Federal Geographic Data Committee

Department of Agriculture • Department of Commerce • Department of Defense • Department of Energy

Department of Housing and Urban Development • Department of the Interior • Department of State

Department of Transportation • Environmental Protection Agency

Federal Emergency Management Agency • Library of Congress

National Aeronautics and Space Administration • National Archives and Records Administration

Tennessee Valley Authority

FGDC-STD-007.4-2002

Geospatial Positioning Accuracy Standards

PART 4: Standards for Architecture, Engineering, 

Construction (A/E/C) and Facility Management

Facilities Working Group

Federal Geographic Data Committee

NSDI

National Spatial Data Infrastructure
4-ii

Federal Geographic Data Committee

Established by Office of Management and Budget Circular A-16, the Federal Geographic Data Committee 

(FGDC) promotes the coordinated development, use, sharing, and dissemination of geographic data.

The FGDC is composed of representatives from the Departments of Agriculture, Commerce, Defense, 

Energy, Housing and Urban Development, the Interior, State, and Transportation; the Environmental 

Protection Agency; the Federal Emergency Management Agency; the Library of Congress; the National 

Aeronautics and Space Administration; the National Archives and Records Administration; and the 

Tennessee Valley Authority. Additional Federal agencies participate on FGDC subcommittees and working 

groups. The Department of the Interior chairs the committee.

FGDC subcommittees work on issues related to data categories coordinated under the circular. 

Subcommittees establish and implement standards for data content, quality, and transfer; encourage the 

exchange of information and the transfer of data; and organize the collection of geographic data to reduce 

duplication of effort. Working groups are established for issues that transcend data categories.

For more information about the committee, or to be added to the committee's newsletter mailing list, please 

contact:

Federal Geographic Data Committee Secretariat

c/o U.S. Geological Survey

590 National Center

Reston, Virginia 22092

Telephone: (703) 648-5514

Facsimile: (703) 648-5755

Internet (electronic mail): gdc@usgs.gov

Anonymous FTP: ftp://fgdc.er.usgs.gov/pub/gdc/

World Wide Web: http://fgdc.er.usgs.gov/fgdc.html
Federal Geographic Data Committee FGDC-STD-007.4-2002

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PART 4: Standards for A/E/C and Facility Management

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CONTENTS

Page

4.1 INTRODUCTION.......................................................................................................................................... 4-1

4.1.1 Objective......................................................................................................................................... 4-1

4.1.2 Scope............................................................................................................................................... 4-1

4.1.3 Applicability................................................................................................................................... 4-1

4.1.4 Related Standards......................................................................................................................... 4-2

4.1.5 Standards Development Procedures.......................................................................................... 4-2

4.1.6 Maintenance Authority................................................................................................................ 4-3

4.2 SPATIAL ACCURACY................................................................................................................................ 4-3

4.3 REFERENCE DATUMS AND COORDINATE SYSTEMS...................................................................... 4-3

4.3.1 Local Construction Control......................................................................................................... 4-3

4.3.2 NSRS Referenced Control............................................................................................................ 4-4

4.4 ACCURACY STANDARDS FOR A/E/C MAPS AND DRAWINGS.................................................... 4-4

4.4.1 ASPRS Large Scale Accuracy Standards.................................................................................. 4-4

4.4.2 Multiple Accuracies in A/E/C Drawings or CADD Levels ..................................................... 4-5

4.5 ACCURACY STANDARDS FOR A/E/C CONTROL SURVEYS............................................................ 4-5

4.5.1 Positional Accuracy...................................................................................................................... 4-5

4.5.2 Relative Closure Ratio Accuracy................................................................................................ 4-5

4.6 ACCURACY TESTING AND VERIFICATION......................................................................................... 4-6

4.7 ACCURACY REPORTING AND CERTIFICATION................................................................................ 4-6

4.7.1 Tested Products ............................................................................................................................ 4-6

4.7.2 Untested Products ........................................................................................................................ 4-6

4.7.3 Reporting Units ............................................................................................................................. 4-6

4.7.4 Variable Accuracies ...................................................................................................................... 4-7

4.7.5 Reporting Statements ................................................................................................................... 4-7

4.8 REFERENCES................................................................................................................................................. 4-8

APPENDIX A RECOMMENDED A/E/C SURVEYING AND MAPPING 

 STANDARDS (Informative)................................................................................................................................... 4-9

A.1 A/E/C CONTROL SURVEY STANDARDS (Informative)..................................................................... 4-10

A.2 TYPICAL ACCURACY STANDARDS FOR SELECTED A/E/C 

 PROJECTS (Informative)............................................................................................................................... 4-11

A.2.1 Target Scale and Contour Interval Specifications (Informative).......................................... 4-12

A.2.2 Feature Location Tolerances (Informative)............................................................................. 4-12
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A.3 A/E/C TOPOGRAPHIC SURVEYS AND CONSTRUCTION SITE PLANS (Informative)................ 4-13

A.3.1 Reconnaissance Topographic Surveys (Informative)........................................................... 4-13

A.3.2 General/Preliminary Site Plans................................................................................................... 4-13

A.3.3 Detailed Topographic Surveys for Construction Plans........................................................ 4-13

A.3.4 As-Built Surveys and AM/FM Mapping................................................................................ 4-13

TABLES

A-1 Minimum Closure Standards for Engineering and Construction Control Surveys........................... 4-11 

A-2 Minimum Elevation Closure Standards for Vertical Control Surveys................................................. 4-11

A-3 Recommended Surveying and Mapping Accuracy-- Engineering, Construction,

and Facility Operation and Maintenance Projects ................................................................ 4-14
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4.1 INTRODUCTION

4.1.1 Objective

PART 4 provides accuracy standards for engineering drawings, maps, and surveys used to 

support planning, design, construction, operation, maintenance, and management of facilities, 

installations, structures, transportation systems, and related projects. It is intended to support 

geospatial mapping data used in various engineering documents, such as architectural, engineering, and construction (A/E/C) drawings, site plans, regional master planning maps, and related 

Geographical Information System (GIS), Computer-Aided Drafting and Design (CADD), and 

Automated Mapping/Facility Management (AM/FM) products. These products are typically 

created from terrestrial, satellite, acoustic, or aerial mapping techniques that output planimetric, 

topographic, hydrographic, or feature attribute data.

