Content uploaded by Ahmed Al-Bayati
Author content
All content in this area was uploaded by Ahmed Al-Bayati on May 07, 2024
Content may be subject to copyright.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
Available online 3 November 2022
2590-1982/© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Locating underground utilities in the United States: A comparative analysis
of services provided by private locators
Ahmed Jalil Al-Bayati
a
, Roy Everett Sturgill
b
,
*
, Louis Panzer
c
, Shani Montes Victorio
b
,
Tarig Omer
b
a
Dept. of Civil and Architectural Engineering, Lawrence Technological Univ., 21000 West Ten Mile Rd., Southeld, MI 48075, United States
b
Dept. of Civil, Construction and Environmental Engineering, Iowa State Univ., 454 Town Engineering Building, 813 Bissell Road, Ames, IA 50011, United States
c
North Carolina 811, 5009 High Point Rd., Greensboro, NC 27407, United States
ARTICLE INFO
Keywords:
Utility investigation
Damage Prevention
Subsurface Utility Engineering
ABSTRACT
The ability to locate underground utilities is imperative for the protection of these facilities and for the coor-
dination of these facilities with transportation projects. The proliferation of underground facilities in the United
States has led to an increase in dig-in strikes resulting in loss of services, project delivery delays, injuries, and
even deaths. In fact, the Federal Highway Administration found utility-related issues to be one of the top causes
of delays for transportation projects. These delays are often attributed to unknown or inaccurate utility location
information. This scenario has led to a vast industry of utility location service providers. Additionally, national
and state damage prevention laws led to the creation of one-call systems for the purpose of providing a
communication conduit between designers or constructors and utility owners and operators. The importance of
accurate utility locates and the risk and liability of providing utility location services also led to the American
Society of Civil Engineers (ASCE) standardizing the practice of Subsurface Utility Engineering (SUE) into a
professional service. Even with this standard, there remains misinformation and misunderstandings regarding
SUE and non-SUE services provided by private utility location rms. The differences between the services pro-
vided by SUE investigations and non-SUE private locating services that do not meet SUE standards has largely
been anecdotal. This study serves as an advancement in understanding the distinction of SUE services versus non-
SUE services and provides evidence of industry misunderstanding of differences in these service types.
1. Introduction
The ability to locate underground utilities became critical with the
mid-20th century building boom (Thorne et al., 1993). Contributing
factors to this need involved improvement in wire coatings and an
emphasis on landscape beautication, which led to increased under-
grounding of utility infrastructure. The proliferation of underground
facilities has contributed to utility-related issues being one of the leading
causes of delays for transportation projects. These delays are often
attributed to unknown or inaccurate utility location information
(FHWA, 2018a). With the increase in underground facilities, dig-in
events and utility strikes also became regular events, resulting in loss
of services, delays, injuries, or even deaths (Sturgill et al., 2018; Al-
Bayati and Panzer, 2020). Damage to underground facilities is consid-
ered one of the most common problems in construction projects. The
average annual number of damage events to subsurface utilities was
470,000 between 2016 and 2019, and this continues to increase in the
United States (Al-Bayati and Panzer, 2022). Protecting underground
infrastructure during construction has become necessary due to the high
number of reported damages to United States infrastructure every year
(Al-Bayati, 2021). The current infrastructure damage prevention prac-
tices and laws in the United States involve locating underground facil-
ities before excavation starts or even during the design. These practices
can be achieved through the use of one-call systems and private utility
locating rms. The synergistic use of both is recommended to improve
the safety of underground facilities and scheduling efciency of con-
struction projects (Jeong et al., 2002).
One-call systems provide a communication mechanism for archi-
tecture/engineering rms (A/E) and construction contractors who are
planning or performing excavation by notifying utility owners and
* Corresponding author.
E-mail addresses: aalbayati@ltu.edu (A.J. Al-Bayati), sturgill@iastate.edu (R.E. Sturgill), louis@nc811.org (L. Panzer), shanim@iastate.edu (S.M. Victorio),
taomer@iastate.edu (T. Omer).
Contents lists available at ScienceDirect
Transportation Research Interdisciplinary Perspectives
journal homepage: www.sciencedirect.com/journal/transportation-
research-interdisciplinary-perspectives
https://doi.org/10.1016/j.trip.2022.100707
Received 1 August 2022; Received in revised form 11 October 2022; Accepted 24 October 2022
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
2
operators with facilities in the vicinity of the planned or proposed
excavation. This notication from a one-call system is referred to as a
“ticket.” Based on the ticket type (e.g., design ticket by A/E rms,
excavation ticket by contractors), utility operators may submit location
information (e.g., as-built drawings) or physically mark the locations of
their facilities. Utility owners are often expected to respond within 72 h
or less of receiving notice from the one-call system, dependent upon
state damage prevention laws. Millions of locate tickets are placed
through one-call services every year in the United States. However, it
must be noted that there are exemptions to one-call laws that vary by
state and could lead to particular utilities not being identied before
construction excavation starts. Frequent exemptions include private
utilities and unowned utilities, which usually require hiring private
locator services to avoid them not being located. Additionally, there are
circumstances where more accurate information on utility’s location is
needed, such as utilities being in close proximity to construction activ-
ities. All these circumstances have contributed to the development of the
practice of Subsurface Utility Engineering (SUE).
SUE is a standardized process dened by the American Society of
Civil Engineers (ASCE) 38–02 “Standard Guideline for the Collection
and Depiction of Existing Subsurface Utility Data.” ASCE 38–02 elevated
utility investigations to a professional service and created an industry
standard for achieving the level of care required to assess and appro-
priately address and mitigate utility risk for projects. In addition to
describing relative costs and benets, the standard provides guidelines
for collecting and designating utility information. This collection is
performed through professional means and the information is presented
at judged quality levels on plans (FHWA, 2018a). The ASCE 38–02
standard claries that SUE is a process, not a technology, that involves
managing certain risks associated with:
•Utility mapping at appropriate quality levels;
•Utility coordination;
•Utility relocation design and coordination;
•Utility condition assessment;
•Communication of utility data to concerned parties;
•Utility relocation cost estimates;
•Implementation of utility accommodation policies; and
•Utility design.
