Tapping Quantities from BIM

Ir Francis LEUNGDirector / Head of BIM

11/9/2013

How long do you need to measure … ?

� No. of Blocks = 10

� No. of Units = 963

� Total Floor Area?

� Long list of Floor Area of Units?

� List of Floor Area of Blocks?

� Floor Area of Different Usages?

� External Wall Area with Different Types?

2 WEEKS or 2 DAYS

How long do you need to measure … ?

� Complex Site Formation …

Net Cut

375,000 m³

Does the client want to … ?

SAVE

45,000 m³(12%)

How long do you need to measure … ?

Which one do you like?

� Get the Quantities quickly

� Get the Correct Quantities

� Get the Correct Quantities quickly

Are the numbers CREDIBLE?

Typical BIM Objectives

3D Geometry

3D Geometry

Design /

Scheme Study

Design /

Scheme Study

Drawing

production

Drawing

productionQuantity

Take-off

Quantity

Take-off

Typical BIM Objectives

Design /

Drawing

Audit

Design /

Drawing

Audit

4 Factors for Credible BIM Quantities

� Source of Information

� Model Accuracy

� Modelling Methodology

� Limitation of BIM QTO

Source of Information

Originator

Drawings …

Drawings …

Quantity Surveyor

QuantitiesQuantities

Source of Information

Originator

Drawings …

Drawings …

Quantity Surveyor

QuantitiesQuantities

BIMBIM

Different Source of Information

≠≠≠≠ ≠INFO

Drawings

BIM

QTO

BIM QTO

Source of Information

Originator

Drawings …

Drawings …

Quantity Surveyor

QuantitiesQuantities

BIMBIM Credible?

Source of Information

Originator

Drawings …

Drawings …

Quantity Surveyor

QuantitiesQuantities

BIMBIM BIM QTOBIM QTO

Model Accuracy

=INFO

Drawings

BIM

QTO

BIM QTO

Modelling Methodology

Modelling Methodology

WSP Standard Method of Modelling

WSP Standard Method of Modelling

Limitation of BIM QTO

Beam side formwork?

Column side formwork?

Limitation of BIM QTO

� Don’t be shy that BIM QTO is not perfect

� BIMers must be honest to tell the limitation

� Or How to make the BIM QTO perfect

� QS must understand the what the numbers mean before it is used

4 Factors for Credible BIM Quantities

� Source of Information

� Model Accuracy

� Modelling Methodology

� Limitation of BIM QTO

QS + BIMers

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