In recent years project owners have recognised the important advantages of gaining an early understanding of existing utilities on construction projects. The considerable advancement in technology available to locate utilities, including multi-antenna radars and advanced vacuum excavation equipment,
combined with the recent introduction of AS5488-2013: Classification of Subsurface Utility Information (SUI), has improved subsurface utility engineering processes and consistency in data delivery options in formats such as CAD and GIS.
In Australia the subsurface utility engineering industry has experienced rapid progression, with greater emphasis placed on the benefits of gathering utility information in the early phases of construction projects. Only a decade ago it was common to design or construct a project relying predominantly on utility information captured on Dial Before You Dig plans. Today, the application of subsurface utility engineering processes for construction projects during the design or construction phase of a project has become a standard requirement for most authorities, municipalities, utility owners and contractors.
Though Dial Before You Dig provides an efficient service with prompt utility plan delivery to the end user, it is important to understand that the utility information published is indicative only, and does not offer accurate horizontal and vertical information. When applied correctly, subsurface utility engineering processes provide the vertical and horizontal position of utilities to designers and contractors, minimising delays, risk of damage and personal injury to project personnel.
In 2013, AS:5488-2013 was released providing the engineering and construction industry with a standard to reference, identifying the quality and classification of existing utility information. By applying all quality
levels defined in AS:5488 throughout the life of a project (Quality Level D through to A), accurate information can be obtained on existing utilities and delivered in a format that can be effortlessly integrated into a design, providing a complete understanding of utilities to avoid or minimise the impact on existing utilities.
The expectation of trenchless contractors to obtain accurate utility information to a Quality Level A standard is virtually mandatory in Australia, with numerous utility owners adopting this as a minimum requirement prior to working within the vicinity of their assets. For projects where trenchless techniques are applied such as horizontal directional drilling (HDD), accurate utility information is highly beneficial to operators of drilling equipment as it allows manoeuvring of the head of the drill through the maze of utilities.
A recent example of a project where subsurface utility engineering processes were applied is the pipeline route analysis of the proposed new gas pipeline route from Hercules Street to Remora Road, Hamilton, Brisbane. This project involved Cardno locating all utilities along the proposed alignment, enabling the client to identify an optimum route to minimise the risk of damage to existing utilities and or delays during construction. Cardno was able to provide the following services to the client:
- Over 2,000 m of electronic detection (Quality Level B) on the existing utilities (communication/gas/water/electricity)
- Approximately 170 potholes (Quality Level A) on the existing utilities (communication/gas/water/electricity)
- Provision of a utility model/plan in CAD and GIS format containing all surveyed utility data in relation to the proposed route
- Ongoing support to the client to assist in the management of any utility relocations.
Cardno was engaged in this project during the planning/design phase and successfully identified all known utilities.
Subsurface utility engineering is now recognised as a necessary component for the design of civil projects due to the numerous benefits the process provides to utility owners, contractors and project owners. Reliable utility data depiction reduces costs and delays by eliminating unexpected conflicts with subsurface utilities, minimising the risk of utility damage, and provides cost-effective management of existing utility information.