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Estimating the Duration

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Ali Hamouda
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Hi there, Following the Question of "Activity sequencing and Duration Estimate" 1-Can any one till me who are the people that will be involved in estimating the duration,and what is the formula used to do that(the way of calculation)?.

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Rafael Davila
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100%

Also useful for these activities you do not have historical records, something must be plugged in, averages from these references are better than pure imagination.

Hi Rafael,
I agree with your statement that "the best production rates are the historical rates, not the national average, not the average from other country but your own experience."
Expert judgements can be used for the beginning and then gathering actual data these estimates may be corrected and improved. Production rates, activity crews are different for different organizations. Reliable estimates are based on the real data.
But if you plan for the Buyer and before the contract negotiations then you shall use some mean estimates. In this case country average estimates may be useful.
Regards,
Vladimir
Rafael Davila
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The following is a link to RS Means.

http://www.rsmeans.com/

an alternate source could be

http://www.constructionbook.com/

Please note it is a USA reference so it units will not be in the metric system. If you need a converter for units you can download one from the following link.

http://joshmadison.com/article/convert-for-windows

When you get the book please pay attention to the column that name the crew, at the end of the book you will find the crew details for manpower, tools and equipment for which the production is valid.

I still believe the best production rates are the historical rates, not the national average, not the average from other country but your own experience. Unfortunately too much emphasis today is on EV (Earned Value, an invention of US Government bureaucracy) of some value to Owners of little or none value to Contractors as we need the missing link, production quantities. EV to me seems like just budgeting and not true Job Costing.

After you get your true production rates I would recommend you to add about a 15% to your time estimate to account for the fact that during the duration of the activity not all resources will be available, a few on vacation, others sick, a few on other temporary assignments. Another approach could be to increase your resource requirements for time estimates and use a reduction factor for cost estimates. It is known that cost estimates are usually more on target than time estimates, time estimates tend to be optimistic.

Best Regards,
Rafael

Keyel Isorena
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hi, Marie Claire. i need the book from rs means that have the production rates, can you please send me the name of the book, its author and if possible, the isbn. i cant find it from their site. thanx. btw, this is my email: dekryptor@gmail.com
We recommend our customers to create their own database on resource productivities on typical assignments. They differ for different companies, depend on people skills and experience. The resulting schedule should reflect the abilities of resources you have and not what others can do.
Creating these databases starts with the expert judgements and then is enhanced by statistics.
Resource productivities on the typical assignments is not the only database that should be created. You should also create databases for material consumption per volume unit of typical activities, volume unit cost for typical activities, resource workload on typical assignments and others if necessary. It is necessary to create typical fragnets library.
These databases will help to create corporate standards and are necessary for implementing portfolio or multi-project management. We have noticed that different companies use different internal norms and it is natural.
Luca Basile
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I am agree with Your first and third point, but the second again must complain with the third, as Youhave to discuss with the procurement depertment in conjunction with the Project manager, because may be they decide to purchase, let say’ say equipment locally and this will reduce drastically the delivery time.
Again Your last point is the most important for a planner "SPEAK TO THE PEOPLE" as we must implement in our schedule the policy adopted for the prject, that may vary project by project also for the same company.

About the industry standard a lot of time the company has already it own productivity in function in which area of the world the project will be. So again "TALK".
Alex Wong
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Gents

I guess there is few main tools we use to estimate durations.
1. Industry Standard - Like no hrs to install and connect a panels with x amount of I/O. or no hrs for a m3 concert to stand. Some activities is related to resource some not you have to determinate whether the activity is resource driven.
2. Common sence - Procurement/Delivery period of a Tx usually is 26 wks so you can make assumption without actual info. It is useful because not all info is accessable in the beginning of the project a guestimate is better no estimate.
3. Speak to the people (PM Supervisor, Designer) there is no better person to speak to other than the one who will carryout the task.

I guess what I mention above is common sence but since the intension of this, is to share knowledge. Hope it help!!
David Bordoli
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Ah Valerio!

When I posted I suddendly realised I recognised your name... what a small world the planning fraternity is!

See you soon I hope... and we can have some serious discussion about estimating activity durations!

Regards

D
David Bordoli
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I hoped Sergio Monterisi’s posting may have shed some light on estimating durations...

Despite my name I don’t speak Italian so have to resort to ’Babel Fish’... This is a very rough literal translation for all those of you who are wondering what is going on!

