1680-06-01-.06
Location And Alignment Criteria For Installation Within Highway
Cite as Tenn. Comp. R. & Regs. 1680-06-01-.06
RIGHTS-OF-WAY.
(1)
Overhead Power and Communication Lines. Type of Construction.
(a)
Longitudinal installations of overhead lines within highway rights-of-way are limited to single
pole type of construction unless approved by the State Transportation Engineer as an exception
to these rules and regulations based on extreme hardship conditions. new facilities or existing
facilities being rebuilt in their entirety shall be designed to provide maximum spacing of poles
within the bounds of sound engineering principles and economic considerations, Alignment
shall be as near uniform as practical to avoid anchors, stub poles and other ground mounted
appurtenances.
(b)
On and along conventional highways in rural areas, poles and related ground mounted
appurtenances shall be located at or as near as practical to the rights-of-way line. As a minimum
the poles shall be located outside the clear zone for the highway section involved without full
access control.
(c)
Joint use construction, as indicated by Rule 222 of Part 2 of the National Electrical Safety
Code, shall be considered at all feasible locations where more than one utility or type of facility
is to be located overhead.
(d)
The minimum vertical clearance for overhead power and communication lines above the traffic
lanes of the highway and the lateral and vertical clearance from bridges shall conform to
currently applicable National Electrical Safety Code.
(e)
Stub poles or guy wires to ground anchors shall not be placed between a pole and the traveled
way where they encroach upon the clear zone.
(f)
Where irregular shaped portions of the right-of-way extend beyond the normal right-of-way
limits, variances in the location from the right-of-way will be allowed as necessary to maintain
a reasonably uniform alignment for longitudinal installations.
(g)
Longitudinal installations will not be permitted in the highway median.
(h)
On crossing a highway, facilities shall not be located in a highway median within the clear zone
from both directions of travel.
(i)
Crossing of the highway shall be as near normal as practical under prevailing circumstances.
(j)
On or along conventional highways in urban areas, poles and related ground-mounted
appurtenances shall be located at or as near as practical to the right-of-way line. Where there are
curb and gutter sections, poles shall be located as far as practical behind the face of outer curbs,
and where sidewalks are provided to the back of sidewalk if at all practical.
It is realized that these sections of highway with closely abutting improvements and usually a
minimum width of right-of-way are special cases which must be resolved in a manner consistent with
the prevailing limitations and conditions. Considerations must be given to designs employing self-
supporting, armless, single pole construction, with vertical alignment of wires or cables, or other
techniques permitted by applicable governmental or industry codes. Exceptions to these clearances
may be considered where poles and related ground-mounted appurtenances are placed behind guard
rails, retaining walls or deep drainage ditches, at the toe or top of steep slopes, or at other similarly
protected locations without full access control.
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
(2)
Underground Power, Communication, Water and Sanitary Sewer Facilities.
(a)
On conventional highways in rural areas longitudinal installations shall be at or as near as
practical to the right-of-way line so as to minimize interference with highway drainage, the
structural integrity of the traveled way, shoulders, embankment and safe operation of the
highway. Alignment of facilities shall be as uniform as possible under prevailing circumstances
in order that points of access for installation and maintenance may be kept to a minimum. No
new installations will be permitted within the normal highway median area, except in extreme
hardship cases where there is no other feasible location.
(b)
On or along conventional highways in urban areas underground utility facilities shall be located
at or as practical to the highway right-of-way line. Where there are curb and gutter sections,
underground utilities shall be located outside the travel lanes whenever practical. No new
installations will be permitted within the normal highway median area, except in extreme
hardship cases where there is no other feasible location. It is realized that these sections of the
highway must be considered as special cases in considering longitudinal encroachment of
underground facilities, and problems must be resolved on a case by case basis consistent with
prevailing limitations and conditions and design considerations to elevate to every extent
possible interference with safety and operations of the highway facilities. Relocation of utility
facilities and/or alterations to accommodate reconstruction of the highway will be reviewed and
considered on a case by case based on the conditions that exist at the time.
