Cost Estimating Method(s) for Public Infrastructure Projects

[westend392]

Hi everyone, I just recently graduate and now working in a firm that concentrate in mostly Public Work related projects (transportation, water, sewer, storm drains, etc.) in SE USA (FL, GA, MS, LA). I'm having problem in deciding the approach that I need to take in preparing "Opinion of Probable Cost" report for our projects (currently water & sewer network). In school, we were introduced to Means Cost data book, but in reality, it seems that not to many people, in my office anyway, rely on Means Cost Data. It seems that we emphasize our efforts by using past projects' bid tab data as the basis of our estimating work. Many in the office claim that Means Cost unit prices are way too conservative. Is this true?

The problem is that the bid tab data that we have right now is sometime 3-4 years old and using some general inflation factor for all of the unit price seems to be too conservative. Sometime , we just don't have the data. Someone has suggested to contact the contractors directly but I don't know how responsive they will be in sharing their unit price info with me nor do I know how to adjust their price info to account for "front-loading" practice, etc. Any help will be greatly appreciated.

 

[ep8934]

The best way to estimate new projects on a conceptual basis is to use historical project data and to escalate it. IF YOU USE a good escalation index that is relevant to your industry.

I use three cost indexes and average them. Then economies of scale adjustment must be applied. All historical data is entered into an excel spreadsheet and automatically adjusted and escalated by changing the new project size.

Using this method I have "adjusted" projects from the 1960's and derived at valid defensible estimates.

 

[ep8934]

If you are interested in learning more you can join the AACE (Cost Engineering Professional Association)

http://www.aacei.org/

Or my "how to" technical paper “Accurate Estimates in Less Than a Minute” which uses historical project data to estimate new projects, can be found here,

http://www.nflaace.org/index_files/Accurate Estimates in Less than a Minute EST24.pdf

Presentation can be found here,

http://www.nflaace.org/index_files/Accurate Estimates in Less Than a Minute Presentation.pdf

If neither of the above links works try,

http://www.nflaace.org/index_files/AnnualMeeting.htm

and follow the links there

 

[westend392]

Thanks a bunch ep8934!

 

[westend392]

What do you guys think about "ENR Construction Cost Indexes"?
What are they? I've actually never seen them but one or two people that I know suggest using them as unit-price base.