4.1.2 Scope

This standard defines accuracy criteria, accuracy testing methodology, and accuracy reporting 

criteria for object features depicted on A/E/C spatial data products and related control surveys. It 

references established voluntary standards that may be used for some smaller-scale A/E/C 

mapping applications. In addition, Appendix A contains general guidance for specifying accuracy 

criteria for selected types of A/E/C features or control surveys. Using the standards and guidance 

contained in this section, end users of A/E/C products (e.g., planners, designers, constructors) can 

specify surveying and mapping accuracy requirements needed for their projects or specific 

CADD/GIS layers, levels, or entities. From these specifications, data producers (e.g., surveyors, 

mappers, photogrammetrists) can determine the instrumentation, procedures, and quality control 

processes required to obtain and verify the defined accuracies. 

4.1.3 Applicability

These standards are applicable to geospatial data products used on various A/E/C or facilities 

management projects. A/E/C projects are normally confined to small geographical areas typically 

less than 4,000 ha (10,000 acres) where simple survey techniques are employed to establish project 

control points, perform topographic or photogrammetric mapping, or provide construction layout 

and alignment control. Unlike geospatial map products covered under PART 3, A/E/C data

products are often only locally referenced within a project site, may not contain absolute 

georeferenced coordinates, and are typically compiled at scales larger than 1:20,000 (1 in = 1,667 ft). 

 These standards may apply to the following types of engineering applications: transportation 

systems (roads, railroads, airfields, canals); utility systems (water supply, sanitary sewer, fuel, 

communication, electrical, mechanical); residential, commercial, recreational, and industrial structures and facilities; flood control and navigation systems (dams, levees, locks); architectural site or 

landscape plans; engineering master planning studies; environmental mapping, modeling, and 

assessment studies; hydraulic and hydrological studies; geophysical exploration surveys; and 

construction measurement and payment surveys. These standards do not generally apply to -

architectural, mechanical, or electrical detail data inside of a building or structure that are typically 

used with a CADD system for engineering and design. 
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4.1.4 Related Standards

This standard was largely taken from existing U.S. Army Corps of Engineers engineering, 

surveying, and mapping standards, and from Department of Defense Tri-Service Facility 

Engineering CADD/GIS standards--see References. The American Society for Photogrammetry 

and Remote Sensing (ASPRS) “Accuracy Standards for Large-Scale Maps” outlined in PART 3, 

Appendix B, also is directly applicable to PART 4--see paragraph 4.4.1 for specific relationships 

between ASPRS and Part 4. 

This PART 4 may be used in conjunction with, or independent of, other Parts of the overall 

Geospatial Positioning Accuracy Standard. 

PART 1 Reporting Methodology applies directly to this Part, in particular, accuracy standard 

reporting. Certain portions of Part 2, Standards for Geodetic Networks, apply to A/E/C projects or 

features within an A/E/C project that are connected by control surveys to an established regional 

geodetic control network (i.e., geo-referenced). 

PART 2 does not apply to engineering, construction, topographic, or photogrammetric mapping 

surveys that are referenced to boundary control or physical features (streets, structures, etc.) 

within, or adjacent, to the project site. If A/E/C projects, or sub features within a project, are 

connected by control surveys to an established regional geodetic control network (i.e., georeferenced), then certain portions of PART 2 may be applicable. 

PART 3, National Standard for Spatial Data Accuracy, applies to those A/E/C map products that 

are fully geo-referenced. The spatial accuracy definitions, accuracy testing, and accuracy reporting 

criteria in PART 3 may be used for georeferenced A/E/C map products. 

PART 4 applies to engineering drawings, maps, and surveys used to support planning, design, 

construction, operation, maintenance, and management of facilities, installations, structures, 

transportation systems, and related projects. Part 4 also applies to marine construction and 

dredging of navigation channels, including related hydrographic surveying support. 

PART 5 should be consulted for hydrographic surveying standards applicable to preparation of 

nautical charts. 

4.1.5 Standards Development Procedures

This standard was developed and periodically reviewed by the FGDC Facilities Working Group 

during the period 1996-1998. The initial draft of the standard was taken from U.S. Army Corps of 

Engineers Engineer Circular 1110-1-87, Standards for Maps, Drawings, Engineering Surveys, 

Construction Site Plans, and Related Geospatial Data Products. 
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4.1.6 Maintenance Authority

The U.S. Army Corps of Engineers is responsible for developing and maintaining the A/E/C 

geospatial positional accuracy data standards for the Facilities Working Group of the Federal Geographic Data Committee. Address questions concerning the standards to: Headquarters, U.S. 

Army Corps of Engineers, ATTN: CECW-EP, 20 Massachusetts Avenue NW, Washington, D.C. 

20314-1000.

4.2 SPATIAL ACCURACY

As defined in PART 1, horizontal spatial accuracy is the circular error of a data set's horizontal 

coordinates at the 95% confidence level. Vertical spatial accuracy is defined by the linear error of a 

data set's vertical coordinates at the 95% confidence level. A spatial data set may include 

CADD/GIS object features, such as points, lines, areas, volumes. Accuracy reported at the 95% 

confidence level means that 95% of positional accuracies will be equal to or smaller than the 

reported accuracy value. The reported accuracy value is the cumulative result of all uncertainties, 

including those introduced by local project control coordinates, field topographic surveys, 

photogrammetric compilation, or final extraction of ground coordinate values in the spatial data. 

