Home PCDS ELCI/GFCI Reducing Cost Media Photo Gallery Contact
As we begin 2008 many state department of transportation’s (DOT’s) are still just now becoming familiar with the recent publication from AASHTO - Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals – 2001. Among other items that make this new guideline from AASHTO significant, is what is found within 12.5.3. This section states the requirements to ensure predictable and safe displacement of the breakaway support. In particular, section 12.5.3 (c) deals with the electrical components of a breakaway structure. This is significant because it is the first time AASHTO has issued guidelines (other than the 1998 Interim specification) directing designers to utilize electrical disconnects specifically designed to compliment the breakaway pole or structure. The issuance of this guideline is predicated upon several factors including:
1. Field observations and feedback of electrical hazards present in downed poles across the U.S.
2. Reports of lawsuits against DOTs and consultants where resulting hazards from pole knockdowns have been the cause of injury or death.
3. McGraw–Hill’s 1996/2003 publication - Highway Engineer’s Handbook - where the impending electrical hazard at the site of downed poles is discussed in detail.
4. The recommended change in breakaway support wiring published by the FHWA in the National Highway Institute – Highway Safety Appurtenance Course #38034.
Although AASHTO’s 1998 Interim specification contained more detail with regards to the “how to” and performance criteria of a safe electrical disconnect system, the language was only suggestive as seen by the use of the words “SHOULD”. In the 2001 guide, AASHTO has revised their language going from a detailed suggestion (“should”) to an absolute requirement as indicated by the usage of the word “SHALL”.
The key language in the new specification reads, “Upon knockdown, the structure shall electrically disconnect as close to the concrete foundation (pole base) as possible.”
A review of any state’s current knockdowns as compared to new systems available on the market and referred to within both the Highway Engineer’s Handbook and the FHWA-NHI Highway Safety Course is needed to determine whether or not a particular state’s current specification adheres to the AASHTO guideline. An assessment of most states today indicate that their current wiring method or system would not comply with the new criteria. Failure to comply with the AASHTO guideline could have several detrimental effects. For example, the Code of Federal Regulations (23 CFR 625) requires National Highway System (NHS) and Federally funded projects (including lighting) to follow the minimum guidelines set forth in AASHTO’s Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals. Variance from the minimum guidelines found within this AASHTO publication can result in a failure to receive federal funds for the respective project and/or unnecessary exposure to lawsuits based upon gross negligence wherein punitive damages can be awarded against an individual engineer.
There are systems available today that can assure compliance with AASHTO and reduce, if not eliminate, future liability in the event of injury or death attributed to electrical wiring of a breakaway structure. If you are a design professional, it is your duty in design to provide the highest practical and feasible level of safety for people and property associated with the Nations’ Highway Transportation Systems, and further, to reduce highway hazards along with the resulting number and severity of accidents on all the nation’s highways. I encourage all DOT engineers and consultants to conduct due diligence in staying abreast of both newly issued design guidelines, published recommendations as well as the technological advances that can save lives and maintenance dollars.
**Also of note in the new AASHTO Specifications is the requirement for breakaway supports to be tested with breakaway wiring devices in place [ section 12.5.1( j ) ]. In the past, poles were tested “hollow” without any wiring whatsoever thereby eliminating a consideration that may very well adversely affect the trajectory of the pole during knockdown.
The complete set of specifications is available from the AASHTO bookstore (www.aashto.org)
-Martin A. Maners, III
|To learn more about the American Association of State Highway and Transportation Officials and/or their Highway Standards, please visit the official website www.aashto.org|