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SPECIFICATIONS FOR SURVEYING, AERIAL PHOTOGRAPHY AND MAPPING

OF A PROPOSED TRANSMISSION LINE CORRIDOR FOR USE IN PLS-CADD

1. INTRODUCTION

The purpose of this specification is to provide guidance to Engineers in developing a

specification for survey data deliverables in such a manner that it integrates seamlessly with
PLS-CADD. The specification provides information for Traditional Ground Survey as well as
Aerial LiDAR and could be applied to other surveying methods. This specification is provided as
an example for use in collecting data for PLS-CADD projects and should be reviewed by the
project engineer to make sure it meets all current project requirements. A final specification
should be compiled by the project engineer.

2. REQUIREMENTS

The survey contractor shall collect and provide survey data such that an accurate digital terrain
model of the corridor can be generated. The method of acquisition shall be determined by the
engineer as described in section 3.3 of this specification. All survey information gathered shall
be classified according to the feature code table referenced in this specification.
At a minimum, the survey contractor shall have a staff with competent technical knowledge of
current industry standards and processing software, including PLS-CADD.
Poorly or minimally coded PLS-CADD survey models will not be accepted.
Relative accuracy of the point data shall be 0.35’ +/- in both the horizontal and vertical planes at
the 95% confidence level.
Absolute accuracy of the point data shall be 0.5’ in both the horizontal and vertical planes.

3. PROJECT SPECIFICATIONS

3.1. Route

{Description of Line Route}. The approximate length of this line is {length of route}. The
width of coverage shall be a minimum of {100 Note: for existing lines one may wish to
consider a much smaller width} feet left and right from the route centerline
Drawing {Drawing Number(s)} dated {mm/dd/yy}, represents the current proposed location
of the transmission line.

3.2. Coordinate System

The survey data and all attachments or references shall be in {UTM, State Plane, etc. – full
description}. Any PLS-CADD .bak files delivered with data will also have their coordinate
system defined with the same coordinate system.

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3.3. Survey Method

The survey method should adhere to Section {5.1, 5.2} below for {Traditional Ground, Aerial
Lidar} Survey.

4. TECHNICAL SPECIFICATIONS

4.1. Feature Code

The Contractor shall use the feature code table provided with this specification for all point
classification. A PLS-CADD .fea file is also available from the prom the project engineer for
use in the PLS-CADD .bak file deliverable. See Appendix A for the feature code table.

4.2. Structure Photography

For surveys of existing transmission lines, digital still photographs shall be obtained for each
transmission structure.
The structure photographs shall be color digital in the .jp2 or .png format with a minimum
resolution of 16 mega-pixels.
Aerial structure photos shall either be at a 45 degree angle or taken from the ground. The
entire structure shall be captured in the photo.
The digital photograph shall be incorporated into the deliverable such that they can be called
up at any specific structure location in PLS-CADD.

4.3. Meteorological Data and Weather Stations

When providing data of an existing line or at the discretion of the project engineer, the
Contractor shall collect the following meteorological data by use of a helicopter mounted
weather probe and/or weather stations to obtain an accurate representation of weather
conditions throughout the duration of the survey:
 Date
 Time
 Ambient air temperature (°F)
 Wind speed (ft/s)
 Wind direction (°) – a value of 0 indicates a wind direction towards North, 90 towards
East)
 Sky conditions
 Solar radiation (W/ft2)
The Contractor shall monitor and collect weather data such that the engineer can
use the data to analyze and design their transmission lines. The type and number of
weather stations shall be detailed in the Contractor’s work plan and approved by the project
engineer.