The reference scheme for radial or linear errors must be defined as relative to absolute geospatial 

reference networks or local (internal construction) schemes. Spatial data may be compiled to 

comply with one level of accuracy in the vertical component and another in the horizontal 

component.

4.3 REFERENCE DATUMS AND COORDINATE SYSTEMS

A/E/C projects should be referenced to local boundary control, spatial datums, plane coordinate 

grids, or vertical reference planes commonly used in the project area. Where practical and feasible, 

A/E/C projects should be referenced to national coordinate systems: horizontal coordinates should 

be in a system (e.g., State Plane Coordinate System, Universal Transverse Mercator Grid) based 

upon the North American Datum of 1927 (NAD 27) or North American Datum of 1983 (NAD 83), 

and vertical coordinates should be based on the National Geodetic Vertical Datum of 1929 (NGVD 

29) or the North American Vertical Datum of 1988 (NAVD 88)--see PART 2. In most instances, 

however, A/E/C projects are not referenced to geodetic datums but are accurately tied into existing 

project or boundary control schemes relevant to the work. Reference datums and coordinate 

systems used shall be clearly identified in reporting A/E/C project data sets--see PART 1.

4.3.1 Local Construction Control

Projects that are not referenced to national coordinate systems based on geodetic datums shall be 

classified and reported as having a local reference or construction control system--local X-Y grid, 

chainage-offset, local reference benchmark elevation, etc. Accuracies of spatial data points are 

determined, reported, and certified relative to this local construction control scheme. If the 
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relationship between the local coordinate system and a National coordinate system is known, 

describe the relationship between the two systems. If the relationship between the local coordinate 

system and a National coordinate system is unknown, identify the local coordinate system but 

state that the relationship in "UNKNOWN"--see PART 1.

4.3.2 NSRS Referenced Control

Accuracies of A/E/C data set coordinates that are referenced to a National coordinate system are 

determined and reported relative to NSRS accuracies. 

4.4 ACCURACY STANDARDS FOR A/E/C MAPS AND DRAWINGS

A/E/C drawings and related spatial data sets may have accuracy standards specified relative to (1) 

a required performance standard based on detailed project requirements, or (2) an establis hed 

standard such as National Map Accuracy Standard (NMAS) or ASPRS. Typically, detailed site 

plan drawings at scales as large as 1:360 (1 in = 30 ft) have acceptable quality levels relative to 

critical construction specifications (e.g., required accuracy of invert elevations, road/curb grades, 

building locations, etc.). Preliminary planning or reconnaissance maps at smaller scales typically 

use general industry standards, such as ASPRS, NMAS, etc. Both types of standards may be 

specified for portions of CADD levels on the same project. Accuracy is evaluated and reported 

based on intended field data acquisition methodology or independent tests. For most A/E/C 

mapping, performance-based (outcome-based) specifications detail the end results to be achieved 

(i.e., map feature accuracy or accuracy standard) and not the means, or technical procedures, used 

to achieve those results. Performance specifications define the required accuracy criteria standards 

for each feature, object, class, layer, level, etc. of topographic and planimetric features depicted, 

along with related mapping limits, feature location and attribute requirements, scale, contour 

interval, map format, sheet layout, final data transmittal, archiving or storage requirements, and 

quality assurance procedures that will be used to verify conformance with the specified accuracy. 

Table A-3 in Appendix A provides examples of accuracy specifications commonly used for various 

types of A/E/C projects.

4.4.1 ASPRS Large-Scale Accuracy Standards

For generalized A/E/C site mapping work at scales from 1:2,400 (1 in = 200 ft) to 1:20,000 (1 in = 

1,667 ft), the ASPRS "Accuracy Standards for Large-Scale Maps" may be used as a reference 

accuracy standard. The ASPRS accuracy standard is linearly dependent on the target horizontal 

scale or target contour interval; thus it is only applicable to mapped features that are compiled 

using a consistent type of data acquisition process (e.g., photogrammetry) where all spatial objects 

receive approximately the same accuracy. The ASPRS standard may not be especially applicable to 

detailed CADD/GIS features at larger scales down to 1:240 (1 in. = 20 ft) where CADD/GIS 

accuracies are usually project dependent, not scale dependent, and where accuracy standards are 

best defined based on project needs. As described in PART 3, the ASPRS standard defines map 

accuracy by comparing the mapped location of selected well-defined points to their "true" location,

as determined by a more accurate, independent field survey. Alternately, when no independent 
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check is feasible or practicable, a map's accuracy may be estimated based on the accuracy of the 

technique used to locate mapped features--e.g., photogrammetry, GPS, total station, planetable. 

The ASPRS standard may be specified for site plans that are developed using conventional ground 

topographic surveying techniques (i.e., electronic total stations, planetables, kinematic DGPS).

4.4.2 Multiple Accuracies in A/E/C Drawings or CADD Levels

4.4.2.1 Horizontal and Vertical Accuracies

Spatial data may have different accuracies in the horizontal and vertical components.

4.4.2.2 A/E/C CADD/GIS Feature Layer/Level Accuracies

A/E/C data is often separated into various layers or levels in CADD/GIS systems. For example, 

planimetric features, utility invert elevations, and topographic elevations are often separated into 

three different levels or layers. These layers often contain objects or geographic areas that were 

surveyed/compiled to widely differing accuracies--e.g., utility invert elevations accurate to 0.05 ft 

versus topographic contours accurate to only 5 ft . If readily available, useful, and practical, these 

variable accuracies may be retained as an attribute to the layer or feature. In addition, accuracy 

information about these layers or features should be recorded in the accuracy section of the 

metadata for this database.

