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Call for Members: New Loading Standard for Structures Supporting Overhead Power Lines & Telecommunications Infrastructure

Monday, September 28, 2020

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Development of a new standard ASCE/SEI XX - Minimum Design Loads for Structures Supporting Overhead Power Lines & Wired Telecommunications Infrastructure will begin in 2021. The committee will be seeking new members thru the end of 2020 to begin work on the new edition of the standard. Michael Miller, P.E., Vice President of Engineering and Business Development at SAE Towers, Ltd., will chair the cycle. Practicing engineers, researchers, building officials, contractors and construction product representatives are all needed and welcome. If you are interested to apply for the committee, please submit an application by December 31, 2020 via the link below. Select SEI from the Institute drop down and then "Minimum Design Loads for Structures Supporting Overhead Power Lines & Wired Telecommunications Infrastructure". Carefully indicate the Membership Category for which you are applying. Associate members can be accepted until balloting begins. Eligible regulatory members can qualify for travel reimbursement per ASCE Travel Policy, when applicable. Contact Jennifer Goupil with questions.

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Executive Summary

This work falls under the jurisdiction of the Structural Engineering Institute's Standards Activity Committee within the American Society of Civil Engineers (ASCE). The objective of this work is to establish an ASCE Standards activity for the development of a national consensus Standard governing the minimum design loads, hazard levels, associated criteria, and intended performance goals to be utilized for the design of structures supporting overhead electrical power lines (electrical transmission and distribution structures) and wired telecommunications infrastructure. This proposed Standard is expected to be a complementary to ASCE/SEI 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures. However, it is well recognized in the structural engineering community that there are unique reliability and resiliency requirements for these critical overhead transmission, distribution, and wired telecommunications infrastructure assets that are much different from buildings and other structures generally referenced and described in ASCE 7. This proposed Standard will also provide a critical Loading Standard that can referenced by the various "Strength" Standards (ASCE 10 Design of Lattice Steel Transmission Towers, and ASCE/SEI 48 Design of Steel Transmission Pole Structures.) Other utility structure "Strength" Standards (Concrete Poles, Fiberglass Poles, Wood Poles) will likely be developed over time from the Manual of Practices currently published, and they all will be able to reference this proposed Standard for the Loads to be used. Users of this standard will include electrical utilities, regional and multi-regional developers as part of the FERC Order 1000 process, engineering consultants responsible for the design and construction of these overhead lines, and federal and state regulators.

Background

Currently, those responsible for the design and construction of these lines can only refer to the ASCE Manual of Practice #74, 2020 Edition (MoP #74 - Guidelines for Electrical Transmission Line Structural Loading) or the National Electric Safety Code (NESC) as a basis for the determination of the loading that is used for this critical infrastructure. As the name implies, MoP #74 is a "recommended practice" or guideline, while the NESC is a Code. Historically, the NESC has been used basis for minimum design loads. However, the NESC, as its name implies, has a focus of "safety" and was never been intended to be used for design. The NESC explicitly states it is a Code for "safety", and over the Code's update cycles, has incorporated a very limited set of information on loading. As loading information has evolved, the NESC focus on safety has created a disconnect between the current state of the science, as prescribed in documents such as ASCE-7 and the implementation of this new information in the NESC Code. It is woefully inadequate for use as a set of minimum design loads on overhead electrical lines. The result of not having a consensus Standard is that lines have been developed across the nation with a patchwork of various levels of reliability and resiliency. When new multi-regional high voltage transmission lines are developed under the competitive environment of FERC Order 1000, those lines are based on a wide variety of loading interpretations and inconstancies. When electrical distribution lines are upgraded or new lines installed, many of which carry wired telecommunications lines as a joint-use application, the result is a wide variety of inconsistences that are either woefully inadequate or marginally acceptable structurally, substantially shortening their service life and increasing their lifecycle costs. The scope of this proposed Standards development will be to start with the "pre-standard" that was developed by the last edition of MoP #74 committee (now being published), and take it through the ASCE Standards process to bring it to a fully reviewed and publicly balloted, consensus ASCE/SEI Standard. The new Standard could then be referenced and utilized as minimum loading requirements for transmission lines, distribution lines, substation facilities, and wired telecommunication, providing a consistent approach to design loading across the US industry. Referenced documents are expected to include all known published and applicable sources such as ASCE 7, MoP#74 and the NESC.

Current Activities

The newest and soon to be published version of MoP #74 includes a "pre-standard" appendix. This appendix is intended to be a primer to a future Standard committee's effort to move the MoP #74 to a Standard by providing the industry and public a draft of what a loading Standard might contain. Any feedback will be accumulated and used to help guide the development of the Standard.

Objectives

The objective of this Standard is to provide a mandatory "Standards" document that can be available to other Codes, or to State or Federal regulatory agencies for incorporation into law by reference. It is intended to be to latest scientific knowledge accumulated on transmission and distribution line loading to be used for any new line or upgrade of existing overhead lines. The Standard is a consensus-based Standard keeping within the robust guidelines on ASCE Standard development. 

Benefits to the Public

The benefits to the public that will result from this standard activity include: 

  • Improved reliability and resilience of new transmission and distribution lines designed and constructed utilizing the well-developed, probabilistic loading criteria that is consistent with the wind loads, ice loads, and other load criteria developed by the ASCE/SEI 7 Committee.
  • Since much of the overhead line systems supporting electrical power delivery ("the grid") also support wired telecommunications systems (fiber optic cables for SCADA, data transmission, as well as joint use telecommunication (internet services) improved reliability and resilience of these systems is increasingly a critical public benefit as well as a Utility operational benefit. 
  • Improved cost of new transmission facilities by providing a consistent and scientifically based loading document that can be referenced as a basis for loading, helping to streamline the design process and provide an improved competitive environment for designers and material suppliers of such facilities.

Appointed Standards Committee Chair

It is proposed that the Chair of this Standards activity be Mr. Michael Miller, P.E. Mike has been intimately involved with the last 2 editions of MoP #74, along with many other ASCE MoP's and Standards including ASCE-91, 113, 141, and 10 as well as past ETS Chair. He is well respected within the Electrical Utility Industry.