| Construction
Route Planning Of Buried Plant
UNITED STATES DEPARTMENT OF
AGRICULTURE
Rural Utilities Service
BULLETIN 1751F-642
SUBJECT: Construction Route Planning of Buried
Plant
TO: All Telecommunications Borrowers
RUS Telecommunications Staff
EFFECTIVE DATE: Date of Approval
EXPIRATION DATE: Seven years from effective
date
OFFICE OF PRIMARY INTEREST: Outside Plant
Branch, Telecommunications Standards Division
PREVIOUS INSTRUCTIONS: This bulletin replaces
RUS Bulletin 1751F-642, Staking of Buried Plant, dated June
26, 1992.
FILING INSTRUCTIONS: Discard RUS Bulletin
1751F-642, Staking of Buried Plant, dated June 26, 1992, and
replace it with this bulletin. File with 7 CFR 1751 and is
available to RUS staff on RUSNET.
PURPOSE: This bulletin provides RUS borrowers,
consulting engineers, contractors and other interested parties
with information concerning construction route planning of
buried plant construction projects.
Adam Golodner 06/30/95
______________________________ __________________________
Administrator Date
TABLE OF CONTENTS
1. General ................................................
5
2. Pre-Construction Route Planning Activities
............. 7
3. National Electrical Safety Code (NESC)
................. 9
4. National Electrical Code (NEC) ........................
10
5. Outside Plant Assembly Units ..........................
10
6. Construction Route Planning ...........................
10
7. Outside Plant Housing Selection .......................
20
8. Terminal Blocks .......................................
20
9. Railroad Crossings ....................................
21
10. Road and Highway Crossings ............................
21
11. Pipeline Crossings ....................................
22
12. Station Installations .................................
23
13. Electrical Protection .................................
23
14. Final Inventory Construction Drawings
................. 24
TABLES & FIGURES
Table 1 Suggested Measurement Techniques .................
18
Figure 1 Example of Typical Construction Drawing
.......... 26
Figure 2 Methods of Locating Buried Pipelines
on Drawings . 27
Figure 3 Example of Final Inventory Construction
Drawing .. 28
Figure 4 Example of Buried Plant Construction
Route
Planning Symbols .................................
29
INDEX:
Outside Plant
Construction Route Planning
Telecommunications
ABBREVIATIONS
BET Building Entrance Terminal
BFCP Buried Filled Cable Pre-Designated Area
Assembly Unit
CATV Community Antenna Television Service
CFR Code of Federal Regulations
HFM Hand-push, Wheel-type Footmeter
LD Loan Design
NEC National Electrical Code
NESC National Electrical Safety Code
NID Network Interface Device
R/W Rights-of-way
RUS Rural Utilities Service
SAIC Serving Area Interface Cabinet
SAVE Serving Area Value Engineering
TE&CM Telecommunications Engineering and
Construction Manual
VFM Vehicle Mounted Footmeter
DEFINITIONS
BFCP: A buried filled cable assembly unit
which informs the contractor that the installation in that
particular area will be much more difficult than normal because
of the presence of underground facilities or severe rights-of-way
restrictions.
Building Entrance Terminal: A building entrance
terminal is comprised of housing containing both primary station
protectors and connector terminals for each conductor pair
provided by the telecommunications company and used by the
customer. The primary station protectors may be fused or fuseless.
Construction Corridor: A corridor having a
minimum width of
1 rod (5.0 meters) along the designated route
for buried cable and wire placement, which permits passage
and operation of the construction equipment.
Construction Drawings: The drawings developed
through the construction route planning process and used to
guide the construction of outside plant facilities.
Construction Route Planning Personnel: Representatives
of the engineer responsible for gathering field data and preparing
construction drawings.
Loan Design: A comprehensive engineering plan
for the project used to support a loan application to RUS.
Network Interface Device: A network interface
device is comprised of a housing suitable for outdoor installation
which contains a compartment accessible by only telecommunications
employees which includes a primary station protector and means
for terminating telecommunications service wire conductors
and/or metallic shields, and a compartment accessible by customers
which includes a RJ-11 plug and jack of the type specified
in Part 68 of FCC regulations.
Reduced Construction Corridor: A construction
corridor having a width less than the standard "Construction
Corridor."
Resident Engineer: The representative of the
Engineer who is delegated full-time "on site" responsibilities
for overall project administration, design, construction route
planning, and construction.
Restricted Construction Corridor: A standard
or reduced construction corridor containing the presence of
existing buried telecommunications and/or other utilities
facilities, rights-of-way restrictions, or other factors.
Rights-of-Way: The strips of land over which
facilities such as highways, railroads, power lines, other
utilities, or telecommunication lines are constructed.
RUS Accepted (Material and Equipment): Material
and equipment which RUS has reviewed and determined that:
a. Final assembly is conducted within the
United States, Mexico, or Canada or any of their respective
territories and the cost of United States, Mexican, or Canadian,
manufactured components, in any combination, is more than
50 percent of the total cost of all components utilized in
the material or equipment, and
b. The material or equipment complies with
pertinent RUS or industry standards and field experience has
demonstrated that the material or equipment is suitable for
use on systems of RUS telecommunications borrowers.
