The USDA Natural Resources Conservation Service (NRCS) defines surveying as “the science, art, and technology by which lines, distances, angles, and elevations are established and measured on or beneath the Earth’s surface”.

Surveying data establishes the foundation for KYTC road construction projects. And decisions made during surveys reverberate across the project life cycle — from roadway design and construction through maintenance. This article gives a brief overview of surveying and its applications on KYTC projects.

Surveying projects generally involve four steps:

• Research
• Fieldwork
• Evaluation
• Publication

2.1 Research

Research involves gathering all available information relevant to a project. For a control survey this might include searching for control monuments or reference base stations on or near the project. Another example is searching plans for available benchmarks to conduct a level loop survey.

Another important component of research is preliminary site visits. During these visits, surveyors determine the scope of work, identify the best surveying methods to use, and determine how many people are needed to complete surveying work safely. For example, if a topographic survey is needed, during site visits surveyors can identify the area to survey, where to establish control points, and determine whether a crew of two or three people is needed.

2.2 Fieldwork

During fieldwork survey crews collect data that are used to generate appropriate plats, plans, or reports. How the work is accomplished depends primarily on the survey’s purpose and the level of accuracy required.

Field notes record data gathered during fieldwork. Notes can be recorded by hand in a field book or logged electronically using a data collector. All notes must be accurate, complete (nothing omitted), legible, clear, concise, and organized using either a standard agency format or personal format.

2.3 Evaluation

Following data collection, results are used to complete calculations required to develop materials such as plats, plans, reports. Field data are evaluated and often plotted to determine its adequacy. Fieldwork and evaluations proceed iteratively because evaluations often reveal the need for more field data.

2.4 Publication

Survey data informs the preparation of plats, plans or reports. For design surveying this primarily involves electronic deliverables for plan production. For construction surveying, it usually entails developing a report or completing a quantity calculation.

The two basic categories of surveys used on KYTC projects are geodetic surveying and plane surveying.

3.1 Geodetic

Geodetic surveying accounts for the earth’s curvature and treats the earth’s surface as three dimensional.  Geodetic surveying employs datums, which are standardized reference frameworks used to measure locations and elevations on the Earth.  The standard horizontal datum currently in use in the United States is the  North American Datum of 1983 (NAD 83).  NAD 83 is based on an ellipsoid model of the earth (GRS 80).  The GRS 80 ellipsoid uses a polar coordinate system with latitude and longitude as its primary horizontal coordinates.

Primary control networks managed by the National Geodetic Survey (NGS) are based on NAD 83, allowing future surveys to be referenced to this datum.   By referencing surveys to a common datum such as NAD 83, data from different agencies can be matched up and aligned, allowing for a seamless data mapping.

Geodetic surveying for KYTC projects is primarily accomplished using Global Navigation Satellite System (GNSS) survey techniques. Survey-grade GNSS receivers use signals from multiple satellites to determine precise positions on the earth’s surface.

For more discussion on NAD 83, see HKP Article Kentucky State Plane Coordinate System and the National Geodetic Survey’s North American Datum of 1983 website. 

3.2 Plane

Plane surveying treats the earth’s surface as a plane surface. Because geodetic survey data do not represent what is measured on the ground, plane surveying techniques are often used for ground measurements and project layouts. Plane surveying usually focuses on smaller areas and primarily involves using traditional survey measuring devices such as electronic distance measuring (EDM) devices, tapes, and levels.

While the GRS ellipsoid model is very convenient for locating the horizontal position of points on the earth, the relative distance between these points is another matter.  Since the points are located on a theoretical best fit model of the earth, the actual ground surface will be above or below the ellipsoid.  The means that the distances between points on the ellipsoid will not match  distances measured on the ground.

The current State Plane Coordinate Systems (SPCS) used in Kentucky are projections of the GRS 80 ellipsoid onto a plane surface.  Using state plane coordinate systems allows for ground measurements to match more closely to the grid measurement on the SPCS surface.  See HKP Article Kentucky State Plane Coordinate System for more information.

Surveys primarily support two Department of Highways functions:

• Project development
• Project delivery and preservation

The main use of project development surveys is to develop mapping for Six Year Plan projects. Surveys for these projects use a mixture of geodetic and plane surveying techniques. Mapping derived from these surveys are delivered in an electronic format and used to lay out and design multiple project elements.

Surveying functions for Project Delivery and Preservation primarily involve the construction and maintenance functions of KYTC.  These  surveys primarily rely on plane surveying techniques and are carried out to:

• Develop reports
• Stake out project components
• Measure quantities
• Check for construction tolerances
• Report construction progress

All KYTC surveying projects are based on the principle of route surveying. Route surveying encompasses all surveying operations needed to design and construct linear infrastructure projects like highways, bike paths, trails, pipelines, utilities, and railroads.

On route surveys, once the survey centerline (or baseline) is established, survey data are referenced to the facility centerline or baseline, which makes the facility itself the primary monument for the survey. 

On Cabinet projects the roadway centerline is usually the reference point for all data. The centerline must be defined using geometric principles so it can be replicated and transferred to the ground. The centerline is defined by a continuous combination of lines, circular curves and spiral curves. 

A linear reference system referred to as stationing is established along the centerline by measuring horizontal distances at regular intervals along the centerline. Points along the centerline are located by their station along the centerline. Points off the centerline are located by their station and offset from the centerline.

The survey crew must respect the property rights of individual landowners and obtain consent before entering their property.  This consent is often referred to as right of entry and may require a Consent and Release.  See HD-305 Preconstruction Activity on Private Property in the Highway Design Manual, CST-503 TC 71-14 form, Consent & Release in the Construction Manual and MAINT-210 Work beyond the Rights-of-Way (Right of Entry) in the Maintenance Manual for more information. 

KYTC Survey Manual (Chapter 300 of Highway Design Manual) (2026). Kentucky Transportation Cabinet.

Using State Plane and Project Datum Coordinates. (2004). Perry Semones, Kentucky Transportation Cabinet.

The Kentucky State Plane Coordinate System Standards and Specifications Document. (2023). Bryan W. Bunch, PLS, PG.

Surveying Equipment and Methods

Kentucky State Plane Coordinate System

Project Development Surveys