4.5 ACCURACY STANDARDS FOR A/E/C CONTROL SURVEYS

Control surveys are performed to locate, align, and stake out construction for civil and military projects, e.g., buildings, utilities, roadways, runways, flood control and navigation projects, training 

ranges, etc. They provide the base horizontal and vertical control used for preliminary studies, 

photogrammetric and topographic mapping, detailed site plan drawings for construction plans, 

construction stake out, construction measurement and payment, preparing as-built drawings, 

installation master planning mapping, and future maintenance and repair activities. Two types of 

survey accuracies may be specified: (1) Positional accuracy or (2) Relative closure ratio accuracy. 

PART 2 geodetic survey accuracy standards are not applicable to locally referenced A/E/C projects 

covered under this PART 4 standard.

4.5.1 Positional Accuracy

Base control surveys should be performed to a 95% positional confidence level consistent with the 

engineering or construction application or specifications. In general, horizontal and vertical control 

point accuracies should be twice as accurate as positional or elevation tolerances required for 

features or objects on the site plans or maps. Determination and verification of 95% radial 

positional accuracies will require use of rigorous least-squares adjustment techniques similar to 

that required under PART 2. 
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4.5.2 Relative Closure Ratio Accuracy

The accuracy of A/E/C control surveys may be evaluated, classified, and reported based on 

closure ratios for the horizontal point or the vertical elevation difference, as obtained in the field 

when points or benchmarks are redundantly occupied. This relative accuracy standard is applicable to most types of survey equipment and practices (e.g., total station traverses, differential 

GPS, differential spirit leveling). Many state codes and/or state minimum technical standards 

require that accuracies of A/E/C surveys be evaluated and reported using survey closure ratios. 

Tables A-1 and A-2 in Appendix A contain orders of closure commonly specified in A/E/C work. 

There is no simple correlation between relative closure accuracies and 95% radial positional 

accuracies; thus, determining a closure order based on a specified feature accuracy requirement is, 

at best, only an approximate process (see guidance in Appendix A). Where practical and allowable, 

positional accuracy standards should be used instead of closure accuracy standards. 

4.6 ACCURACY TESTING AND VERIFICATION

Project specifications will specify the geographic extent of data to be tested and the amount of 

testing (if any). Map testing should be performed within a fixed time period after delivery. 

Normally, a mapping organization will perform quality control tests under quality assurance 

oversight by the requesting agency. Accuracies of A/E/C features are reported at the 95% 

confidence level. Field observed X, Y or Z coordinate differences are converted to 95% confidence 

errors following the procedures outlined in PART 3. Horizontal accuracy is tested by comparing 

the planimetric coordinates of well-defined ground points with coordinates of the same points from 

an independent source of higher accuracy, following the methodology outlined under PART 3. 

Vertical accuracy is tested by comparing the elevations of well-defined points with elevations of 

the same points as determined from a source of higher accuracy, also following the methodology 

outlined in PART 3. Both ground surface topography and object elevations may be tested.

4.7 ACCURACY REPORTING AND CERTIFICATION

4.7.1 Tested Products

 Maps, surveys, and related geospatial data that are tested and found to comply with a specified 

standard shall have a certification statement. If applicable, the statement shall clearly indicate the 

target map scale at which the map or feature layer was developed.

4.7.2 Untested Products

Due to the high cost of field testing, not all deliverable map products will be tested. In such cases, 

the statement shall clearly indicate that the procedural ground surveying or aerial mapping specifications were designed and performed to meet a certain accuracy standard (project dependent, 

ASPRS, NMAS, etc.), but that the accuracy is estimated. An estimated accuracy statement is especially applicable to CADD, GIS, or FM databases that may be compiled from a variety of sources 

containing known or unknown accuracy reliability.
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4.7.3 Reporting Units

Report accuracy of A/E/C spatial data in ground units using either metric (SI) units or English (IP) 

units, consistent with the project units.

4.7.4 Variable Accuracies

Report varying accuracies in the same spatial data set if information exists that relates accuracy to 

individual portions/objects of the data set, and only if such detailed sub-feature data set reporting 

is practical and warranted. If data of varying accuracies are composited and cannot be separately 

identified AND the data set is tested, report the accuracy value for the composited data. If a 

composited data set is not tested, report the accuracy value for the least accurate data set 

component.

4.7.5 Reporting Statements

Report tested and non-tested accuracies following general guidance provided in PART 3 

(Accuracy Reporting).
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4.8 REFERENCES 

American Society for Photogrammetry and Remote Sensing (ASPRS) Specifications and Standards 

Committee, 1990, ASPRS Accuracy Standards for Large-Scale Maps: Photogrammetric Engineering 

and Remote Sensing, v. 56, no. 7, p. 1,068-1,070. 

Federal Geographic Data Committee, Part 1, Reporting Methodology, Geospatial Positioning 

Accuracy Standards, FGDC-STD-0007.1-1998, Washington, D.C., 1998.

Federal Geographic Data Committee, Part 2., Standards for Geodetic Networks, Geospatial 

Positioning Accuracy Standards, FGDC-STD-007.2-1998: Washington, D.C., 1998.

Federal Geographic Data Committee, Part 3., National Standard for Spatial Data Accuracy, 

Geospatial Positioning Accuracy Standards, FGDC-STD-007.3-1998: Washington, D.C., 1998.

U.S. Army Corps of Engineers, Engineer Circular 1110-1-87, Standards for Maps, Drawings, 

Engineering Surveys, Construction Site Plans, and Related Geospatial Data Products, 1 July 1996.

U.S. Department of Defense, Tri-Service CADD/GIS Technology Center, Tri-Service A/E/C CADD 

Standards and Spatial Data Standards, (latest version at <http://tsc.wes.army.mil>)
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APPENDIX A Recommended A/E/C Surveying and Mapping Standards

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APPENDIX A

RECOMMENDED A/E/C SURVEYING AND MAPPING STANDARDS

(Informative)
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APPENDIX A Recommended A/E/C Surveying and Mapping Standards

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A.1 A/E/C CONTROL SURVEY STANDARDS

Engineering and construction surveys are normally specified, classified, and reported based on the 

horizontal (linear) point closure ratios or the vertical elevation difference closures. This performance criterion is most commonly specified in Federal agency, State, and local surveying 

standards. These control surveys are performed to establish control, location, alignment, and grade of various types of construction. 

Local accuracy standards for survey control will vary with the type of construction. Commonly 

specified and reported Orders of horizontal closure accuracy standards are shown in Table A-1. 

Relative accuracy closure ratios for horizontal A/E/C surveys typically range from a minimum of 

1:2,500 up to 1:20,000. Lower accuracies (1:2,500-1:5,000) are acceptable for earthwork, dredging, 

embankment, beach fill, and levee alignment stakeout and grading, and some site plan, curb and 

gutter, utility building foundation, sidewalk, and small roadway stakeout. Moderate accuracies 

(1:5,000) are used in most pipeline, sewer, culvert, catch basin, and manhole stakeouts, and for 

general residential building foundation and footing construction, major highway pavement, 

bridges, and concrete runway stakeout work. Somewhat higher accuracies (1:10,000-1:20,000) are 

used for aligning longer bridge spans, tunnels, and large commercial structures. For extensive 

bridge or tunnel projects, 1:50,000 or even 1:100,000 relative accuracy alignment work may be 

specified. 

Orders of elevation closure ratio standards are shown in Table A-2. Most construction work is 

performed to Third-Order standards. These standards are applicable to most types of engineering 

and construction survey equipment and practices (e.g., total station traverses, differential GPS, 

differential spirit leveling).
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Table A-1

Minimum Closure Standards for Engineering

and Construction Control Surveys

Classification Order Closure Standard

Engr & Const Distance Angle

Control (Ratio) (Secs)

Second-Order, Class I 1:50,000 3oN 1

Second-Order, Class II 1:20,000 5oN

Third-Order, Class I 1:10,000 10oN

Third-Order, Class II 1: 5,000 20oN

Construction 1: 2,500 60oN

 (Fourth-Order)

1

 N = Number of angle stations 

Table A-2

Minimum Elevation Closure Standards for

Vertical Control Surveys

Elevation Closure Standard

Classification Order (ft)1(mm)

First-Order, Class I 0.013oM 3oK

First-Order, Class II 0.017oM 4oK

Second-Order, Class I 0.025oM 6oK

Second-Order, Class II 0.035oM 8oK

Third-Order 0.050oM 12oK

Construction Layout 0.100oM 24oK

1

 oM or oK = square root of distance in Miles or Kilometers

A.2 TYPICAL ACCURACY STANDARDS FOR SELECTED A/E/C PROJECTS

General guidance for determining project-specific mapping accuracy standards is contained in 

Table A-3 at the end of this Appendix. This table may be used in developing specifications for 

map scales, feature location and elevation tolerances, and contour intervals for typical A/E/C 

projects. Since Table A-3 is based on current industry practices (and primarily those used by the 

Corps of Engineers), the scales and corresponding 95% positional tolerances shown in this table 

will differ from the ASPRS positional or elevation accuracy standards. Where available, project-
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specific accuracy standards should be used rather than generic standards such as ASPRS. Metric 

(SI) conversions from IP units are only approximate since standardized use of SI units is still under 

development. 

A.2.1 Target Scale and Contour Interval Specifications

Table A-3 provides commonly used map scales and contour intervals for a variety of A/E/C applications. The selected target scale for a map or construction plan should be based on the detail 

necessary to portray the project site. Topographic elevation density or related contour intervals 

are specified consistent with existing site gradients and the accuracy needed to define site layout, 

drainage, grading, etc., or perform quantity take offs. Photogrammetric mapping flight altitudes or 

ground topographic survey accuracy and density requirements are determined from the design map 

target scale and contour interval. In practice, design or real property features are located or layed 

out during construction to a far greater relative accuracy than that which can be scaled at the target 

(plot) scale, such as property corners, utility alignments, first-floor or invert elevations, etc. 

Coordinates/elevations for such items are usually directly input as feature attributes in a CADD or 

AM/FM database.

A.2.2 Feature Location Tolerances

Table A-3 indicates recommended positional and elevation tolerances of planimetric features at the 

95% confidence level. These tolerances define the primary topographic mapping effort necessary 

to delineate physical features on the ground. A/E/C feature tolerances are defined relative to adjacent points within the confines of a specific area, map sheet, or structure--not to the overall project, 

installation boundaries, or an external geodetic control network. These relative accuracy tolerances 

are determined between two points that must functionally maintain a given accuracy tolerance between themselves, such as adjacent property corners; adjacent utility lines; adjoining buildings, 

bridge piers, approaches, or abutments; overall building or structure site construction limits; 

runway ends; catch basins; levee baseline sections; etc. Feature tolerances indicated are 

determined from the functional requirements of a typical project/structure (e.g., field construction/fabrication, field stakeout or layout, alignment, etc.). Few A/E/C projects require that relative 

accuracies be rigidly maintained beyond the range of the detailed design drawing for a project/structure (or its equivalent CADD design file limit). In many instances, a construction feature 

may need to be located to an accuracy well in excess of its plotted/scaled accuracy on a construction site plan; therefore, feature location tolerances should not be used to determine the required scale of a drawing. In these instances, surveyed coordinates, internal CADD grid coordinates, or rigid relative dimensions are used.
Federal Ge ographic Data Committee FGDC-STD-007.4-2002