RUS Technically Accepted (Material and Equipment):
Material and equipment which RUS has reviewed and determined
that:
a. Final assembly is not conducted within
the United States, Mexico, or Canada, or any of their territories,
or the cost of components within the material or equipment
which are manufactured within the United States, Mexico, or
Canada, or any of their territories, cost 50 percent or less
than the total cost of all components utilized in the material
or equipment, and
b. The material or equipment complies with
pertinent RUS or industry standards and field experience has
demonstrated that the material or equipment is suitable for
use on systems of RUS telecommunications borrowers.
1. GENERAL
1.1 Construction route planning is the process
of reviewing and assessing proposed construction routes and
preparing drawings and tabulations to show the locations and
quantities of construction units required. It should be consistent
with the construction proposed in the Loan Design (LD). It
should be undertaken with the objective of constructing buried
plant which conforms to Rural Utilities Service (RUS) standards,
is free from hazards, and is economical. The information and
recommendations in this bulletin are advisory.
1.2 Personnel performing the construction
route planning should be familiar with and have access to
the following materials:
a. The approved LD (including maps) and any
revisions;
b. List of subscribers giving map locations
and grades of
service;
c. List of held service orders;
d. Maps showing any available, executed or
planned
rights-of way (R/W) easements;
e. National Electrical Safety Code (NESC)
(latest edition);
f. National Electrical Code (NEC) (latest
edition);
g. Existing local and State electrical codes,
especially
where they are more stringent than the NESC
and NEC
codes;
h. Construction routing and R/W selection;
i. Route, pole, and housing numbering;
j. Existing construction drawings;
k. Capabilities of various types of plowing
and trenching
equipment;
l. Station installation procedures;
m. Clearances according to NEC and NESC Codes;
n. Association of American Railroads Crossing
Standard;
o. Design and construction of joint buried
plant (electric
and telephone) according to NEC and NESC codes;
p. RUS Form 515, Telephone System Construction
Contract;
q. RUS Bulletin 345-150, Specifications and
Drawings for
Construction of Direct Buried Plant (RUS Form
515a);
r. RUS Bulletin 345-154, Specifications and
Drawings for
Service Entrance and Station Protector Installation
(RUS Form 515g);
s. RUS Bulletin 380-1, Right-of-Way and Title
Procedures;
t. RUS Bulletin 1751F-626, Staking of Aerial
Plant;
u. RUS Bulletin 1751F-640, Design of Buried
Plant -
Physical Considerations;
v. RUS Bulletin 1751F-641, Construction of
Buried Plant;
w. RUS Bulletin 1751F-670, Outside Plant Corrosion
Consideration;
x. RUS Bulletin 1751F-801, Electrical Protection
Fundamentals;
y. RUS Bulletin 1751F-805, Electrical Protection
at
Customer Locations;
z. RUS Bulletin 1751F-815, Electrical Protection
of Outside
Plant;
aa. RUS Bulletin 1753F-401(PC-2), RUS Standard
for Splicing
Copper and Fiber Optic Cables (codified under
7 CFR
1755.200);
bb. The following RUS Telecommunications Engineering
and
Construction Manual (TE&CM) Sections:
1. 116, Plant Engineering and Record System;
2. 210, Telephone System Design - Sizing Criteria;
3. 230, General Principles of Feeder - Distribution
Cable Engineering (Serving Area Value Engineering
[SAVE]);
4. 231, Design Techniques of Feeder-Distribution
Cable
Engineering (SAVE);
5. 232, Transmission Design Cost Considerations
of
Feeder-Distribution Cable Engineering (SAVE);
6. 424, Design Guideline for Telecommunications
Subscriber Loop Plant;
7. 628, Plastic-Insulated Cable Plant Layout;
8. 629, Cable Plant Layout - Serving Area
Value
Engineering (SAVE) for Rural Systems;
9. 648, Serving Area Value Engineering-Physical
Plant;
and
10. 822, Electrical protection of Carrier
Equipment.
1.3 Construction route planning personnel
along with representatives of the borrower should attend the
Pre-Construction Route Planning Conference and construction
route planning should conform to the agreements and requirements
contained in the Pre-Construction Route Planning Conference
minutes. When construction is planned to be performed on public
R/W, it may be advantageous to have a Department of Transportation
official present at the Pre-Construction Route Planning Conference.
1.4 Even though it is beneficial for construction
route planning personnel to be familiar with the material
listed in Paragraph 1.2 above, construction route planning
personnel are not usually expected to design the buried outside
plant. They are expected to make field measurements of cable
and wire lengths as well as miscellaneous unit lengths, unit
locations, and locate outside plant housings for loading (when
loaded lines are determined by RUS to be economically feasible
and the overall system design complies with the Modernization
Plan [7 CFR 1751, Subpart B]), branch splices, subscriber
terminations, etc. They also locate obstacles such as culverts
and underground facilities of other utilities as discussed
later. They verify the general route which has been tentatively
selected by the engineer and should discuss any difficulties
noted in the proposed routing with the engineer before making
any changes.
1.5 Investigation, coordination, and thorough
planning of the route should be of paramount importance to
avoid future problems that the borrower may encounter in the
operation and maintenance of the plant. In the case of buried
plant, firm decisions should be made in the design stage.
1.6 The physical presence of the buried plant
facilities, characteristics of the terrain, and electrical
and mechanical protection of the buried plant facilities should
also be considered in determining the construction route.
2. PRE-CONSTRUCTION ROUTE PLANNING ACTIVITIES
2.1 Before construction route planning begins,
construction route planning personnel should receive assurances
from the borrower that R/W agreements or permits have been
obtained. Any suitable means, such as easement strip maps
to indicate the R/W conditions, may be used for this purpose.
Property owners who wait until construction route planning
is performed to observe the route taken before granting an
easement should be noted as well as the status of easements
on other properties. The RUS borrower should furnish a qualified
representative to accompany the construction route planning
personnel to negotiate with landowners for easements. Any
precautions to be observed during construction should be noted
on the construction drawings.
2.2 When service order activities indicate
changes in subscriber estimates, the resident engineer should
be informed and if necessary, action should be taken to revise
the initial design to ensure that construction will be adequate
to meet subscriber demands. Any design changes should be reflected
in the construction drawings of the project, but 7 CFR 1753.3
requires that written approval for significant changes must
be obtained from the borrower and RUS.
2.3 Construction route planning personnel
should mark only those lines shown in the approved LD except
for minor changes dictated by field conditions. The resident
engineer should inform the construction route planning personnel
of any routes, leads, or service connections which for any
reason are not to be constructed and for those additional
routes that are to be constructed.
2.4 Careful consideration should be given
to the usability of R/W obtained on each parcel of land on
which cables and/or wires are to be constructed. If R/W are
not satisfactory from a construction standpoint because of
poor routing, hazardous conditions, heavy clearing, rock,
swampy soil, lawns, insufficient construction corridor width
for the plow train, etc., the resident engineer should discuss
the conditions with the borrower so that an attempt can be
made either to procure additional R/W or to relocate the proposed
section of route.
2.5 When the borrower is required to submit
engineering information as a prerequisite for procuring a
permit, license, franchise, or authorization from public bodies
or private corporations in connection with proposed construction,
construction route planning personnel should furnish the resident
engineer with the necessary field data to prepare the required
information and drawings for the borrower. Examples of situations
for which permits may be required are:
a. Plowing or trenching on or adjacent to
roads and
highways;
b. Crossing of highways;
c. Bridge attachments;
d. Crossing navigable streams or other bodies
of water;
e. Crossing railroads;
f. Joint occupancy trenches with another utility;
g. Crossing buried facilities of other utilities;
h. Crossing land owned or controlled by public
bodies;
i. Location of outside plant housings or poles
on public
R/W; and
j. Other sensitive environmental areas.
2.6 The borrower and resident engineer should
agree on the construction route planning markers (such as
stakes, bright colored paint, etc,), installation time of
the markers, and marking symbols to be used during the construction
route planning operation to identify the proposed construction
route. All of the above items should be agreed to at the Pre-Construction
Route Planning Conference and discussed at the Pre-Bid Conference.
3. NATIONAL ELECTRICAL SAFETY CODE (NESC)
3.1 It is very important that construction
route planning personnel know and understand the requirements
set forth in the NESC for telecommunications system outside
plant construction as well as the requirements of the local
authorities in the particular locality where construction
route planning is to be performed.
3.2 Some localities (States and/or municipalities)
have requirements for telecommunications buried plant which
are more stringent than those of the latest edition of the
NESC. The authorities administering these provisions expect
that the more stringent requirements be observed. For localities
where no requirements are established, the provisions of the
latest edition of the NESC should be followed. RUS Loan Contracts
and Mortgages require borrowers to observe all appropriate
codes that may pertain.
3.3 The portions of the NESC that construction
route planning personnel should be particularly concerned
with are Parts 2 and 3 which deal with the installation and
maintenance of overhead and underground lines. NESC rules
are not intended to serve as a basis for designing or construction
route planning of telecommunications plant. The rules should
be considered as the minimum standards that should be met
to help assure the plant is constructed to withstand the mechanical
loads and stresses to which it will be subjected, be reasonably
protected from the possible effects of electrical disturbances,
and be relatively free from hazards to the general public
and to telecommunications maintenance personnel.
4. NATIONAL ELECTRICAL CODE (NEC)
4.1 The purpose of the NEC is the practical
safeguarding of persons and property from hazards arising
from the use of electricity. The NEC includes the basic minimum
provisions for installation of telecommunications facilities
on subscribers' premises.
4.2 Chapter 8, "Communications Systems,"
Article 800, "Communication Circuits," of the NEC
discusses minimum conductor insulation requirements and station
grounding. Most authorities make it mandatory to observe the
requirements set forth in the NEC unless their local requirements
are more stringent, in which case the latter should be observed.
5. OUTSIDE PLANT ASSEMBLY UNITS
5.1 The general buried plant design in the
approved LD should be translated by the resident engineer
into a specific design in sufficient detail to enable construction
of the plant. To facilitate the specific design, standard
"assembly units" have been devised for most major
components of outside plant. Detailed descriptions of all
standard buried plant assembly units are given in RUS Bulletin
345-150, Specifications and Drawings for Construction of Direct
Buried Plant (RUS Form 515a).
5.2 Where standard assembly units are insufficient
to provide for unique construction requirements, "nonstandard
assembly units" should be created in detail to meet those
requirements. RUS 7 CFR 1753.6 requires that the nonstandard
assembly units and related drawings be RUS approved when RUS
loan funds will be used to finance their construction. RUS
prefers, however, that the number of "nonstandard assembly
units" be kept to the absolute minimum and that every
effort be made to utilize RUS "standard assembly units"
as far as practical.
5.3 The complete physical outside plant as
contemplated in the LD should be depicted by specifying the
appropriate types, quantities and locations of standard and
nonstandard assembly units on construction drawings.
6. CONSTRUCTION ROUTE PLANNING
6.1 Construction route planning personnel
should begin construction route planning by checking the status
of R/W and permit easements, by marking control points on
the LD maps, by making a reconnaissance of the proposed construction
areas, and checking and noting the items listed below:
a. Terrain;
b. Location of establishments;
c. Natural control points;
d. Plowing or trenching locations as determined
by fences,
roads, R/W easements, rivers, bridges, etc.;
e. Obstacles for plow trains or trenchers;
f. Sufficient construction corridor R/W for
plow trains;
g. Locations of other buried utilities; and
h. Locations of existing outside plant housings.
6.2 Control points are those points or areas
along a proposed construction route where circumstances demand
special consideration by construction route planning personnel
in specifying appropriate construction units. Examples of
control points are:
a. Street, alley, and highway intersections;
b. Rivers, streams, drainage ditches, and
canals;
c. Private driveways, field entrances, and
fence corners;
d. Railroad R/W;
e. Other buried facilities;
f. Junctions between cable and wire;
g. Junctions with branch cables;
h. Housing locations;
i. Subscribers' premises;
j. Trees;
k. Reduced and restricted construction corridor
R/W;
l. Outcropping of rock;
m. Buried splice closures; and
n. Areas identified in the Borrower Environmental
Report,
Environmental Assessment or Environmental
Impact
Statement.
6.3 Housings should be placed along buried
cable or wire leads at the following locations:
a. At subscriber distribution points within
a reasonable
service distance to all prospective subscribers;
b. At junctions with lateral runs of cable
or wire
including possible future extensions;
c. At bonding and grounding locations for
fiber optic
cable plant;
d. At aerial inserts, if it is necessary to
splice the
cable or wire. (Ready-access closures may
be used for
splicing to aerial cable inserts);
e. At cable loading points for initial or
ultimate loading
(when loaded lines are determined by RUS to
be
economically feasible and the overall system
design
complies with the Modernization Plan [7 CFR
1751,
Subpart B]); and
f. At Serving Area Interface Cabinet (SAIC)
and digital
carrier and lightwave repeater locations.
6.4 For buried copper cable or wire plant,
direct buried filled splice cases should be considered in
lieu of outside plant housings at the following locations:
a. When above-ground splicing as referenced
in
Paragraph 6.3 is not practicable; or
b. At reel end splices.
6.5 For buried fiber optic cable plant, direct
buried filled splice cases installed in handholes are the
preferred method of splicing fiber optic cable plant.
6.6 Data to be shown on construction drawings
may be recorded in a notebook or on construction drawings
as the route is being traveled in the field. This field data
may then be recorded on construction drawings back at the
office. Information that will be necessary for construction
is recorded on one set of drawings. Information pertaining
to removal of existing plant is recorded on a separate set
of drawings.
6.7 Information to be included on construction
drawings is that which is necessary to prepare the plans and
specifications and to construct the outside plant. The construction
drawings should be prepared so that they may be used as permanent
plant records.
6.8 After the subscriber data is brought up-to-date
on the construction drawing and the actual construction route
is selected, the actual sizing of the cables or wires for
the plant layout, line assignments, and the proper sizes for
outside plant housings or direct buried filled splice cases
may be performed in the engineer's office. The construction
drawings containing the above information should be made available
to the interested parties for discussion at the Pre-Bid Conference.
6.9 Low cost placement of cable or wire is
usually obtainable when the burial depth of the cable or wire
can be maintained within the shoulders or backslopes of roads
and highways. The cable or wire route should be selected so
as to minimize property damage from heavy equipment used in
the plow train. Locations of the proposed outside plant housings
should be selected to minimize possible damage from vehicular
traffic and to allow for easy maintenance access. Burying
of cable or wire directly in the roadbed should always be
avoided if possible.
6.10 Burying the cable or wire across private
R/W in rural areas having fences or where land is cultivated
to extreme depths generally is not economical in certain situations
and should be avoided. However, the use of private R/W for
placement of cable or wire should be considered if placement
would be more economical than in or along road shoulders or
backslopes of roads and highways.
6.11 When a private R/W is chosen as the construction
route, each property owner should be contacted. Discussions
should be held with each property owner to emphasize to the
owner the need to provide protection to cable or wire. The
selection of the cable or wire route, and cable or wire depth
is of utmost importance when using the private R/W. The type
and placement of above ground warning and route signs to identify
the construction route should be discussed with each property
owner. Each property owner should also be provided with a
construction drawing showing the proposed construction route
and the proposed locations of all buried facilities, housings,
and signs to be located on the owner's property.
