Understanding As-Builts

nullSince Roman times city planning has included the provisioning of Water. Moving forwards a couple of thousand years has taken us away from the obvious aqueduct to an immensely complex underground network of pipe’s servicing the 3 water system; Wastewater, Storm water and drinking Water.

Changing City, Changing Networks

As cities develop and evolve, particularly when they expand, a lot of new infrastructure goes into the ground. Keeping track of this is important for a number of reasons:

  • Finance planning – knowing how much budget to set aside each year for maintenance or expansion
  • Finding and fixing – being able to fix leaks and pressure issues in the system
  • Health and water inspections – finding access points for legally required tests
  • Flood prevention – Integrating infrastructure into flood modelling
  • Charging for work – properly assigning the expense of a water network to the people who use it.

Inaccuracies and their consequences


Getting this stuff wrong causes big problems! If you fail to account for your cities ability to afford the infrastructure then rates can skyrocket out of control. If you’re unable to fix the network when it does wrong then residents end up with a supply of fresh drinking water, or storm drains get and remain blocked or the sewerage system shuts down.

As-Built Processing

In New Zealand as-builts are received by council once engineering work has been completed, they serve two primary purposes:

  1. They are a legal record of the engineering work requested and as well as what was actually done
  2. They are a practical reference guide for finding the assets again

I’m talking particularly in this post about a city’s water network, Waste, Storm and Water, although the same holds true for much of a city’s infrastructure.

As-builts are provided by engineers and surveyors. These guys rely on Computer Aided Design (CAD) programmes to get the required precision. However, they are not setup for typical asset management, and so the drawings are eventually converted into an asset management program such as Hansen (now IPS).

Councils will usually receive the digital copies of the plans along with the paper copies. We are finally starting to see the paper copies become less of a requirement but the practice still persists.

CAD to Asset Management

Once an as-built is received it is entered into an asset management piece of software. This is primarily to fulfill the legal requirements by central government, covering areas such as renewal schedules and financial valuations. It maintains a database system which records a lot of detail on the asset. Below is a snapshot of the IPS system front page of a gate valve water asset.


In New Zealand, prior to Asset management becoming a national political issue, as-builts were converted to a GIS system so that they were easily trackable and mappable. As a result we have ended up with two separate databases’, GIS & Asset Management (IPS in my case). Because of this most assets are still updated by using GIS.

Uploading plans:

The GIS component is still critical because IPS doesn’t have an adequate alternative upload solution. If IPS were a more complete system we would aim to consume it as a GIS service.

At a very high level this is how I upload plans from a receive CAD plan to an asset management system.

  • Loading data from CAD format (DWG) to Geodatabase and extract usable data. Extracting usable data can be difficult from CAD as they come from many different contracts, who use different standard formats.
  • Load the data to a GIS database and fill in all relevant metadata using python tools which I can share if people are interested
  • Use the GIS plugin from IPS to create assets in the IPS database using a unique field. And then synchronize the metadata from GIS to IPS

Processing a completed as built into a GIS and Asset Management System system is huge hidden cost for most councils. Depending of complexity, this can take day or weeks to complete as they have to manually enter the data into their GIS and Asset Management systems one asset at a time.

As-built Automation

As built automation is well overdue and something I’m working on using ArcPro and Python Toolboxes. If anyone is interested in helping or would like more details please leave a comment and I’ll get back to you.


Some councils around the country have made fantastic progress by controlling the datanull input, working more closely with the Surveyors and Engineers to have data uploaded in a standard formats. I think this is probably the best solution as the data I receive is extremely varied in quality. However, I am unfortunately not in a position to enforce requirements so I have another solution to present, and will do so in coming posts.

Thanks for reading,


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