Reducing Underground Utility Damage during Construction

The $10 trillion global construction industry is facing a crisis. For many of the world’s advanced economies including Japan, Germany, U.S., South Korea, and U.K., construction productivity has been stagnant or even declining. Historically, investment in research and development by the construction industry has been very low compared to other industries. However, 2018 was an inflection point with venture capital investment in startups in the construction sector quadrupling.

Underground utilities are an important contributor to low construction productivity. According to the Federal Highway Authority (FHWA), underground utilities are a major cause of delays on civil construction projects. Comparing utility damage in the United States and Japan reveals a startling difference between the two countries. In the United States, utility damage is between 400,000 and 800,000 incidents per year. In Japan, the number of incidents in 2016 was 134. Clearly something can be done to reduce the risk on underground utility damage during construction.

TECHNICAL ADVANCES IN DETECTION AND CAPTURE

As a result of accelerating investment in detection technology, new developments are changing how underground utilities are located and digitally mapped. Electromagnetic (EM) detection is the industry standard and used by most locators. However, a major drawback to EM is that it involves a manual process which results in marking the ground, but it does not produce a permanent record of the location of the utilities detected. A recent development combines EM detection with GNSS (and RTK for high accuracy) and digital recording to capture an accurate digital record of the location of detected utilities.

Advances in ground-penetrating radar (GPR) have made it possible to safely capture scans at roadway speeds. Stacking, or statistical averaging, is increasing the depth where GPR is effective. One of the important inhibitors to the broader use of GPR, for example, among surveyors is that interpreting GPR scans has required a trained geotechnician. New GPR post-processing software combines successive scans to produce a tomographic image of underground utilities rather than the typical hyperbolas. This capability simplifies the interpretation of GPR scans, enabling surveyors and other professionals to use GPR technology effectively.

The simultaneous capture of above- and below-ground scans using Lidar and GPR can create a complete 3D model of all existing infrastructure for planning, design and construction. Inertial mapping can be used to map underground pipe networks for up to two kilometres. Acoustic locating has been shown to be effective in detecting underground objects down to 30 feet.

Mixed reality applications for visualizing underground utilities on mobile devices are increasingly being deployed to the field. Existing 2D and 3D records and site investigation results can be integrated into a 3D model to provide greater context for visualizing above- and below-ground infrastructure in augmented reality.

TECHNICAL DEVELOPMENTS IN RECORDING AND SHARING

In the U.S., it has been estimated that $10 billion is spent annually locating existing underground utilities. This includes utilities and telecoms responding to One Call notifications either using commercial locate services or their own staff, and efforts by excavators to detect and verify the location of underground utilities prior to commencing digging. The result of these locate efforts is typically painted or flagged on the ground, but often it is not recorded on paper or digitally. At best, this data becomes part of project documentation and is effectively lost at the completion of the project.

Recent legislation in some jurisdictions requires the digital recording and sharing of the results of locate operations. Online systems have been developed to share the location of underground infrastructure among stakeholders in construction projects. The Colorado Department of Transportation (CDOT) has adopted a hybrid online system that incorporates elements of survey and GIS technology and enables the recording and sharing of information about underground utilities among CDOT, large and small construction contractors, network operators, and other stakeholders. Access to this data is provided over the web, enabling staff to access underground utility location maps on a handheld device in the field.

Some jurisdictions are even creating open portals with access to publicly available maps of underground infrastructure. For example, the Colorado Oil and Gas Conservation Commission (COGCC), which requires the oil and gas industry to provide accurate maps of flow and gathering lines in the state, has created an open portal where maps of these underground lines are open to the public.

IMPROVING DATA QUALITY

A key challenge in reducing damage to underground utilities is the low quality of the existing records maintained by many network operators.

Some jurisdictions are mandating that survey-grade as-builts be submitted for all new underground infrastructure. For example, the state of Montana has recently made it mandatory that survey-grade as-builts stamped by a PE or PLS be submitted on completion of construction. However, for smaller projects it may not be cost-efficient to conduct a traditional survey. New developments in technology are providing other options. For newly-installed pipelines, Lidar is being applied to efficiently capture location to millimeter precision prior to filling the trench. New reality capture solutions can generate as-builts accurate to ± five centimeters from a video taken with an Android smartphone using RTK GNSS or accurately surveyed control points.

In addition, improving the quality of records of existing infrastructure is essential to enable continuous reduction in underground utility damage. The Colorado online system provides for feedback from handhelds in the field during construction. This increases field staff engagement and enables staff to actively contribute to improving the locational accuracy and other information about existing underground infrastructure.

RELIABLE METRICS

Reliable metrics are essential for assessing the social and economic impact of utility damage and the effectiveness of new policies, legislation, regulation, and technologies in reducing underground utility damage. In North America, the Common Ground Alliance (CGA) has been collecting voluntarily submitted incident reports since 2003. Based on this data, CGA statistics reveal that utility damage, when prorated to construction activity, is actually increasing. In the Netherlands, an online One Call system called KLIC has been implemented. Reporting incidents of utility damage is mandatory. The statistics reveal that while construction efficiency has improved, there has been no reduction in underground utility damage. In Japan and at Heathrow International Airport where programs of continuous improvement have been implemented, statistics reveal a sustained long-term reduction in underground utility damage.

CONCLUSION

A review of recent international initiatives involving changes in legislation, regulation, and business processes as well as new technical developments concluded that a successful program for reducing utility damage during construction not only avoids service disruptions and prevents injuries and fatalities, but also improves construction productivity by reducing the risk of project delays and budget overruns. However, it also concludes that there is no silver bullet for reducing utility damage during construction. A comprehensive approach involving many stakeholders is required, but there are significant additional benefits. Reducing risk reduces insurance costs for an industry where margins are typically low. Furthermore, developing and maintaining an accurate 3D map of underground infrastructure has potential benefits for other use cases beyond construction such as utility outage management, disaster planning, emergency response, urban digital twins and smart cities.

The white paper Reducing Damage to Underground Utility Infrastructure During Excavation has been published by the Geospatial Information and Technology Association (GITA) and is available for free download at gita.org.

Geoff Zeiss is a scheduled speaker at the 2021 Global Excavation Safety Conference.

Geoff Zeiss tracks the contribution of geospatial technology to the digitalization of the construction and energy industries on his “Between the Poles” blog and other media. His area of special focus is locating, mapping, and sharing information about underground utility infrastructure.

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