by Bruce Potter, AS5488-2013 Committee Member
Knowing the precise location of a subsurface utility, what it is, its condition and its status can significantly reduce the occurrence of interference and conflict with valuable infrastructure.
In the February 2014 edition of Utility, Anthony Johnstone of Access Detection discussed what the new Classification of Subsurface Utility Information Standard AS5488 means for utility locators. Now AS5488-2013 committee member Bruce Potter explains some of the background to the development of the standard, and how it is intended to be used.
The standard provides a common method for utility owners, operators, locators and engineering professionals to capture and make available more accurate and consistent information about the characteristics of subsurface utilities than in the past.
Based on the four quality levels of the American Society of Civil Engineers, outlined in 38-02 Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data, the new Australian standard incorporates absolute and relative spatial tolerances while providing supplementary information on how to display utility codes and colours on plans, electronic models and in the field.
Prepared by Standards Australia Committee IT-036 Subsurface Utility Engineering, the standard is the first of its kind in Australia, and was officially released to the public in June 2013. The committee, chaired by Mark Gordon, consisted of representatives from 20 nominated organisations who convened for their first committee meeting in August 2011.
The 20 nominated organisations are ANZLIC – the Spatial Information Council, Australasian Railway Association, Australian Institute of Mine Surveyors, Australian Local Government Association, Australian Services Union, Austroads, Dial Before You Dig, Energy Networks Association, Engineers Australia, Geospatial Information and Technology Association, Heads of Workplace Safety Authorities, Institute of Public Works Engineering Australia, National Broadband Network, National Utility Locating Contractors Association, NSW Streets Opening Conference, Surveying and Spatial Sciences Institute, Telstra Corporation, University of New South Wales, Water Services Association of Australia and WorkCover New South Wales.
The new Australian standard is intended to be used by those involved in the process of identifying, capturing, conveying, coordinating and designing underground utility information, and combines the principles of civil/utility engineering, utility data and asset management, along with geophysics and locating methods and techniques.
A study sponsored by the Federal Highway Administration (FHWA) in the United States found that $4.62 for every $1 spent on identifying, collating, conveying and coordinating accurate underground utility information was saved on overall project costs.
The quality levels from the new Australian standard represent a transition from unreliable to reliable underground utility data defining the activities and outcomes of underground utility designation and coordination for utility owners/operators, utility locators and engineering professionals. Quality levels can be used individually, but are more effective if used sequentially, to identify and mitigate potential utility conflicts at each stage of a typical project – from original concept to detailed design.
Utility owners/operators who adopt the quality levels have a mechanism to define, receive and communicate reliable utility information based upon better defined design, as-built and asset management attribute and metadata recording requirements.
Utility locators are provided with a clear set of attribute and metadata requirements to obtain and designate underground utility data based on a defined scope of work. To meet the minimum spatial tolerance of the new Australian standard, utility locators must select the appropriate locating equipment, depicting and conveying point, and line data in the form of utility survey information to the required quality level.
Engineering professionals now have a more consistent approach to utility investigations, coordination and design than ever before. Using quality levels and their respective attribute and metadata as a design manual enables an engineering professional to understand the accuracy of, and to classify the utility data they receive, such as Dial Before You Dig (DBYD) data, as-builts, design plans and utility surveys. They may then confidently assess and rectify the effects of potential underground utility conflicts throughout various stages of design and construction.
In order to begin the process of obtaining underground utility information, the engineering professional in particular needs to understand the minimum requirements of each quality level and determine the extent of information required.
Quality Level D (QLD) information is likely to be associated with feasibility or business case activities, providing due diligence utility investigations and reporting from site sketches, DBYD enquiries, anecdotal evidence and the like to determine the existence of underground utilities within a project.
Quality Level C (QLC) information is likely to be associated with conceptual or preliminary design activities, forming a database of existing utility information from feature topographic surveys and/or site measurements supplemented by any information obtained and classified as QLD. This collated information allows the identification and reporting of likely conflicts/clashes from existing and known utility designs within a project.
Quality Level B (QLB) information is likely to be associated with design development activities, based on electronic surface detection and supplemented by any information obtained and classified as QLC, collating a database of existing and known utility design information to develop protection and/or relocation strategies to those existing utilities in direct conflict within a project. By default, these strategies develop into design coordination and construction sequencing.
Quality Level A (QLA) information is likely to be associated with detailed design activities, based on a utility database from validated/positively identified horizontal and vertical components of existing and known utility design information, supplemented by relevant information collated and classified as QLB and in some instances QLC.
Coordinated, engineered plans and/or electronic models in accordance with the relevant design requirements are produced, consisting of three-dimensional geometry of all protected or relocated utilities, by implementing and refining the design coordination and construction sequencing developed in QLB.
For all parties, particularly engineering professionals involved in the process of identifying, capturing, conveying, coordinating and designing underground utility information, the new Australian standard represents a common language to make accurate, confident and realistic decisions about the spatial positions of utilities.
This allows action to be taken to mitigate and solve potential utility conflicts, thus minimising damage and associated delays.
About Bruce Potter
Bruce Potter is a current Standards Australia, Subsurface Utility Engineering committee member (IT-036), who represented Engineers Australia in the development of Australian Standard AS5488-2013 ‘Classification of Subsurface Utility Information (SUI)’. He is a Certified Engineering Technologist and registered engineering technologist experienced in all aspects of civil engineering, utility design and a specialist in the field of Subsurface Utility Engineering/Public Utility Plant, encompassing professional utility coordination, utility data management, field data gathering and utility asset management.
