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Estimated Duration

23 replies [Last post]
Wed, 2009-07-08 07:14
moutaz aldeib
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Dear Planners,

As a contractor, how to estimate the activity duration if there is no productivity rate or any history data for the contractor.

Regards,

Moutaz
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Replies

Fri, 2009-07-17 23:49
#1
Samer Zawaydeh
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Dear Patrick,

Software is a tool. Garbage in Garbage out.

You need to make sure that the list is correct, the sequence is correct and the durations are as per the users requests. Then you start the development and trial and error. Give your team members what you get the first time, and let them correct their rates of production and duration. This way the Program will be realistic.

With kind regards,

Samer
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Fri, 2009-07-17 16:09
#2
patrick chuks
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So In response, there is no way primavera can help atleast?

Thanks
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Fri, 2009-07-17 15:58
#3
Se de Leon
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It’s kind of hard to say that what your supervisors has given you has too much float or in other case, aggressive. You really have to demonstrate to them that what they gave you is unrealistic. You can only do this if you have the right experience to convince them.

If you follow certain norms or standards, they may say you’re being bookish and unrealistic.

If you don’t have the experience, ask a 2nd expert’s opinion or maybe 3rd. Pretty much after that, you can have a guage of what is realistic or not.

My 2 cents.
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Fri, 2009-07-17 15:22
#4
patrick chuks
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Yes
I have activity list from the supervisors but most of them have too much float, If there is a way at all, atleast I can benchmark thier estimates and allow some float for emergent works, then I will be satisfied

Thanks
Patrick
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Fri, 2009-07-17 09:25
#5
Samer Zawaydeh
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Dear Patrick,

The first thing that you must do is creat an activity list. Try to use and active verb and a noun for each activity.

Planning is a group work. You invite the people responsible for completing these activities and ask them how much time they need to complete them. They are the best source of information.

With kind regards,

Samer
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Fri, 2009-07-17 07:23
#6
patrick chuks
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Hello
I work with LNG company, as Turnaround Planner, having received scope of works from various units, how do I determine with P3, the actual number of personnel required to execute the entire project.

Thank you
Patrick
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Thu, 2009-07-16 13:03
#7
Samer Zawaydeh
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Dear Moutaz,

Try to post a few activities that you are working with and we will try to assist you as much as possible.

Also, please remember that planning is a TEAM activitiy, not an individual job left for the Planner.

With kind regards,

Samer
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Thu, 2009-07-16 10:37
#8
Anoon Iimos
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Hi Moutaz,

How are you? I believe you know how to do it, and of course you got all the productivity rates with you (just go to the library) but just in case you might ask me,: Productivity depends on the resources or the type of resources being used.

For example: Excavation, first you may define what type of soil it is, or is it a rock? For sure there is a soil analysis from your engineering dept. And are you going to use machines (excavators)? or just manual?

But don’t worry, we are doing your project.

Best regards
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Thu, 2009-07-16 08:13
#9
Mike Testro
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Hi David

I often have to put together resource modelled programmes based on BoQ rates that are just extracts from sub-contractor’s prices.

No unit breakdown into Lab Plant Mat or OH&P.

If the budget allows I run the BoQ through Wessex software otherwise I use the labour percentage method.

Very few UK construction firms prepare estimates from historical data and none that I have come across keep production records on current projects.

Best regards

Mike Testro
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Thu, 2009-07-16 06:03
#10
David Wallace
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I have a tendancy to agree with Ronald here, where is your historical data?

As an experienced contractor your first port of call should be what you hve achieved in the past.
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Thu, 2009-07-16 05:13
#11
Mike Testro
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Hi Moutaz

There are a number of publishers of estimating software that use industry standard output rates that can be adopted for resource modelling.

Care must be taken that the work description is the same as that in your project.

I use Wessex Estimating - which is now published by the RICS on a set of discs.

Hutchinsons is used a lot.

They are not cheap.

I would avoid the PP rates as there is no audit trail to the source and don’t even bother with wikipedia.

