30 November 2012

Where's the contractor? BIM Execution Plan for contractors

To be effective BIM needs to be used right from when a project starts. There are already enormous benefits in using BIM during brief consolidation and master planning. Therefore BIM plans need to start at the very beginning so that work done early on can be utilised later. But current BIM guides assume the contractor is a major party in a BIM plan. Why do these BIM guides assume a contractor is on board right from early conception of a project?

Integrated Project Delivery (IPD) is an attempt to get all the players in a construction project together from the beginning of a project. The theory being, if you can do this, BIM processes for the entire project can be worked out in advance.
IPD assumes enough is known about a project at the beginning to do this. That at the briefing stage, before there is a design, enough will be known to select the best and most cost efficient contractor.
It also assumes the owner is willing to pay for participants that won't be needed on the project (besides this BIM 'pre-planning') for months or years into the future. That's if the project actually proceeds to construction - which many do not.

There is a fundamental flaw in this thinking. The Contractor is rarely around at the beginning of a project.
Yet current BIM guides assume they will be.
I've been in a situation like this. We were meeting to put together the project BIM Execution plan, there was no contractor, yet there were clearly contractor driven BIM processes to be included in the document. The client's BIM 'consultant' wanted to use their take on BIM best practice, even though no contractor had actually done any of it to date. Which would mean the design team would be doing a whole lot of stuff no-one would ever use. When we complained the client wanted us, as lead consultant, to determine what the builder would do, what is 'reasonable' as they put it.
As an architect, I don't pretend to know what goes on in the head of a contractor. We try and detail construction in a way that is buildable, but we can't predict what a contractor will actually do. When we cleverly detail a fa├žade so scaffolding is not necessary, they scaffold it anyway. When we design so components can be prefabricated off site, they make them on site. And this is as it should be. They are the experts at construction. There is no way we could predict what BIM an unknown contractor might require.
So the only alternative is to leave contractor requirements blank until one is appointed. The problem with this is all requirements are integrated in a single BIM plan. When you add things in later it is misleading. For example, 4D (construction sequencing) is left blank. A contractor is appointed and wants to use 4D, so the blank is filled in. Now the BIM plan reads as though 4D has always been a requirement, but of course no-one has modelled to suit 4D. You can't add requirements after the fact.
Which brings us back to IPD.
IPD is being heavily pushed as necessary for BIM because BIM plans (based on current BIM guides) only work if IPD is used as a delivery process.
Do we really have to completely re-engineer procurement processes to accommodate BIM? Why not just have BIM plans that reflect what is possible with current procurement practices. Let's use BIM now, not in some utopian future.
For more on my thoughts on IPD read my blog post Integrated Project Delivery: Bad News for Architects?


One thing I do agree on though, is that the contractor should be part of BIM planning. It can't be the overall project BIM plan because they are not around when the project starts. And it is pointless to totally rework a project BIM Plan done for design after the design is finished. Particularly when construction requirements are so different it would require restructuring the plan, not just 'tweaking' it.

My solution is to have a separate document, a contractor's BIM Execution Plan (BXP) to set out how the contractor intends to use BIM. This BXP would be part of a group of documents that form the BIM Management Plan (BMP).
Read my previous posts on the structure of a BMP, and the other plans, the Project BIM Brief (PBP), Participant BIM Plans (PBP), and the Design Collaboration Plan (DCP).

I've called it the BIM Execution Plan because most lay people, including owners, seem to assume a project starts when construction starts, not when design starts. So to most people the BXP is the BIM plan for the project. And in terms of concrete deliverables it is. The contractor delivers a building and information about that building for future management. How the information deliverable would be provided is covered by the BXP.


The contractor's BIM Execution Plan would use the pre-existing BIM plans as a starting point. These plans will provide information about what type and quality of BIM information is available, and in the case of the owners BPB, what is required. If a Contractor has a BIM manual for their own standard BIM processes this would also go into the mix.
Even if the contractual power exists to do so, there is little point forcing the design team to adopt the contractor's standard BIM processes. Most of their work is already done. Getting the design team to redo their work to the contractor's requirements will take extra time, be likely to introduce errors, and be met with demands for extra payments. It is far more realistic for the contractor to utilise what is available the best way they can. That said, there will be be areas the design team can do things differently, but they need to be assessed against what is realistically achievable and the what actual benefits will be attained.

The process to create a contractor's BXP might look like:
  • Refer to BPB to define owner deliverables.
  • Refer to PBPs and DCP to ascertain receivable BIM  data from designers.
  • Refer to contractors BIM Manual for desirable BIM construction practices.
  • Work out processes required to turn receivable BIM data into owner deliverables.
  • Work out processes that will utilise BIM receivables for BIM construction practices.
  • Negotiate changes to DCP, and possibly some PBPs, to help those processes.

The Contractor, or a BIM consultant engaged by the contractor.

As soon as the contractor is engaged for the project.
It could be requested as part of the bid process if all other BIM plans for the project were made available to all bidders.

How this BXP fits into the overall BIM Management Plan (BMP) as defined in the BIM Project Brief (BPB).
Purpose and uses of this BXP.
Who is author / responsible for this BXP and key people on the project.
Contact information for these people.
Record of revisions to this BXP.
Meeting & review timetable.

Contractor specific BIM objectives.
Contractor only specific BIM uses.
Sub-contractor BIM Plan requirements (for shop drawings).
Minimum modelling requirements for each discipline & sub-contract, either:
- general description;
- specific description;
- LOD table.
File deliverables and schedule.

Clash Detection.
Construction Sequencing.
Cost Control.
RFI and Variation (change order) management.
As-Built document creation.
FM data capture.

Like the design team's Participants BIM Plans (PBP), contractors should develop their own standard BIM Manual that can be used to inform BXPs they do for individual projects. It is always better to start with what you want, not what others demand.
But I think it unrealistic to believe this BIM Manual could be used to create every project BXP, as each project will have owners with different BIM deliverables, and design teams with different BIM capabilities.
Perhaps this BIM Manual is hierarchical. A series of stepped scenarios. If we get 'X' BIM information from the design team we can do 'A' construction BIM processes and deliverables, but if we get 'Y' we can only do 'B' processes and deliverables.

But I might be getting a little ahead of myself. I'm an architect, part of the design team, so I have to admit I'm guessing a little bit here about what are realistic construction BIM processes. I hope those better experienced in construction will get more involved in this BIM Plan debate, and not leave it up to us so called BIM experts, and certainly not to the BIM evangelists.

This was my last post on my take on the different plans that should make up an overall Project BIM Management Plan. After setting out the logic and philosophy behind this idea, now to see how it works in practice! If you are giving it a try, I'd be interested in how you get on.


  1. Your posts about the BIM Execution Plan are my favorite idea to date. They are solidly grounded in dealing with the issues of actual practice. I would like to put these ideas into practice and when I do Ill let you know how it turns out.

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