Asset breakdown structure

Keep the end in mind.

BIM aims at delivering a wealth of information to whoever needs it to answer a question, make a decision or carry out an activity, but who is the bulk of the information intended and what is the client actually paying for?

Unless you’ve not started your BIM journey at the beginning with the “Government Soft Landings” document you should know by now that it encourages an early engagement of the end user. And in our case the person who needs that information on a daily basis is the maintainer.

So how do they need their information structured? Have you asked them?

Whether you call them systems, functional groupings or relational hierarchies the simple explanation is this:

If I need to take this asset out of action to maintain or repair it, what will that impact on?

Two examples:

If I need to work on this light fitting, how do I isolate it and what other lights, cabling, sockets etc will be impacted and also what locations might be taken out of use because they need that light to allow them to carry out the function?

If I needed to replace a damaged crash barrier, I need to know that it will have an impact on this bridge structure, which means closing part of this junction and affecting this part of the road network.

If I needed to replace a damaged crash barrier, I need to know that it will have an impact on this bridge structure, which means closing part of this junction and affecting this part of the road network.

Asset Breakdown Structure

Asset Tagging Strategy

Asset Information Requirements

Employer's Information Requirements

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To make a decision on when, where, what and how I need to carry out that activity, I need to have information that will tell me its relationship with the other things around it. To do this we create an asset breakdown structure.

That breakdown structure goes from the highest level all the way down to individual assets at the level we expect to maintain them.

In a simple world this would be kept to 4 layers of hierarchy, but that isn’t realistic as our assets have very complex relationships.

Assets Don't have to be physically connected to be Functionally connected 

The exact wording isn’t important but the level of the relationship is.

At the top we have a Complex, this is essence is everything whether it be a infrastructure network like highways or a university campus, airport or railway.

Below that we have hubs and connectors of the Facility. In this example every junction or motorway section between them is a facility. This could be the same for buildings and the infrastructure between them, power stations and the lines between them and so on.

Next we have functional groupings or Entities. In the highway example above this could be earthworks, drainage, gantry systems, structures or indeed the permanent way itself. For a building this could be an HVAC, lighting or fire suppression system.

When we have complicated functional groupings, they may be split down even further into Sub Entities. Think here of a gantry system on a motorway, this would need to be broken down into individual gantries with their electrical, communications and structural sub entities.

Finally at the bottom of the pile we have the individual maintainable asset called the Element.

In this instance it is a safety barrier. You’ll notice that we do not go further down this into the nuts, bolts, plates or foundations. These are of course all included in the information about the barrier.

The key with all of it, is that it should meet the requirements of the maintainer.

Levels of Definition

This breakdown structure also helps us during the lifecycle to define our levels of definition. If you imagine a new road project, at briefing phase, we know a new road Facility is required. We can create an identity for that level and start to hang information off of that instance. Moving into the concept phase, we now know that there is going to be a bridge Entity along that road, we can create an identity and build up further information that will impact the Facility.

In the detailed design phase, we now can identify individual Elements that will make up the Entity. Once again allowing us to build more information that will have an impact all the way back up the asset breakdown structure.

Finally, when we get to construction, we can then talk to the manufacturers who will supply us with products and PDT’s/ PDS’s that will fulfil the need defined by this build-up of information.

CAD & BS1192:2007

When creating detailed 3D models of our assets, we need to break things down into manageable chunks. This is talked about in BS1192:2007 as zoning.

If you intend to hand that 3D model over to the client for use in Operations and Maintenance it is best to split it up and label it along the same lines as the asset breakdown structure.


In the UK we have chosen Uniclass as our method for classifying our assets. The Uniclass tables are a good starting point to assist in your creation of an asset breakdown structure.

Every asset if different

Yes, your asset is different from their asset, but it has the same basic elements that make up those entities and so on. To help control and understand even the most complicated of assets we have taken a leaf out of the oil and gas world and recommend the next step is defining your Asset Tagging Strategy.

An “asset tag” is a collection of information that helps us to define the duty, relationship and ID of an asset before we even know what product will fulfil that need. This is covered in another document.


An Asset Breakdown Structure is key to ensuring the impact of one asset on another in understood and that the information provided in any BIM deliverable is structured in a way that the end user is best served.

© 2017 - 2020 by COMIT Projects Ltd.


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