Progress towards a roadmap for mapping underground utilities in Singapore

In 2017, the Singapore Land Authority (SLA), Singapore-ETH Centre, and the Geomatics Department of the City of Zürich started the Digital Underground project as a first step toward achieving an accurate, current, and complete map of subsurface utilities in Singapore. I had a chance to chat with Rob van Son, of the Singapore-ETH Centre and Project Lead of the DU project, and in this article we describe progress to date and the next steps toward developing a reliable map of underground utilities in Singapore.

A number of years ago Singapore recognized the urgency for a map of its underground utilities for a number of purposes; planning, design, construction, ownership and maintenance of underground infrastructure. Recently the Urban Redevelopment Authority (URA) of Singapore unveiled its Draft Master Plan 2019 to guide Singapore's development for the next 10 to 15 years which identified increased use of underground space as one of its strategies to create more space for Singapore's growing needs. In 2017 the Singapore Land Authority (SLA) started the Digital Underground project. The project aims to establish a reliable map of underground utilities in Singapore. Part of the first phase of the project was an experiment which applied a combined LiDAR and ground penetrating radar array to capture above and below-scans of various areas in Singapore. The experiment contributed to an assessment of the quality of Singapore's underground infrastructure information and the feasibility of large area utility mapping techniques. The first phase of the project resulted in a set of recommendations for moving forward toward a reliable digital twin of Singapore's underground utilities. These represent a comprehensive checklist of how at a national and city level we can begin to address the pressing problem of creating a reliable digital twin of underground utilities.

Singapore has recognized that insufficient quality of information about the subsurface can lead to poor decisions, unnecessarily lengthy planning processes, increased cost of construction, more litigation and missed business opportunities.

When designing and building new utilities and other facilities underground, a reliable map is needed to plan for the optimal use of scarce and often already congested space and avoid utility damage causing loss of service and creating delays in the construction process. Land ownership regulations require an accurate record of the alignment of subsurface utilities in order to minimize conflicts in the use of underground space.

Although professionals from land development agencies, utility owners, and engineers in Singapore are able to access various sources of utility information, this information cannot be considered reliable. It lacks accuracy, does not always represent the latest and current situation, and may not be complete, lacking information on legacy utilities. Furthermore, data quality itself is a largely unmanaged and unknown aspect, leading to uncertainty. Recently in Singapore, important steps have been taken to ensure that all newly built utilities are captured according to the same standard and exclusively by qualified persons. However, the lack of quality of existing information remains to be reconciled. Similar to the U.S. and the UK, in Singapore the contractor has full liability for damage to underground infrastructure, which means there is little motivation from the perspective of liabilities for network operators to improve the quality of their location information about underground utilities.

Since its release in 2017, the Standard and Specifications for Utility Survey in Singapore has progressively been mandated for all newly built utilities by utility regulatory authorities. The standard is for open trench cases only. It covers the techniques to be employed, the data to be captured, and the requirement for a qualified professional (a Registered Surveyor at the Land Surveyors Board of Singapore) to do the job.

In 2017, the Singapore Land Authority, Singapore-ETH Centre, and the Geomatics Department of the City of Zürich started the Digital Underground project with an initial objective of developing a road map for achieving a reliable map of subsurface utilities. One of the first activities was to assess the state of the art for reality data capture technologies and how these might be used to improve the accuracy of underground data for both new and existing buried utilities. The DU project is looking at the whole workflow relating to underground infrastructure from data capture to application which is a different approach from most of the rest of the world which takes a bury and find it approach.

For new infrastructure, non-conventional reality capture techniques were documented. For open trench utilities, this included the use of handheld laser scanners. For trenchless construction, a technique for determining location by pulling a gyroscopic mapping device through pipes was investigated.

For existing utilities the latest ground penetrating radar (GPR) technology was assessed to determine the effectiveness of GPR as a mapping technique with Singapore's soil conditions. Singapore soils are not particularly good for GPR, which is able to penetrate down to 2 meters. The DU project collaborated with Leica Geosystems and IDS GeoRadar to deploy the Pegasus:Stream, a combined LiDAR and ground penetrating radar array, for the first time in Southeast Asia. It was used to capture above and below-scans of nine distinct areas in Singapore. In the Toa Payoh estate, which has undergone continuous development since the 1960s, data was captured along a 1.8 kilometre four-lane road at a speed of 15 kilometres per hour. Scanning of the entire area took five hours. Post-processing of the data back in the office required three weeks. A total of 109 subsurface pipes and ducts were detected in the area. By comparing the detected utilities to available information on existing utilities, it was found that in older areas the location of a lot of underground infrastructure was not recorded or does not have an accurate location. Only around 30% of detected utilities could be identified using the existing information. For newer areas, this figure was higher, but many detected utilities linking to new developments were not mapped yet.

Data modeling was a second key objective of the first part of the project. The goal was to develop a data model that enables the captured subsurface infrastructure data to meet the requirements of end users use cases. With the data collected with LiDAR and GPR, the Digital Underground team explored how available map data and the subsurface utilities detected during the pilot could be combined to create a 3D model that could be fused with Singapore's cadastral maps. The results were showcased in a demonstrator application highlighting the value of reliable 3d information subsurface utilities for land administration purposes.

The invaluable results of the first part of the project resulted in a set of recommendations for moving forward toward a reliable digital twin of Singapore's underground utilities. These provide a set of high level requirements with which at a national level we can begin to address the pressing problem of accurately mapping underground utilities. The first main recommendation is to establish a single, consolidated national map of subsurface utilities that enables data quality management. This is underway in the UK and is part of a national strategy for a national infrastructure map that has been initiated in the U.S. Secondly a national mapping strategy for accurate mapping of subsurface utilities was proposed that is supported by two pillars. The first is to ensure that all newly built utilities are captured accurately. The second is to capitalize on data capture opportunities during the life cycle of existing utilities. For example, capital construction projects are expected to benefit directly from utility mapping in the design phase, and the captured information can be consolidated for use beyond their scope and timeline. Other events, such as visibility or accessibility of utilities during trial trench, maintenance and rehabilitation works may provide suitable data capture opportunities that can each be matched with the appropriate data capture technique. Another key requirement is accessibility, that this data is available to the people that need it, i.e. land administrators, planners, designers, utilities and telecoms, construction contractors, and emergency responders, but in a way that protects privacy, does not reveal information about networks that could be used competitively, and prevents misuse.

The first part of the Digital Underground project was just completed 2 months ago. Funding has been approved for Part 2 of the project. Over the next two years, SLA and its partners intend to further develop the foundations of an ecosystem that supports and enables a reliable map of subsurface utilities. The project will cover a wide array of themes such as governance, legislation, capacity development, data capture standards, and a prototype platform for quality control and consolidation of 3D utility information for planning and land administration applications. One of its early results is the launch of Digital Underground Connect: a community of practice for subsurface utility mapping together with Bentley Digital Advancement Academies.