National Academies Press: OpenBook

Subsurface Utility Engineering Information for Airports (2012)

Chapter: Chapter Three - State of the Art

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Page 16
Suggested Citation:"Chapter Three - State of the Art." National Academies of Sciences, Engineering, and Medicine. 2012. Subsurface Utility Engineering Information for Airports. Washington, DC: The National Academies Press. doi: 10.17226/22751.
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Page 17
Suggested Citation:"Chapter Three - State of the Art." National Academies of Sciences, Engineering, and Medicine. 2012. Subsurface Utility Engineering Information for Airports. Washington, DC: The National Academies Press. doi: 10.17226/22751.
×
Page 17
Page 18
Suggested Citation:"Chapter Three - State of the Art." National Academies of Sciences, Engineering, and Medicine. 2012. Subsurface Utility Engineering Information for Airports. Washington, DC: The National Academies Press. doi: 10.17226/22751.
×
Page 18
Page 19
Suggested Citation:"Chapter Three - State of the Art." National Academies of Sciences, Engineering, and Medicine. 2012. Subsurface Utility Engineering Information for Airports. Washington, DC: The National Academies Press. doi: 10.17226/22751.
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Page 19

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

16 This chapter describes the processes, standards, and procedures available to collect, store, and use utilities data. It describes the practical approaches that can be used, not necessarily those that are being used (the subject of the next chapter). Much of this information comes from outside the aviation industry; however, the issues, technologies, and challenges addressed are fairly universal. Some of this information comes from the interviews with airport personnel and their consultants who find these processes and procedures desirable. Some of this information comes from interviews performed by the authors as part of related utility and airport research in progress. Existing Utility REcoRds Existing records come in many forms and degrees of accuracy. Many times the quality of the data is not known or assumed, so the users must judge whether the accuracy and completeness of the data are sufficient for their purpose. This judgment is constrained unless all legacy data are available and indexed. The users of utility data include maintenance and operating personnel, planners, and engineers—each of whom has dif- ferent needs. Some records may be pertinent to those needs, whereas others may not. Interview and survey respondents reported that knowing where records can be found, having the ability to find a specific record that includes the pertinent information, keeping those records secure and being able to access this information in a timely manner are all important. Reported SOA procedures include: • Having all records available electronically so that the user can access them at will from any location in a secure manner. Formats include scanned documents (e.g., PDFs and TIFs) and CADD files. • Indexing records to indicate the area for which the record has pertinence (e.g., the entire airport property or the boundaries of a particular project); the source of the record (e.g., unknown or project as-built); and the age of the record. • Geographically referencing utility record drawings using GIS. Utility compositE REcoRds Of all utilities on the airport property regardless of owner- ship, the one SOA component to have is a Utility Composite Record (UCR), with updates performed by experts in utility data development. UCRs come in two basic formats: CADD and GIS. The concept is to have a single source that shows the current best available location of all utilities with as many pertinent attributes as possible. This provides a resource that will suffice for a majority of users and eliminate the need for each user to conduct records research every time utility information is needed. Judgment on what data are considered “best” is a crucial issue. This requires a qualified expert, such as a subsurface utility engineer. UCRs are updated on a con- tinual basis as new utility information is created from valid sources. The qualified expert must evaluate the new informa- tion against the older information to ascertain whether the UCR should be changed (CSA 2011). Utility network models Once utilities data have been consolidated into a standardized and comprehensive data set, sophisticated queries, analyses, and reports can be carried out. Information can be added to indicate the flow and capacity of individual components of a utility network. Interview and survey respondents reported that developing such utility networks enables peak demand forecasting, identification of where pollutants may have entered or exited a system, isolation of network branches in the event of a break, and other more sophisticated analyses. As-Builts The best way to record where utilities are located is to sur- vey their location in three dimensions during installation and to incorporate this information into standardized drawings that depict as-built conditions. This is important for making effective risk management decisions when these utilities are involved in future construction issues (CSA 2011). Ideally, these “as-builts” include such attributes as date of installation, type of utility, size, material, owner, and number of direct-buried cables. Metadata such as the accuracy of the survey information, the method used to collect the data, and the name of the firm or individual who collected the data are also included. These attributes and metadata are associ- ated with the geometric features in a manner that can be eas- ily and intuitively read by planners, engineers, maintenance technicians, and others. This can be achieved by labeling or annotating utility features on maps, applying informative symbology and an associated legend, and providing data chapter three stAtE of thE ARt