6.12 Permission should be obtained from Department
of Transportation authorities at locations where public R/W
are to be used. Possible highway improvements, such as road
widening, should be considered in planning the construction
route. Future road work can result in costly telecommunications
plant rearrangements.
6.13 Investigations should also be made to
locate other buried facilities such as water, gas, sewer,
power, community antenna television (CATV), telecommunications
and oil lines. The location of these facilities should be
performed by obtaining maps from the other utilities and by
means of cable locators. Located facilities should be indicated
on the construction drawings to warn the contractor of their
presence. Predesignated Areas should be established on system
detail maps where in the judgement of construction route planning
personnel installations will be much more difficult because
of the presence of numerous or complex existing underground
facilities or severe R/W restrictions. Such system map locations
are possible areas to note predesignated construction units
such as the BFCP units. The units should appear on the construction
drawings in advance of bidding. A recommended procedure to
be followed for showing the general location of pipelines
is discussed in Paragraph 11.3.
6.14 Cable and wire routes should be marked
on construction drawings by reference to natural or manmade
landmarks to facilitate the placement and future location
of cable or wire.
6.15 Where difficulty may be encountered in
finding stakes used as construction route planning markers
at a later date, the stake locations should be indicated by
driving four-foot building laths adjacent to the stakes or
by providing some other suitable method of identification.
Where stakes are used as construction route planning markers
on R/W that are hidden from the road because of brush, trees,
crops, etc., a suitable identification marker (such as a strip
of bright colored cloth or plastic marking tape tied on a
fence or some other visible roadside location) should be provided
to indicate each stake location from the road. Where permitted
by transportation department authorities, a colored stripe
could be painted on the edge of the pavement to show the approximate
location of the stake. It will also be helpful to place appropriate
notes on the construction drawings.
6.16 Construction route planning personnel
should proceed along the route, marking and detailing the
following information (some of which may be done in the resident
engineer's office) on construction sheets:
a. Cable and wire routes;
b. Footage measurements along the route;
c. Road names, road numbers, road surfaces,
road widths,
R/W, fences, pole lines, etc.;
d. Lakes, ponds, streams, etc.;
e. Approximate locations of obstructions that
may be
encountered during actual construction of
the project,
such as other buried utilities, pipelines,
etc.;
f. Locations and types of the outside plant
housings and
poles;
g. Locations of direct buried filled splice
cases;
h. The distances in feet or meters from the
plow or trench
line to each outside plant housing or pole;
i. The distances in feet or meters along the
buried
construction route between lateral trenches
to outside
plant housings or poles. These distances should
be
chain or wheel measured but under certain
conditions
such as flat terrain, cable paralleling road,
or highway
R/W, a vehicle mounted foot-meter may also
be used for
the measurement (See Table 1 and Paragraph
6.18);
j. Vertical footage measurements in feet or
meters inside
each outside plant housing;
k. The lengths of service wires or cables
in feet or meters
from outside plant housings to subscriber's
network
interface devices (NIDs), building entrance
terminals
(BETS), or fused primary station protectors;
l. Outside plant housing numbers;
m. Pair sizes, gauges and types of copper
cables or wires;
n. Number of optical fibers and types of fiber
optic
cables;
o. Tentative load point locations (when loaded
lines are
determined by RUS to be economically feasible
and the
overall system design complies with the Modernization
Plan [7 CFR 1751, Subpart B]);
p. Tentative digital carrier repeater locations;
q. Tentative lightwave repeater locations;
r. Types of station protection and grounding;
s. Special considerations such as increased
depths, minor
route deviations, easement reservations, etc.;
t. Construction corridor widths, reduced construction
corridor widths, and restricted construction
corridors;
u. Grounding and bonding procedures at all
splice
locations;
v. All miscellaneous construction units for
the plant
installation such as warning signs, etc.;
and
w. All outside plant assembly units necessary
to construct
the buried plant.
An example of a blank construction drawing
designed for this purpose is given in Figure 1. Other forms
of construction drawings depicting similar information may
be used.
6.17 Construction route planning markers should
be used to show the location of the following:
a. Proposed outside plant housings;
b. Proposed direct buried filled splice cases;
c. Proposed handhole and manhole locations;
d. Proposed control danger points such as
underground
utilities, culverts, etc.;
e. Proposed poles and anchors for aerial inserts;
f. Proposed miscellaneous units such as split
metal guards
and warning signs;
g. Proposed road and/or highway crossing locations;
and
h. Proposed railroad crossing locations.
The applicable cable or wire route numbers,
outside plant housing numbers, or pole numbers should be appropriately
marked on the construction route planning markers so as to
be legible at the time of construction.
6.18 Acceptable measuring techniques used
in construction route planning of buried plant are (See Table
1):
a. Chaining;
b. Vehicle mounted footmeter (VFM);
c. Hand-pushed, wheel-type footmeter (HFM);
or
d. Stadia rod.
