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Section 6: Other Maintenance Considerations


Duct Cable

Duct cable is a conduit system and must be treated as such. If the system is damaged the duct may be spliced, however, the electrical conductors in the duct cannot be spliced inside the duct. Depending on the length of the duct run, maintenance personnel may want to remove the existing wire and pull new conductors or consider placing a ground box and splicing the conductors.

If the conductors are spliced, a UL approved compression-type or split-bolt connector must be used to make the splice. Heat shrink tubing or gel caps are the only recommended splice insulators. Where two or more conductors enter one heat shrink tube, wrap the conductors with heat shrink tape. Heat shrink tubing must then be applied to insulate the splice. It is important to note that when duct cable is severed to make a splice, the ends of the duct must be cut straight and neat. Ends must also be reamed to remove sharp edges.

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Prior to about 1975, grout was required to be placed between the illumination pole base plates and concrete foundations. Since then, it has been determined that such grout placement under pole or sign bridge base plates causes moisture to become trapped. This, in turn, contributes to excessive corrosion of the pole, support, base plate, anchor bolts, nuts, and other appurtenances.

It is imperative, therefore, that this grout be removed from under existing poles and not placed under newly installed poles. Anchor bolts should then be cleaned and painted with zinc rich paint. If severe deterioration is discovered, a more detailed investigation should be made into the remaining strength of the bolts.

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Rehabilitation of Old Circuits

For older roadway illumination systems where maintenance requirements are excessive due to faulty circuits, rehabilitation of the circuits by TxDOT should be considered to reduce city maintenance costs.

When practicable, existing two-wire circuits should be replaced with a three-wire system that includes a continuous grounding conductor.

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Maintenance Level of Service

The Maintenance Management Manual establishes guidelines for planning and performing various maintenance activities in accordance with available funds. Three possible funding levels are defined: desirable (the highest), acceptable, and tolerable (the lowest). Maintenance priorities are assigned based on the level of funding, and maintenance forces are directed to “substantially maintain” the various highway components accordingly. Chapter 3 of the Maintenance Management Manual explains the concept in detail, and Section 2 includes the maintenance level of service guidelines for highway illumination.

For general guidelines on maintenance practices related to highway illumination, see the Maintenance Operations Manual, Chapter 4, Section 3.


Maintenance Responsibilities of Cities

Maintenance of freeway illumination systems provided by some cities under agreement with the TxDOT sometimes falls below acceptable levels. Unless an adequate level of lighting maintenance is being provided by a city, no further agreements for city maintained illumination should be executed with that city until corrective action is taken.

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Maintenance problems involving electrical and illumination design and materials should be brought to the attention of TRF so that possible alterations can be made on the Traffic Operations Standard Plans.

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