17 tables that present attributes in a tabular manner. The attri- butes and metadata are also stored in a manner that can easily be loaded into a GIS database with minimal conversion and data re-entry (CSA 2011). Achieving these goals requires identifying the types of data collection methods that are acceptable, methods of coordina- tion with airport operations and security personnel as well as with contractors and other consultants, the process for submit- ting data to the airport, and the means by which submitted data will be evaluated for acceptance. In addition, as-built standards define the format, layer- ing, symbology, and annotation required. The structure of the data in terms of acceptable geometry types, attribution storage, and metadata formats are also defined. Templates that reflect this structure but do not include any data are developed and shared with consultants to make it easier for them to comply with these requirements, which may lower the costs of producing the as-builts and ensure a higher level of conformance. Consultants are aware of the airport’s procedures and standards for as-builts as a part of the bid process and at project kick-off meetings. Interview and survey respondents report that at early delivery points during a project, drawings are checked for compliance so that misunderstandings can be resolved before final as-builts are prepared and submitted. Conformance with as-built procedures and standards can be encouraged in many ways. Enforcement mechanisms include withholding retainer fees and/or considering past as- built delivery performance during procurement. Providing past as-built data to consultants at the beginning of projects, clear and thorough as-built specifications, templates to ease the burden of as-built development, and fast evaluation and acceptance of submitted deliverables also encourages con- sultants to conform to an airport’s standards. Interview and survey respondents report that their prac- tice is that if as-built procedures and/or standards are not fol- lowed, then fees can be withheld to allow airport staff and/or on-call consultants to collect the necessary information and develop the required data. This can also be done as a matter of policy on all projects, so long as the resources can be made available to provide the staff and equipment and/or outside consultant support. Once as-built data are received and accepted by an airport (typically by the airport’s project manager), the data can then quickly be entered into a document management system for archival and future retrieval. The data can also be converted and loaded into consolidated utilities drawings and, if avail- able, a centralized GIS. Interview and survey respondents reported that track- ing as-built projects from the time the contract is awarded through to delivery and recording of data into a document management system, consolidated utilities drawings, and/or a GIS helps ensure conformance and consistency of data in the end. Spreadsheets maintained by records librarians and/ or GIS managers are an effective means of tracking projects. These spreadsheets can be reviewed at periodic construction coordination meetings that many airports conduct. While as-built procedures, standards, and enforcement mechanisms can be extensive and require ample resources, they can be scaled down so that smaller airports can apply these principles as well. National standards, data templates from the FAA, and simplified procedures can be leveraged by even the smallest airports in a manner that is proportion- ate to the level of construction they have planned. dAtA REliABility Reliability of data is difficult to judge. One of the reasons state governments have regulated the practice of engineering and surveying is to provide a mechanism whereby the reli- ability of data can be assured through training and certifica- tion. Unfortunately, utility data are often gathered, judged, and referenced by uncertified individuals. One of the prime motivators for the development of ASCE 38 was to make it easier to assess data reliability by recording a utility QL attri- bute. This attribute, when associated with the identity of the registered professional who assigned the QL, establishes a basis for confidence in the data. Barring a QL attribute, other information is necessary for the data user to assess the qual- ity of the data themselves. This information may include who gathered the data, what geophysical equipment was used, when that equipment was calibrated, what survey method was used, when the survey equipment was calibrated, and the training and certifications of the person gathering the data (Noone 2004). The SOA for data reliability is for an appropriately- registered professional to stamp record drawings that indi- cate the QL of the data, along with a statement of accuracy for the survey component of that data, as required by ASCE 38 (Anspach 2004). creating a Utility mapping program For facilities that have gaps in their utility records, or have unknown quality or poor quality records, utility mapping programs (UMPs) can be implemented to help fix the prob- lem. Some important elements of such programs include: • Prequalification criteria for SUE providers. All mapping work needs to be performed under the direct charge of a licensed professional in accordance with state statutes. Mapping generally consists of many components that are integrated into a deliverable report. These compo- nents include records research; surveying geophysical