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The Contractor shall space their weather stations no more than 15 miles apart. In
mountainous terrain, the Contractor shall place their weather stations such that each major
valley has at least one weather station. This is advisable due to frequent, significant
differences in weather conditions on either side of mountain ridges in the project area. This
may require that weather stations be spaced significantly less than 15 miles apart.
Data shall be collected, at a minimum, of every five minutes for LiDAR survey and at every
instance of overhead wire data collection for Traditional Ground survey.
The weather stations shall have a minimum accuracy of:
 Ambient air temperature: 0.5°F
 Temperature range: -30°F to 150°F
 Wind threshold speed: 0.3 MPH
 Wind speed accuracy range: 0.3 MPH to 130 MPH
 Wind direction: 10°

5. SURVEY METHOD

5.1. Traditional Ground Survey

In addition to the items listed below, the contractor shall provide photographs and field notes
for all traditional ground surveys.

5.1.1. Existing Structures

Existing structures shall have the following features surveyed:

 Top of structure – pole, lattice tower, etc.
 Base of structure – pole, base plate, each lattice tower leg, etc.
 Wire attachment points – point where the wire and the insulator (or clamp) meet
 Insulator attachment points –point where the insulator meets the structure
 Structure attachment points – point where items like crossarms, x-braces, and guys
are attached to the structure

5.1.2. Existing Overhead Wire

All existing shield wires and transmission, distribution, and communication conductors
are to be surveyed. All wires survey should include a minimum of five (5) locations per
span, including the mid-span (low-point) of conductors.
All distribution and service taps and crossings are to be surveyed out to the second
structure (where possible). See section 5.1.1 for details on surveying the crossing and
tap structures.

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Any equipment on the wires shall also be surveyed and photographed, including marker
balls, detuning pendulums, and bundle spacers unless project engineer specifies
differently.
Contractor shall ensure the information provided in section 4.3 for the meteorological
data specifically applies to any crossing wires.

5.1.3. Existing Terrain and Underground Facilities

All underground facilities shall be located and captured. The locate flags, with
underground facility owners listed, shall be photographed according to the project
engineer’s discretion.
The existing terrain shall be surveyed such that a representative ground profile can be
determined. A minimum of one point every 10 feet along the centerline shall be
collected. In addition, the Contractor shall collect one point a minimum of {50 Note:
different widths should be considered for different voltages} feet left and right from the
route centerline in 10’ increments. In addition, the Contractor shall differentiate between
ground and farm fields, roadways, sidewalks, water bodies, streams, drainage ditches,
culverts, top of slope, and toe of slope features as shown in the feature code table.

5.1.4. Existing Obstructions and Features

All aerial and ground obstructions shall be captured. This includes, but is not limited to
the following:
 Guy Wires
 Anchors
 Equipment
 Buildings – Residential, Commercial, Storage, etc.
o Enough points shall be surveyed to outline the building
 Roof Peaks - nearest survey centerline
o Enough points shall be surveyed to outline the roof peak
 Fences
 Streetlights
 Pools
 Playgrounds
 Wells
 Outline of Signs and Billboards
 Irrigation Systems
 Bridges
 Railroad Tracks

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 Railroad Appurtenances (e.g. x-ing arms, connection points, lights, etc.)

 LP and Fuel Tanks
 Silos, Grain Bins, Farm Equipment etc.
 Any other additional miscellaneous clearance obstructions

5.2. Aerial LiDAR

The Contractor shall record flight start and stop times for each line, deliver the data in .LAS
or .LAZ file format, and show aircraft position and time in a vector file (dxf or shp files).

5.2.1. Data Acquisition

All LIDAR-derived coordinates shall be three-dimensional with a sufficient density to

satisfy the requirements of this specification. Sufficient density shall also constitute the
ability to develop a detailed surface model of the ground surface over the entire width of
the surveyed corridor which can be rendered to a TIN in PLS-CADD. The Contractor
shall extract coordinates from all topographical features, above ground obstacles, and
features which would impact the design or analysis of transmission lines. The
Contractor shall ensure the accuracy of his work so that extensive ground verification
shall not be required.
All LIDAR-derived coordinates shall be referenced using the coordinate system from
section 3.2.
All LIDAR-derived coordinates shall be assigned feature codes according to the feature
code table found in Appendix A of this document.
All LIDAR-derived feature-coded coordinates shall be interpreted from the LIDAR data
and shall not be depicted as ‘point clouds’. For example, in the case a building, the
corner positions shall be calculated and delivered as points. Acceptance of the ‘closest
LIDAR return’ shall not be permitted.

