Mixed reality applications for visualizing underground utilities in 3D have been available from many companies for years, but have not been widely used. There are signs this is changing. For example, vGIS is an augmented reality (AR) visualization application that integrates traditional BIM, CAD, GIS and other types of 2D and 3D data including Autodesk BIM and CAD models, Bentley BIM designs and Esri ArcGIS data, into augmented reality visuals to provide survey-grade accuracy on consumer handheld devices. A recent study has quantitatively assessed the benefits of applying AR to underground utility locate operations.
Background
In most jurisdictions locating underground utilities is performed just prior to excavation by network operator staff or by commercial professional locators in response to an information request submitted to the local one call centre. Locates involve remote sensing devices such as ground penetrating radar, electromagnetic wands, and other devices augmented by maps of underground utilities provided by network operators. The result of a locate operation is marks on the ground, paint or flags. The locate may be independently validated in a quality assurance process, often by the contractor. It is estimated that $10 billion is spent annually in the U.S. on underground utility locates. Any technology such as augmented reality that can improve the efficiency and effectiveness of underground locates needs to be seriously assessed. The application of AR to locate work provides an opportunity to improve the process and outcomes including productivity, accuracy and safety.
While it may seem obvious that being able to visualize underground utilities in 3D on-site would be highly beneficial, there are practical obstacles that hinder realizing the full benefits of the technology. A major issue is that much utility GIS data is incomplete, out-of-date and and inaccurate. Secondly, environmental conditions, terrain, and accessibility specific to a locate job may make the application of AR impractical.
Assessing the benefits of AR for underground utility locates
To assess the practical benefits of applying augmented reality to underground utility locates a leading Canadian locate services provider, Promark-Telecon, has joined with the developer of a leading augmented reality solution vGIS, to initiate a study to measure the quantitative benefits of applying AR to underground utility locates. The study was conducted in the city of Toronto, a major metropolitan setting containing a diverse mix of personal housing, industrial and commercial buildings. In addition to different types of buildings, Toronto possesses an assortment of new and aging infrastructure, some well-documented and others sporadically documented. The infrastructure located included gas, water and sewer. The study was conducted from January 2018 through May 2018. During that period, the locators participating in the study recorded the time that it took to perform locate tasks with and without AR. In addition to the time measurements for each locate job, the study participants recorded the technology’s impact on several other factors including safety, locate accuracy, and any issues encountered.
Augmented reality involves a smartphone or a tablet that has a screen, camera, GPS and an accelerometer that detects camera motion and orientation. The real world "background" is comprised of data, including location, of real world objects or visible objects . For example, in the context of construction virtual objects representing a model of underground infrastructure can be superimposed on a map showing existing conditions or a map of surface structures such as roads and buildings. The augmented reality application superimposes the virtual design objects or the underground infrastructure on the map of existing objects or the surface map. In this case 2D data showing the location of underground assets are projected onto a photographic view of the surface.
Using an iPad, locators in the field used the vGIS application to access city 2D GIS data and overlay it on the 3D view of the surroundings captured by the on-board camera. A calibration process was used to ensure that the GIS data and the view captured by the camera are aligned.
The Toronto study evaluated the impact of AR visualization technologies on utility locates conducted in real-life conditions. By collecting empirical data over the course of several months, the study measured the effectiveness of applying augmented reality technology to utility locates using multifaceted criteria, including productivity, safety and locate accuracy.
Time savings from using AR for underground utility locates
The time savings identified by the Promark locators ranged from negligible to four hours. For just under 90% of the jobs, the time savings were significant ranging from 10 minutes to more than 2 hours. The average time saved was 30 minutes per job.
Perhaps more meaningful is the proportion of total job duration saved by using AR. In 40% of jobs AR reduced job duration by a half. In a third of the jobs locators realized even larger time savings of 66% or more.
The study did not identify statistically significant differences based on the infrastructure type (gas, water and sewer). Informal feedback suggested that the more accurate and complete the location information about underground utilities was, the greater the time savings. In other words accurate utility records amplified the benefits of the AR visualization system.
The study evaluated differences in savings based on different types of jobs, such as industrial, residential, and other types of locates. The comparison revealed that the time savings for validation jobs were significantly higher than for other types of jobs, ranging from 66% to 90%, suggesting that AR is exceptionally effective for quality assurance jobs.
On average, utility locators using AR reduced the time required to complete jobs by 50%. At the same time, QA validation time was reduced by 66–85%. This translates to cumulative savings of 12–20 hours per locator per month.
The impact on the ease of doing a job was assessed by asking participants to evaluate each job using a three-level scale whether AR made the job easier, made the job harder or had no impact. In 84% of jobs, participants reported that AR made the job easier.
AR and safety
Underground utility locates can be hazardous work, especially in heavy track. This study assessed the impact on safety of using AR for underground utility locates. For 85% of jobs participants reported that AR had no impact on safety. In 11% of jobs, AR increased safety, while in 4%, AR had a negative impact. The notes provided by the participants suggested that the negative impact on safety was experienced when locators strayed into hazardous situations while concentrating on tracing lines using AR.
Regarding the issue prevention aspect, participants reported that AR helped prevent issues in 49% of cases. Issue prevention was experienced during validation locates where supervisors would “test” validated locates using AR, giving them confidence about the completed job. In 4% of jobs locators reported issues resulting from inaccurate utility data and unreliable base maps that misled locators.
Conclusion
The study has quantified the practical benefits of visualizing existing underground infrastructure in augmented reality for underground utility locates. The benefits were found to be significant; utility locators using AR reduced the time required to complete jobs by 50% and QA validation time by even more 66–85%. The approximately 10% productivity boost recorded by the study confirms the potential of augmented reality for the locate industry including network operators. There was no apparent downside to using AR in the field, for example, AR had no significant impact on safety. The quality of utility GIS data was found to be a key factor in maximizing the benefits of applying AR to underground utility locates.
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