(c)
Crossings shall be located as near normal to the highway alignment as practical. Crossing shall
have a minimum of 36 inches of cover under the low point of the highway for uncased
installations and 30 inches for encased installations.
(d)
Conditions which are generally unsuitable or undesirable for underground crossings should be
avoided. These include locations such as in deep cuts; near footings of bridges and retaining
walls; across intersections at grade or ramp terminals, at cross drains where flow of water, drift
or stream bedload may be obstructed; within basins of an underpass drained by a pump; and in
wet or rocky terrain where it will be difficult to attain minimum cover.
(e)
Longitudinal underground installations under sidewalks or grass plots of curb and gutter urban
sections and installations located within 8-fect of the right-of-way line or rural highways
(except as specified below) shall have a minimum cover of 24-inches. Longitudinal
underground installations other than plowed cable which are located between the ditches of the
highway template or within 5-feet of the ditch line shall have a minimum cover of 36-inches.
All longitudinal underground installations which cross under drainage ditches will be located a
minimum of 36-inches below the flow line of the ditch. All other underground installation shall
have a minimum cover of 30-inches. A minimum cover of 24-inches is acceptable for any
longitudinal installation where encasement or mechanical protection is provided. Cable plowed
into shoulders shall have a minimum cover of 30-inches. (See Page 918.012)
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
REQUIRED MINIMUM COVER FOR LONGITUDINAL UNDERGROUND INSTALLATIONS
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
(f)
Pedestals, fire hydrants, markers or other above ground utility appurtenances installed as a part
of underground utility facilities shall be located at or as near the highway right-of-way line as
practical. In all cases they must be outside the clear zone.
(g)
Manholes will not be permitted in the median, pavement or shoulder of the highway in rural
areas, nor will they be permitted in the median, pavement or shoulder in urban areas except
where this practice is shown to be impractical or creates an undue hardship.
(h)
Provisions shall be made in the overall installation of underground facilities to provide shut-off
valves or sectionalizing devices in order that segments of the facility may be taken out of
service promptly in case of damage or failure.
(i)
Water mains and water service lines in excess of two inches in diameter and sanitary sewer
mains crossings normal to and under the traveled way of existing highways shall be encased
when installed by boring or pushing under the traveled way. Length of encasements shall be
consistent with paragraph (3), subparagraph (g) of these rules and regulations. Water mains,
water service lines, or sewer mains installed and/or relocated during construction or
reconstruction of the highway may be installed without an encasement when trenched
construction consistent with the Department of Transportation’s standard specification for pipe
structures is utilized.
(j)
Sanitary sewer force mains shall be constructed of durable mechanical joint or lock joint
material when located on highway bridge structures.
(3)
Pipelines or Transmission Lines Carrying Flammable, Corrosive, Expansive, Energized or Unstable
Transmittants.
(a)
This section applies to interstate and intrastate carriers whose facilities are operated as pipelines
or transmission lines as defined by applicable ANSI Standard Code (Example: Definition of
pipeline or transmission line as set in Section 805.62 of ANSI Standard Code for Pressure
Piping, Gas Transmission and Distribution Piping Systems, ANSI B31.8-1968).
(b)
For all crossings, the angle of crossing shall be based on economic considerations of practical
alternates. The crossing shall be located as near normal to the highway alignment as practical.
(c)
Conditions which are generally unsuitable or undesirable for crossings shall be avoided. These
include locations in deep cuts; near footings of bridges and retaining walls; across intersections
at grade or ramp terminals; at cross drains where flow of water, drift, or stream bedload may be
obstructed; within basins of an underpass drained by a pump if pipeline carries a liquid or
liquefied gas; and in wet or rocky terrain where it will be difficult to attain minimum cover.
(d)
Longitudinal installations of pipelines or transmission lines within highway rights-of-way will
be considered only in extreme hardship cases. Each request will be considered on its own merits
subject to the following conditions:
1.
Longitudinal installations on conventional highways in rural areas shall be located as
near the right-of way line as possible and alignment shall be as near uniform as practical.
The structural integrity of the traveled way, shoulders, and embankment; and the safe
operation of the highway shall be maintained in all instances. Highway drainage shall not
be impaired by the installation.
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
2.
Longitudinal installations oil conventional highways in urban areas shall be located as
near as practical to the right-of-way line. In any event they shall be located so as to be
removed train the traveled way as far as possible. installation in these areas pose special
problems and require special design consideration to provide the most feasible solution
where minimum widths of right-of-way are available.
(e)
Vertical and horizontal clearance between a pipeline and highway structures or other highway
or utility facilities shall be sufficient to permit maintenance of the pipelines and the other
facilities
(f)
The following controls shall apply to the burying of pipelines or transmission lines within
highway rights- of-way:
1.
Minimal cover for longitudinal installations shall be consistent with applicable ANSI
Standard Code or orders issued by appropriate governmental authority.
2.
The minimum cover shall be thirty inches below the low point of the highway cross-
section for encased crossings and thirty-six inches for uncased crossings.
(g)
Pipelines or transmission lines may be installed under State highways without using an
encasement pipe under the following conditions:
1.
When trenched construction is utilized in the adjustment of existing pipelines to
accommodate reconstruction of the highway. Wall thickness of carrier pipe, coating and
wrapping, welds and cathodic protection shall be in accordance with applicable ANSI
Standard Code, industry, or applicable governmental codes.
2.
New installations under existing State highways where soil conditions permit the
installation of the carrier pipe at a depth with minimum cover or greater without damage
to its protective coating. Wall thickness of the carrier pipe, welds and cathodic protection
shall be in accordance with applicable ANSI Standard Code, industry, or applicable
governmental codes.
3.
The Department of Transportation will not permit the cutting of pavement of traveled
lanes or excavation of adjacent shoulders for replacement, maintenance or inspection of
uncased pipeline crossings. Excavation of highway rights-of-way will be limited to an
area that will not disturb the highway embankment.
4.
At crossings of uncased pipelines. where the pipeline has a cover less than four feet to
the highway drainage flow line, the side ditches of the highway shall be paved a distance
of five feet either side of the pipeline centerline with concrete at elevation of highway
ditch or at the toe of slope where there is no ditch in accordance with the Department’s
specifications, to alleviate the problem of erosion or damage to the pipeline during
maintenance of the highway.
(h)
Encasement or provision of allied mechanical protection by installation in tunnel or gallery;
grouting by mortar filling borehole annulus; cradling; capping; walling; boxing or jacketing, as
detailed in Appendix #5, shall be required under file following conditions:
1.
For crossings where it is not possible to obtain minimum cover due to other utilities, soil
conditions, water table, local ordinances, or other reasons.
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
2.
All crossings where soil conditions preclude the installation of carrier pipe under existing
highways by boring or jacking without damage to the protective coating.
3.
Where pipelines are located near footing of bridge or other highway structures; across
Unstable of subsiding ground; or near other locations where there may be hazards.
4.
On conventional highways the encasement of mechanical protection shall extend a
distance of five feet beyond the highway embankment or back of side ditch. On curbed
portions of conventional highways the encasement or protection provided shall extend to
the back of curb or sidewalk.
5.
On freeway highway projects the encasement or allied :mechanical protection shall
extend the entire width of the rights-of-way including adjacent frontage roads where
topography will permit replacement or maintenance of the pipeline. Exceptions to the
length of encasement will be considered on freeway project: where the pipeline crossing
is located in an area where the median width is in excess of eighty feet or overall right-
of-way width is greater than normally acquired for the type of highway involved and in
areas where topography precludes use of encasement to repair or replace the carrier pipe.
(i)
Every pipeline or transmission line shall be identified by a permanent marker at the right-of-
way lines or as near thereto as possible.
(j)
Encased crossings shall be vented in order that gases may be exhausted or evacuated from the
encasement pipe. Vents shall be placed at the high end of short casing,, and at both ends for
casings greater than 150 feet in length. Vent standpipes shall be located at or as near to the
right-of-way line as possible so as not to interfere with maintenance of the highway and in a
place where they will not be obscured by vegetation.
(4)
Gas Mains, Gas Distribution Mains and Gas Service Lines.
(a)
For all crossings, the angle of crossing shall be based on economic considerations of practical
alternatives. The crossing shall be located as near normal to the highway alignment as practical.
(b)
Conditions which are generally unsuitable or undesirable for crossings shall be avoided. These
include locations in deep cuts; near footings of bridges and retaining walls, across intersections
at grade or ramp terminals; at cross drains where flow of water, drift, or stream bedload may be
obstructed; within basins of an underpass drained by a pump if a main carries a liquid or
liquefied gas; and in wet or rocky terrain where it will be difficult to attain minimum cover.
(c)
Longitudinal installations on conventional highways in rural areas shall be located as near the
right-of-way line as possible and alignment shall be as near uniform as practical. The structural
integrity of the traveled way, shoulders, and embankment; and the safe operation of the
highway shall be maintained in all instances. Highway drainage shall not be impaired by the
installation.
(d)
Longitudinal installations on conventional highways in urban areas shall be located as near as
practical to the right-of-way line. In any event they shall be located so as to be removed from
the traveled was as far as possible. Installations in these areas pose special problems and require
special design consideration to provide the most feasible solution where minimum widths of
right-of-way are available.
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
(e)
Vertical and horizontal clearance between a gas main or gas distribution main and highway
structures or other highway or utility facilities shall be sufficient to permit maintenance of the
gas main or gas distribution main and other facilities.
(f)
The following controls shall apply to the cover over gas mains, gas distribution and gas service
lines within highway rights-of-way:
1.
Minimum cover for longitudinal installations shall be consistent with ANSI Standard
Code USAS B31.8 or orders issued by appropriate governmental authority.
2.
The minimum cover shall be thirty inches below the low point of the highway cross-
section for encased crossings and thirty-six inches for uncased coverings.
(g)
Gas mains, gas distributions mains or gas service lines may be installed within highway rights-
of-way and under the traveled way of highways without encasement under the following
conditions:
1.
When trenched construction is utilized in the adjustment of existing facilities to
accommodate reconstruction of the highway or installation of new mains or service lines
within highway rights-of-way. Wall thickness or carrier pipe, coating and wrapping,
welds and cathodic protection shall be in accordance with ANSI Standard Code for
Pressure Piping Gas Transmission and Distribution Systems ANSI B31.8 or orders of
appropriate governmental authority.
2.
Crossing under existing highways where soil conditions permit the installation of the
carrier pipe without damage to its protection coating. Wall thickness of carrier pipe,
coating and wrapping, welds and cathodic protection shall be in accordance with ANSI
Standard Code for Pressure Piping Gas Transmission and Distribution Systems. ANSI
B31.8
3.
At crossings of uncased pipelines the side ditches of the highway shall be paved a
distance of five feet either side of the pipeline centerline with concrete at elevation of
highway ditch or at the toe of slope where there is no ditch in accordance with
Department of Transportation specifications to alleviate the problem of erosion or
damage to the gas main during maintenance of the highway.
4.
When a gas main or gas distribution main or gas service line is adjusted to accommodate
highway construction and an uncased crossing of the highway is proposed, consideration
shall be given to future replacement or maintenance of the facility at locations where it
would be impractical to borer or jack a replacement pipe under the highway. Provision
for replacement at such locations may include, but is not limited to:
(i)
A casing enclosing the carrier pipe.
(ii)
A spare encasement pipe.
(iii)
Enlargement of the carrier pipe to a size sufficient to be used as a casing.
(iv)
A gallery or box culvert for future installation of carrier pipe.
5.
The Department of Transportation will not permit the cutting of pavement or traveled
lanes or excavation of adjacent shoulders for replacement, maintenance or inspection of
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
uncased gas main crossings. Excavation of highway rights-of-way will be limited to an
area that will not disturb the highway embankment.
(h)
Encasement or provision of allied mechanical protection by installing gas mains or gas
distribution in tunnel or gallery; grouting by filing borehole annulus; cradling; capping; walling;
boxing or jacketing; as detailed in Appendix #5, shall be required under the following
conditions:
1.
Crossings where it is not possible to obtain minimum cover due to other utilities, soil
conditions, water table, local ordinances, or other reasons.
2.
Crossings where soil conditions preclude the installations of carrier pipe under existing
highways by boring or jacking without damage to the protective coating.
3.
Where pipelines are locate near footing of bridge or other highway structures; across
unstable or subsiding ground; or near other locations where there may be a hazard.
4.
On conventional highways the encasement or mechanical protection shall extend a
distance of five feet beyond the highway embankment or back of side ditch. On curbed
portions of conventional highways, the encasement or protection provided shall extend to
the back of curb or sidewalk. On freeway highway projects the encasement or allied
mechanical protection shall extend the entire width of the rights-of-way including
adjacent frontage roads where topography will permit replacement or maintenance of the
carrier pipe. Exceptions to the length of encasement will be considered on freeway
projects where a gas main or gas distribution main is located in an area where the median
width is in excess of eighty feet or overall rights-of-way width is greater than normally
acquired for the type of highway involved and in areas where topography precludes use
of encasement to repair or replace the carrier pipe.
(i)
Crossings of the highway shall be identified by a permanent marker placed at the right-of-way
lines or as near thereto as possible. In all cases they shall be located so as not to interfere with
maintenance of the highway.
(j)
Encased crossings shall be vented in order that gases may be exhausted or evacuated from the
encasement pipe. Vents shall be placed at the high end of short casings and at both ends for
casings greater than 150 feet in length. Vent standpipes shall be located at or as near to the
right-of-way line as possible so as not to interfere with maintenance of the highway and in a
place where they will not be obscured by vegetation.
(5)
Roadway Lighting
(a)
The Department of Transportation has developed these rules in an effort to provide a safe,
effective and economical lighting system. This can be obtained by utilizing greater mounting
heights which results in a more uniform illumination with fewer poles, by using break-away
supports and by placing the supports a sufficient distance from the edge of the travel way. The
following are prime considerations:
1.
Emphasis on minimizing maximum to minimum footcandle ratios.
2.
Optimizing average to minimum footcandle ratios.
3.
Providing adequate levels of illumination.
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
4.
Minimizing the amount of glare.
5.
Reducing the number of poles required.
(b)
New lighting installations on the State system of roads will be reviewed by the Department of
Transportation on the basis of the following criteria:
1.
Minimum Mounting Height-45 feet. In the relocation of utility poles on State highway
rights-of-way, every effort shall be taken to relocate these poles to provide for their use
for roadway lighting. This will provide an economical system, allowing utility poles to
be used for street lighting as well as electrical distribution. It will also reduce the number
of the fixed objects most frequently involved in motor vehicle accidents.
Where electrical distribution or communication lines are in existence, mounting heights
less than 45 feet may be approved in order to utilize existing poles to the full extent;
however, the effectiveness of a satisfactory lighting job should not be jeopardized just to
use existing poles.
2.
Pole setback from the edge of pavement-20 feet minimum, or at the right-of-way line if
located less than 20 feet from the edge of pavement. In urban areas, poles shall be
located as near to the right-of-way line as possible, but in no case shall they be less than
2 feet from the face of the curb. Where a utility strip or grass plot is located between the
face of curb and the sidewalk, poles may be allowed in this area if they can be set at least
2 feet from the face of the curb. All installation must meet the minimum requirements set
by the National Electric Safety Code.