Geospatial Positioning Accuracy Standards

PART 4: Standards for A/E/C and Facility Management

APPENDIX A Recommended A/E/C Surveying and Mapping Standards

4-13

A.3 A/E/C TOPOGRAPHIC SURVEYS AND CONSTRUCTION SITE PLANS

Topographic surveys and construction site plan surveys are performed for the master planning, design, and construction of installations, buildings, housing complexes, roadways, airport facilities, 

flood control structures, navigation locks, etc. Construction plans are developed using electronic/DGPS total stations, plane tables, or low-altitude photogrammetric mapping methods. Some 

of the more common surveys are described below:

A.3.1 Reconnaissance Topographic Surveys

Reconnaissance surveys are typically performed at scales from 1:4,800 (1 in = 400 ft) to 1:12,000 (1 

in = 1,000 ft). They provide a basis for general studies, site suitability decisions, or preliminary site 

layouts. General location of existing roads and facilities are depicted, and only limited feature and 

rough elevation detail is shown – 5- to 10-foot contour intervals usually being adequate. Enlarged 

USGS 1:24,000 maps may be substituted in many cases. 

A.3.2 General/Preliminary Site Plans.

General or Preliminary site plans are performed at scales from 1:2,400 (1 in = 200 ft) to 1:4,800 (1 in = 

400 ft). They depict general layout for potential construction, proposed transportation systems, 

training areas, and existing facilities.

A.3.3 Detailed Topographic Surveys for Construction Plans

These surveys are performed at scales from 1:240 (1 in = 20 ft) to 1:2,400 (1 in = 200 ft) and at 

contour intervals of 0.2 m or 0.5 m (1 or 2 ft). They are performed to prepare a base map for detailed 

site plans (general site layout plan, utility plan, grading plan, paving plan, airfield plan, demolition 

plan, etc.). The scope of mapping is confined to an existing/proposed building area. These 

drawings are used as a base for subsequent as-built drawings of facilities and utility layout maps 

(i.e., AM/FM databases).

A.3.4 As-Built Surveys and AM/FM Mapping

As-built drawings may require topographic surveys of constructed features, especially when field 

modifications are made to original designs. These surveys, along with original construction site 

plans, should be used as a base framework for a facility's AM/FM database. Periodic topographic 

surveys also may be required during maintenance and repair projects in order to update the 

AM/FM database.
Federal Ge ographic Data Committee FGDC-STD-007.4-2002

Geospatial Positioning Accuracy Standards

PART 4: Standards for A/E/C and Facility Management

APPENDIX A Recommended A/E/C Surveying and Mapping Standards

4-14

Table A-3. RECOMMENDED ACCURACIES AND TOLERANCES:

ENGINEERING, CONSTRUCTION, AND FACILITY MANAGEMENT PROJECTS

Target Feature Position Tolerance Contour

Map Scale Horizontal Vertical Interval

Project or Activity SI/IP SI/IP SI/IP SI/IP

DESIGN, CONSTRUCTION, OPERATION & MAINTENANCE OF MILITARY FACILITIES

 Maintenance and Repair (M&R)/Renovation of Existing Installation Structures, Roadways, Utilities, Etc

General Construction Site Plans & Specs: 1:500 100 mm 50 mm 250 mm

 Feature & Topographic Detail Plans 40 ft/in 0.1-0.5 ft 0.1-0.3 ft 1 ft

Surface/subsurface Utility Detail Design Plans 1:500 100 mm 50 mm N/A

 Elec, Mech, Sewer, Storm, etc 40 ft/in 0.2-0.5 ft 0.1-0.2 ft

 Field construction layout 0.1 ft 0.01-0.1 ft

Building or Structure Design Drawings 1:500 25 mm 50 mm 250 mm

40 ft/in 0.05-0.2 ft 0.1-0.3 ft 1 ft

 Field construction layout 0.01 ft 0.01 ft

Airfield Pavement Design Detail Drawings 1:500 25 mm 25 mm 250 mm

40 ft/in 0.05-0.1 ft 0.05-0.1 ft 0.5-1 ft

 Field construction layout 0.01 ft 0.01 ft

Grading and Excavation Plans 1:500 250 mm 100 mm 500 mm

 Roads, Drainage, Curb, Gutter etc. 30-100 ft/in 0.5-2 ft 0.2-1 ft 1-2 ft

 Field construction layout 1 ft 0.1 ft

Recreational Site Plans 1:1,000 500 mm 100 mm 500 mm

 Golf courses, athletic fields, etc. 100 ft/in 1-2 ft 0.2-2 ft 2-5 ft

Training Sites, Ranges, and 1:2,500 500 mm 1,000 mm 500 mm

 Cantonment Area Plans 100-200 ft/in 1-5 ft 1-5 ft 2 ft

General Location Maps for Master Planning 1:5,000 1,000 mm 1,000 mm 1,000 mm

 AM/FM and GIS Features 100-400 ft/in 2-10 ft 1-10 ft 2-10 ft

Space Management Plans 1:250 50 mm N/A N/A

 Interior Design/Layout 10-50 ft/in 0.05-1 ft

As-Built Maps: Military Installation 100 mm 100 mm 250 mm

Surface/Subsurface Utilities (Fuel, Gas, 0.2-1 ft 0.2 ft 1 ft

Electricity, Communications, Cable,
Federal Ge ographic Data Committee FGDC-STD-007.4-2002

