6.2.2 Utility Identification

Utility data is needed before establishing final alignments of the roadway and related features (e.g., storm drains and other excavation work) so that the design engineer may avoid or design around conflicts. This task involves identifying and marking the physical features of utilities and specifically determining elevations as well as horizontal positions. Examples might include manhole covers, gas pipes, overhead lines, water lines, sanitary sewer lines and fiber-optic cables.
The designer must
AVOID
,
MITIGATE
, or
ACCOMODATE
(in that order) for project utility conflicts to prevent delays and additional project costs. Early design and planning phases must include subsurface site characterization of various geologic, environmental, and utility features.
Existing utility locations must be furnished with the geometric schematic and/or plan sheets. Methods of identifying existing utility locations include:
  • District Utility Installation Request records (utility permits);
  • Existing Utility Joint Use Agreements from prior projects;
  • Texas 811 call location services;
  • SUE services (see
    Section 6.2.2.1
    );
    • Utility companies may be urged to consider SUE usage to determine critical or unknown locations of their facilities; and
    • TxDOT design teams are encouraged to make use of SUE services to optimize design.
  • Known utilities that the district may be aware of, and can identify, or of other utility service providers/utility facilities in the nearby area; and
  • Site visit and thorough examination of the proposed project location by TxDOT personnel.
While developing geometric schematics, there may be times when it is preferable to obtain some of the utility location data (i.e., for potentially very costly conflicts). Otherwise, most of this data is collected before beginning final design.
Undocumented utilities may have been installed without a record of their location
. Electromagnetic line location (EMLL) or ground-penetrating radar (GPR) should be used to mark locations on the ground followed by potholing or excavation to determine the utility type. GPR can detect non-metallic targets without tracer wire.
Prior to performing any excavation work to identify underground utilities, a “locate request” through OneCall Board of Texas (OCB) (commonly referred to as “811”) is required. A minimum 48-hour notice to 811 is required subject to the provisions in the Texas Utilities Code or TAC.
TxDOT or its contractor must contact the relevant railroad for any utilities within the railroad ROW including where the State crosses railroad ROW.
Utilities within railroad ROW are not identified in the OCB system.
All utilities identified on a project should be documented in the Utility Conflict Analysis Template.
Considerations in identifying utilities:
  • Engage District and utility SMEs to coordinate closely with utility owners. Utility owners will often supply copies of maps and as-built construction plans and do the potholing. It is in their interest to avoid relocating the utility and avoid damage by construction activities;
  • Rural water authorities
     do not register with Texas 811 and are not included in the utility location request. Coordinate with these entities directly to have their lines marked, especially when the project is in a rural location;
  • Typically, utility owners are responsible for accommodating TxDOT's proposed facilities subject to the provisions in Texas Utilities Code; therefore, it is advisable to meet with and inform utility owners of the proposed construction and potential for conflicts early in the planning phase.
    Smaller utility owners may not be able to budget for relocations without extensive notice
    ; and
  • For all bridge projects, this work must be completed prior to the project letting date. For locally owned bridges (i.e., off-system bridges), the cost for accommodating utilities is the responsibility of the bridge owner.
6.2.2.1 SUE
SUE is a non-destructive utility investigation to accurately locate, identify, and map underground utilities. It is an interdisciplinary service, involving professional engineers, geologists, and licensed land surveyors. SUE is a professional service resulting in signed and sealed deliverables. Accurate SUE information is critical to prevent costly redesign and change orders.
Major activities involved in SUE are:
  • Scope of Work
    : A project-specific work plan that determines level of service versus risk allocation, schedule, and delivery method. SUE provider and TxDOT agree on work plan describing the SUE work to be performed.
    • Designating: Using surface geophysical techniques to determine the existence and horizontal position of subsurface utilities. Above ground surface markers (stakes, flags, etc.) or on the ground surface marking (paint) mark the locations.
    • Locating: Process of exposing precise horizontal and vertical position, size, and configuration of subsurface utilities.
  • Data Management
    : Process of locating, surveying, and designating information and transferring it into project GIS files, plans, or CAD system.
  • Conflict Analysis
    : Using a utility conflict matrix (UCM) or 3D model clash detection to do an engineering evaluation and comparing designated information with proposed plans to inform all stakeholders of potential conflicts, possible resolutions, and costs to resolve.
The various levels of SUE investigations are described below.
  • Quality Level D (QL-D).
     The most basic level of information. It comes from existing utility records or oral recollections. Its usefulness must be confined to project planning and route selection activities.
  • Quality Level C (QL-C).
     Involves surveying visible aboveground utility facilities, such as manholes, valve boxes, posts, etc., and correlating this information to Quality Level D. Its usefulness must be confined to rural projects where utilities are not prevalent or are not too expensive to repair or relocate.
  • Quality Level B (QL-B).
     Uses appropriate surface geophysical methods to determine the existence and approximate horizontal position of subsurface utilities. This two-dimensional horizontal mapping information is usually sufficient to accomplish preliminary engineering goals. Decisions can be made on where to place storm drainage systems and other design features to avoid conflicts with existing utilities. Slight adjustments in the design can produce substantial cost savings by eliminating utility relocations.
  • Quality Level A (QL-A).
     Precise vertical and horizontal location of subsurface utilities obtained by exposure and subsequent measurement, usually at a specific point. Information provides the highest level of accuracy presently available. When surveyed and mapped, precise plan and profile information is available for use in making final design decisions. The use of nondestructive digging equipment, particularly vacuum excavation, eliminates damage to underground utility facilities traditionally caused by backhoes.
Commonly, Level C and Level D SUE are performed in the preliminary stages of project development to identify approximate utility locations. Level B SUE is typically performed to evaluate alternative alignments. When a recommended alternative has been identified, Level A SUE will be performed to affirm the exact utility location.
A consultant contract is typically needed to perform SUE services. It can take several months to execute a consultant contract. Coordinate with the District and Division SMEs to understand the timeframe to include in the project schedule.
  • Authority documents:
  • Coordination:
  •  District ROW and utility staff
  •  ROW staff
  •  OneCall Board of Texas (OCB) – Also referred to as 811
  • Tools to use: