Tenn. Comp. R. & Regs. 1680-06-01-.06 - LOCATION AND ALIGNMENT CRITERIA FOR INSTALLATION WITHIN HIGHWAY 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.

(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)

REQUIRED MINIMUM COVER FOR LONGITUDINAL UNDERGROUND INSTALLATIONS

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(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.

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.

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.

(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 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.

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 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.

Notes

Tenn. Comp. R. & Regs. 1680-06-01-.06

Original rule filed August 8,1983; effective September 7, 1983. Amendment filed July 20, 1984; effective August 19, 1984. Amendment filed February 1, 1989; effective March 18, 1989.

Authority: T.C.A. § 4-3-2303(2).