One-call centers do not utilize the SUE process, and care should be
exercised when including one-call information in SUE investigations.
Thus, construction project owners must utilize private locating rms to
achieve SUE according to the standard of practice. This study aims to
better understand the services provided by private locating rms such
that there can be a clear distinction between their services and the
services of one-call systems in order to better manage and protect sub-
surface utilities.
2. Literature review
The authors of the paper conducted a systematic literature review to
collect information related to the services provided by one-call systems
and private locating rms. The rst step to conduct the systematic re-
view and search was to identify the scope of the literature review based
on the study’s research objectives. The literature review scope was
dened as presented in Fig. 1.
Once the scope of the literature review was clearly dened, the next
step was to develop the criteria for excluding or including studies, which
must be also based on the study’s main objective. These criteria should
be used to guide decisions in the review process when selecting the
primary studies for the literature review synthesis. The research team
dened the following criteria:
•The study is published in general academic databases.
•The study is related to private locating services, SUE service, one-call
system, and underground utility infrastructure.
•The study was developed within the US and published between 2000
and 2022.
•The study reports ndings that are relevant to the survey ndings.
The research team decided to use as reference the Preferred
Reporting Items for Systematic Reviews and meta-Analysis (PRISMA)
owchart, presented in Fig. 2, to depict the process followed for research
selection. This owchart is part of the PRISMA 2020 Statement, which
was designed to help systematic reviewers transparently report the re-
view process and its ndings. (Page et al., 2021).
The next step of the review was to select the electronic academic
databases and the keywords for the systematic search process. The au-
thors utilized the following databases to search for studies: Transport
Research International Documentation (TRID), the American Society of
Civil Engineers’ (ASCE) library, and Elsevier’s abstracts and citations
database (Scopus). The keywords selected were subsurface utility en-
gineering, private utility locators, one-call system, and underground
facilities data. Using these databases and keywords, the authors con-
ducted an online search to identify all publications that included one or
more of the selected keywords, individually and together, in either
publication titles or abstracts. Through this step, approximately 407
publications were identied. After compiling all these publications into
one generalized list, the authors proceeded to exclude all duplicate (32
publications) and irrelevant studies (258 publications) based on the
inclusion criteria previously dened. These 258 irrelevant studies
included 51 studies published before 2000, 28 studies developed outside
the US, and 179 publications whose titles did not seem to have any
relationship to this study. Accordingly, the list was narrowed to 117
publications, which were reviewed again to exclude those reports that
were not determined relevant to the focus of this study, which further
Fig. 1. Literature Review Scope.
A.J. Al-Bayati et al.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
3
identied 40 irrelevant publications. Although the 40 excluded studies
were related to utility infrastructure, they seemed to be more focused on
topics such as utility accommodation guidelines/policy, utility risk
management, and maintenance of underground utility systems. The
remaining 77 studies were those that seemed to be related to topics such
as SUE service, one-call systems, underground damage, underground
location tools and techniques, and underground information delivery
methods, which are more relevant to this study’s purpose.
Next, to identify coding variables, a random sample of 22 publica-
tions was selected out of the 77 articles remaining. These 22 publications
were randomly selected by assigning a number to each report and using
a random number generator for identication. Once the sample was
selected, the authors read the abstracts of the 22 reports to further
identify and conrm the coding variables, presented in Table 1.
After the coding structure and variables were determined, the au-
thors reviewed the abstracts of the remaining reports and coded them
accordingly. The abstract reviews narrowed the list of 77 publications to
64 after identifying 13 reports that did not seem to present relevant
information to the coding variables. Next, the remaining 64 publications
were given a full-text review. The full-text review narrowed the appro-
priate literature to 12 published articles, as shown in Table 2. These 12
studies were selected because not only were their contents aligned with
the literature review scope, but they present ndings that are relevant to
the main objective of this study. The reports used to develop a synthesis
of the literature review are presented in the following subsections.
2.1. The One-Call system
The one-call system was created to protect underground utilities
from damage during construction work. The objective of this system is to
coordinate efforts that aim to notify utilities before excavating and to
improve communication between utility owners and excavators (Al-
Bayati et al., 2019). The system plays a critical role in minimizing un-
derground utility damages during construction work of transportation
projects. The one-call system consists of the following steps: (1) con-
tractors must contact one-call centers to notify them of excavation plans;
(2) one-call centers notify utility owners/operators who may have utility
Fig. 2. Study Method Flowchart – adapted from PRISMA owchart.
Table 1
Coding Variables.
a) One Call Systems b) Private Locating and SUE Services
(a.1) Description and Purpose
(a.2) Benets
(a.3) Limitations
(a.4) Location Tools and Technologies
(a.5) Data Delivery Methods
(b.1) Description, Purpose, and Practices
(b.2) Service Benets
(b.3) Service Limitations
(b.4) Service Customers & Project Phases
(b.5) Location Tools and Technologies
(b.6) Data Delivery Methods
A.J. Al-Bayati et al.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
4
facilities within the proposed excavation area via a ticket; (3) utility
owners/operators decide if they are clear of the excavation activity or
they, or their contracted locators, mark their utilities and provide a
response; (4) contractors then proceed with their excavation plans and
avoid damages by respecting the marks and exercising care within the
tolerance zones around the marked utilities (Al-Bayati and Panzer,
2019). Utility owners have the option of clearing the ticket or marking
the location of their facilities on the ground either with in-house
personnel or contracting with a third party to provide those locating
services (Sturgill et al., 2018). The one-call system is a nationwide sys-
tem that has been recognized to contribute to better management of
underground utilities efciently and effectively (Al-Bayati et al., 2019).
The system is funded through fees assessed to operators of underground
utilities, but it is free to contractors performing excavations (Sturgill
et al., 2018). Thus, it is the contractors’ rst choice because it is a free
service that satises the legal requirements (Al-Bayati, 2021). The cur-
rent practice for most contractors is to rely on the state’s one-call system
as required by law (Hutchins and Sinha, 2009).