5.2.2. LiDAR Acquisition:

LiDAR pulse rates, helicopter altitude, and speed shall be established such that:
 Point Densities shall be a minimum of 15 points per square meter
 Frequency shall be a minimum of 50 kHz
 Up to four (4) return values per pulse. No first or last pulse only systems are to be
used.
 Statistics on the data shall be collected, including average point density, frequency,
pulse rate, satellite coverage, and meteorological information. Detailed
meteorological specifications are found in the section 4.3 of this document.

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5.2.3. LiDAR Equipment:

The Aerial LIDAR Contractor shall submit a full description of the LIDAR unit to be used,
along with certificates of calibration.
The LIDAR system is required to be FDA certified to be eye safe, and shall have an
automatic shutdown feature.
The LIDAR system shall be capable of collecting four (4) coordinate points from each
laser pulse.

5.2.4. Ground Control

The Contractor shall provide adequate GPS base stations along the right of way of each
transmission line to support the LIDAR data accuracy requirements. GPS base stations
shall not be placed at excessive intervals resulting in gap areas, and shall have at all
times adequate overlap between stations.
The Contractor shall provide a Ground Control Report(s) outlining all ground control
points used during the survey. Reports shall be generated for each line surveyed.

5.2.5. Ground Truthing

Contractor(s) shall field-verify LiDAR data by collecting ground truth data along the
surveyed corridor on surfaces considered permanent and/or semi-permanent.
A snow tolerance of up to 0’-6” of snow will be acceptable provided that depths are
recorded at ground control and ground truthing locations.
Contractor(s) shall use one (1) of the three (3) options below to generate the ground
truthing reports:
1. Ground truth variance reports that calculate the expected accuracy of the laser-
scan by comparing laser points immediately adjacent to known USGS
monuments to the absolute location of the USGS monuments that are referenced
for the LIDAR capture flights. At least two accuracy checks will be made for each
transmission line; OR
2. Ground truth variance reports that calculate the expected accuracy of the laser-
scan by comparing laser points immediately adjacent to known USGS survey
control monuments to the absolute location of the USGS survey control
monuments that are referenced for the LIDAR data capture flights. The LIDAR
accuracy reports will also calculate the achieved accuracy of the laser scan by
comparing laser points along permanent or semi-permanent surfaces to actual
surveyed points along the same permanent or semi-permanent surfaces. An
accuracy check will be made at least every ten miles along a right-of-way. At
least two accuracy checks will be made for each transmission line; OR
3. Ground truth variance reports that calculate and check the achieved accuracy of
the laser-scan by comparing, in a selected area, the locations of 20 ground
survey points along pavement, 20 ground survey points along a grassy area, 20
ground survey points along a brush area, and 20 ground survey points along a
forested area of the transmission line with LIDAR (laser scan) points in the same

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locations. An accuracy check will be made at least every 10 miles along a right-
of-way. At least two accuracy checks will be made for each transmission line.
The ground truth variance report will include the following:
 Average statistical deviations of vertical data.
 Minimum and maximum statistical deviation of vertical data.
 Statistical verification of confidence levels.

5.2.6. Aerial Imagery

Digital, color, full motion, forward looking 45 degree video shall be acquired. The video
shall cover the whole corridor width, shall be delivered in MPEG format, and shall be
fully integrated with PLS-CADD.
The Contractor shall provide full color georeferenced, ortho-rectified aerial photography
for the entire width and length of the transmission corridor. The Contractor shall acquire
the imagery at the highest sun-angle possible, limiting shadows.
The Contractor shall provide the photographs in the either .jp2 or .png format with no
image collars and incorporate them into the PLS-CADD deliverable.

