Singapore is a land-scarce city-state with limited land to build on. While the city-state has successfully dealt with this challenge throughout its history, it is looking into new solutions to meet its ever-growing needs. Singapore is currently undertaking strategic initiatives to make better use of the available land, including tapping the underground space for future (re)development.
An accurate map of subsurface utility infrastructure is essential for effective planning and administration of underground space, reduction of uncertainty and risk for capital infrastructure projects, and safe construction practices. The project is working towards establishing a consolidated 3D database that brings together data on all underground utilities in Singapore and facilitates a gradual and continuous improvement of data quality. Ultimately, the effort is estimated to support better land use above and below the ground and time and cost efficiency to developers and construction workers.
In 2019, the Urban Redevelopment Authority (URA) unveiled the Draft Master Plan 2019, which, for the first time, provided a framework to develop the underground space for selected areas in the next 10 to 15 years. Singapore’s underground space is currently home to extensive infrastructure including train lines, utility networks, pedestrian walkways, and fuel and ammunitions storage units. In the future, it is bound to become more congested, leading to increased challenges in managing and planning of the underground space to accommodate current and future needs. Mr. Rob van Son, Project Lead of the Digital Underground Project at the Singapore-ETH Centre, says, “Unlike in Western Europe or in North America, where Subsurface Utility Mapping is driven by a need to reduce utility strikes, Singapore’s plans are primarily driven by a need to efficiently plan and manage the subsurface space”.
In view of the guidelines established by the URA, the planning agencies recognized the need for a reliable map of subsurface utilities. A lack of reliable information might result in lengthy planning and development processes, inefficient and costly land administration process, loss of services due to utility strikes during excavation works, and additional recurring costs to locate underground utilities.
To address the challenge, in 2017, the Singapore Land Authority, in a research collaboration with Singapore-ETH Centre (SEC) and the City of Zürich, Switzerland, initiated the Digital Underground Project −a research-to-application initiative. The motivation for the project was the urgent needto better plan and manage the underground space and be ready to support Singapore’s future plans. The first phase of the project concluded in June 2019 with the release of a roadmap containing a set of strategies and recommendations that would prove helpful in developing reliable maps of underground utilities in Singapore. Currently, the project has progressed into the second phase, which aims to establish the foundations of a sustainable utility mapping ecosystem in Singapore.
The Digital Underground Project was initiated by the Singapore-ETH Centre, a research institution established by the Swiss Federal Institute of Technology Zürich (ETH Zürich) and Singapore’s National Research Foundation (NRF), under its CREATE program. In this research collaboration, the team works closely with both Singapore and Zürich government agencies so that both cities may benefit from the results of research on subsurface surveying technologies and advanced data modelling techniques.
Additionally, the project includes research into digital twins for the underground to advance our understanding of the multitude of dimensions of subsurface infrastructure. To ensure that the research meets the needs on the ground, the team conducted research to analyse subsurface utility information needs in Singapore, along with an analysis of the utility mapping ecosystem currently in place in and beyond Singapore.
A review was carried out to understand currently available subsurface mapping techniques, such as conventional surveying tools, laser and photogrammetry, Ground Penetrating Radar (GPR), RFID markers, and gyroscopic mapping. A series of pilot studies was undertaken to evaluate the feasibility of the various techniques in Singapore. Furthermore, the captured data was modelled and integrated with data from other sources to demonstrate its potential applications in urban planning and land administration. This led to new insights and lessons learned, which paved the way for developing a roadmap.
A coordinated and integrated approach to mapping Singapore’s underground utilities—a whole ecosystem approach—is needed to produce reliable information to effectively and efficiently plan, administer and develop the underground space. To this end, a single, consolidated 3D digital twin of underground utilities is in the works to ensure the quality of newly captured data and drive the continuous improvement of the quality of existing data through trial trench investigations and subsurface utility engineering and mapping.
Unlike conventional one-off mapping approaches, the digital twin is continuously linked to the physical world through a connected data environment in which it both provides and ingests data. It is also designed to make quality a known and managed property of the data. To provide accurate data and support new digital data capture workflows, professionals in the surveying and mapping domain need to equip themselves with new capabilities, techniques, and knowledge of new technologies.
To survey the subsurface, GPR—a non-destructive geophysical technique—was used to detect and locate subsurface utilities. The Digital Underground project collaborated with Futurus Construction – a local provider of non-destructive surveying techniques – to conduct field trials to locate and map existing utilities in Singapore and reconcile a lack of locational accuracy of the data. Further, the stakeholders also collaborated with Leica Geosystems and IDS Georadar to use the Pegasus: Stream in its field study. The Leica Pegasus: Stream is a towable mapping platform that includes Leica Pegasus laser scanner and IDS Georadar Stream EM GPR, which captures high-resolution data at an unprecedented speed and volume in a single pass.
“We had an extensive look at (3D) GPR in phase 1 of the project but also covered EML, RFID markers, inertial mapping, and conventional techniques such as total station, GNSS RTK, and laser scanning. In Phase 2, we are staying up to date with technological advancements and are supporting trials using quantum gravimeters. We are also exploring the use of photogrammetry and laser scanning as rapid mapping techniques for open trench installations to deal with the narrow time window in which newly built utilities are visible and accessible for surveying,” adds Rob van Son.
Using the data collected by the scanner and the GPR, a conceptual data model was developed, which consisted of a 3D representation of subsurface utility assets, accurate and reliable survey information, and LADM, which linked existing cadastral maps to the subsurface utilities.
A roadmap was developed in the first phase of the Digital Underground project, proposing an integrated, “whole ecosystem” approach. It not only includes spatial information and the value proposition of using geospatial technology, but also considers legislation, collaboration, capacity building, governance, and R&D. The roadmap details recommendations in five themes: coordination, consolidation, capture, capacity, and community.
The project is now in its second phase, whereby the team is working towards establishing the foundations of a reliable digital twin and a sustainable utility mapping ecosystem that can support it. The team will propose a number of instruments that could help Singapore put its plans for mapping the underground into action, including:
Furthermore, the team has successfully established the Digital Underground Connect community of practice, together with Bentley Systems’ Digital Advancement Academies and the Singapore Institute of Surveyors and Valuers.
The use of reliable spatial information and underground map data will continue to lead to better decisions that reduce costs, delays and safety hazards, before and after moving to the underground. Going forward, the Digital Underground initiative will help establish a nationwide map of subsurface utilities, integrating data on existing utilities and including new data in one place. It will give an important boost to the implementation of a national mapping strategy for subsurface utilities.