At the fourth Digital Underground Connect (DUConnect) session, Rob Martindale, Utility Program Manager at the Colorado Department of Transportation (CDOT) provided an overview of a remarkable initiative by the State of Colorado to address the challenge of improving the quality of information about the location of underground utilities, specifically as-builts.
According to the Federal Highway Administration (FHWA) underground utilities are a major cause of highway construction schedule and budget overruns. In addition to construction delays, damage to underground utilities during construction makes every construction project a potential disaster site with risks to workers and the public. All states and most provinces in North America have legislation creating one call centres that connect network operators to excavators for locate services. However, statistics collected by the Common Ground Alliance have not shown a reduction in underground utility damage in recent years. In 2017 as the result of a gas explosion Colorado began a comprehensive approach involving legislation, technology and regulation to address the challenge of incomplete, inaccurate and out-of-date information about underground utilities.
In 2017 there was an explosion at a home in Firestone, Colorado that resulted in two deaths and a serious injury. Prevously in 2014 the Pipeline and Hazardous Materials Safety Administration (PHMSA) had found that the Colorado one-call system had serious deficiencies. Most importantly it found that the current legislation did not assign an agency to enforce the legislation. In 2018 the Colorado legislature revised its one-call legislation. The latest legislation differs from the one call legislation in other states and provinces for two important reasons
- It explicitly mandates subsurface utility engineering (SUE) during engineering design for public civil engineering projects to determine the 2D location of underground utilities to ASCE 38 quality level B by a licensed professional engineer. (ASCE quality level B requires the application of remote sensing detection technologies such as electromagnetic detection and ground penetrating radar.)
- It has provisions to ensure that owner/operators provide complete, accurate and current "as-constructed" electronic drawings recording the location of their underground facilities with penalties if they are not compliant.
At the DUConnect session Rob outlined how the new legislation is being implemented and how it works in practice. For decades one of the challenges facing utilities has been how to integrate survey data, engineering design (as-designed), typically CAD files, and what is actually constructed (as-constructed), which may or may not be recorded as red lines on paper construction documents, into utility GISs. The result has been that the data in utility GISs is incomplete, inaccurate, and out-of-date. For the past few decades there has been little motivation for network operators to improve the quality of their information about the location of underground facilities. The new legislation provides for on-site construction oversight to ensure that complete and accurate "as-constructed" documents in electronic form are submitted at the completion of construction.
For collecting and maintaining location information about underground utilities CDOT has adopted a hybrid approach that incorporates elements of survey and GIS technology and practices. This approach enables data from disparate sources including surveys, GIS, design files, construction documents, subsurface utility engineering reports, and utility relocations into a shared database managed by a server application (Transparent Earth) that is accessible in the field from a handheld app (Pointman). An advantage of this approach is that it is not only a GIS but enables the capture of survey grade location information.
For new and relocated underground utilities it enables all location information to be captured at survey level including the metadata typically recorded in a surveyor's field book such as when the survey was conducted, who conducted it, the equipment used, and so on.
In the CDOT system all location information has pedigree or metadata associated with it. The system was developed by a private developer Prostar Geocorp. The system is natively built to be open source using GeoServer and seamlessly integrates with other modern technologies such as Bentley and ESRI and legacy systems of record such as GE Smallworld. It uses standard map services such as Google Maps, Bing, and OpenStreetMap for base mapping as well as LiDAR and drone imagery when higher levels of precision are required. The ProStar system leverages Open Geospatial Consortium (OGC) standards including Web Mapping Services (WMS) and Web Feature Services (WFS) and supports quality standards such as ASCE 38-02 and the imminent ASCE 38-20. It offers permissions-based security to protect the data. The Prostar system integrates with Colorado 811 in real-time, making it possible to display the location of all open tickets and their status on a PC or mobile device such as a tablet or smart phone.
The primary goal of the system is to provide easy-to-use access to high quality location data at low cost and to fit into the existing engineering and construction practices or network operators to minimize the learning curve and avoid adding to costs. Pointman is free and offers an affordable handheld solution for small contractors. The Transparent Earth server application is available to network operators, large construction contractors and engineering consulting firms, and government agencies such as CDOT. It enables all stakeholders in a construction project to share data about underground infrastructure.
Another advantage of the system is that it enables survey-grade information to be captured by survey technicians as well as GIS professionals with some additional training in survey technologies.
Pointman can be paired with a number of devices including RTK for survey grade location determination and GPR and EMI underground scanning devices to provide a record of SUE locating. Furthermore, relocations of existing utility infrastructure can be captured with the Pointman handheld app during construction.
The new legislation differs from previous legislation by explicitly making the State of Colorado, through its agency CDOT, responsible for regulating infrastructure installed in the the public right-of-way. In practice every network operator that plans to install network facilities in the public ROW, is required to apply to CDOT for a permit. One of the requirements of the permit is that for all newly installed facilities network operators must ensure that the the new facilities are locatable, either by marker balls and tracer wire and by an accurate survey. Furthermore, within 45 days of the completion of construction the network operator is required to provide "as-constructed" plans in PDF format to CDOT. The as-constructed document must comply with the ASCE standards 38-02, which specifies quality levels A through D, and 38-20, which specifies seven accuracy levels ranging from Level 1 ( XY ± 50 mm, Z ± 25 mm ) to Level 7 (indeterminate).
The real teeth behind the permit system is that it mandates CDOT to conduct quality control as part of construction oversight. Specifically it requires third party inspectors registered with CDOT and paid for by the network operator to conduct construction oversight to ensure that the "as-constructed" PDFs submitted to CDOT accurately reflect what was actually installed in the ground. Various measures including denial of further construction permits and civil penalties can be levied against non-compliant network operators.
In summary this is a ground-breaking initiative involving legislation, regulation and new technology to address one of the chief causes of highway construction delays and cost overruns. CDOT's solution is now getting the attention from other state DOTs as well as several Federal agencies. For example, Utah DOT has followed CDOT and has implemented the ProStar Solution.
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