While the one-call system is excellent for promoting damage pre-
vention, it is important to point out that this system has some limita-
tions. The one-call legislation requires utility owners to mark the
location of their utilities on the horizontal (x-y) plane. The lack of utility
depth or elevation information provided by the locating marks is one
contributing factor to damage of underground utilities (Al-Bayati and
Panzer, 2019). Furthermore, utility owners are only required by law to
mark their facilities on the ground surface before construction/excava-
tion begins (i.e., construction ticket), which is often too late for design or
contractor bidding purposes. Thus, many states have included a design
ticket in their one-call process. However, these tickets usually have
longer response times, and sometimes do not require physical marks. As
a result, utility operators can satisfy the law by providing only infor-
mation and plans. Yet, there is no assurance that these plans are accurate
(Al-Bayati, 2021).
Additionally, one-call systems only notify utility owners who are
members of their system. This means that there is no guarantee that all
underground utilities will be marked because utility owners who are not
members of the one-call system will not be notied. The damage pre-
vention laws dictating which utility operators must be members of this
system vary across states. Some utility operators are exempt from taking
part in the one-call system, such as departments of transportation
(Sturgill et al., 2018). Furthermore, one-call systems only provide in-
formation about active utilities, not abandoned, out-of-service, or un-
known subsurface utilities. Abandoned utilities not only compromise
locate accuracy but also confuse excavators by giving them false con-
dence or concern that they have uncovered an active utility line. Exca-
vators could confuse this line for a line they expected to encounter and
may start excavation using mechanical means; within tolerance zones of
the one-call marks, excavation must typically be done by hand until the
utility is exposed (Al-Bayati and Panzer, 2020).
2.2. Private locating services and SUE
The information gathered through one-call systems is often supple-
mented by additional locating services when needed (Uslu et al., 2016).
Utility operators often hire subcontractors to locate and mark their
underground facilities. However, these contracted locators are typically
providing these services for multiple companies, must respond to large
ticket volumes, and therefore have minimal time to locate these facilities
(Al-Bayati and Panzer, 2021). Often a single subcontractor locates and
marks facilities for all utilities impacted within an excavation area
(Sturgill et al., 2018). Thus, utility locators are often unable to complete
the locating process within the specied time and with the desired level
of accuracy. Other contributing factors to late and inaccurate locates are
workforce shortages, lack of training, and excavators’ insufcient
practices (e.g., inaccurate ticket information and improper ticket type)
(Al-Bayati and Panzer, 2020). In addition, locators often rely on as-built
information provided by utility owners to mark utilities in the proposed
excavation area. However, the accuracy of this as-built information is
often questionable. In fact, existing records and visible feature surveys
have often been found to be 15–30 % off the mark and, in some cases,
Table 2
Selected Reports from Systematic Literature Review.
Authors/
Publication
Year
Article Title Publisher Topic
Al-Bayati and
Panzer
(2021)
One-Call Centers -
Underground Utilities
for Construction
Practitioners and
Homeowners –
Chapter 2
ASCE One-call system,
subsurface utility
engineering
service
Al-Bayati
(2021)
Infrastructure
Damage Prevention
Approaches in the
United States
ASCE One-call system,
subsurface utility
engineering service
Sturgill et al.
(2021)
Implementation of
Subsurface Utility
Engineering for
Highway Design and
Construction
NCHRP Subsurface utility
engineering service
Al-Bayati and
Panzer
(2020)
Reducing Damages to
Underground
Utilities: Importance
of Stakeholders’
Behaviors
ASCE One-call system,
underground
location
technologies, data
delivery methods
Al-Bayati and
Panzer
(2019)
Reducing Damage to
Underground
Utilities: Lessons
Learned from Damage
Data and Excavators
in North Carolina
ASCE One-call system,
underground
location
technologies, data
delivery methods,
subsurface utility
engineering
service
Al-Bayati
et al. (2019)
Reducing Damages to
Underground
Infrastructure:
Performance
Evaluation of One-
Call Notication
Program
ASCE One-call system
Sturgill et al.
(2018)
Implications of State
Department of
Transportation (DOT)
Participation in the
One Call Process as an
Underground Facility
Operator
NCHRP One-call system
Anspach and
Scott
(2019)
Subsurface Utility
Engineering for
Municipalities
Prequalication
Criteria and Scope of
Work Guide
ASCE Subsurface utility
engineering service
Uslu et al.
(2016)
Underground Utility
Locating Technologies
for Condition
Assessment and
Renewal Engineering
of Water Pipeline
Infrastructure Systems
ASCE Underground
location
technologies, data
delivery methods
Hutchins and
Sinha
(2009)
Identifying
Appropriate Means
and Methods for
Locating Buried
Utilities
ASCE Underground
location
technologies
Jeong et al.
(2004)
Evaluation of an
Emerging Market in
Subsurface Utility
Engineering
ASCE Subsurface utility
engineering
service
Jeong et al.
(2003)
Imaging and Locating
Buried Utilities
Indiana
Department of
Transportation
One-call system,
subsurface utility
A.J. Al-Bayati et al.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
5
considerably worse (Maree et al. 2021; Al-Bayati and Panzer, 2020;
Metje et al., 2015; Jeong et al., 2004). Thus, excavation contractors
should use other methods, such as private locating rms and SUE pro-
viders, to check and validate marks provided through the one-call sys-
tem (Al-Bayati, 2021).
Private locating rms may or may not provide SUE services. Thus,
SUE is seeing increased use and becoming a standard process during the
early stages of construction projects (Hutchins and Sinha, 2009).
Although this service was initially used for mainly state and federal
projects, the current customers for SUE are also engineering rms,
municipalities, utility companies, and construction companies (Jeong
et al., 2004). While designating utilities may require the use of surface
geophysical techniques such as electromagnetic technology (mainly
used by one-call locators) and ground penetrating radar (GPR), the
utilization of these techniques is not to achieve SUE.
