US projects pilot defect detecting software

31 October 2018 | By Stephen Cousins

Five projects in the US are piloting new BIM software that uses algorithms to automatically spot defects during construction.

Avvir is an ‘Automated Construction Verification’ tool that compares as-built scan data, recorded progressively during the build phase, against the BIM model to automatically highlight any elements that deviate from the design.

The software was developed to help building owners, developers or main contractors keep tabs on quality assurance and quality control issues and produce a highly accurate BIM for handover.

It also functions as a BIM management tool able to automate progress monitoring to identify elements that have, or have not, been built to meet the construction schedule, and keep tabs on poorly performing trades by calculating the number of elements installed defectively or out of line with the programme.

Avvir is currently being deployed on five active construction sites, which is expected rise to 10 by the end of the year. Company CEO Raffi Holzer claims the system is more efficient than current approaches to Scan-to-BIM: “Some general contracting companies have started to scan regularly to compare against the BIM, but it typically requires a human to analyse the data, so things get missed and the process takes a long time. We speed up the process, we see everything.” 

Avvir offers two options to clients: firms can either determine a scanning schedule then scan the site themselves as work progresses and submit the point clouds to Avvir to interrogate, or Avvir can do the scanning at an additional cost. The cost of using the software alone is typically between 0.2 and 0.5% of the project value. 

Each deviated element is shown twice, once in solid red to show where it should be built according to the BIM, and once in a translucent red to show where it is actually built.

Holzer says its scanning service helps reduce complexity for customers and it has to take responsibility if something goes wrong.

As the scans come in at regular intervals, Avvir first cleans them up to remove any unwanted objects such as people or site equipment, then aligns them with the BIM, either based on survey control points or a ‘best fit’ algorithm.

“Once aligned, the algorithm starts running to find discrepancies between reality, as represented by the scan, and the design intention, as represented by the BIM. Everything is  automatic, although we need to keep humans in the loop to identify certain building elements, such as small electrical conduits, but we expect those to be automated soon too,” says Holzer.

When users log in to an online portal to view the results, each deviated element, such as a column or a beam, is shown twice, once in solid red to show where it should be built according to the BIM, and once in a translucent red to show where it is actually built. Measurements are provided to show how far out of tolerance each deviated element is.

Users must then decide whether to keep an element that is out of tolerance, and update the BIM with the click of a button to reflect that, or ask the contractor to go out into the field and change the location of the element. Once the element has been moved, the area is then re-scanned and the portal updated to display the element as green to indicate that the problem has been fixed.

The software can track if particular building elements have been installed and update the schedule to reflect it.

According to Holzer, the ability to keep BIM up-to-date throughout the building process ensures that it reflects the real-world conditions, giving facility managers an accurate model of the asset at handover for ongoing operations and maintenance. 

When used as a BIM management tool, the software can track if particular building elements have been installed and automatically update the schedule to reflect it. “If a firm is running behind it can project a new completion date, which if accepted will automatically update the schedule. Main contractors spend an inordinate amount time trying to keep schedules up to date and in line with reality, we can automate the process,” says Holzer.

The ability to track progress in terms of the number of deviations makes it possible to spot poorly performing trades and remove them from a project before there are major knock on effects.

Looking ahead, Avvir plans to introduce new functionality to the software such as semantic tags that define the type of deviation or error detected, photorealistic walkthroughs and integration with banking systems to automate construction payments.