Hello Valerio, apparently has had to me to enroll to an association of architects and engineers in order it makes you the crescent auguries old things. How you are? I write you from Boston, where I am in order to end my according to year to the Conservatory. You are well? Lathes in Puglia some time? I staro` li` nearly all the summer. If it goes to you, my number e` 347,6040868, while the email e` sergio.monterisi@libero.it. Not to often answer me on this news letter perche` not creed consultero` the a lot... I embrace, soon

My aplogies to all those who do speak Italian!

Arrivederci

David
dbordoli@burofour.co.uk
Visit Buro Four on the web
sergio MONTERISI
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Ciao Valerio,
apparentemente mi sono dovuto iscrivere ad un’associazione di architetti ed ingegneri per farti gli auguri di crescente vecchiume.
Come stai?
Ti scrivo da Boston, dove sto per finire il mio secondo anno al Conservatorio.
Tu stai bene? Torni in Puglia qualche volta? Io staro` li` quasi tutta l’estate. Se ti va, il mio numero e` 347.6040868, mentre l’e-mail e` sergio.monterisi@libero.it.
Non mi rispondere su questa news letter perche` non credo la consultero` tanto spesso...
Un abbraccio, a presto
Zq qz
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MR valerio,
Have you read the book? RS means has the complete production rates for all discipline. And I have copy of it. Try to Scan more. Or if you are are the construction site Start tracking / preparing your own production rates data which i think more efficient to use.

Best regards
Zq qz
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Try RS Means books
David Bordoli
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I agree the Delphi Method is good for making estimates and gaining opinions (not of course limited to finding out about activity durations). I would suggest it is a bit of a ‘heavy’ tool to use for estimating activity durations if carried out correctly. The problem with involving third parties like that is that you have to retain their interest in your project sufficient for you to generate sufficient data. I doubt many ‘experts’ would be too motivated to contribute their time and energy to help produce activity durations for your programmes. I may be wrong and my apologies if you have used this method successfully.

David
dbordoli@burofour.co.uk
Visit Buro Fours NEW website Click Here
Mehdi Rashidi Ala...
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Hi,
there are many methods for estimating durations. and based on project.
I think delphi method is enough for estimating durations

Regards
David Bordoli
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Hi Ali...

Im sorry that you seemed to have received so much anger in response to your question. I am surprised, I would have thougth that it is easier to say nothing than to say something unpleasant.

However, I hope this helps:

Quantities and Outputs: Use BoQ or take-off basic quantities then use work study or estimating outputs to covert the quantity to a time.

Specialist Advice: Best for specialist operations, seek the sepcialist/subcontractors advice, afterall it is they who will be carrying out the work.

Past Experience: What happened in similar activities on your last job.

Similar Work: Is this activity similar to another, if it is could their outputs/rates/times also be similar?

Data Generation: Durations based on building area, durations based on activity cost.

Guess: When all else fails take a guess, putting something down is often better than doing nothing at all.

Best regards
David.
Mike Harvey
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Duration is based on
Quantity/Standard Performance = Duration

Visit hpcconsult.co.uk and visit ’Production Rates’ this may assist your thinking?

Regards

Mike Harvey
Daya Sugunasingha
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The Planner or Planning Engineer is the person who would work out the duration of an activity. He would do this by using a rule of thumb rate i.e. xx m2 per man/machine hour such as available on this web site.

If he has the time he would speak to the specialist sub contractor who does this activity every day and obtain his advise.

Hope this helps
Mohd Mahd
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u left me no way, but only to ask ur kindness to forgive my hard words. let's start over again, with better understanding. pls try with me to get use of this situation. let's think of creating a policy, or rules for all of us to follow in asking and answering each other. i will start new message of this subject. last hint, in fact no body is perfect my best regards, and wishes, mohd
Ali Hamouda
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thank you for your advise. would you pls choose Kind way for talking to the people... you can give your Ideas and advise,but with a friendly and polite way. But till me who will accept your way of talking? you have some rules in your mind, don,t expect all the people to follow your rules. So pls be polite...and willcome by your advise. I admit my mistakes, I did not till that I am perfect.and no one is got perfect. Best wishes for your future way of discussing with others. Ali --------------------------------
Mohd Mahd
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A 15 years exp planning or even planner, can answer most of ur questions. and if after 15 years, u do not know the formula to estimate duration, then when? after other 15?
in fact i like this, and get fed up from ur poor questions with improper language!
just small advise! to know or not to know, is not the problem, but how to ask is the one!
Ali Hamouda
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Dear Mohd,
(I already know the answer)

If you observe thay most of my Questions Is to activate the Planners to share Knowledge..that was my aim..nothing else

Regards
Ali
----------------------
Mohd Mahd
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i have a better question! i was wondering, if u r a qualified planning engineer? or even a planner? regards mohd