The paragraph also touches on the concept of three-point estimating, which incorporates optimistic, most likely, and pessimistic estimates to account for uncertainty. The speaker mentions that while parametric estimating is structured and useful if data is available, expert judgment is often necessary due to the lack of precise information on site.

15:10

❓ Closing Questions and Summary

The final paragraph opens with an invitation for questions, serving as a conclusion to the discussion on project duration estimation techniques. It emphasizes the importance of accurate estimation as a foundation for effective project planning and management. The speaker warns against the common pitfall of working backward from an assumed duration without proper planning for resources and productivity, which can lead to project delays and inefficiencies.

Keywords

💡Piling activity

Piling activity refers to the process of driving piles into the ground to provide foundation support, especially for structures like bridges. In the video's context, it is the central operation being discussed, with different soil conditions affecting the productivity and duration of the work. For instance, the script mentions a piling activity for a bridge with varying soil conditions on each side, impacting the project's planning and execution.

💡Soft soil

Soft soil is a type of ground material that is easily compressible and can pose challenges for construction projects due to its instability. In the script, soft soil is contrasted with soft rock as the two different soil conditions on either side of the bridge project, which influences the piling process and the required work adjustments.

💡Productivity

Productivity in this context is the rate at which work is completed, measured in meters of pile driven per hour or day. The script discusses how soil conditions affect productivity, with the winch-operated system's normal productivity being 1.5 meters per hour in soft soil, which is a critical factor in estimating the project's duration and resource allocation.

💡Winch-operated system

A winch-operated system is a mechanical setup used to pull, lift, or let out cable or chain, often used in construction for piling. The script describes this system being used to drop the hammer for piling and extract soil, emphasizing its role in the piling process and its impact on the rate of work.

💡Abutment

An abutment is a solid support for a bridge or a retaining wall, typically at the ends of the span. The script specifies that there are 20 piles per abutment, which is important for calculating the total quantity of work and planning the piling operation.

💡Duration

Duration in project management refers to the total time required to complete a task or project. The script discusses the duration of piling activities in both soft soil and soft rock, and how adjustments to working hours and conditions can affect the overall project timeline.

💡Parametric estimating

Parametric estimating is a technique used to estimate the duration or cost of a project by using a statistical relationship between historical data and other variables, such as quantity or productivity. The script uses this method to calculate the piling duration based on the number of piles, their length, and the productivity rate.

💡Uncertainty

Uncertainty in the context of the script refers to the unpredictability or variability in factors that can affect project duration estimates. It is highlighted as a significant challenge in project planning, as it can lead to disruptions in the project schedule if not adequately accounted for.

💡Expert judgment

Expert judgment is the use of an expert's knowledge, experience, and insight to make informed estimates or decisions. The script mentions this as a method for estimating duration when specific data is not available, relying on the expertise of individuals familiar with similar projects.

💡Three-point estimate

A three-point estimate is a statistical technique used to account for uncertainty in project estimates by providing three values: optimistic, most likely, and pessimistic. The script discusses this method as a way to capture more information about the variability in project duration estimates.

💡Resource allocation

Resource allocation involves the process of assigning available resources, such as labor, equipment, and materials, to various project tasks. The script touches on this concept when discussing the need to balance the number of working hours and crew sizes to match the estimated durations for different soil conditions.

Highlights

The transcript discusses a piling activity for a bridge with varying soil conditions affecting production and productivity.

The number of piles per abutment is 20, with each pile being 15 meters long.

A winch-operated system is used for piling, involving pulling the winch to drop the hammer and extract soil.

Productivity in soft soil is given as 1.5 meters per hour, a key factor in estimating work duration.

The transcript explores the impact of soil conditions on the duration of piling work.

A calculation is performed to estimate the work duration for piling in soft soil and soft rock.

The concept of productivity is discussed in the context of piling work, with different rates for soft soil and soft rock.

The transcript mentions adjusting working hours to balance durations for both soil conditions.

Parametric estimating is introduced as a method for estimating project duration based on productivity and quantity.

The challenges of estimating duration when there are uncertainties in productivity are highlighted.

Different techniques for duration estimating are presented, including expert judgment and analogous estimating.

The limitations of expert judgment in the absence of concrete data or productivity values are discussed.

The use of heuristics and expert estimates in practical scenarios where detailed calculations may not be feasible is explained.

The transcript touches on the importance of understanding the uncertainty in duration estimates for effective project planning.

The concept of three-point estimating is introduced to account for optimistic, most likely, and pessimistic scenarios.