There are four distinct SUE quality levels (Q.L.) that vary from QLA
(the highest level of judged denition) to QLD (the lowest level of
judged denition), all of which must be achieved through professional
judgement. Based on FWHA recommendations, SUE rms must be able
to provide well-trained, experienced professionals in accordance with
state professional registration requirements for each SUE level. Each
quality level includes various combinations of existing records research,
site surveys, geophysical technology, and utility uncovering using hand
or soft excavation. These judged Q.L.s and SUE deliverables must be
certied by an engineer or surveyor (depending on jurisdictional law).
The following describes the four quality levels in more detail (FHWA,
2018b).
•SUE Quality Level D (QLD): Contains data that is primarily obtained
from existing utility records or verbal recollections, both typically
considered unreliable sources. Combined, these sources may provide an
overall “feel” for the congestion of utilities, but they are often highly
limited in terms of comprehensiveness and accuracy. This is the most basic
level of information for utility locations. QLD is useful primarily for
project planning and route selection activities.
•SUE Quality Level C (QLC): This is the most commonly used level of
information. It involves surveying visible utility facilities (e.g., manholes,
valve boxes, etc.) and correlating this information with existing utility
records (QLD information). When using this information, it is not unusual
to nd that many underground utilities have been either omitted or
erroneously plotted. Its usefulness, therefore, is primarily in rural projects
where utilities are not prevalent or are not too expensive to repair or
relocate.
•SUE Quality Level B (QLB): This involves the application of appropriate
surface geophysical methods to determine the existence and horizontal
position of virtually all utilities within the project limits. This activity is
called “designating.” The information obtained in this manner is surveyed
to a project control (known location benchmark). It addresses problems
caused by inaccurate utility records, abandoned or unrecorded facilities,
and lost references. The proper selection and application of surface
geophysical techniques for achieving QLB data is critical. Information
provided by QLB can enable the accomplishment of preliminary engi-
neering goals. Using QLB information, decisions regarding location of
storm drainage systems, footers, foundations, and other design features
can be made to successfully avoid conicts with existing utilities. Slight
adjustments in design can produce substantial cost savings by eliminating
utility relocations.
•SUE Quality Level A (QLA): Also known as “locating,” this is the highest
level of accuracy presently available and involves the full use of the
subsurface utility engineering services. It provides information for the
precise plan and prole mapping of underground utilities through the
nondestructive exposure of underground utilities and provides the type,
size, condition, material, and other characteristics of underground fea-
tures (FHWA, 2018b).
Projects usually entail a mixture of utility quality levels (QLs) based
on the information obtained, the information needed, and the manner of
integrating methods of the geophysical, record, and site-visible features
investigations. It is important to note that both the precision and reli-
ability of underground information increases from QLD to QLA because
superior technologies and processes are involved (Jeong et al., 2004).
The costs for obtaining utility data also usually increase from QLD to
QLA (Anspach and Scott, 2019). The cost of QLA has been found to be
four times the cost of level B (Sinha et al. 2008). For example, achieving
quality level A requires the excavation of potholes to nd and survey the
exact location and dimensions of a facility at a specic point or location
(Sturgill et al., 2021). However, the return on investment for utilizing
SUE can be signicant for certain construction projects, especially when
utility location accuracy is needed. Only QLA identies the x-y-z loca-
tions of subsurface utilities (Al-Bayati, 2021). The project development
team can determine the necessary quality level for underground infor-
mation to adequately design and construct their project and seek more
certain levels at specic locations as needed (Sturgill et al., 2021). To
fully achieve the benets of SUE, it is important to systematically
incorporate this service during all stages of the project lifecycle (Jeong
et al., 2004). There are many factors to consider when selecting a SUE
provider. Achieving SUE levels requires competent personnel, special-
ized equipment, proven experience, professional registrations as
required by statute, and professional liability insurance coverage to
provide such services (Anspach and Scott, 2019). Project owners and
private locating rms should be aware of these requirements (Hutchins
and Sinha, 2009).
One of the most common tools for SUE applications are geophysical
tools and technologies. These tools and techniques include electro-
magnetic methods (e.g., pipe and cable locators, ground penetrating
radar, metal detectors, etc.), magnetic methods, and elastic wave
methods (e.g., resonant sonic, active sonic, and passive sonic). These
methods typically align with judging SUE QLB location information.
FHWA notes that proper selection of subsurface geophysical method
cannot be overlooked (Sturgill et al., 2021). On the other hand, to
achieve QLA vacuum excavations must be employed. Each locating
technology has its own capabilities and limitations that should be
carefully evaluated when selecting the proper technology for specic
scenarios. Factors such as utility characteristics, SUE quality level,
geological conditions, environmental conditions, and the experience of
the operators should be considered in order to increase accuracy (Uslu
et al., 2016). Thus, it is crucial for a private locating provider to be
equipped with varying instruments (Hyung Seok et al., 2004). Another
important consideration for private locating providers is that the
knowledge and expertise of the personnel conducting the locating sur-
veys can affect the accuracy of the data. Most of underground locating
technologies require an experienced crew to evaluate the site conditions
effectively and interpret the results properly (Uslu et al., 2016). These
requirements stem from SUE necessitating the expertise of geophysical
conditions and the proper use of geophysical equipment for the detec-
tion of subsurface utilities (Jeong et al., 2002).
Many potential clients confuse SUE investigations and information
gathered through one-call systems. However, one-call objectives are
limited to mere avoidance of utility strikes during the construction stage,
whereas SUE is a consulting service providing benets throughout the
whole project (Jeong et al., 2004). Moreover, the scope of a SUE
investigation is more comprehensive than the scope of the one-call
system, which is only concerned with active subsurface utilities,
whereas SUE investigations collect reliable information about active,
abandoned, and unknown utilities (Al-Bayati, 2021). While it is possible
to receive information similar to SUE quality levels (e.g., QLC or QLD)
utilizing a one-call service is not a substitute for SUE due to the absence
of engineering judgements in locates provided through the one-call
system (Al-Bayati and Panzer, 2021). However, unlike the one-call ser-
vice, SUE is not offered for free to designers and excavators (Al-Bayati
and Panzer, 2021).