3.
Poles shall not be set in the median of the roadway, except where a 20 feet minimum
setback can be obtained, or where protected by guardrails already existing because of
other safety considerations.
4.
Mast Arm Length-Provision shall be made for the horizontal distance from the lamp to
the edge of the pavement to be no greater than 5 feet, except as dictated by approved
special lighting design.
5.
Maximum maintained average horizontal footcandle level shall be used as recommended
in the latest edition of the AASHTO Publications “An Information Guide For Roadway
Lighting”.
6.
Maintenance factor-as suggested by the manufacturer.
7.
Maximum allowable uniformity ratio 3.00:1 based on Average/Minimum Horizontal
Footcandle Level.
8.
Maximum allowable uniformity ratio - 6.00:1 based on Maximum/Horizontal Footcandle
Level.
9.
Concrete pole bases preferably should be flush but shall not extend over 4 inches above
ground level.
10.
Luminaire pole mountings shall be of an approved AASHTO breakaway type. in urban
or highly developed areas where travel speeds are low and pedestrian activity high,
consideration will be given to the installation of non-breakaway mountings where there
is eminent danger of an impacted support striking a pedestrian, private property or other
RULES AND REGULATIONS FOR ACCOMMODATING UTILITIES
CHAPTER 1680-6-1
WITHIN HIGHWAY RIGHTS-OF-WAY
traffic. Poles to be located behind existing guardrail, rock bluffs, embankments or ditches
are not required to be the breakaway type.
11.
Poles used in a lighting system required to be located greater than 20 feet front the edge
of the highway due to physical constraints and not meeting acceptable uniformity ratios
should be designed using offset lighting applications.
12.
Luminaires mounted 45 feet above the pavement on bridges often become inoperable
because of excessive vibration from traffic. Therefore, the mounting height for bridge
lighting may vary, Light standards may be installed 30 or 35 feet above the pavement if
appropriate uniform ratios can be achieved for that portion of the design. If satisfactory
uniform ratios cannot be obtained for the design using the shorter mountings, mountings
of 40 to 45 feet should be considered for the lighting design. All luminaries mounted on
bridges must be approved by the Structures Division.
13.
Transitional lighting should be provided when the average maintained horizontal
footcandle level of illumination for lighting designs exceeds 1.00 footcandles. The
roadway sector requiring transitional lighting should be illuminated so as to allow the
motorist’s eyes to adjust to a different level of illumination and should be traditionally
illuminated for no less than 15 seconds. The level of illumination for transitional lighting
sector should be equal to approximately one-half of the preceding higher lighted sector.
The terminal illumination in the lowest sector should not be less than 0.25 footcandle nor
more than 0.5 footcandle. An expedient formula for calculating the required roadway
lengths for transitional lighting is as follows:
L = (RS) (C) (T)
Where L = Length of Transitional Lighting
RS = Running Speed Along Roadway Section in MPH
C = 1.47 (Converts MPH to Feet per Second)
T = 15 See (Recommended exposure time to allow motorist’s eyes to adjust to
different level of illumination).
14.
Transitional lighting is best provided by maintaining the same average spacing and by
using lower wattage lamps. This allows for future extension of the lighting system
without having to relocate mountings.
(c)
The Engineering Director of the Department of Transportation’s Maintenance Division will be
responsible for reviewing and approving all requests for roadway lighting on existing
conventional highway projects. Requests for roadway lighting on existing freeway projects will
be reviewed and approved by the Engineering Director of the Design Division.
(d)
It is recognized that certain locations will not permit installation of lighting consistent with
these rules and regulations in every respect. In such cases the proposal submitted to the
Department of Transportation will be reviewed by the Engineering Director of the Maintenance
or Design Division and forwarded along with recommendations to the State Transportation
Engineer for approval or disapproval of the installation.