Best regards

Mike Testro
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Thu, 2009-07-16 04:41
#12
moutaz aldeib
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Dear Planners,

Thanks for all responses but my question is that if the company has no productivity rate (no historical data)

Regards,

Moutaz
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Wed, 2009-07-15 12:24
#13
Samer Zawaydeh
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Dear Waseem,

Thank you for your kind note. That is why it is important to keep the hired team until the end of the project. If you keep changing the people you miss the opportunity to increase your production rates.

With kind regards,

Samer
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Wed, 2009-07-15 10:06
#14
Waseem Saber
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Samer,

working 10th time (repeated) will take less time than the 9th time etc.... provided you have the same resources and no change in hand has taken place, i have noticed that more often then not when the resources change hands the productivity take the dips, the repeat fuction helps when all the enviornment and the labour and plant is remained the same.

hope this will kick start some good discussion on this aspect

cheers

Wazsab
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Tue, 2009-07-14 00:59
#15
Shah. HB
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Dear Samer

Alright ,Thanks
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Tue, 2009-07-14 00:11
#16
Samer Zawaydeh
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Dear Shahul,

There are other factors that you need to take care of:

1. Efficiency (level of skill)
2. Environmental factors.
3. Repetition. (working the same thing for the 10th time at site will take less time than the 1st time.)

With kind regards,

Samer
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Mon, 2009-07-13 23:48
#17
Shah. HB
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Hi to all

Plz check this message is useful

Activity Duartion = Work Quantity/(Production rate * Resource usage)

Ex:

____Excavation Acitvity Duration = 5 days___
Work Quantity = 3000 cft
Production rate=100cft/day
Resource usage=6 labour
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Mon, 2009-07-13 11:20
#18
Samer Zawaydeh
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Dear moutaz,

Please let us know what activities that you are talking about. Chances are, PP members can assist in providing you with the duration.

With kind regards,

Samer
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Mon, 2009-07-13 10:07
#19
Mike Testro
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Hi Moutaz

1. OH&P means Overheads and Profit.

If the percentage is - say - 15% then the arrithmetic is that 15% is added to the net figure - so if you just deduct 15% from the gross figure you will get a lower number. Use Gross/(1+OH&P%) to get the net total.
2. No - you have to convert the labour % in money to labour hours by dividing by the labour rate.

The percentage band differs by the ratio of plant and material to labour so for instance:

Fix Chrome Tap - Rate = $20 - Lab % about 30%
Fix Gold Plated Tap - Rate = $200 Lab % about 10%

You will have to apply experience and common sense to get the percenatges right and it is better to apply it to BOQ section summaries rather than individual items.

Best regards

Mike Testto
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Mon, 2009-07-13 07:00
#20
moutaz aldeib
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Dear Planners,

Thanks a lot for all response but my question to Mike is that:

1-What you mean by OH&P.
2-Do you mean that if I have BOQ (e.g. excavation 500 m3) multiply by 15-55% to get the hours spent for this activity.

Regards,

Moutaz
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Wed, 2009-07-08 08:27
#21
Arnold Puy
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Hi Moutaz,

1. You can apply your previous experienced in construction.
2. Based on the Milestone dates stated in your contract.
3. Ask your construction team and all discipline concerned to assist you.
4. And other members of Planning Planet can help you.

Regards,

Arnold
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Wed, 2009-07-08 08:19
#22
Mike Testro
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Hi Moutaz

The most usual way is by personal experience and guesswork.

This works better if you have to make a lot of guesses rather that one big one.

If you have a cost plan or BOQ you can ascertain resource hours by use of labour percentages for each trade.

These will range from 15% to 55% after adjustment for OH&P.

You will also need to know the hourly labour rate to convert the money to hours.

With the application of a suitable Gang Size and the work hours per day you can estimate the duration in days fairly accurately.

Best regards

Mike Testro
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Wed, 2009-07-08 08:18
#23
Ronald Winter
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Presumably, the contractor was hired because he or she is an expert in building the desired product. If there is no written historical data, then surely there is a resident expert who can estimate the task duration. If you lack such an expert, one wonders why you ever bid to perform such work. Good luck!
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