A.J. Al-Bayati et al.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
6
3. Research objective and methodology
Transportation projects’ stakeholders, including designers and con-
struction managers, should fully understand the current practices
related to private locating rms and SUE standards to fully utilize the
available services. This advanced understanding will contribute to
effective management practices for underground utilities during various
phases of the transportation project development process (e.g., planning
and design). Accordingly, an online survey was developed to identify the
current practices and market trends of private utility locating in the
United States. The survey was reviewed and approved by Lawrence
Technological University’s Human Subject Institutional Review Board
(HSIRB) in March 2021. The online survey was made available between
March and August 2021 and distributed through a network of con-
struction practitioners who work with private locating rms. The study
used convenience sampling, instead of probability sampling, which is a
common research methodology in construction research (Al-Bayati,
2021; Abowitz and Toole, 2010). According to Scheaffer et al. (2012),
the response rate can be easily calculated for a probability sample survey
because the population and sample size are known. However, it is not
feasible nor benecial to report a response rate for convenience sam-
pling due to the fact that the overall population is unknown and as
consequence the sample size is not determinable.
Respondents were presented with a consent form, which led to the
questionnaire only after the respondent voluntarily agreed to partici-
pate. Furthermore, participants who voluntarily consented to complete
the questionnaire were free to withdraw from the study at any time. A
total of 25 private locating rms participated in the survey. However,
the total number of responses varied from question to question due to
unanswered questions. Overall, the construction industry is known for
its lack of participation in surveys and questionnaires (Nabi and El-
Adaway, 2021). This is especially true of the population this study tar-
geted due to the limited number of rms that specialize in this type of
work.
4. Results and discussion of survey ndings
The survey participants included rms in various geographical areas
such as North Carolina (28 %) and Michigan (8 %). All participants who
reported their level of experience indicated they had more than six years
of experience. The job titles of the participants fell within the following
categories: president, director, locate manager, and solo owner. The
survey was designed to collect qualitative and quantitative data. The
following subsections will discuss the data analysis ndings of the
survey.
4.1. Survey quantitative data analysis
The collected data indicates that 17 of the participant rms (68 %, n
=25) provide SUE services. Among these 17 SUE providers, 12 reported
that they also utilize the one-call system. On the other hand, among the 8
non– SUE providers (32 %, n =25), only 4 rms utilize the one-call
system. This makes a total of 16 private locating rms, among SUE
and non-SUE providers, that utilize the one-call system in their work.
This highlights the vital role of the one-call system. In general, private
locating rms should always utilize the one-call system to identify
existing utilities within the transportation project limits (e.g., right of
way), collect utility records, and comply with damage prevention laws
(Al-Bayati and Panzer, 2022). The SUE providers were asked to score the
frequency of the SUE quality levels requested by their customers on a
scale from 1 to 10, where 1 indicates being rarely requested and 10
indicates being usually requested. Fig. 3 shows the average score of each
quality level. As indicated in the gure below, QLB is the most requested
SUE quality level because it provides high condence in the horizontal
location of the underground utilities at an acceptable cost in comparison
to QLA. QLB is often sufcient for project design decisions and
excavation planning by construction contractors.
To better understand the market of the private locating rms, par-
ticipants were asked about their customers (i.e., departments of trans-
portation [DOT], utility owners [UO], homeowners [HO], general
contractors [GC], and architectural/engineering rms [A/E]) on a 1 to
10 scale, where 1 indicates rarely requesting their service and 10 in-
dicates usually requesting their service. Table 3 shows the average score
of each potential customer type. As shown in this table, although some
respondents gave a minimum score of 2 to A/E rms and general con-
tractors, the mean values indicate that these customers are the most
frequent customers of the private locating rms who participated in the
study. A factorial ANOVA was conducted to determine whether there are
signicant differences between the frequency of the customer types who
make requests for services. The results indicate a statistically signicant
difference in request frequency among the customer types based on
respondent experience (F =3.8 df =4; p =0.005). A statistically sig-
nicant difference means that there is a 0.005 or less chance that the
difference in scores could be attributed to random effects.
Similarly, the participants were asked to score the frequency of the
project phases during which their services are requested on a scale from
1 to 10, where 1 indicates being rarely requested during the phase and
10 indicates being usually requested during the phase. Fig. 4 shows the
survey results for each project phase. A factorial ANOVA was conducted
to determine whether there were signicant differences between the
results. The analysis indicates a statistically signicant difference in the
results based on participant experiences (F =4.8; df =3, 96; p =0.003).
A statistically signicant difference means that there is a 0.003 or less
chance that the difference in scores could be attributed to random ef-
fects. Furthermore, the results reveal that the services of private locating
rms are most frequently requested during the construction phase.
However, the SUE service is more benecial to use during the design
phase to avoid utility conicts and costly utility relocation while also
potentially heading off issue during construction.
The SUE providers were also asked about the need for a registered
professional to deliver SUE quality levels. The collected responses
indicate that 68.7 % of SUE providers who participated in the survey
believe there is need for a registered professional to provide QLA and
QLB, whereas only 50 % believe that a registered professional is needed
5.8
8.6
5.1
3.4
0.0
2.0
4.0
6.0
8.0
10.0
QL A QL B Q LC QL D
Scores -
Frequency of SUE QL
Requested
SUE Quality Levels (QLs)
10 = Usually requested
1 = Rarely requested
Fig. 3. The average score of requested SUE quality levels.
Table 3
Private Locating Customer Type Frequency.
Service Requester Mean Standard
Deviation
Minimum
Score
Maximum
Score
DOT 4.4 3.0 1.0 10.0
Utility Owners 5.0 2.7 1.0 10.0
Homeowners 4.9 3.4 1.0 10.0
General
Contractors
6.5 2.5 2.0 10.0
A/E Firms 7.0 2.5 2.0 10.0
1 =Rarely Requested 10 =Usually Requested.
A.J. Al-Bayati et al.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
7
to provide QLC and QLD. This nding is problematic because a regis-
tered professional is needed to provide an engineering judgement for all
SUE quality levels.
