American Society of Civil Engineers

Collecting and Converting 2-D Utility Mapping to 3-D

by James H. Anspach, P.G., (J.H. Anspach Consulting / Chair - ASCE Board Committee Codes & Standards. PO Box 5994, Bend, OR 97708. E-mail:
Section: Design, pp. 278-284, (doi:

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Document type: Conference Proceeding Paper
Part of: Pipelines 2010: Climbing New Peaks to Infrastructure Reliability: Renew, Rehab, and Reinvest
Abstract: Assigning depth or elevation values to existing utility mapping is becoming more pervasive as we move from a 2-D CAD design platform to 3-D platforms, whether they be CAD or GIS based, or used for more than just design issues. 3D data depiction allows for a robust visualization of mapping elements that can benefit virtually all aspects of a project’s development. That benefit is only realized when the collected data are accurate, reliable, and comprehensive, or else we fall into the "garbage in, garbage out" syndrome. Achieving utility data depiction that fits these criteria of accurate, reliable, and comprehensive is not trivial. Accurate data can only be assured through direct measurements, and most of our utility infrastructure is buried and unable to be directly measured except at surface appurtenances and excavation spots. Reliable data are only achieved when the means and methods of collecting and depicting data follow strict protocols. Comprehensive data may in some cases not be achievable, due to budget or technologic constraints. Many times we are forced to make judgments or assumptions on the presence or location of a utility, since these utilities are not exposed and therefore able to be directly observed and measured. We use a variety of sources for these judgments; utility records, historical project data, visual cues, indirect surface geophysical sensing methods, our past experiences, reliance upon someone else’s past experiences, and government or private GIS systems are examples of these sources. Sometimes the source data is incorrect. We are forced to interpret the data from these sources, because positional references are usually vague, out-of-date, non-existent, or non-recoverable or source data may be illegible to the user. All of these problems could have historically been addressed if only we had good protocols regarding recording utility data, referencing that data to recoverable survey control, and providing secure and accessible certified record drawings. But we didn’t, and so we are in the dilemma of having an estimated 20 million miles of underground utilities in this country for which data is not accurate, reliable, and/or comprehensive. Planners, engineers, and constructors must build this risk of poor data into their decisions, thus increasing project costs and time or ratepayer costs. CI/ASCE 38-02, "Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data, uses a system of Utility Quality Levels that addresses primarily the horizontal component of a utility’s location. Adding the z component to utility mapping data is not trivial. We use a variety of sources for these judgments. It is important to document the sources for these judgments. This paper discusses source information and documentation issues.

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