Elements for improving underground utility mapping to reduce risk of damage during construction

Without accurate maps of underground infrastructure, every construction project has the potential to become a disaster site. Unlike the aviation industry where reliable data is collected and is accessible to investigators to prevent disasters from happening in the future, there is limited access to data about the location of underground infrastructure and what data is accessible is inaccurate, out-of-date and incomplete with the result that serious incidents during construction with injuries and fatalities occur again and again.  It is estimated that in the United States $10 billion is devoted to locating underground infrastructure prior to and during construction, but the available statistics indicate that this is not reducing the number or severity of incidents of underground utility damage.  Furthermore inaccurate and missing information about underground infrastructure increases the risk of schedule and budget overruns.  It has been estimated that this represents a $50 billion drag on the U.S. economy and upto a £6 billion drag on the U.K. economy.

Nearly every month the news carries reports of explosions caused by damage to underground utilities during construction excavation. In the last few months of this year there have been explosions in Murrieta, California (July) where a utility worker was killed and 15 others injured, downtown San Francisco (February), Durham, North Carolina (May), and I could go on. These incidents are more frequent than many people realize. 

This is not an impossible problem. A number of cities, regions and countries around the world have recognized the importance of accurate information about the location of underground infrastructure and implemented processes to reduce the risk of these events. For example, comparing the United States and Japan reveals a startling difference in the number of incidents of underground utility damage during construction. The number of incidents in the U.S. is between 400,000 and 800,000 per year (roughly one or two every minute). For all of Japan the number of incidents in 2016 was 134. Clearly something can be done to reduce the risk for construction workers and the public.

Over the years I have personally compiled information on 25 jurisdictions including airports in the Americas, Europe, and Asia Pacific that have implemented various policies and organizational structures for sharing information about the location of underground infrastructure. These range from government mandated and implemented, government mandated and privately implemented, voluntary industry associations, and private companies. In this article I provide a synthesis of measures most of which have been implemented, are being implemented, or have undergone pilot implementations. These can be grouped in several broad categories.

• Reliable statistics on underground utility damage

• Policies, procedures, and technologies for raising the level of accuracy, timeliness and completeness of information about the location of underground infrastructure.

• Digitalizing the capture, sharing and updating of location information about underground infrastructure.

• Ensuring security and privacy of location information about underground networks including protection for competitive information. 

• Providing access to stakeholders to underground infrastructure location information throughout the construction project life-cycle from planning and design through construction to operations and maintenance.

• Liability model for sharing responsibility for costs of underground utility damage.

Airports, university campuses, and industrial campuses are characterized by a greater density of underground utilities and by more types of underground equipment( communications cables, aeronautical ground lighting cables, gas mains, low voltage electric power cables, high voltage electric power cables, storm water mains, sanitary waste water mains, potable water mains, grey water mains, fuel mains, fire fighting water mains, and a variety of underground structures.) Underground infrastructure in airports, university and industrial campuses typically has a single owner though not always.

Public jurisdictions such as national, regional, state or provincial and municipal governments are responsible for the public right of way.  Typically underground infrastructure in the public right of way involves multiple private owners; telecom network operators, electric power utilities, gas network operators, water and wastewater operators,and others such as heating and fuel transmission pipeline operators. Dealing with multiple private owners who attempt to maintain information about their network facilities typically in a GIS considerably complicates the process of acquiring and maintaining accurate location information about underground cables and pipes.

1. Reliable statistics are essential to determine the social impact of underground utility damage and to assess the effectiveness of policies, procedures and technologies designed to reduce the number and severity of incidents of underground utility damage. Every incident of damage to underground infrastructure should be reported including injuries, fatalities and direct cost. Indirect cost is a nice to have, but very difficult to estimate. Cause is difficult to determine because it depends on who is reporting the incident - network operator, the excavator, or by an independent organization.  A network operator's perspective may be that the contractor did not exercise care during excavation, whereas the contractor's perspective may be that the location of the cable or pipe as identified as a result of a one-call request was inaccurate.  Responsibility for submitting this information has to be assigned to the   One option for doing this efficiently is to classify incidents by seriousness and assign different levels of reporting based on this classification. For pipelines PHMSA assigns levels of seriousness based on cost, consequence, injuries and fatalities.  Significant incidents include any of the following: (1) Fatality or injury requiring in-patient hospitalization, (2) $50,000 or more in total costs,(3) release of significant volumes of gas or hazardous liquid. Serious incidents include a fatality or injury requiring in-patient hospitalization.  In civil aviation each serious incident is investigated by the NTSB, an impartial group of experts who determine technical cause but do not assign blame. The available evidence from the U.S. civil aviation industry, pipeline industry, and many national statistical agencies suggest incident reporting should be mandated to ensure statistically reliable data.  This entails significant penalties for not reporting incidents. Ex. Pipeline and Hazardous Materials Safety Administration (PHMSA), Heathrow International Airport, Japan Construction Industry Association