4.2. Survey qualitative data analysis
The participants were also asked about the reasons that construction
stakeholders use their services. The provided responses indicate that
locate accuracy is the primary reason for hiring SUE private locators, see
Fig. 5. On the other hand, the reasons for hiring a non-SUE private
locating rm include accuracy, time, and location of utilities that are not
covered by the one-call system. This nding is justied because the
primary value of SUE providers is SUE quality levels that improve the
overall accuracy of locates. On the other hand, participants were asked
about the tools and techniques they use to locate underground utilities.
Electromagnetic methods (E.M.) are the primary methods for locating
within the one-call system approach (Al-Bayati and Panzer, 2021).
However, as shown in Fig. 6, other methods are utilized by private
locating rms, such as ground penetrating radar (GPR), a combination of
E.M. and GPR, and vacuum (soft) excavation. In addition, Fig. 6 shows
that GPR is utilized more by SUE private locating rms. This can be
explained by the fact that the ndings of these rms must achieve the
SUE quality levels.
Similarly, the collected data shows that 75 % of the SUE providers
use soft excavation/potholing to locate underground utilities, whereas
only 38 % of non-SUE providers utilize excavation/potholing. Soft
excavation or potholing is often used by private locating rms to provide
accurate locates, QLA in the case of SUE providers. According to the
private locating companies that provide SUE, when asked about the
circumstances that motivate them to use potholing, they gave the
following responses:
•In most cases, vacuum excavation services are undertaken during
construction to locate a utility that was not identied during the
design phase.
•Vacuum excavation is done during construction or during design
phases to determine the depth of utilities underground.
•To expose existing infrastructure, vacuum trucks are used.
•Conicts must be identied and mitigated when underground
infrastructure improvements are being planned. Similarly, conicts
must be identied and mitigated when a signicant cut is expected.
•Soft excavation is used if contractors are installing utilities and need
to provide a QLA plan and prole.
•Vacuum excavation is used to collect information about the depth,
size, and line.
•Vacuum excavation is required for QLA projects.
When the participants were asked about unknown or abandoned
5.2
6.6
7.4
4.6
0.0
2.0
4.0
6.0
8.0
10.0
Planning Phase Design Phase Construction Phase Emergencies
Scores - Frequency of Service Request
Project Development Phases
10 = Usually requested
1 = Rarely requested
Fig. 4. Service request frequencies based on project phase.
32% 32%
20%
12%
4%
40%
20% 20%
10% 10%
0%
10%
20%
30%
40%
50%
EM GPR EM & GPR Vacuum
Excavation
Other
% of Participants
Tools and Techniques for Underground Utilities Location
SUE Non-SUE
A.J. Al-Bayati et al.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
8
underground structures or utilities, 100 % of the SUE providers indi-
cated that they identify unknown utilities as part of their service,
whereas only 57 % of non-SUE providers reported providing such a
service. Finally, study participants were asked about the format in which
they deliver ndings to their customers. The collocated data indicates
several methods, such as physical marks, CADD les, and GIS formats.
Fig. 7 shows the breakdown in frequently used methods between SUE
providers and non-SUE providers. SUE providers appear to depend less
on physical marks, which closely aligns with the SUE standard that
promotes deliverables in the form of a report.
5. Contextualizing the ndings
Identifying the approximate location of underground utilities during
the design phase and before construction starts is a vital tool for de-
signers to avoid utility conicts and costly utility relocation during
construction in transportation projects. Currently, there are two
methods that can be utilized by A/E rms and general contractors: the
one-call system and private locating rms. These approaches have
varying levels of detail and purpose, although similar locating methods
and technologies are often used to execute both, as shown in Fig. 6. Even
with these similarities, care must be exercised as to how this information
is used and relied upon within projects. These similarities have also been
noted to cause misunderstandings and misnomers related to non-
standardized practices versus standardized practices (i.e., the ASCE 38
standard for practicing SUE). Seemingly because SUE has become a
colloquialism in the practice of utility location, it is often misused to
describe any subsurface utility investigation. To date, there is little more
than anecdotal evidence to suggest differences among practices of utility
investigation. Here is an example of the language in a report submitted
by a private locating rm to a county: “A level B/C SUE investigation.
This level of SUE includes marking and designating the underground
utilities through an 811 call or by contacting the individual utility
companies to mark the locations (level B) and surveying the marked
locations and aboveground utility features (level C).” Clearly, the one-
call system is mistakenly utilized in this report to achieve QLB.
One-call systems do not locate utilities, they notify utility owners and
operators of the need to mark the locations of utilities in project areas.
These marks indicate (inclusive of their buffer area) where contractors
need to hand dig to expose utilities in lieu of mechanical excavation
methods. Excavators who dig without using one-call or who mechani-
cally dig in the buffer area of marked utilities are liable for damages they
cause by striking utilities. In instances where the one-call marks are
inaccurate, the utility becomes liable for those damages. In these terms,
the one-system serves as a liability assignment tool. Of course, rst and
foremost, the objective of the one-call system is to promote and organize
damage prevention efforts. One-call system should not be utilized to
achieve SUE quality levels. In certain cases, the information collected
60%
14% 16%
4% 6%
33%
25% 21% 21%
0%
20%
40%
60%
80%
Accuracy Not covered by
one call
Time SUE Other
% of Participants
Reasons for Service Request
SUE None-SUE
Fig. 5. Reasons for Hiring Private Locating Firms.
32% 32%
20%
12%
4%
40%
20% 20%
10% 10%
0%
10%
20%
30%
40%
50%
EM GPR EM & GPR Vacuum
Excavation
Other
% of Participants
Tools and Techniques for Underground Utilities Location
SUE Non-SUE
Fig. 6. Methods Used to Locate Underground Utilities.
A.J. Al-Bayati et al.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
9
through the use of a one-call system, and more specically the marks of
locators responding to one-call tickets, may provide information for a
SUE investigation but should not be considered a means to reach any
SUE QL.
