Engineering Manhour Estimate

can anybody share a practical guideline for estimation of engineering manhour for different projects?

Furthermore, is there any rule for estimation of engineering manhour required in each discipline? Electrical, I&C, Civil, Structure, Piping, etc.?

Engineering Estimation "norms" are normally known as intellectual property of the various Companies and are not available otherwise another Company could undercut. Always remember the fundamental Rule "a job takes as long as it takes" and the second Rule "don't try and cut corners".

An engineering estimate is as good as the guy preparing the estimate. If he has insufficient experience then the estimate is more like a guesstimate!!!.

Another "golden Rule" is for "nuclear work" estimate as for a normal job then multiply the result by at least a factor of 4 or 5!!!

As DSB123 pointed out, companies estimate man-hours based on their own experiences. For instance a company like PDVSA, Venezuelan oil company, has a manual (if you speak spanish I could sent you a copy) where stablish for the type of engineering your are going to do (Conceptual, Basic, Detail) the typical documents and drawings required by each discipline. With that, and some criteria of your own, such as determining how many Process Flow Diagrams (PFD´s) for instance might be required to a certain job, you estimate the man-hours. In the company whre I work, a engineering consultant, that is done by senior engineers of each discipline (Process, Mechanical, Electrical, etc). You as coordinator put al the man-hours togheter and estimate the staff hours such as Project Manager, Engineering Coordinator, Planner, Contract Administrator, Cost Estimators, etc. Many of those are full time, some are partial time, as might be the case of cost estiamtor, which is required once youa have sized the main equipment or bill of materials, depending of the type of engineering.
Other thing is determine the categories of required engineers, based on their experience. The more early stage in engineering, the more experienced engineers you required. For instance, for a conceptual engineering, you might require more experienced engineers, as more design criteria is required. Also for man-hours estimates you have to use judgment, as a more experienced engineer can develope some task more quickly and efficiently that a les experienced one, but is more costly.
So my dear friend, there is not a rule of thumb or a clear cut way of estimating man-hours for a project. Even some companies estimate engineering man-hours based on the number and type of equipment. And as DSB123 said, you almost always underestimate. Worst if you are competing against other engineering companies.
Based on you requirements I posted the book Engineering & Construction Project Management - A. Kerridge (Gulf Professional Publishing, 1986), where chapters 14 and 15 explained some methodology for estimating man-hours.
Againg for your benefit, I will be uploading another book with more information, but in a different thread to benefit more people. The book is Planning, Estimating and Control of Chemical Construction Projects (2nd Ed.) - P. Navarrete (Dekker). Look for it.

Dear Gusgon,
You are right the manhours are to be considered based on once personal experiance. But not all are so experianced and if possible let us share what ever info we can provided so that it can become the basis for others to make their own benchmarks.

I will for sure try to share some of the materials shortly and request all the forum members / friends to do the same for the sake of others. Pls bear for a short time until gather the data for posting here.

Best of luck to all.
Regards.

Dear DSB123
Dear Gusgon

So many Thanks for the explanations. But still I am looking for some information to make my own benchmarks, as said by npsrinivasarao.
As I posted in another thread, the book Engineering & Construction Project Management was interesting to me but some contents in chapters 14 and 15 are not readable.

I wish the best for you friends
Regards

the book link

[url]http://w13.easy-share.com/1699723284.html[/url]

Thanks you

Thanks for the book :)

Thanks josefreitas.

Many thanks José Freitas for the book you've posted

Hello, Gusgon. Is at your ability to send me a copy of the PDVSA costs estimating manual. I speak spanish (I'm from Uruguay). My email is [email]carlosdiperna@gmail.com[/email]. TThank you very much. Best regards, saludos. Carlos