Attachment of utility lines to a highway structure may be allowed where such attachment shall conform to sound engineering considerations for preserving the highway, its safe operation, maintenance and appearance. The attachment shall be in accordance with the following:

(1) Each proposed bridge attachment should be considered on its individual merits and separately designed so as to be compatible with the appearance of the structure.

(2) Bridge attachment of a utility should not be considered unless the structure in question is of a design that is adequate to support the additional load and to accommodate the utility facility without compromise of highway features, including reasonable ease of bridge maintenance.

(3) Utility positionings on a structure which would inhibit access to any structure part for bridge painting, repair or maintenance should not be allowed. Manholes for utility access shall not be allowed in the bridge deck on overcrossings.

(4) Attachment on a structure of a pipeline carrying a hazardous transmittant shall be avoided where practical.

(5) The utility attachment shall not effectively reduce the clearance of the structure where such clearance is critical.

(6) Generally, utility attachments should be beneath the structure's floor, between the girders or beams or within a cell and at an elevation above low superstructure steel or masonry. Attachment to the outside of the bridges should be avoided where there are reasonable alternatives.

(7) Utility mountings should be of a type which will not create noise resulting from vibration.

(8) The hole created in the bridge abutment shall be of the minimum size necessary to accommodate the utility line. The hole shall be sealed to prevent any leakage of water or backfill material.

(9) The utility line back of the bridge abutment should curve or angle out to align outside the roadbed area in as short a distance as is operationally practicable.

(10) Acceptable utility attachment methods are hangers and/or roller assemblies suspended from inserts in the underside of the bridge floor or from hanger rods clamped to the flange of some substructure member or as otherwise specified by the department.

(11) Utility construction shall conform to applicable codes, standards and specifications.

(12) The utility company shall be responsible for any restoration or repair of any portion of bridge or highway disturbed by the utility installation or use.

(13) Communication and electric power line attachments shall be suitably insulated, grounded, and carried in protective conduit or pipe from point of exit from ground to reentry. The cable shall be carried to a manhole located beyond the backwall of the structure. Carrier pipe and casing pipe shall be suitably insulated from electric power line attachments.

(14) WAC 468-34-210 shall apply to installations on structures.