TThe recently published Digital Underground: Imagining a digitally enabled future is full of insights derived from a four year effort by the Singapore Land Authority in developing a road map for a coherent national mapping strategy for underground utilities and, most recently, supporting an ecosystem to produce and deliver accurate and complete digital data to stakeholders..
The recognition that the quality of the existing data about underground infrastructure represents a major inhibitor to developing a reliable subsurface digital twin is a central theme. For example, the Singapore Digital Underground document states that "virtually all stakeholders are aware that much of the available information is unreliable and that this has repeatedly led to losses of time, money and opportunities."
Another challenge is accessing underground infrastructure data. In many jurisdictions worldwide including Singapore records of the location of utility and telecom networks and facilities are often owned and maintained by private utility and telecom operators. The result is that access to underground infrastructure data is often restricted and not available to all stakeholders on construction projects. Jurisdictions have addressed the accessibility problem through organizational structures that often involve government such as government mandated one call systems in North America and the DT DICT system in France. Systems that are not mandated by government have been developed, for example, the private one call system LineSearchBeforeYouDig in England and the industry voluntary Vault system in Scotland.
The Singapore Digital Underground project identified measures that it considers necessary to address these challenges. Current business practices for data production, data management, data sharing, and data use are largely dependent on individual land administrators, network owners, contractors and surveyors and are not consistent for all stakeholders. The result is that every day significant effort and resources have to be invested to work around the lack of reliable information about underground infrastructure.
Data accessibility for all stakeholders
The foundation for addressing the data accessibility issue in Singapore is a new subsurface utilities data governance framework. Among other measures it provides a basis for making government and network owners' data accessible to all stakeholders. The UK's National Underground Register (NUAR) initiative has an analogous framework in the form of data sharing agreements that were signed among 40 or so utilities and government agencies during the pilots in the North East of England and Central London and enabled data sharing among all the participants. Achieving a long term framework of this type for the nearly 700 network owners is a top priority of the NUAR implementation, currently underway in England, Wales, and Northern Ireland.
In Colorado enabling access to underground utility data initially involved requiring contractors working on public construction projects for the Colorado Department of Transportation (CDOT) to use a mobile+cloud solution developed for CDOT. The source of the data was SUE surveys and high accuracy as-builts mandated by recent state legislation and regulations. It did not include data of uncertain reliability maintained in utility and telecom GISs. Sometime later network owners with equipment and locators and others working in the state ROW were also required to use the same mobile+cloud solution providing all stakeholders on CDOT construction projects access to the same high accuracy data.
Improving data quality
The biggest challenge with existing underground data, generally stored in network owners' utility GISs, is that the data is often inaccurate, out of date or simply missing. A key question for any jurisdiction attempting to create a subsurface digital twin is whether to rely on unreliable data from network owners' records or to create a new high accuracy database with new data, for example, from recent SUE surveys or survey-grade as-builts.
Some jurisdictions such as Vault in Scotland and the NUAR initiative in the UK rely on the network documentation captured and maintained by network owners. Utilities have processes for updating and improving the quality of their data. These are supplemented by the NUAR application support for feedback from the field - implemented as "observations" in the online application developed by the Ordnance Survey for the pilots.
Other jurisdictions such as Colorado have decided not to rely on utility and telecom GIS data but to build new high accuracy databases using the results of recent SUE surveys and survey-grade as-builts with known quality levels, defined by ASCE 38-22 and ASCE 75-22.
Singapore has had a contractual standard for survey-quality as-builts since 2017. The key provisions of the new data governance proposal are designed to improve data quality and to establish an authoritative single source of truth. Specifically it introduces the concept of a national Data Quality Hub which is comprised of a consolidated underground infrastructure database and data flows that are designed to co-exist with Singapore's current utility data workflows but which enforce data quality management. The Data Quality Hub requires the digital submission of all newly captured data on subsurface utilities, quality control of submitted data based on a common set of rules, and the consolidation and integration of newly collected and legacy data for legacy data quality improvement.
Integrating new high accuracy data with legacy data
For jurisdictions with new sources of high accuracy data from new legislation and regulations that are developing high accuracy databases, a crucial question is whether to attempt to integrate the unreliable data from network owners into these new databases. In Colorado, the data from the mandatory SUE surveys and high accuracy as-builts with assigned quality standards based on ASCE 38-22 and ASCE 75-22 that goes into the new database is also made available to network owners who can use it to correct and update their records, but are not required to.
Singapore's approach is to require all data going into the Data Quality HUB to pass the set of quality rules defined by the new data governance framework. If combining legacy data with new data, for example, from SUE surveys or from surveys of recently exposed underground utilities, results in data that can pass the quality rules then it is expected that that data should be eligible to be integrated into the Data Quality Hub.
A second challenge is that most legacy data is 2D and does not include depth or elevation. The Singapore Digital Underground project attempted to address this issue by suggesting several ways of generating 2.5D data from legacy 2D data, but none of these is capable of producing the reliable data that the quality rules would seem to require.
Conclusion
Singapore has recognized the implications of the problems resulting from inaccurate, outdated and incomplete maps of underground infrastructure and adopted a comprehensive approach for addressing data quality and access issues. Because of the approach that Singapore has adopted and the fact that the Digital Underground project has actively engaged the international community, many international jurisdictions are watching closely as Singapore moves into the implementation phase.
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