N.M. Admin. Code § 17.4.2.15

Current through Register Vol. 36, No. 1, January 14, 2025

Section 17.4.2.15 - INSTALLATIONS ON HIGHWAY STRUCTURES

Attachment of utility lines to a highway structure can materially affect the capacity of the structure, the safe operation of traffic, the efficiency of maintenance and reducing the aesthetic appeal of the structure.

A. Where it is feasible to locate utility lines elsewhere, attachments to highway structures should be avoided. However, when installation of the utility at an alternate location proves to be extremely difficult or unreasonably costly, consideration will be given for an attachment of utility lines to a highway structure. The attachment shall be made by a method acceptable to the Bridge Engineer of this Department.

B. All proposed attachment methods shall conform to adequate engineering considerations for preserving the highway structure's integrity, safety, ease of maintenance, and its appearance. In this respect, the following considerations shall govern:

C. Due to variations in highway structure designs and site specific considerations, it is not feasible to completely standardize the method by which utilities are attached to structures. Therefore each proposed attachment shall be considered on its individual merits, and shall be individually designed for the specific structure.

D. Utility line attachments to a highway structure shall not be considered unless the structure in question is of a design, age, and physical condition that is adequate to support the additional load and accommodate the utility without any compromise of the highway features, including reasonable ease of maintenance.

E. Attachment of a pipeline carrying a hazardous transmittant to a highway structure shall be avoided whenever possible. When such an attachment is permitted, the facility design shall be at a level to provide maximum safety.

F. Utility positioning on a highway structure which will inhibit access to any structure part for maintenance shall not be allowed. Utility access manholes shall not be allowed in a structure deck or load carrying member.

G. The entire utility installation on a highway structure shall be so located as to not reduce the vertical clearance otherwise available above river, stream, roadway surface or rails. In general, acceptable utility installations are those designed to occupy a position beneath the deck an in an interior bay of an I Girder Beam, or within a cell of a Box Girder Bridge. Installations shall always be above the bottom of girders on a Girder Bridge or above the bottom of the bottom cord on a Truss Bridge.

H. Utility line attachments to the visible outer portions of structures are unsightly, susceptible to damage, and shall not be permitted unless there is no reasonable alternative.

I. Utility line mountings shall be of sufficient strength to carry the weight of the utility and shall be of a type which will not rattle or loosen through vibrations caused by vehicular traffic. This is a matter of particular concern on steel structures. Utility attachments shall be designed to accommodate differences in thermal movements between the highway structure and the utility.

J. Where a utility facility is to pass through an abutment wingwall or other wall of a highway structure, the utility is required to neatly restore the disturbed construction by approved methods which shall preclude any leakage of water or backfill through the substructure elements. Where such construction is approved, any hole created in the highway structure shall be of a minimum size necessary for the installation. The annular space between the structure and pipe shall be completely filled with grout so as to seal the opening and effectively preclude the leakage of any moisture or backfill material through the substructure. Where a pipe or conduit is to be sleeved (cased) through the structure, the sleeve shall be tight sealed into the opening, and the annular space between the pipe conduit and the sleeve shall be sealed with a Department approved material.

K. Acceptable utility attachment methods are hangers or roller assemblies suspended from the underside of the bridge deck, or from hanger rods clamped to the flange of some superstructure member. Bolting through the bridge floor or deck shall not be permitted. Where there are transverse floor beams sufficiently removed from the underside of the deck to allow adequate clearances for the utility, the Bridge Engineer may consider a proposal to support the utility line on top of the floor beams.

L. Clearances of utility facilities from bridge members shall conform to all governing codes, and shall be such as not to render any portion of the structure inaccessible for any maintenance or other highway function.

M. The utility shall be required to make satisfactory provisions for lineal expansion and contraction of its facility as a result of temperature and pressure differentials. Line bends or expansion couplings are generally used for this purpose.

N. The utility shall restore or repair any portion of the structure or highway disturbed or damaged by utility installation or use.

O. If weatherall steel is utilized in the highway structure, utility attachments shall be of similar material.

P. A pipeline carrying volatile fluids, pressurized gas, water or sewage poses an element of risk when mounted on a highway structure. When such a carrier is placed in a casing pipe of leakproof construction, the hazard to the utility, the highway facility, and the traveling public can be minimized. It is good practice to case all such pipeline attachments through the highway structure. The casing pipe should be carried beyond the back of the structure abutment and be effectively vented at each end to detect leakage and prevent possible build-up of pressure. In addition, all welds shall be tested by non-destructive means.

Q. Where a casing is not provided for a pipeline attachment to a bridge, additional protective measures shall be taken. Such measures shall include, but are not limited to, higher safety factors in design and pressure testing. The safety design factor shall be twice that normally used.

R. Communication and electric power line attachments shall be suitably insulated, grounded and carried in a protective steel conduit or pipe from below the point of ground exit, to below the point of ground re-entry. Carrier pipe and casing pipe shall be suitably insulated from electric power lines.

S. All pipeline attachments carrying gas or liquid under pressure, which by nature of the transmittant might cause damage or injury if the transmittant escapes on or in the vicinity of the highway structure, shall be provided with emergency shutoff valves of automatic design. Such valves shall be placed within an effective distance on each side of the structure. Exceptions to this rule may be considered by the Engineer, upon written justification submitted by the utility.

T. The responsibility of the utility owner requesting a bridge or highway structure attachment cannot be over stressed. The utility shall ascertain the extent of the Department's design requirements prior to initiating the design for attachment. A Registered Professional Engineer experienced in structural design shall be responsible for the design effort. Complete plans showing all details of the proposed work, together with pertinent design documents shall be prepared and submitted, along with the New Mexico Public Highway Utility Accommodation Permit Application. Traffic control plans must also accompany the permit. The plans must be complete and adequate enough to show in detail the full extent of the proposed work.

U. All materials integrated into the design must be certifiable for quality and strength, and full specifications must be provided in support of the design.

U. A complete written justification must support the need for attachment and demonstrate that there is no viable cost effective alternative.

V. All components of the utility attachment shall be protected from corrosion. Steel components shall be galvanized or painted in accordance with current Standard Specifications For Highway And Bridge Construction.

N.M. Admin. Code § 17.4.2.15

3/10/71, 11/15/96; Recompiled 12/31/01