The transcript concludes with a summary of the duration estimating methods and their applicability in project management.

The importance of accurate duration estimation in driving the entire project management process is emphasized.

Transcripts

Now, I would like you to read this; it is an example in piling, and I would like you

to work this out.

So, what we have here is a piling activity for a bridge.

On one side you have soft soil and the other side it is soft rock.

In case, so now, this is yet another factor which can change your production and productivity

and the number of piles per abutment is 20, length of each pile is 15 meters, the working

time for the winchÉ.

So, you can see here, it is a winch

operated system, that they keep dropping the, you know where you pull it, pull the winch

and then you drop the hammer, and you know grab out soil and then you start pouring the

pile.

The normal productivity of a winch is 1.5 meters an hour is a progress you will make,

productivity in soft rock is so much.

So, you can assume that this is the productivity of soft soil.

Straight forward, why do not you just do the calculation and let . So, if you have any

questions, ask me.

So, what is our quantity?

.

So, I can take, so look at the productivity, it is given inÉ

per hour

What per hour?

Meter per hour.

Meter per hour meansÉ

Meter per hour or of pile length per hour.

So, it makes sense to put my quantities in what.

Meters

Meters, which means it isÉ

20 into 15

That is it.

After that on your soft soil, my productivity isÉ

1.5 meters per hour.

It is soft soil 1.5-meter perÉ

day

per hour

Normal productivity is 1.5 meters per hour.

Where did you get the day from?

15 meters into hours

Taking that is what, I am taking, okay there is a point here,1.5 meters per hour which

mean durationÉ

10 hours for one day

10 hours for one day, for soft rockÉ

coming to be 50, 0.5 into 7, 57 and two days and 60 days.

Duration

Duration is 1, 10 hours a day.

10 hours a day, 0.5 meters.

So, you have a total of 300 meters.

No, 300 minus 15 to pin out.

300 minusÉ

300 minus 15, because already we haveÉ 20 piles on each side per hour length.

20

20, 20

Piling for each of the abutment, so there will be two different times that will ((Refer

Time:).

So, the duration for this also is 10 hours a day.

No, no, the duration is for putting 300 meters of piling.

Okay, so that is okay.

The notation is same.

What is the conclusion?

I mean below soft soil you written it is the same duration.

So, I thought it was, both the same.

Not duration, so here I am actually going 15 meters an hour or as we said, I mean 1.5,

15 meters per day.

So, actually I should do 20 days.

Duration is 20 days.

So, duration of this thing, so total is equal to 20 days.

Here it is 65 meters, duration ofÉ

Work duration 10 hours, activity duration, how much.

60 days

60 days.

Now, in one case you have 20, the other case you have 60.

So, based on some of our earlier discussion, what would you do?.

I will decrease the number of working hours.

Would you decrease the number of working hours?

Actually I will decrease it for soft soil, and I will increase it for soft rock.

You can do that, but let say what I mean, let say from our project perspective I would

like both durations to be roughly the same.

If I decrease, see the problem were decreased the working day duration is I am going to

be paying the person the same amount for that day.

Now, productivity and orders.

I will finish this on 20 days and shift the equipment to the other side, and I have two

crew working.

So, on 20 days these only finish one-third and I have two crew, they are working to try

to bring this enough, so these are some of the options you will have when you start doing

things.

So, let us go through this, you have aÉ We have, this is 15É You have 15 meters per

day

and going in at 20 days as we calculated.

If you look at it for the soft rock, we have factored, we have taken the factored, and

it comes in 60 days.

So, here the other part look at is the way we have said 20 number of piles, but we are

looking at productivity asÉ So, we would, I mean the term they would use it depending

on piles diameter and length, it is dia into dia length, but here we have just taking length

assuming the dia because the diameters are constant.

Now, we can again take this with the working time factor, and we take it again as an 8.5

instead of a 10 hour day and what was 20 now becomes, 24 days; what 16 now becomes 71 days.

So, all these shows us that even something that is so simple can get a little more twisted,

it starts getting more and more complicated as we get variations and uncertainties from

different regions.

Are there any questions on what we call right now parametric estimating?

So, this is typically what we did here productivity; quantity is parametric estimating, the most

what do you think numerically sound way to go about it and you understand the challenges

behind it too.

We probably at least as far as the rest of this class goes we will not look at so much

as the factoring, we will mostly take duration as the value given and focus on doing other

calculations with that.

