CEE 422 Construction, Cost Analysis. Prof. Ibrahim Odeh University of Illinois, Urbana –...
-
Upload
melissa-mcmahon -
Category
Documents
-
view
215 -
download
3
Transcript of CEE 422 Construction, Cost Analysis. Prof. Ibrahim Odeh University of Illinois, Urbana –...
CEE 422 Construction, Cost Analysis.
Prof. Ibrahim Odeh
University of Illinois, Urbana – Champaign. Fall ’09.
Ayuss S. Kumar
Accuracy of Construction Cost Estimating
CONTENTS
04 Composition of Project Price
05 Types of Estimates
06 Accuracy by Error
Prevention
02 Estimating Techniques
03 Range Estimating
01 Importance of Accuracy
In Cost Estimating
00 Abstract 02 - 03
04
05
06 - 07
08
09
10
00 Abstract
02Ayu
ss S
. K
um
ar
Accuracy in Cost Estimating helps the Architect – needs to make informed decisions to the owner regarding:
Feasibility
Scale of Project
Phases of Construction
Materials Building Systems
Space Planning
Built up Areas
00 AbstractA
yu
ss S
. K
um
ar
Cost Estimating Accuracy depends on :
Scope of Project
Time Factor Site & Weather Conditions
Historical Data
Reliability on Info.
Government Rules & Taxes
Labor Unions
03
01 Importance of Accuracy in Cost
Estimating
04
Investment to revenue generated – financing.
Helps keep the project on budget during execution.
Control on cash flow.
Helps justify progress payment to the contractor.
Updates historical data base for future project references.
Arbitration – unresolved claims.
Ayu
ss S
. K
um
ar
02 Estimating Techniques
05
4 Main types of Estimating Techniques
Project Comparison or Parametric Cost Estimating
Area & Volume Estimating
Assembly & System Estimating
Unit Price & Scheduling Estimate
15-20% Accuracy
5-15% Accuracy
10% Accuracy
2 - 5% Accuracy
Ayu
ss S
. K
um
ar
Fig.1 - Source: From Concept to Bid… Successful Estimating Methods by John D Bledsoe.
03 Range Estimating
06
Assessment of how far a project’s final cost may vary (+/- %) from the single point value that represents the estimate.
Estimate - range of cost outcomes - Represented as a probability distribution curve.
Fig.2 & 3- Source: From Concept to Bid… Successful Estimating Methods by John D Bledsoe.
Contingency helps increase accuracy of estimating.
Depends on where the contingency is placed about the point estimate.
Ayu
ss S
. K
um
ar
03 Range Estimating
07
Estimate accuracy tends to improve with project definition.
Fig4 - Source: From Concept to Bid… Successful Estimating Methods by John D Bledsoe.
Class 5 – High Range +30% to 100%
Low range -20% to -50%
Class 4 – High Range +20% to 50%
Low range -15% to -30%
Class 3 – High Range +10% to 30%
Low Range -
10% to -20%
Class 2 – High Range +10% to20%
Low Range -
10% to -15%
Class 1 – High Range + 5% to 10%
Low Range -5%
to 10%
Ayu
ss S
. K
um
ar
04 Composition of Project Price
08
3 Main types of pricing for a project
Direct Costs
Contingency Costs
Margin
Labor
Material
Equipment
Industry or Facility Approach
Discipline or Trade Approach
Estimate Contingency
Owners Contingency
Designers Contingency
Contractors Contingency
Indirect Costs
Company Wide Costs
Profit
Parametric
Meth
od o
f ca
lcula
tion
Meth
od o
f ca
lcula
tion
Area or Volume Assembly & systems
Unit Price
Location
State of Economy
Type of Discipline
% of project cost
Ayu
ss S
. K
um
ar
05 Types of Estimates
09
ProgrammingSchematic Design
Design Development
Construction Documents
Design Process
Preconstruction Services Construction Operations
Bid Construction Operations
Negotiated Construction Procurement Process
Bid Construction Procurement Process
Programming Budget Estimate
Schematic Design Budget Estimate
Design Development Budget Estimate
Owners Final Cost Estimate
Preconstruction Services Estimate
Guaranteed Maximum Price Estimate
Change order Estimate
Detailed Lump sum or Unit-price estimate
Change order Estimate
Feasibility Estimates
Order of Magnitude Estimate
Preliminary Estimate
Baseline Estimate
Definitive Estimate
Fixed Price Estimate
Claims and Changes Estimate
Ayu
ss S
. K
um
ar
06 Accuracy by Error Prevention
10
Common estimating errors:
1. Incorrectly adding a column of numbers.
2. Incorrectly calculating the price.
3. Incorrectly transferring the numbers from one page to another.
4. Making errors in dimensional conversions.
5. Omitting a page of the estimate.
6. Misplacing decimals.
7. Manual scaling of drawings – resolution error.
Ayu
ss S
. K
um
ar
11
Thank you
Ayu
ss S
. K
um
ar