2. 3D mapping of underground infrastructure prior to planning and design. Making the location of underground infrastructure available to engineers so that designers have access to not only accurate above-ground survey but also accurate below-ground location information enables engineers to avoid underground infrastructure during design. 3D maps of underground utilities also contributes to reducing unnecessary and costly utility relocation. Below-ground location information should be at least ASCE quality level B.  The entire area should be should be assessed by an SUE engineer in collaboration with utilities and telecoms with equipment in the area. The assessment may include scanning with modern remote-detection tools (EMI, GPR and inertial locating ) to raise the quality of location of all underground facilities to QL B and to identify abandoned or unknown infrastructure.  The cost of raising the quality level of facilities in the design area to B could be assigned to the relevant network operator, engineering firm or shared. For unknown and abandoned equipment an attempt should be made to find the original owner. Ex. Colorado 811

3. Locating unknown and abandoned facilities.  The current one-call system is targeted toward utilities locating their own facilities, typically based on their as-builts.  But there is no formal mechanism for locating facilities that have been abandoned or are not shown on network operator as-builts.  Requiring a full SUE survey in addition to a traditional surface survey at part of planning and design at the beginning of a construction project helps avoid surprises during construction. Ex. Colorado 811
   

4. Capturing and sharing the location of infrastructure detected as a result of a SUE survey at the beginning of a project or as the result of an information request to one-call/811.  Currently utilities are required to paint the ground and in some jurisdictions to provide a paper sketch indicating the location of underground utilities.   This information needs to be captured digitally and shared.  The objective is over time to build up a high quality (QL A and B) database of the location of underground infrastructure that can be shared.  Ex. Colorado Department of Transportation

5. Capturing and sharing the location of infrastructure exposed during construction. In the United States it is estimated that $10 billion is spent annually to locate underground infrastructure prior to and during construction.  Much of this information is not shared and the next time excavation occurs in the same area, the underground infrastructure must be located again.  If this information is captured and shared, over time a high quality (QL A and B) database of the location of underground infrastructure will be formed that will avoid locating the same infrastructure over and over again.  Alternatives for recording the location of exposed infrastructure include total station, RTK, and LiDAR, which tend to be expensive but high quality (QL A). Other alternatives are consumer photography with control points or structures with accurately known locations.  It is essential that this does not increase excavation costs for the contractor.  Contractor margins are tight and having to keep a survey crew on hand during excavation would significantly increase costs. There have been experiments by the City of Chicago, Bentley and Costain aimed at efficiently capturing location information about utilities exposed during construction.

6. An efficient process to update the information recorded in network operators' databases. Information captured as part of a SUE survey, as a result of an information request to one-call/811, or detected during excavation may differ from the records contained in network operators' databases.  For continuous improvement of the quality of the information about the location of network facilities requires an efficient way to compare and update this information.

7. Reducing or eliminating the update backlog.  Utilities regularly maintain underground infrastructure, move it as part of a construction project, or abandon it.  This information has to be reported back to the network operator to update the information in the utility GIS.  There are two dimensions to updates; the accuracy of the location information provided from the field and the update backlog, the time it takes for updates to be entered in the utility GIS.  As with the as-built backlog this backlog can stretch into months.  The objective should be better than a day. This issue can also be resolved by regulation or by a suitable liability model. Ex. Ofgem in the U.K. requires backlogs to not exceed 42 calendar days.

8. Improving the accuracy of location information for new underground infrastructure.  If all new facilities are located to survey quality, over time location accuracy will continue to improve  as older facilities are retired. Alternatives for recording the location of newly installed infrastructure include total station, RTK, LiDAR, and photogrammetry with control points or structures with accurately known locations.  Whatever the technology the result should be ASCE quality level A.  Special provision must be made for capturing the location of facilities installed using horizontal (trenchless) drilling, for example, inertial mapping of pipe networks.  Since reliable as-builts are generally a network operator responsibility - policies are required to ensure that as-builts for newly installed equipment are accurate. There are several ways to do this; legislation which enables a government or regulator to conduct QA/QC checks on submitted as-builts or a shared liability model that assigns some responsibility for subsurface utility damage to network operators whose as-builts are inaccurate or out-of-date. A  liability model would assign liability of any underground damage during subsequent excavation to the network operator if the as-built location information is incorrect. Ex. City of Calgary, Singapore

9. Reducing or eliminating the as-built backlog.  If the time it takes for as-built information to enter the utility GIS or other database from the time new infrastructure is installed is measured in months or longer, the utility GIS is not sufficently reliable for locating underground infrastructure for construction purposes.  The objective should be better than a day. This can be resolved by regulation or by a suitable liability model.  Ex. Ofgem in the U.K. requires as-built backlogs to be less than 42 calendar days.