6. DELIVERABLES

6.1. Specific Deliverables

The following deliverables will be provided:

 All projects shall be delivered in the coordinate system delineated in section 3.2 of
this specification.
 All project notes and structure photography shall be included in a .zip file.
 Meteorological report and weather data shall be included in a .zip file.
 For LiDAR surveys, the Ground Truthing Report, Survey Control Report, and Video
file shall be included.
 Either the Traditional Ground Survey data file as described in section 6.2 or the PLS-
CADD design as described in section 6.3.

6.2. Traditional Ground Survey Data File

All Traditional Ground Survey will be provided in one of the following formats:
 .csv (comma separated value)
 .xlsx (Excel spreadsheet)
 .asc (ASCII text)
 .txt (text – no formatting, space separated)
 .dxf (drawing interchange format) – ASCII based, not binary
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6.3. PLS-CADD Design File

For all Aerial LiDAR surveys, a PLS-CADD design file will be the main deliverable for the
Contractor. Each design file shall include the following:
 PLS-CADD .BAK file containing the feature coded XYZ data as found in Appendix A.
 LiDAR Data in .las or .laz format. LiDAR Data shall be organized so all associated
survey data loaded into the individual PLS-CADD.BAK files is contained within a
folder with the same name.
o Vegetation XYZ data shall be provided in a separate .las or .laz files that
contain all vegetation for each individual PLS-CADD .BAK file.
 Digital, color, georeferenced, ortho-rectified photography in either .jp2 or .png format
 Digital video of the corridor in MPEG format
 Planimetric drawing of the corridor in ASCII DXF format (not binary). The drawing
shall be for the entire width and length of the corridor and shall be in one complete
file. The drawing shall include, but is not limited to:
o Transmission centerline of the circuit being surveyed
o State plane coordinates and deflection of each PI
o Streets, roads, and highway centerlines and edge of pavement
o Edge of unpaved roads, trails, and driveways
o Centerlines and base of poles for any utilities within the survey corridor
o Fences
o All structures, including homes, sheds, garages, barns, buildings, windmills,
antennas. The outline or footprint of each of these features shall be depicted
o Banks and centerlines of creeks, streams, rivers, ponds, and lakes
o Areas of forestation. Drip edges for trees and groups of trees and brush shall
be shown

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APPENDIX A

A list of codes required to define the characteristic feature of surveyed points is as follows.
Feature codes shall be consistent for each point type or discreet feature. Alternate points, shall
be approved by Engineer prior to commencement of the survey work.

