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2D Input

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Surprisingly the use of 2D inputs still forms an integral part of the design cycle and is a quick and convenient way of sharing initial ideas with a wide range of team members particularly when all design disciplines are represented.

I have seen this mode of working first hand recently on one of our larger projects. It was where we had been engaged pre-concept by the owner to work with the Architect, Interior designer and Structural team to set out the principles of the complex 216,000sqm project.


This approach allowed the senior partners to very quickly rough out where the key elements of the building had to be located to not only account for the interior but also external factors and proximity to other nearby structures.

It is also quite common for Forsspac to be called upon to take schematic or detail design output that is well advanced in a 2D format or similar from which we then build the 3D model.


This often happens when a project owner decides part way through the design cycle that the benefits of having a 3D model outweigh the cost production in ultimate cost and time savings during the construction process. 

Forsspac teams are therefore well versed in receiving information in a wide variety of formats from simple hand sketches, PDF's, dwg's or even photo's which are then used to produce the 3D model.

2D Input

3D Modelling

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3D modelling is the most effective way of representing a design that can be shared visually between all team members. Once the model is built any non-CAD literate person on the project can access the model using one of the many free downloadable viewers and contribute towards the final result by feeding back to the team opportunities for change.

BIM360 from Autodesk is fast becoming the platform of choice for most projects. Access to the model is by invitation only but once invited the model can be accessed anywhere in the world and worked on. By chance this developing platform is now enabling team members to work from home on a project with maximum efficiency.

The 3D model can be operated on a the preferred federated or collaborative basis giving a high degree of project management flexibility.


Keys to success when building a 3D model for coordination are:

  • Robust BIM Execution plan that all parties sign up to that also defines the BIM Level

  • Defined Quality Assurance plan that directs Quality Control activities

  • Placing model control authority in the BIM Manager who should be independent of the key teams. This is a very specialised role, mission critical and should not be underestimated.

  • Working to a common set of level of detail (LOD) definitions from LOD100 through to LOD500

  • Developing a design stage plan with LOD's defined having specified uses and authority at each stage. This part of the plan is often called a BIM Model element or attribute table

3D Modelling

3D Coordination

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3D Coordination is by far the most difficult aspect of BIM to get right as it requires the absolute dedication and commitment of all parties involved usually including MEP designers, structural, civils and architectural teams.


Hence the recommendation that a BIM Manager be employed  to manage this process.

Keys to success in 3D model spatial coordination are:

  • Strong leadership from the BIM Manager

  • Consistent platform (Don't upgrade the 3D model software for the life of the project)

  • Make sure that all parties submit a test/set up model to demonstrate that the xRef's are correct

  • Robust BIM Execution plan

    • That locks in the clash detection and resolution process

    • Controls model sychronisation

    • Specifies trade hierarchy when resolving clashes

  • Regular (weekly) BIM meetings​

3D Coordination

Coordination Loop

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3D modelling and coordination is not a one shot process. It is an iterative process. 

If you have ever played Othello then you will know that at any time the black can go white across the board or vice verse.


Spatial coordination in 3D environment can be the same when resolving reticulation and equipment location challenges forced by inputs from any team member. When this occurs then the time and money burn accelerates at an alarming rate.

There is only one fundamental key to success during the coordination loop:


Coordination Loop


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In an ideal world the fully coordinated and clash free 3D model would be the only deliverable from which all parties then extract the construction information they seek. A 3D model is particularly useful for understanding reticulation in congested spaces where you can for example take an infinite number of cross section cuts or views to see what is going on.

However, we do not live in an ideal world and so the documentation phase often calls for the production of 2D drawings, in some extreme cases even old fashioned blue prints!

How much information required to be added by the CAD team during documentation depends upon the density of data captured within the 3D model as it is being produced, the more that is captured during model build the easier and quicker the documentation process.


Ket to documentation success are:

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