10. Assigning a quality level based on a generally accepted quality standard to every piece of underground infrastructure. This is critical for determining the type of excavation equipment that it is appropriate to use. It can also provide the basis for a shared liability model.  Ex. ASCE 38-02 in the U.S., CSA S250 in Canada, PAS 128 in the U.K., France DICT

11. Digitalizing the capture and sharing of information about the underground.  In North America, most one-call legislation only requires marking the ground prior to the initiation of construction.  In Ontario a written record is required in addition to marking the ground. At the federal level in Canada there is legislation initiated in the Senate and that offers the alternative of the exchange of only a written record of the location of utilities mapped prior to excavation - no visit to the site to mark the ground is required. This would open the door to exchanging a digital record of the location of utilities found prior to excavation which would be much more efficient because it could obviate the need to visit the site of the proposed excavation.  However, it would also a higher quality standard for the location of underground infrastructure than is currently the practice.  Ex. ROADIC (Japan), KLIP in Flanders, KLIC in the Netherlands

12. Digitalizing the flow of information about underground infrastructure requires a generally recognized standard for sharing information about the subsurface. The Open Geospatial Consortium (OGC) is developing an underground information exchange standard, with the appropriate acronym MUDDI, that is intended to provide an open standards-based way to share information about the below ground. There are a number of data models for different types of underground infrastructure and geotechnics. MUDDI builds on and augments existing standards to create a unified model supporting multiple use cases. The MUDDI model is intended to support routine street excavations, emergency response, utility maintenance programs, large scale construction projects, disaster planning and response, and smart cities programs. For street excavations the requirement is location of all entities with high horizontal, medium vertical accuracy (2.5D) of underground infrastructure; for large construction projects, detailed 3D geometry of underground infrastructure and detailed 3D geotechnics; for emergency response, interdependencies between different networks; for utility maintenance, network topology and facility location and condition; and for smart cities the ability to monitor and relate streams of data from sensors. This has not yet been adopted by a jurisdiction, but agencies in the U.K. (Ordnance Surevy), Singapore (Singapore Land Authority), and New York (Fund for the City of New York) are actively supporting the development of the standard.

13. Efficient information flow.  Requiring vans with locating crews from several network operators to visit the site of a proposed excavation just prior to construction to scan the ground for their facilities using EMI and GPR and mark the ground is inefficient. An on-line system that allows an engineer or contractor to go online and define a polygon enclosing the proposed excavation and then within less than a day providing access to maps of underground infrastructure in the area can save network operators time and money.  However, the effectiveness of this solution is highly dependent on the quality of the location information maintained by network operators.  In North America the current one-call system requires that underground facilities be mapped to ASCE QL B before starting construction.  An online system providing digital maps composed of utility operators' as-builts would lower the accuracy of the location information provided to contractors and in the absence of other measures would likely increase underground utility damage. Ex, KLIP in Flanders, KLIC in the Netherlands.

14. Rules for the appropriate type of excavation equipment.  Rules are required that restrict the type of excavation equipment based on the quality level of underground utilities identified by network operators.  For example if facilities have been assigned ASCE quality level C or D, only hydraulic, vacuum or hand excavation may be used.  Ex. Heathrow airport

15. Security, privacy and protecting competitive information. To enable this information to be useful in reducing the risk of underground infrastructure damage during construction it has to be shared in a secure way which respects privacy.  In particular it must protect competitive information. There are a number of organizational ways of doing this; government can mandate, implement and run the system, government can mandate but leave it to the private sector to implement and run, an industry consortium with or without government mandate can implement and run the system, regulations could require sharing this information but leave it to the private sector to implement and run, or a private company could take overall responsibility.  Around the world there are examples where each of these alternatives can be found.  The information should be available to engineers during the planning and design phases of construction projects, to contractors for use during excavation, and to organizations responsible for operating and maintaining highways and other civil structures.  Other potential use cases for this data include disaster planning and emergency response.  Ex. KLIP in Flanders and KLIC in the Netherlands, North East Underground Infrastructure Hub (NEUIH) in Newcastle, England

16. Liability model for sharing responsibility for costs of underground utility damage.  The advantage of a rule-based shared liability model that assigns varying levels of responsibility to both contractors and network operators is that it provides motivation to network operators to improve the quality of their location information about their underground infrastructure existing and new.  An example of a shared model is the following: if a network operator identifies the location of a piece of underground equipment as Quality Level A according to the ASCE 38-2 standard and an excavator hits it, the excavator would be liable for costs if the facility was where the network operator said it was, or the network operator would be liable if it wasn't.  For an excavator intending to dig in an area where there is underground infrastructure assigned to level C or D, the cost to bring all infrastructure to quality level B would lie with the network operator (as it does now with North American one-call systems). If the network operator declines to do this, the liability for any underground damage would lie with the network operator. Ex. France DICT

These measures not only can reduce the risk of underground utility damage and the associated risk to the public during construction and thereby lower insurance costs, but can also significantly reduce the cost of infrastructure construction, for example, by avoiding major utilities and reducing the unnecessary and costly moving of utilities on civil engineering projects.

Experience has shown that over time these elements can result in increasingly accurate digital representations showing the location of underground infrastructure that is available to stakeholders in construction projects including planners, engineers, contractors and facilities managers, for utility maintenance, and potentially for other use cases such as utility outage management, disaster planning, emergency response and smart city programs.