SUE, as dened by ASCE 38, is an engineering service considered the
standard of care for utility investigations. SUE services must be certied
by licensed engineers or surveyors (depending on jurisdiction) and
entail a holistic investigation of utility facilities within project foot-
prints. A SUE investigation will provide location information to judged
quality levels for the utilities that are known to exist in a project foot-
print as well as for those that are unknown or abandoned. This was also
highlighted in the survey results showing that 100 % of the SUE pro-
viders identify unknown utilities as part of their service, whereas only
57 % of non-SUE providers reported providing such a service. SUE
providers are also responsible for making judgements and recommen-
dations and analyzing their results. This differentiation was also high-
lighted in the survey results showing the investigation technologies and
indication of unknown utilities by SUE providers. The utility locations
are classied to judged quality levels, and SUE deliverables include as-
sessments of utility impacts, which are typically reported in documents
and plans, another point of distinction from non-SUE services that was
highlighted in the survey. SUE is not a replacement for the use of one-
call systems because the use of one-call is required by law where exca-
vation is imminent and has a unique objective differentiated from the
objective of SUE. The central object of procuring SUE services is risk
reduction for a project through a thorough investigation of the project
limits that will capture utilities listed and not listed in the one-call
system.
A nal group providing utility investigation services are private
locator rms that do not provide SUE. These companies may provide
utility location information through similar or the same methods as SUE
providers but cannot be considered a replacement for SUE. Unfortu-
nately, these providers sometimes claim to provide SUE. This came to
light in the survey results where those who identied themselves as
providing SUE also indicated an engineer or surveyor was not required
to certify the investigation results. As mentioned in the literature review,
achieving SUE levels requires competent personnel with proven expe-
rience and professional registrations as required by statute. However,
the collected survey responses indicate that only 50 % of participants
SUE providers believe that a registered professional is needed to provide
QLC and QLD. This clearly shows a misunderstanding of the ASCE 38
SUE standard because according to it a registered professional is needed
to provide an engineering judgement for all SUE quality levels. Neither
are these non-SUE private locators a replacement for one-call systems,
for the same reasons described in the paragraph above. These private
locator rms denitely have their role, as they may provide locating
services to utility owners responding to one-call tickets, or they may
provide locating services on projects where SUE investigations are not
cost effective (e.g., small rural projects judged to have low utility risks).
These three distinct avenues of utility investigation and location
often become misunderstood or misrepresented, and the construction
and design industries must use care and be more informed of the services
they are procuring. The ASCE 38 standard and the imminent publication
of its revision aim to clarify a distinction between SUE and non-SUE
services, but to be effective, this standard must be well understood by
the design and construction industry and locating service providers
alike. Despite the limited number of participants, which represents one
of this study’s limitations, the collected ndings of the study are valu-
able and vital to better understand private locating rms.
6. Conclusions
This paper represents a step toward providing a scientic study of the
differences among utility locating approaches. It is critical that those
delivering transportation projects understand these variations, the
source of the information being provided to them regarding utilities, and
the potential accuracy of the utility location data being provided to them
according to the varying approaches. One-call systems use tickets as a
communication mechanism for designers and constructors who are
performing excavation or design in an area to notify utility owners and
operators with facilities in the vicinity of the imminent work. Utility
owners are then expected to respond within stipulated timelines
dependent upon state damage prevention laws. Millions of locate tickets
are placed through one-call services every year in the United States. The
frequent exemptions to being a member of a one-call system present a
vital need for private locator services. This, coupled with circumstances
necessitating more accurate utility location, such as utilities being in
close proximity to construction activities, and the need to locate private
and abandoned utilities contributed to the development of the practice
of SUE. The cost of SUE practices as standardized by ASCE 38 likely led
to the need for location services by non-SUE providers. These non-SUE
providers often use the same or similar methods and technologies but
are not bound by the same professional standard of care as those
providing ASCE 38 compliant SUE investigations. To date, many of the
differences among SUE and non-SUE private locate rms have been
anecdotal. This study sheds light on differences between these service
provider types using the data they provide in survey responses. The
conclusion of this work is not to note that either of these service provider
types are irrelevant but that they provide different services, and all
stakeholders need an understanding of these differences. Both SUE and
non-SUE private location services are vital to the protection of our utility
infrastructure. Their services entail advantages and disadvantages. It is
17%
33%
17% 20%
13%
55%
27%
0% 0%
18%
0%
20%
40%
60%
Physical Marks Mapping
(CADD)
Hand sketches MicroStation &
GIS format
Other
% of Participants
Information Delivery Formats
SUE Non-SUE
Fig. 7. Methods Used to Deliver Locate Findings.
A.J. Al-Bayati et al.
Transportation Research Interdisciplinary Perspectives 16 (2022) 100707
10
imperative that these differences are understood.
CRediT authorship contribution statement
Ahmed Jalil Al-Bayati: Conceptualization, Data curation, Formal
analysis, Investigation, Methodology, Project administration, Resources,
Supervision, Validation, Writing – original draft, Writing – review &
editing. Roy Everett Sturgill: Conceptualization, Data curation, Meth-
odology, Project administration, Resources, Supervision, Validation,
Writing – original draft, Writing – review & editing. Louis Panzer:
Conceptualization, Data curation, Writing – original draft, Writing –
review & editing. Shani Montes Victorio: Data curation, Formal anal-
ysis, Investigation, Writing – original draft, Writing – review & editing.
Tarig Omer: Data curation, Formal analysis, Investigation, Writing –
original draft, Writing – review & editing.
Declaration of Competing Interest
The authors declare that they have no known competing nancial
interests or personal relationships that could have appeared to inuence
the work reported in this paper.
Data availability
The authors do not have permission to share data.
Acknowledgement
This research was not funded by a specic grant or funding agency in
the public, commercial, or not-for-prot sectors.
References
Abowitz, D.A., Toole, T.M., 2010. Mixed Method Research: Fundamental Issues of
Design, Validity, and Reliability in Construction Research. J. Construct. Eng.
Manage. 136 (1), 108–116.
Al-Bayati, A.J., Panzer, L., 2019. Reducing Damage to Underground Utilities: Lessons
Learned from Damage Data and Excavators in North Carolina. J. Construct. Eng.
Manage. https://doi.org/10.1061/(ASCE)CO.1943-7862.0001724.
