New ASCE standard guideline for recording and exchanging utility infrastructure data is imminent

The release of the new ASCE Standard Guideline for Recording and Exchanging Utility Infrastructure Data (also referred to as the utility as-built standard) developed under the auspices of the American Society of Civil Engineers (ASCE’s) Construction Institute(CI) and Utility Engineering and Surveying Institute (UESI) is imminent. The standard draft passed committee ballot in November 2019 and in January 2020 all comments were addressed. Next step is a reconciliation report and then the standard will be available for public comment. The Open Geospatial Consortium (OGC) has already adopted the standard draft for the Model for Underground Data Definition and Integration (MUDDI) initiative.

The purpose is to facilitate data collection, data management, and data exchange among stakeholders. It is designed to complement the widely used ASCE 38-2 Standard Guidelines for the Collection and Depiction of Existing Subsurface Utility Data. 

As a reminder ASCE 38-02, published in 2002, is intended to standardize the classification of the quality of location information about existing subsurface utility networks on engineering drawings. The standard defines four quality levels based on method used to determine the location of underground assets. 

1. Precise horizontal and vertical location of utilities obtained by the actual exposure and subsequent measurement of subsurface utilities, usually at a specific point.  Accuracy is typically set to 15-mm vertical and to applicable horizontal survey and mapping accuracy as defined or expected by the project owner.
   
2. Information obtained through the application of appropriate surface geophysical methods to determine the existence and approximate horizontal position of subsurface utilities.
3. Information obtained by surveying and plotting visible above-ground utility features and by using professional judgment in correlating this information to Quality Level D.
4. Information derived from existing records or oral recollections.

The basic deliverable for utility information is a CAD file or plan sheet that has quality levels A, B, C, and D and assigned to each asset.  Quality level A data typically requires a supplemental data form with additional information. This standard does not address the quality of vertical information other than for quality level A data.

New ASCE Standard Guideline for Recording and Exchanging Utility Infrastructure Data

A white paper on the new ASCE standard was published in 2018 which provided an overview of the new standard and its intended use cases. (The actual standard when it is made available publicly may differ from the white paper.)The new guidelines are targeted on two use cases;

1. capturing and recording the location of new utility data at the time it is installed and for
2. recording location data for existing utilities exposed during construction.

It is intended as non-binding guidance to assist right-of-way and utility owners in establishing their own standards.  The objective of the guideline is to provide a common definition for communicating the positional accuracy of utility assets and define a minimum set of data attributes necessary to communicate the position along with the type of equipment, geometry, function, ownership, materials, status and other information for each asset. The guideline specifies essential elements for documenting the location and attributes of underground and above-ground utility infrastructure, especially for newly installed utilities and for utilities exposed during construction. It defines levels of positional accuracy of utility infrastructure.

Positional accuracy

ASCE 38-02 is not prescriptive with respect to accuracy and is generally 2D in focus, whereas more modern quality standards such as PAS 128, the French DICT, and Canadian CSA S-250 which reflect modern technical developments specify accuracy in 3D. The new standard guidelines specify positional accuracy. 

Data model

The guideline does not provide a prescriptive utility data model but defines the elements of utility data needed to facilitate exchange of a 3D utility model with sufficient attributes for civil engineering.

The guidelines also require that metadata should be provided with all exchanged data including feature type, how and when the data was collected, the coordinate reference system and datum used, the individual(s) who certified the data, and any known limitations.

By the way March 16th is the deadline for public consultation and comments on the PAS128 2020 Revision.