FEATURE CODES
Feat.
Code Feature Description
1 PI
2 INTERPOLATED POINTS
10 GROUND
11 GROUND - PEDESTRIAN ONLY
12 GROUND - CENTER PROFILE
13 GROUND - LEFT PROFILE
14 GROUND - RIGHT PROFILE
20 AGRICULTURE - ACTIVE
21 AGRICULTURE - INAVTIVE
22 FIELD - EDGE OF
23 FIELD ROAD
30 ROAD - EDGE OF
31 ROAD - PAVED
32 ROAD - UNPAVED
33 ROAD - CENTERLINE
35 PARKING
36 PARKING - EDGE OF
40 DRIVEWAY - RESIDENTIAL
41 DRIVEWAY - COMMERCIAL
42 DRIVEWAY - EDGE OF
43 DITCH
44 DITCH - CENTERLINE
45 DRAIN
46 DRAIN - CENTERLINE
47 CULVERT
60 FENCE - BASE
61 CURB
62 SIDEWALK
63 PAVEMENT
70 CAMPGROUND
71 CEMETERY - EDGE OF
72 TRAIL - EDGE OF
73 TREE LINE - EDGE OF
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Feat.
Code Feature Description
74 LAND FILL - EDGE OF
75 QUARRY - EDGE OF
76 PROPERTY - CORNER
77 PROPERTY - LINE
78 PLAYGROUND - EDGE OF
90 RAILROAD - CL
91 RAILROAD - CROSSING
92 RAILROAD - RAILS
100 WATER (UNDETERMINED)
101 WATER - EDGE OF
102 WATER - HIGH WATER LINE
103 CREEK - EDGE OF
104 CREEK - CENTERLINE
105 CREEK - HIGH WATER LINE
106 CREEK - DRY CREEK BED
107 WETLAND - EDGE OF
110 WATER - NOT SUITABLE FOR SAILBOATING
111 WATER (NO RAMP) - LESS THAN 20 ACRES
112 WATER (NO RAMP) - 20 - 200 ACRES
113 WATER (NO RAMP) - 200 - 2000 ACRES
114 WATER (NO RAMP) - OVER 2000 ACRES
121 WATER (WITH RAMP) - LESS THAN 20 ACRES
122 WATER (WITH RAMP) - 20 - 200 ACRES
123 WATER (WITH RAMP) - 200 - 2000 ACRES
124 WATER (WITH RAMP) - OVER 2000 ACRES
200 POLE - BASE
210 H-FRAME - CL
211 H-FRAME - POLE BASE
220 LATTICE - CL
221 LATTICE - LEG BASE
230 TOWER - CL
231 TOWER - LEG CL
240 ANCHOR
300 GAS - METER
301 GAS - VALVE
302 GAS - WELL
310 WATER - METER
311 WATER - VALVE
312 WATER - WELL
320 BUILDING (AT GND)

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Feat.
Code Feature Description
325 HOUSE (AT GND)
330 SCHOOL (AT GND)
340 MANHOLE
341 MANHOLE - ELECTRIC
342 MANHOLE - GAS
343 MANHOLE - TELEPHONE
344 MANHOLE - STORM AND SEWER
350 UNDERGROUND - ELECTRIC
351 UNDERGROUND - UTILITY
352 UNDERGROUND - TELEPHONE
353 UNDERGROUND - GAS
354 UNDERGROUND - WATER
500 ANTENNA
505 BILLBOARD
510 BRIDGE - DECK
511 BRIDGE - GUARD RAILING - TOP
512 BRIDGE - RAILROAD - EDGE OF
513 BRIDGE - WALKING - BICYCLE
514 BRIDGE - WITH SUPERSTRUCTURE
515 BRIDGE - WITHOUT SUPERSTRUCTURE
520 BUILDING
521 BUILDING - TOP
530 CONVEYOR SYSTEM
535 DIVING PLATFORM
540 FENCE - CORNER
541 FENCE - POST
542 FENCE - SUBSTATION
543 FENCE - TOP
545 FIRE HYDRANT
550 FLAG POLE
555 GATE
560 GRAIN BIN - W/PERMANENT EQUIP
565 GRAIN BIN - W/PORTABLE EQUIP
570 IRRIGATION - TOP
575 MAST
576 MISC STR OR OBJECT
580 OVERHEAD WALKWAY
581 PHONE BOOTH
585 PIPELINE - ABOVE GROUND
590 ROOF (ACCESSIBLE)

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Feat.
Code Feature Description
591 ROOF (NOT ACCESSIBLE)
600 RR - COMMUNICATION LINE
601 RR - SIGNAL - TOP
602 RR - SIGNAL LIGHT-BARRIER - TOP
610 SIGN (W/OUT PEDESTRIAN ACCESS) - TOP
611 SIGN (W/PEDESTRIAN ACCESS) - TOP
615 SOLAR PANEL
620 STREETLIGHT - TOP
625 SWIMMING POOL
630 TANK
631 TANK - TOP
635 TRAFFICE SIGNAL TOP
640 TREE
641 TREE - STUMP
642 TREE - TOP
645 VEGETATION
650 WALL
655 WELL
1000 CROSSING - DISTRIBUTION
1005 CROSSING - 69KV
1010 CROSSING - 115KV
1015 CROSSING - 138KV
1020 CROSSING - 230KV
1025 CROSSING - 345KV
1080 CROSSING - SHIELD WIRE
1085 CROSSING - UNIDENTIFIED
1200 WIRE - UNIDENTIFIED
1205 WIRE - SERVICE DROP
1210 WIRE - SHIELD WIRE
1211 WIRE - FIBER OPTIC
1215 WIRE - TELEPHONE
1220 WIRE - DISTRIBUTION
1225 WIRE - 69KV
1230 WIRE - 115KV
1235 WIRE - 138KV
1240 WIRE - 230KV
1245 WIRE - 345KV
1250 WIRE - 500KV
1500 GUY WIRE
1501 GUY WIRE - CATV