Geospatial Positioning Accuracy Standards

PART 4: Standards for A/E/C and Facility Management

APPENDIX A Recommended A/E/C Surveying and Mapping Standards

4-15

Table A-3 (Contd). RECOMMENDED ACCURACIES AND TOLERANCES:

ENGINEERING, CONSTRUCTION, AND FACILITY MANAGEMENT PROJECTS

Target Feature Position Tolerance Contour

Map Scale Horizontal Vertical Interval

Project or Activity SI/IP SI/IP SI/IP SI/IP

Storm Water, Sanitary, Water Supply, 1:1000 or 50-100 ft/in (Army)

Treatment Facilities, Meters, etc.) 1:500 or 50 ft/in (USAF)

Housing Management GIS (Family Housing, 1:5,000 10,000 mm N/A N/A

Schools, Boundaries, and Other Installation 100-400 ft/in 10-15 ft

Community Services)

Environmental Mapping and Assessment 1:5,000 10,000 mm N/A N/A

 Drawings/Plans/GIS 200-400 ft/in 10-50 ft

Emergency Services Maps/GIS 1:10,000 25,000 mm N/A N/A

 Military Police, Crime/Accident Locations, 400-2000 ft/in 50-100 ft

 Post Security Zoning, etc.

Cultural, Social, Historical Plans/GIS 1:5000 10,000 mm N/A N/A

 400 ft/in 20-100 ft

Runway Approach and Transition Zones: 1:2,500 2,500 mm 2,500 mm 1,000 mm

 General Plans/Section 100-200 ft/in 5-10 ft 2-5 ft 5 ft

 Approach maps 1:5,000 (H) 1:1,000 (V)

 Approach detail 1:5,000 (H) 1:250 (V)

DESIGN, CONSTRUCTION, OPERATIONS AND MAINTENANCE OF CIVIL

 TRANSPORTATION & WATER RESOURCE PROJECTS

 Site Plans, Maps & Drawings for Design Studies, Reports, Memoranda, and Contract Plans and

 Specifications, Construction plans & payment

General Planning and Feasibility Studies, 1:2,500 1,000 mm 500 mm 1,000 mm

Reconnaissance Reports 100-400 ft/in 2-10 ft 0.5-2 ft 2-10 ft

Flood Control and Multipurpose

Project Planning, Floodplain Mapping, 1:5,000 10,000 mm 100 mm 1,000 mm

Water Quality Analysis, and Flood 400-1000 ft/in 20-100 ft 0.2-2 ft 2-5 ft

Control Studies
Federal Ge ographic Data Committee FGDC-STD-007.4-2002

Geospatial Positioning Accuracy Standards

PART 4: Standards for A/E/C and Facility Management

APPENDIX A Recommended A/E/C Surveying and Mapping Standards

4-16

Table A-3 (Contd). RECOMMENDED ACCURACIES AND TOLERANCES:

ENGINEERING, CONSTRUCTION, AND FACILITY MANAGEMENT PROJECTS

Target Feature Position Tolerance Contour

Map Scale Horizontal Vertical Interval

Project or Activity SI/IP SI/IP SI/IP SI/IP

Soil and Geological Classification Maps 1:5,000 10,000 mm N/A N/A

400 ft/in 20-100 ft

Land Cover Classification Maps 1:5,000 10,000 mm N/A N/A

400-1,000 ft/in 50-200 ft

Archeological or Structure Site Plans & Details

(Including Non-topographic, Close Range, 1:10 5 mm 5 mm 100 mm

Photogrammetric Mapping) 0.5-10 ft/in 0.01-0.5 ft 0.01-0.5 ft 0.1-1 ft

Cultural and Economic Resource Mapping 1:10,000 10,000 N/A N/A

 Historic Preservation Projects 1000 ft/in 50-100 ft

Land Utilization GIS Classifications 1:5,000 10,000 mm N/A N/A

 Regulatory Permit Locations 400-1000 ft/in 50-100 ft

Socio-Economic GIS Classifications 1:10,000 20,000 mm N/A N/A

1000 ft/in 100 ft

Grading & Excavation Plans 1:1,000 1,000 mm 100 mm 1,000 mm

100 ft/in 0.5-2 ft 0.2-1 ft 1-5 ft

Flood Control Structure Clearing & Grading 1:5,000 2,500 mm 250 mm 500 mm

 Plans (e.g., revetments) 100-400 ft/in 2-10 ft 0.5 ft 1-2 ft

Federal Emergency Management 1:5,000 1,000 mm 250 mm 1,000 mm

Agency Flood Insurance Studies 400 ft/in 20 ft 0.5 ft 4 ft

Locks, Dams, & Control Structures 1:500 25 mm 10 mm 250 mm

 Detail Design Drawings 20-50 ft/in 0.05-1 ft 0.01-0.5 ft 0.5-1 ft

Spillways & Concrete Channels 1:1,000 100 mm 100 mm 1,000 mm

 Design Plans 50-100 ft/in 0.1-2 ft 0.2-2 ft 1-5 ft

Levees and Groins: New Construction or 1:1,000 500 mm 250 mm 500 mm

 Maintenance Design Drawings 100 ft/in 1-2 ft 0.5-1 ft 1-2 ft
Federal Ge ographic Data Committee FGDC-STD-007.4-2002

Geospatial Positioning Accuracy Standards

PART 4: Standards for A/E/C and Facility Management

APPENDIX A Recommended A/E/C Surveying and Mapping Standards

4-17

Table A-3 (Contd). RECOMMENDED ACCURACIES AND TOLERANCES:

ENGINEERING, CONSTRUCTION, AND FACILITY MANAGEMENT PROJECTS

Target Feature Position Tolerance Contour

Map Scale Horizontal Vertical Interval

Project or Activity SI/IP SI/IP SI/IP SI/IP

Construction In-Place Volume Measurement 1:1,000 500 mm 250 mm N/A

 Granular cut/fill, dredging, etc. 40-100 ft/in 0.5-2 ft 0.5-1 ft

Beach Renourishment/Hurricane 1:1,000 1,000 mm 250 mm 250 mm

Protection Project Plans 100-200 ft/in 2 ft 0.5 ft 1 ft

Project Condition Survey Reports

 Base Mapping for Plotting Hydrographic 1:2,500 10,000 mm 250 mm 500 mm

 Surveys: line maps or aerial plans 200-1,000 ft/in 5-50 ft 0.5-1 ft 1-2 ft

Dredging & Marine Construction Surveys

 New Construction Plans 1:1,000 2,000 mm 250 mm 250 mm

 100 ft/in 6 ft 1 ft 1 ft

 Maintenance Dredging Drawings 1:2500 5,000 mm 500 mm 500 mm

200 ft/in 15 ft 2 ft 2 ft

 Hydrographic Project Condition Surveys 1:2500 5,000 mm 500 mm 500 mm

200 ft/in 16 ft 2 ft 2 ft

 Hydrographic Reconnaissce Surveys - 5,000 m 500 mm 250 mm

15 ft 2 ft 2 ft

 Offshore Geotechnical Investigations - 5,000 mm 50 mm N/A

 Core Borings /Probings/etc. 5-15 ft 0.1-0.5 ft

Structural Deformation Monitoring

 Studies/Surveys

 Reinforced Concrete Structures: Large-scale 10 mm 2 mm N/A

 Locks, Dams, Gates, Intake Structures, vector 0.03 ft 0.01 ft

 Tunnels, Penstocks, Spillways, Bridges movement (long term)

diagrams

or tabulations

 Earth/Rock Fill Structures: Dams, N/A (same as 30 mm 15 mm 

 Floodwalls above)
Federal Ge ographic Data Committee FGDC-STD-007.4-2002

Geospatial Positioning Accuracy Standards

PART 4: Standards for A/E/C and Facility Management

APPENDIX A Recommended A/E/C Surveying and Mapping Standards

4-18

Table A-3 (Contd). RECOMMENDED ACCURACIES AND TOLERANCES:

ENGINEERING, CONSTRUCTION, AND FACILITY MANAGEMENT PROJECTS

Target Feature Position Tolerance Contour

Map Scale Horizontal Vertical Interval

Project or Activity SI/IP SI/IP SI/IP SI/IP

Levees, etc. -- slope/crest stability & 0.1 ft 0.05 ft

 alignment (long term)

Crack/Joint & Deflection Measurements: tabulations 0.2 mm N/A N/A

 piers/monoliths--precision micrometer 0.01 inch

REAL ESTATE ACTIVITIES: ACQUISITION, DISPOSAL, MANAGEMENT, AUDIT

 Maps, Plans, & Drawings Associated with Military and Civil Projects

Tract Maps, Individual,Detailing

 Installation or Reservation Boundaries, 1:1,000 10 mm 100 mm 1,000 mm

 Lots, Parcels, Adjoining Parcels, and 1:1,200 (Army)

 Record Plats, Utilities, etc. 50-400 ft/in 0.05-2 ft 0.1-2 ft 1-5 ft

Condemnation Exhibit Maps 1:1,000 10 mm 100 mm 1,000 mm

50-400 ft/in 0.05-2 ft 0.1-2 ft 1-5 ft

Guide Taking Lines/Boundary Encroachment 1:500 50 mm 50 mm 250 mm

 Maps: Fee and Easement Acquisition 20-100 ft/in 0.1-1 ft 0.1-1 ft 1 ft

General Location or Planning Maps 1:24,000 10,000 mm 5,000 mm 2,000 mm

2,000 ft/in 50-100 ft 5-10 ft 5-10 ft

GIS or LIS Mapping, General

 Land Utilization and Management, Forestry 1:5,000 10,000 mm N/A N/A

 Management, Mineral Acquisition 200-1,000 ft/in 50-100 ft

Easement Areas and Easement 1:1,000 50 mm 50 mm -

 Delineation Lines 100 ft/in 0.1-0.5 ft 0.1-0.5 ft

HAZARDOUS, TOXIC, RADIOACTIVE WASTE (HTRW) SITE INVESTIGATION,

MODELING, AND CLEANUP

General Detailed Site Plans 1:500 100 mm 50 mm 100 mm

 HTRW Sites, Asbestos, etc. 5-50 ft/in 0.2-1 ft 0.1-0.5 ft 0.5-1 ft
Federal Ge ographic Data Committee FGDC-STD-007.4-2002

Geospatial Positioning Accuracy Standards

PART 4: Standards for A/E/C and Facility Management

APPENDIX A Recommended A/E/C Surveying and Mapping Standards

4-19

Table A-3 (Contd). RECOMMENDED ACCURACIES AND TOLERANCES:

ENGINEERING, CONSTRUCTION, AND FACILITY MANAGEMENT PROJECTS

Target Feature Position Tolerance Contour

Map Scale Horizontal Vertical Interval

Project or Activity SI/IP SI/IP SI/IP SI/IP

Surface Geotoxic Data Mapping 1:500 100 mm 500 mm 500 mm

 and Modeling 20-100 ft/in 1-5 ft 1-2 ft 1-2 ft

Contaminated Ground Water 1:500 1,000 mm 500 mm 500 mm

 Plume Mapping/Modeling 20-100 ft/in 2-10 ft 1-5 ft 1-2 ft

General HTRW Site Plans & 1:2,500 5,000 mm 1,000 mm 1,000 mm

 Reconnaissance Mapping 50-400 ft/in 2-20 ft 2-20 ft 2-5 ft