18 equipment selection, use, and interpretation; and plot- ting and developing a map. (Examples of such prequali- fication criteria are provided in Appendix C.) • SUE can be used on capital improvement projects above a certain cost threshold. • A scope of work that includes QLB mapping of all utili- ties within project boundaries including a geophysical search for known and unknown utilities within that boundary. • A plan to fill in the gaps between project boundaries over the course of time. An SOA mapping program would contain all of the above elements. The end result of a UMP that encompasses design and construction projects, maintenance activities, and responses to “one-call” locating requests is an increasingly more accu- rate and comprehensive record. At some point in the future, a utility would only need to create as-builts of new facilities and update the existing UCR as a result of abandoned or removed utilities or attribute changes. An SOA utility program con- tinually increases the quality of data and makes certain it cap- tures all additions and changes. Quality level B Utility mapping An SOA QLB utility mapping effort includes the use of a wide range of EML, advanced GPR (if soil conditions allow for sufficient depth of penetration), EMTC, MAG, and SOUND methods (if utility and site conditions allow). All structures on the surface or exposed during construction are photographed with GPS-enabled cameras. Where good images cannot be obtained, diagrams showing details of the utilities within the structures are developed. All empty conduits are imaged through the insertion of sondes or other conductors, if GRP did not image them. The project area is completely covered by at least two different geophysical sensors in an attempt to identify unknown or incorrectly documented utilities (TSA). Utilities of record that cannot be imaged with geophysics are portrayed at QLC or QLD (ASCE 2002). Depth attributes on all utilities are collected where pos- sible at valves, in vaults, in basement walls, and by indirect geophysical means. These attributes are also cross-referenced with the method of depth determination (i.e., GPR, EML, EMTC, Sonde, or as-builts) (Anspach 2010). If advanced geophysical methods are used, raw data are retained so that the user can use it to identify other structures if desired. The SOA for QLB utility mapping is to use all appro- priate geophysics to acquire as complete a set of data on the utilities within a project area as possible (Sterling 2007). sURvEy of gEophysics Because each element of the NAS is tied to a single reference framework, it is important that every utility survey conducted on an airport be accurately integrated into the National Spa- tial Reference System. One accepted method of doing this is to tie the survey to the Primary and Secondary Airport Con- trol Stations (PACS/SACS) available at most airports. This can be complicated when an airport uses a locally developed grid reference system for project design and construction. To tie a local grid to a commonly recognized coordinate system, a surveyor is required to develop an accurate transformation between the coordinate systems. The SOA for a survey is to reference all utility mapping to the PACS and SACS established at the airport. Data for x and y coordinates is integrated into North American Datum of 1983 (NAD 1983) for the airport; z values are recorded in North American Vertical Datum of 1988 (NAVD 88) datum with U.S. survey feet being the unit of measure (FAA 150 2009). maintenance and Repair Activities The UCR is made available to maintenance personnel. Wire- less tablet computers are made available so that technicians working in the field can instantly access and view the geo- referenced UCR. When tablets are taken to the field, GPS automatically documents the user’s location and provides a menu of options based on that location. Survey-grade GPS is available to maintenance personnel. When exposing a utility for repair, an accurate x, y, z loca- tion is gathered. Menus and automated routines are avail- able on the wireless tablet to facilitate automatic metadata and completeness of data. Interview and survey respondents reported that data are automatically submitted to the depart- ment or person responsible to update the UCR and the record is automatically archived in the central repository. Pictures are taken of the repair with a GPS-enabled camera. Asset management An SOA practice among airport interviewees is to develop asset management programs. These programs seek to iden- tify and monitor the condition of facilities, equipment, and infrastructure under the airport’s control. These systems can capture not only the location and key characteristics of assets (as in a GIS) but also track condition, useful life, replacement value, and other considerations. damage prevention/one-call Activities Interview and survey respondents reported that a staff mem- ber or consultant is retained to respond to all requests for utility locating and marking prior to construction activities. All utilities are marked or checked for completeness and