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Feat.
Code Feature Description
1502 GUY WIRE - DISTRIBUTION
1503 GUY WIRE - EXISTING
1504 GUY WIRE - TELEPHONE
1505 GUY WIRE - TRANSMISSION
1510 JUMPERS
1515 POLE - DISTRIBUTION TOP
1516 POLE - STREETLIGHT TOP
1517 POLE - TRANSMISSION TOP
1518 POLE - UNIDENTIFIED TOP
1520 STRUCTURE
1521 STRUCTURE - ARM
1522 STRUCTURE - BRACE
1523 STRUCTURE - EXISTING
1524 STRUCTURE - FOUNDATION
1525 STRUCTURE - H-FRAME
1526 STRUCTURE - SUBSTATION
1530 TOWER - CL TOP
1531 TOWER - MICROWAVE
1532 TOWER - OBSERVATION
1533 TOWER - TL
1534 TOWER (GUYED) - LATTICE TOP
1550 CABLE ATT - TELEPHONE
1551 CABLE ATT - FIBER OPTIC
1552 CABLE ATT - SERVICE DROP
1560 SW ATT 1A
1561 SW ATT 1B
1562 SW ATT 2A
1563 SW ATT 2B
1564 SW ATT 3A
1565 SW ATT 3B
1566 SW ATT 4A
1567 SW ATT 4B
1580 INS ATT 1A
1581 INS ATT 1B
1582 INS ATT 1C
1583 INS ATT 2A
1584 INS ATT 2B
1585 INS ATT 2C
1586 INS ATT 3A
1587 INS ATT 3B

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Feat.
Code Feature Description
1588 INS ATT 3C
1589 INS ATT 4A
1590 INS ATT 4B
1591 INS ATT 4C
1600 INSULATOR 1A
1601 INSULATOR 1B
1602 INSULATOR 1C
1603 INSULATOR 2A
1604 INSULATOR 2B
1605 INSULATOR 2C
1606 INSULATOR 3A
1607 INSULATOR 3B
1608 INSULATOR 3C
1609 INSULATOR 4A
1610 INSULATOR 4B
1611 INSULATOR 4C
1620 SW 1A
1621 SW 1B
1622 SW 2A
1623 SW 2B
1624 SW 3A
1625 SW 3B
1626 SW 4A
1627 SW 4B
1640 COND 1A
1641 COND 1B
1642 COND 1C
1643 COND 2A
1644 COND 2B
1645 COND 2C
1646 COND 3A
1647 COND 3B
1648 COND 3C
1649 COND 4A
1650 COND 4B
1651 COND 4C
1660 DIST 1A
1661 DIST 1B
1662 DIST 1C
1663 DIST 2A

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Feat.
Code Feature Description
1664 DIST 2B
1665 DIST 2C
1670 NEUTRAL
1675 COMM 1
1676 COMM 2
1677 COMM 3
2200 ?UNKNOWN FEATURE CODE?

*Note: Assign other feature codes for other miscellaneous features, as necessary. The same
feature code shall be used for each type of feature, and consistency shall be maintained
in grouping the new feature code near similar codes of other features. The use of
miscellaneous features shall be kept to a minimum, and additional feature codes added
shall be provided to the Engineer.

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