Author: Sarah Rock, Associate, Construction and Engineering, London
Following my recent blog post providing a general introduction to BIM, I will now explore the levels and dimensions of BIM and what makes up the Government mandated Level 2 BIM.
There are widely adopted definitions of maturity for BIM which use levels graded according to the amount of technical or collaborative working involved.
· Level 0 — Unmanaged 2D CAD with paper as the most likely data exchange mechanism;
· Level 1 — Managed 2D or 3D CAD with a collaboration tool providing a common data environment;
· Level 2 — Managed 3D environment. 3D models containing data or information are produced independently by all members of the design team; and
· Level 3 — Fully integrated and collaborative process using web services. All disciplines feed into one single model.
The levels of BIM are distinct to the digital dimensions of BIM but the two are often confused. The digital dimensions of BIM are as follows:
-3D BIM – modelling with three dimensional data;
-4D BIM – modelling with three dimensional data with the addition of construction sequencing;
-5D BIM – modelling with three dimensional data with the addition of cost data; and
-6D BIM – modelling including facilities management specific data.
Therefore a Level 2 model could be 3D, 4D, 5D or 6D.
In conjunction with the BIM Task Group the Government set the mandate for Level 2 BIM to incorporate 7 pillars. Since the draft publication of PAS1192-5 there are now arguably eight pillars which make up a Level 2 BIM project.
1) PAS 1192-2 Specification for information management for the capital/delivery phase of assets using building information modelling. This specification sets out the overall outline for a BIM project including the requirements for Employer's Information Requirements and the BIM Execution Plan (to be discussed in a later post).
2) PAS 1192-3 Specification for information management for the operational phase of assets using building information modelling. This specification builds on PAS 1192-2 and develops the processes for the operational phase of the asset. This document is crucial for BIM in the facilities management stage of an asset's life cycle.
3) BS 1192-4 Collaborative production of information Part 4: Fulfilling employer's information exchange requirements using COBie – Code of practice. COBie is the Government's chosen information exchange scheme. It is effectively a spreadsheet which allows for interoperability and information exchange across the project. In BIM the exchange of information is as critical as the exchange of geometric design.
4) The BIM Protocol. A standard form BIM Protocol was developed and published by the CIC in 2013. I will discuss the Protocol in more detail in a later post but it is effectively the means of achieving commonality across the design team with regard to the structure, co-ordination and use of project information.
5) Government Soft Landings. 'Start at the end to inform the start'. Through Government Soft Landings (GSL) the end user of the asset is involved from the start. GSL is a form of soft handover which incorporates the operational team into design decisions. The design team are also on hand after completion to assist with the handover and learn lessons from the real everyday use of the asset
6) Digital Plan of Work. An industry standard method of detailing concepts, definition templates and details of the management of the built asset data. The NBS BIM Toolkit is a free to use digital plan of work accessible on line.
7) Classification. A structured and standardised information classification system. This integrates with the digital plan of work and is also accessible in the NBS BIM Toolkit.
8) PAS 1192-5. Specification for security-minded building information management, digital built environments and smart asset management. This specification is designed to provide a framework to assist asset owners in understanding the key vulnerability issues and the nature of controls required to enable the trustworthiness and security of digitally built assets.
In order to be truly Level 2 BIM compliant the above eight processes and documents should be incorporated into the project. In reality most projects are addressing some but not all of the above, which is a great step forward towards industry compliance.
In my next Construction post on BIM I will address the Employer's Information Requirements, the BIM Execution Plan and the BIM Protocol and how these documents may affect the contractual matrix of a project.
For more information please contact:
Sarah RockAssociate, Construction and Engineering, London
+44 20 7466 2776