6.18.1 Chaining or VFM is the method of measurement
generally used in urban areas. When the chaining method is
used, caution should exercised used to avoid the following
most common errors:
a. Dropping or adding a complete chain length;
b. Reversing the chain so that the wrong figure
is read;
and
c. Not holding the end of the chain even with
the chaining
pin.
6.18.2 Chaining, VFM, or HFM is the method
of measurement generally used in rural areas.
6.18.3 Since measurements are intended to
represent the length of the telecommunications plant, they
should be made along the contour of the ground surface for
buried plant. When gullies or sharp breaks in the terrain
are encountered, measurements should be made approximately
parallel to the route where the cable or wire is expected
to be installed.
6.18.4 VFMs or HFMs may be used to check field
observed measurements. Such checks should result in fewer
major measurement errors. VFMs or HFMs should be calibrated
at least once a day over a measured 1000 foot (304.8 meter)
distance. VFMs should not be used in situations where the
vehicle wheels could slip, such as in mud, snow, loose gravel,
or on steep slopes resulting in excessive or erratic VFM rotation.
6.18.5 The stadia rod is a relatively accurate
and fast method of measuring distance when there are no obstructions
in the line of vision and the terrain is flat between the
transit and rod. It may be used to good advantage for measuring
distances across bodies of water, etc.
6.18.6 Measurements of cable or wire length
should be made twice, either by rechecking the distances on
existing plant records or by actually remeasuring the cable
or wire routes. This is particularly important for cables
or wires ordered to specified lengths for placing in conduit
systems, or between major predetermined control points, especially
with fiber optic cable plant.
6.18.7 Measurement Techniques: Listed in Table
1 are suggested measurement techniques for most situations:
TABLE 1
Suggested Measurement Techniques
Type of
Area Measurement
Situations Original
Measurement Check
Measurement
Urban Conduit Systems Chain Chain
Cables and Wires Chain or VFM
(See Note 1) Chain, VFM, HFM,
or existing
records
(See Note 1)
Rural Cables and Wires
Public R/W
Private R/W Chain or VFM
(See Note 1) VFM, HFM, or
existing
records
(See Note 1)
Chain of HFM
(See Note 1) HFM or existing
records
(See Note 1)
Distance between
load points
(See Note 2) Chain, VFM, or
HFM (See Note 1) VFM, HFM, or
existing records
(See Note 1)
Distance between
digital carrier
or lightwave
repeaters. Chain, VFM, or
HFM (See Note 1) VFM, HFM, or
existing records
(See Note 1)
Urban
or
Rural Drops - Aerial Chain, VFM, or HFM
between drop poles.
HFM from drop pole
to house
(See Note 1) Chain or use
HFM during
final
inventory
(See Note 1)
Drops - Buried HFM from buried
plant housing to
house
(See Note 1) Use sequential
marking during
final
inventory
Note (1): VFMs and HFMs should be calibrated
frequently and used in accordance with the manufacturer's
recommendations.
Note (2): When loaded lines are determined
by RUS to be economically feasible and the overall system
design complies with the Modernization Plan (7 CFR 1751, Subpart
B).
6.19 Outside plant housings should be specified
within a reasonable service distance from potential subscribers.
The housings should be specified at junction points from which
future extensions may be run even though not required in the
initial construction. The size of the housing should be large
enough to accommodate future branch cables or wires. Future
loading requirements (See Note 2 on Page 18) should also be
taken into account in sizing the housings. Pole mounted housings
or riser guards should be specified at junctions of buried
plant and aerial plant. The housings mounted on stub poles
should be specified where additional mechanical strength or
protection is required.
6.20 Outside plant housings on highway R/W
should be placed as close to the fence line as possible to
provide maximum protection to the housings from traffic and
road and farm equipment. If such placement is not possible
due to the absence of fences or because of planned highway
widening programs, the housing should be placed in some other
reasonably protected location. The construction route planning
personnel should consider appropriate methods of guarding
against damage if the housing will be exposed to road or farm
machinery, farm animals, or other hazards. Such methods may
include the use of stub poles, orange colored housings or
buried splices (RUS recommends, however, that buried splices
be used only as a last resort). Long stub poles may be used
in high vegetation areas. Consideration may also be given
to mounting the housing high on a stub pole with a riser guard
to protect the cable or wire for the desired height. This
may be advantageous in areas subject to flooding or heavy
snow. If this type of construction is used, the bottom of
the housing should be sealed with a material that will not
allow entry of birds, rodents, or insects into the base of
the housings.
6.21 Outside plant housing and pole numbering
should be in accordance with RUS Telecommunications Engineering
& Construction Manual (TE&CM) Section 116, Plant Engineering
and Record System, or some other suitable numbering system.
All housings should be marked with the appropriate cable,
load point (See Note 2 on
Page 18), route, and housing number.
6.22 When the field work has been completed
by construction route planning personnel and the necessary
entries on the construction drawings are completed, construction
route planning personnel turn the construction drawings over
to the resident engineer. The resident engineer inserts other
data and prepares final form construction drawings which will
be used for preparing the "Plans and Specifications."
6.23 In computations made to locate load points
(See Note 2 on Page 18), the engineer adds to the in-line
plowed lengths, the lengths which are trenched from the plow
line to housing or pole, plus an amount representing the vertical
runs in the housing or on poles.