Al-Bayati, A.J., Panzer, L., 2020. Reducing Damages to Underground Utilities:
Importance of Stakeholders’ Behaviors. J. Construct. Eng. Manage. 146 (9) https://
doi.org/10.1061/(ASCE)CO.1943-7862.0001899.
Al-Bayati, A.J., Panzer, L., 2021. Underground Utilities for Construction Practitioners
and Homeowners. Am. Soc. Civil Eng. ASCE Press. https://doi.org/10.1061/
9780784415818.
Al-Bayati, A.J., Panzer, L., 2022. Resilience of Infrastructure Damage Prevention: Vital
Role of One Call Centers in the United States. Practi. Period. Struct. Design
Construct. 27 (2) https://doi.org/10.1061/(ASCE)SC.1943-5576.0000674.
Al-Bayati, A.J., Panzer, L., Karakhan, A., 2019. Reducing Damage to Underground
Infrastructure: Performance Evaluation of One-Call Notication Program. Pract.
Period. Struct. Desig. Construct. 24 (4) https://doi.org/10.1061/(ASCE)SC.1943-
5576.0000441.
Al-Bayati, A.J. (2021). “Infrastructure Damage Prevention Approaches in the United
States.” Prco. Pipelines 2021, Virtual Conference. https://doi.org/10.1061/
9780784483619.011.
Anspach, J.H., Scott, P., 2019. Subsurface Utility Engineering for Municipalities –
Prequalication Criteria and Scope of Work Guide. Am. Soc. .Civil Eng. Press.
https://doi.org/10.1061/9780784415368.
FHWA, Federal Highway Administration, (2018a), “National Utility Review: Utility
Coordination Process” FHWA-HIF-18-039, Federal Highway Administration,
Washington, D.C. <https://www.fhwa.dot.gov/utilities/hif18039.pdf>(Accessed
May 30, 2022).
Federal Highway Administration (FHWA), “Subsurface Utility Engineering,” FHWA,
Washington D.C., (2018b) [Online]. Available: https://www.fhwa.dot.gov/
programadmin/history.cfm [accessed May 15, 2022].
Hutchins, L., and Sinha, S. (2009). “Identifying Appropriate Means and Methods for
Locating Buried Utilities.” Proc. Pipelines 2009: Infrastructure’s Hidden Assets.
https://doi.org/10.1061/41069(360)36.
Jeong, H.S., Arboleda, C.A., Abraham, D.M., Halpin, D.W., 2002. “FHWA/IN/JTRP-
2003/12 Imaging and Locating Buried Utilities”. Accessed May 30, 2022 Joint
Transport. Res. Progr. https://docs.lib.purdue.edu/cgi/viewcontent.cgi?arti
cle=1585&context=jtrp.
Jeong, H. S., C. A. Arboleda, D. M. Abraham, D. W. Halpin, and L. E. Bernold. Imaging
and Locating Buried Utilities. Publication FHWA/IN/JTRP-2003/12. Joint
Transportation Research Program, Indiana Department of Transportation and
Purdue University, West Lafayette, Indiana, 2003. doi: 10.5703/1288284313237
(Accessed May 30, 2022).
Jeong, H.S., Abraham, D.M., and Lew, J. (2004). “Evaluation of an Emerging Market in
Subsurface Utility Engineering.” J. Construct. Eng. Manage., Vol. 130 (2). https://
doi.org/10.1061/(ASCE)0733-9364(2004)130:2(225).
Maree, S., Rotimi, F.E., Rotimi, J.O.B., 2021. The Primacy of As-Built Drawings in the
Management of Underground Utility Operations: A New Zealand Study. Buildings 11
(9), 1–14.
Metje, N., Ahmad, B., Crossland, S.M., 2015. Causes, impacts and costs of strikes on
buried utility assets. Proc. Inst. Civ. Eng. Munic. Eng. 168 (3), 165–174. https://doi.
org/10.1680/jmuen.14.00035.
Nabi, M.A., El-Adaway, I.H., 2021. Understanding the Key Risks Affecting Cost and
Schedule Performance of Modular Construction Projects. J. Manage. Eng. 37 (4),
04021023.
Page, M.J., McKenzie, J.E., Bossuyt, P.M., Boutron, I., Hoffmann, T.C., Mulrow, C.D.,
et al., 2021. The PRISMA 2020 Statement: An Updated Guideline for Reporting
Systematic Reviews. The BMJ. https://doi. https://doi.org/10.1136/bmj.n71.
Sinha, S.K., Jung, Y. J., Thomas, H., and Wang, M. C. (2008). “Subsurface Utility
Engineering for Highway Construction.” Proc. International Pipelines Conference
2008, Atlanta, Georgia. https://doi.org/10.1061/40994(321)7.
Sturgill, R.E., Taylor, T.R.B., and Li, Y. (2018). “Implications of State Departments of
Transportation (DOTs): Participation in the One Call Process as an Underground
Facility Operator. National Cooperative Highway Research Program.”
Transportation Research Board of the National Academies of Sciences, Engineering,
and Medicine. https://onlinepubs.trb.org/onlinepubs/tcrp/docs/Task%20389%
20Final%20Report%20Final%20Draft.docx (Accessed May 30, 2022).
Sturgill, R.E., Madson, K., Anspach, J.H., and Decker, M. (2021). “NCHRP 20-05
Implementation of Subsurface Utility Engineering for Highway Design and
Construction. National Cooperative Highway Research Program.” Transportation
Research Board. National Research Council. https://www.trb.org/Publications/
Blurbs/182718.aspx (Accessed May 30, 2022)..
Thorne, J., Turner, D., and Lindly, J. (1993). “Highway/Utility Guide. Report FHWA-SA-
93-049”, Ofce of Technology Applications, Washington, D.C. <https://www.fhwa.
dot.gov/utilities/010604.pdf (Accessed May 30, 2022).
Uslu, B., Jung, Y.J., Sinha, S.K., 2016. Underground Utility Locating Technologies for
Condition Assessment and Renewal Engineering of Water Pipeline Infrastructure
Systems. J. Pipeline Syst. Eng. Pract. 7 (4) https://doi.org/10.1061/(ASCE)PS.1949-
1204.0000221.
A.J. Al-Bayati et al.