But, remember the uncertainty of getting this duration itself is the big question mark,

which sometimes causes most of the disruption in a project schedule.

When you get back into a, now looking a duration; there are certain durations which are independent

of productivity.

For example, a pile load test.

It has to be done, it will take a certain time independent of, you know what you do

and how you do, or you know, what is happening.

The same thing is curing of concrete.

I can change curing based on curing compounds, but given a certain spec it will take it is

time to cure.

I mean, the accelerated curing is possible, but again within that aspect, that is what

I have to wait for.

I cannot change it on the site based on a certain; you know crew size or anything else.

So, we are actually now coming back to the various techniques which we had shown earlier

for duration estimating.

You can see we had expert judgment, analogous estimating, parametric estimating, three point

estimate and reserve analysis.

Now, taking the first two, you know expert judgment and analogous estimating, these are

very much used in construction, but the only problem is they do not have a real base in

which people are using it today.

It just comes out what we called c to the points estimate and it continuous like that.

There are more formal ways such as the Delphi technique, you know which you have a serious

of experts when you keep asking them a question, now the question to like converge on a specific

number.

But, you know we have not used this into in the level which we need to yet, but that is

from the scientific perspective, but from the, here heuristic perspective it is used

significantly, and the main reason for this is as we discussed.

So, you know I will not have factored productivity value, I will not have a number of crew, I

will not know what the number of crew available to me when I go on to a site visit.

I will not know actual productivity, I only know total quantity of work, how can I actually

estimate activity duration.

So, all of the arithmetic we did will not be; we will not be able to do, and so we have

to result to the expert of heuristic; that is one, and sometimes it just does not make

sense to, you know calculate all these factors.

When there are experienced people, who can actually give you a fairly good reliable estimation.

I mean we did this kind of duration estimating last week in the earlier class, how much time

you need to study for a subject.

So, if I take that as an example, what isÉ Their standard estimate will give you a, based

on what.

heuristic expert

Absolutely heuristic expert, if wanted to make a parametric, what could I do.

parametric type, the number of chapter.

Number, you will start breaking down and the number of chapters, each chapter start putting

times on it you know and then, factor in your lunch breaks, factor in this, factor in that,

but sometimes the effort of making that estimate is more than you know the number that comes

you.

So, you will say I am just going to say half a day, and that is good enough.

So, that is the reason the experts estimates were used and it is very practical, and if

it is used correctly, it is something that is very valid.

When we, another fact we talked about uncertainty, you know duration three point estimate, so

this is a certainly more advance.

We know there is a lot of duration, I mean all the durations we talk about are come up

with uncertainty, and we have to start using probabilistic distributions, and we have options.

We can, the simple option is a three point estimate, which says again this is an expert

judgment, but not giving a single value; that giving a three value saying, you we can call

it the lowest more likely highest are you know optimistic most likely pessimistic.

So, you can have values like this, which are based on expert judgment or if you really

have data, you can go ahead and start plotting distributions of your duration and if you

start plotting distributions; obviously, you get capturing much more information than an

average.

So, far we have talked about the only average productivity, average and everything is based

on average.

Here we have a factored average, average for this kind of work in this height; that is

average on that, and that is how we are factoring it from on a basic.

Now, we start talking about more characterizing it in terms of uncertainties.

So, we will see both of this kind of duration distributions, one for PERT and one for Montecarlo,

later in the course.

We will not discuss very much about you know the derivation of the distributional things

that we learn how to use it at that stage.

So, if I go back to the techniques you know we have actually covered all of these techniques

very briefly; that is expert judgment, analogous and three point estimate.

We have covered parametric estimate in you know more detail because it is what is structured

and probably easier to use it if those numbers are available.

The reserve analysis is again like I said a buffering technique, which is mostly based

on expert judgment.

So, I am not covering that in detail, like I said there is very little material available

on how one technically goes about the reserve analysis.

And to summarize, we have covered all of these methods.

We talked about the duration; we have talked about the way to estimate; we discussed in

detail the parametric methods and the applicability of different methods.

If there are questions, I will take.

So, this is an important foundation to the whole planning issue, but a lot of times not

given appropriate time and we will just go with values, which then kind of squeeze the

whole thing and sometimes people actually work backward this.

We say this is the duration we want and without actually going into resources or anything,

we start plugging in the numbers which are expected without planning the resources or

the productivity and when they actually get on to the site and try to meet that duration

which they had assumed, they find they cannot, so very important estimate which drives the

whole project management.

Any questions?

Thank you.