6.24 To meet transmission objectives, especially
with respect to maintaining the proper end sections beyond
the last load point (See Note 2 on Page 18), particular care
has to be exercised when making subscriber assignments. A
thorough explanation of bridge taps and excessive end sections
and their effect on transmission loss and frequency response
is given in RUS TE&CM Section 424, Design Guidelines for
Telecommunications Subscriber Loop Plant.
6.25 The locations determined for load coil
housings (See Note 2 on Page 18) following the field construction
route planning may indicate places where a housing for service
connections can be combined with load coil locations. The
reverse (moving the load point) is not desirable because of
the precision required in locating load coils.
7. OUTSIDE PLANT HOUSING SELECTION
7.1 RUS accepted or technically accepted outside
plant housings should be selected to allow sufficient room
for splicing, loading (See Note 2 on Page 18), carrier equipment,
terminating the initial cable or wire installation, and future
cable or wire installations as well as for ease of maintenance.
All manufacturers of housings design their product to contain
minimum specified components. They are designed for splicing,
loading (See Note 2 on Page 18), carrier equipment or looping
in and out various size cables and wires but will not necessarily
be large enough to perform all four functions for a given
size cable or wire. The recommended capabilities of all housings
are specified in RUS Bulletin 1753F-401(PC-2), RUS Standard
for Splicing Copper and Fiber Optic Cables. This data should
be studied to select the proper size housing.
7.2 Outside plant housings also may be used
to provide above-ground appearances of buried fiber optic
cables. RUS accepted or technically accepted outside plant
housings for use on buried fiber optic plant are available
to accommodate the fiber optic cable slack and the fiber optic
splice case.
7.3 One objective in the selection of housings
is to preserve the natural beauty of the countryside. There
are, however, instances where it may be desirable that facilities
be clearly identified and visible. This may be done by mounting
the housing on tall stub poles or using orange colored housings.
8. TERMINAL BLOCKS
8.1 Moisture collecting on the inside of outside
plant housings should seldom be a problem if RUS accepted
or technically accepted filled splicing connectors are used
for connecting service wire drops instead of terminal blocks.
8.2 However, in locations where use of filled
splicing connectors is not practical due to high service order
activity, filled terminal blocks having RUS acceptance or
technical acceptance may be used to avoid moisture and corrosion
problems.
8.3 RUS in accordance with RUS Bulletin 1753F-401(PC-2),
RUS Standard for Splicing Copper and Fiber Optic Cables, does
not allow the use of nonfilled terminal blocks on RUS financed
construction projects.
9. RAILROAD CROSSINGS
9.1 The NESC specifies minimum vertical and
horizontal clearances for aerial and underground railroad
crossings, as well as minimum strength requirements for poles,
conductors, anchors and guys, and maximum crossing spans.
The Association of American Railroads also publishes requirements
regarding clearances, strength of poles, conductors, anchors
and guys, and span lengths titled "Specification For
Communication Lines Crossing the Tracks of Railroads."
9.2 Some railroads owners as well as States
or municipalities may have specifications which differ from
the NESC and the Association of American Railroads. Therefore,
before design and construction route planning work is undertaken,
railroad and/or State or municipal officials should be consulted
regarding their crossing requirements. The more stringent
requirements should be followed.
9.3 A drawing showing the detailed crossing
layout is often necessary for submission to railroad and/or
State or municipal officials for approval and for inclusion
in the crossing agreement. This drawing should also be included
with the construction drawings.
10. ROAD AND HIGHWAY CROSSINGS
10.1 The most acceptable method of crossing
State and local roads and highways and the most acceptable
procedures to be used in both cutting and repairing pavements
should be discussed and agreed to with transportation department
officials at the Pre-Construction Route Planning Conference.
Such cutting and repairing agreements should be made available
to the bidding contractors to assist them in preparing their
proposals. Any local regulations concerning the cutting and
repair of private roads, lanes, and driveways should also
be called to the attention of all contractors at the Pre-Bid
Conference.
10.2 After discussions with transportation
department officials and visual inspection of the route, construction
route planning personnel can verify the preliminary entries
of control points on the LD maps or construction drawings.
10.3 The cable or wire route should be planned
to cross the road as necessary to serve subscribers without
the use of aerial inserts, if possible. Such crossings could
be constructed by cutting or sawing perpendicularly across
the road, by trenching perpendicularly across the road, by
directional boring under the road, or by pipe pushing under
the road. Since road crossings are often undesirable and expensive,
construction route planning personnel should select the side
of the paved road for the most general routing of the cable
or wire which will result in the fewest crossings. If numerous
crossings are necessary, burying the cable or wire on both
sides of the road may be the most economical choice.
10.4 Existing conduit under roads and highways,
as well as across bridges, should be used where available.
Lengths of new conduit may be placed along with the cable
or wire where the road or highway is opened. This will facilitate
future reinforcement or replacement.
11. PIPELINE CROSSINGS
11.1 Crossing of pipelines and facilities
of other utilities should be done in the most economical and
mutually satisfactory manner. This would normally involve
placing the cable or wire directly over these facilities.