19 accuracy if other entities did the marking. This staff member or consultant is equipped with a full range of EML devices, a mobile tablet enabled to be connected to the UCR, and survey-grade GPS. In areas where no utilities have previ- ously been mapped, it may be necessary to supply extra per- sonnel to assist in using the geophysical equipment properly, or to enter confined spaces. One-Call markings are surveyed and if discrepancies are found between the UCR and the field markings, they are brought to the attention of the resident utility expert, who makes judgments as to which informa- tion is likely to be more accurate. If it is determined that the One-Call mark should be part of the UCD, then it is treated as a new record. Radio frequency identification program An SOA utility program includes RFID. Programmable RFID markers are placed on each newly installed utility at regular intervals so that during One-Call operations or maintenance activities the exact location of the utilities can be positively identified, along with other attributes that may be useful to the future contractor. RFID markers can also be placed on utili- ties during repair operations or anytime a utility is exposed. Specifications regarding correct installation and program- ming are developed. Survey respondents place survey RFID markers in the GIS or CADD UCR at their actual location. permitting of new installations An SOA is to establish a notification system that indicates when any construction may involve installing, changing, or removing utilities. A condition of receiving a construction permit is following applicable SUE policies and procedures. Upon final inspection and close-out of the permit, a contrac- tor is required to submit accurate as-built drawings indicat- ing the location of any utilities installed or removed. integrating Utility mapping into the project development process SOA projects have a mechanism to evaluate the potential impacts that the project will have on utilities, review the qual- ity and completeness of existing utility information, and tailor a utility mapping effort so as to reduce utility issues. Typi- cally, this includes a QLB mapping effort within the proj- ect limits. If QLB cannot be achieved on a particular utility, an engineer reviews available utilities data and the project design so as to make recommendations on further risk reduc- tion measures. Recommendations may include the excava- tion of a utility to obtain QLA data, special provisions for the contractor to follow to avoid damage, or changes in the design to avoid conflict with a suspected utility. This QLB mapping effort is performed as early in the project as pos- sible (APWA 2007). AASHTO also states that project own- ers should “Ensure utilities are depicted at appropriate quality levels on all highway plans. Collect Subsurface Utility Engi- neering (SUE) information early in the development of all highway projects” (AASHTO 2004). Where potential con- flicts with the construction and the utilities still exist, the engi- neers should consider the need for QLA data to determine the exact location and characteristics of the utility (Ellis 2009). Utility coordination UC is the integration of tasks taken during project develop- ment to identify and resolve conflicts between the construc- tion activities and any existing or planned utilities. It requires a commitment to communication and cooperation between the stakeholders, including utility owners (private, public, airport, tenant, and FAA), consultants, construction contrac- tors, and others involved in the airport project development process (AASHTO/FHWA 2002). Typical tasks include but are not limited to: • Designing to avoid conflict with existing utilities when- ever possible • Determining potential utility conflicts • Estimating the costs of utility conflicts • Assessing the impacts conflicts can have on project timetables • Determining the impacts that potential conflicts can have on safety • Identifying potential resolutions of those conflicts • Determining cost responsibility for any utility relocations • Determining and communicating necessary utility easements • Determining who is responsible for any utility relocations • Designing the utility relocation • Coordinating the timing and execution of relocations • Communicating safety and coordination issues to contractors. An SOA utility coordination effort involves a written checklist of procedures and a formalized system to identify, document, resolve, and track utility conflicts (Ellis 2009). Tools are being developed through the SHRP2 R-15B proj- ect to assist project owners and engineers in this task.

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TRB’s Airport Cooperative Research Program (ACRP) Synthesis 34: Subsurface Utility Engineering Information for Airports examines ways in which information on subsurface utilities is collected, maintained, and used by airports, their consultants, and the U.S. Federal Aviation Administration to help increase the effectiveness of, and enhance safety during, infrastructure development programs at airports.

The report also compares the current state of technology and effective processes from other industry sectors with what airports do today.

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