If sufficient depth cannot be obtained, it may be necessary
either to place split cable guards over the cable or wire
at the crossing, to cut and resplice the cable or wire, or
to use directional boring to achieve the greater depth.
11.2 Some pipeline companies require that
telecommunications cable or wire be placed a fixed distance
below the pipeline. This may require either cutting the cable
or wire, trenching, splicing and installing a buried splice
enclosure or an outside plant housing or the use of the directional
boring method. This applies to all crossings of railroads,
roads, highways, bridges, pipelines, etc. Generally, it is
the responsibility of the construction route planning personnel
to determine the most advantageous and economical method to
use. Generally, it is the responsibility of the contractor
to avoid damaging facilities which are crossed and to restore
them and their contents if damaged.
11.3 Since a pipeline can only be precisely
located by exposing it to view, construction route planning
personnel should make special markings on the construction
drawings showing approximate pipeline locations and also should
provide appropriate cautionary notes regarding the facilities
to cross. This is especially important as to the exact location
of the pipes. Suggested correct and incorrect locating methods
are shown in Figure 2.
12. STATION INSTALLATIONS
12.1 Station installations include the construction
route planning of buried service wire assembly units, NID
assembly units, BET assembly units, or fused protector assembly
units.
12.2 Where the objectives of safety and electrical
protection conflict with the objectives of appearance and
economy, the decision should always favor safety and protection.
12.3 Construction route planning of the buried
service wire or cable should conform with the NID, BET, or
fused station protector location which will facilitate connections
to the subscriber's inside wiring and which, at the same time,
will ensure interconnection between the telephone, power,
and water pipe grounds. RUS recommends that the NID, BET,
or fused station protector location be chosen to be as close
as practicable to where there is easy access to the electric
service grounding system (electric service grounding conductor,
metal conduit covering the electric service grounding conductor,
or other means of access to the electric service grounding
system).
13. ELECTRICAL PROTECTION
13.1 Construction route planning personnel
should be provided with the detailed protective measures to
be employed which have been decided upon in the system design.
RUS Bulletins 1751F-801, -802, -805, and -815 include details
regarding applicable protection practices.
13.2 In order to minimize the possibility
of conflict with or interference from power distribution systems,
crossings of power and communication systems should be minimized.
Where joint occupancy of power and telecommunications facilities
is contemplated, the provisions of the NEC and NESC codes
and any more stringent local codes should be followed.
13.3 RUS recommends that joint occupancy construction
be limited to 1/2 mile (800 kilometers) or less to help minimize
possibilities for telecommunications interference caused by
power line harmonics.
13.4 Auxiliary protection of buried wire or
cable against direct contact with power conductors is not
required. Station instal-lations connected by buried wire
from aerial extensions may require auxiliary protection as
described in appropriate sections of RUS Bulletin 1751F-805,
Electrical Protection at Customer Locations.
13.5 It is important that construction route
planning personnel understand the difference in the objective
of station protection as compared to plant protection. Plant
protection is primarily concerned with balancing the cost
of maintaining unprotected plant and the value of service
interruption against the cost of applying and maintaining
protective devices which will reduce or eliminate this plant
maintenance. Station protection is concerned with the personal
safety of the subscriber and maintenance personnel, protection
of the subscriber's premises against fire and protection of
the station equipment and wiring against damage and circuit
outage. Adequate protection of persons and premises should
be provided at all station installations.
14. FINAL INVENTORY CONSTRUCTION DRAWINGS
14.1 Final inventory construction drawings
are usually made after construction completion by correcting
the initial construction drawings. Due to design changes during
construction, the initial construction drawings may require
some modifications, particularly in regard to cable or wire
lengths, load points (See Note 2 on Page 18), digital carrier
repeater locations, and lightwave repeater locations. The
resident engineer and contractor should agree on all the quantities
and units appearing on the final inventory construction drawings.
The corrected construction drawings are then prepared in final
form as permanent plant records.
14.2 The "as built" or final inventory
construction drawings should provide the following information
in complete detail:
a. An inventory of all outside plant units
installed; and
b. The physical location of the buried facilities.
14.3 These construction drawings should give
a record of the amount of materials and their locations in
the field, and also provide the borrower with a basis for
a reliable schematic with which to locate the cable or wire
either for trouble-shooting, upgrading, or coordinating with
other utilities and construction activities that might occur
in the future. An example of a final inventory construction
drawing, as well as the construction symbols used in preparing
the drawings, are shown in Figures 3 and 4, respectively.
14.4 To facilitate future reinforcement, the
construction drawing should be corrected and marked with reasonable
accuracy so future construction crews will know the approximate
locations of existing cables or wires and the approximate
locations and depths of any underground facilities. If a greater
than normal depth has been specified to facilitate future
reinforcing, the resident engineer should make certain that
this depth is achieved during construction. For instance,
a nominal cable or wire depth of 36 inches (914 millimeters)
may be used with the thought that additional cable or wire
may be placed at a nominal depth of 24 inches (610 millimeters)
in the future.
14.5 The outside plant housings, buried
splices, cable or wire lengths, etc., required for cable or
wire repairs should be so designated on the construction drawings
to facilitate trouble-shooting later; however, this repair
material information should not be included in the final inventory
for compensation purposes.
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