My boss says look the other way? 17

[transmissiontowers]

I am a structural engineer and have been working for over 30 years analyzing transmission towers and poles that support wire. My boss is an Electrical Engineer with a PE. His boss is a business major. The Vice President is a Mechanical Engineer.

The problem is the analysis of towers with a skewed wind angle. Due to geometry, a wind at an angle will produce maximum loads and cause leg failure. If the wind is only considered normal to the wires, the legs are OK.

Back in the old days, we did not have the software tools to consider skewed wind. With better PC's and better software, we can now analyze hundreds of wind angles and determine which wind angle will control.

My EE boss says it is a management decision of risk vs reward and it costs too much to fix the towers when adding more equipment to the tower. As a PE, I feel it is my duty to inform him that it is my opinion that the tower will fail if the wind hits the maximum design wind speed and at the most critical direction.

The NESC code we work under has some generic guidance that the wind at an oblique angle may cause higher loads. Guying the tower inline will help brace it and reduce the leg loads to acceptable levels, but it costs more and the construction folks don't like to do it and are concerned with trucks running into the guy wires.

I have been told to ignore the oblique wind direction and allow the extra equipment to be installed on the towers. I have a few options:
1) State my concerns to the manager and let him decide
2) Run the oblique wind cases and note the failures, then run the normal wind case and note the loads and write a note in the file that the tower will fail in the right conditions.
3) Prepare a letter and have it signed by the EE and his boss that they are aware that the tower may fail.
4) Report my EE boss to the State Board of Registration for ethics violations.

Is it ethical for the EE to order me to look the other way?

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[JAE]

Ha....here's a VERY similar example for you - a building where the diagonal winds weren't first considered, then later considered and found to be a huge problem....this is one of those classic ethics text-book cases.

Read it:

http://onlineethics.org/moral/lemessurier/4.html

 

[transmissiontowers]

"...what method do you use for analyzing transmission towers? What frame progra? Is there a standard for loading/design? Is there an on line *.pdf file? "

I can talk on this subject for hours, so be prepared to be bored. The software is from Power Line Systems and can be found here:

http://www.powline.com/products/tower.html

It is a comprehensive line design program. You do a structural model of the lattice tower or pole (steel, wood, concrete) and we have over 5000 individual structural models in our library. You place the towers in a line and string a cable element between the structures. You then can pick a structure or range of structures to analyze with a FE program. The program runs a sag & tension program to determine the wire tensions for the wind and temperature and passes the loads to the tower program which runs the analysis for each load case you have specified which can include wind from an arbitrary angle.

All this takes place in about a minute depending on the number of joints in the tower and the number of load cases you specify. The work done in 5 minutes is equivalent to what took weeks to do when I started analyzing towers 30 years ago.

The prep work of modeling the lattice towers is what takes the time (about a week for each one) and the line layout takes several days. Browse around the PLS web site to get an idea of the graphics and I think there is a PDF demo available.



_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[dik]

Thanks, Dik

 

[kontiki99]

I saw the term whistle blowing in one of the earlier posts.

I think it's good to not be naive. It may not be so much what you need to do, but how you do it that makes the difference.

I found this old article, I think it contains some good advice and references.

http://kontikilink.home.mindspring.com/01279195.pdf

 

[stevenal]

"Safety is being compromised for the sake of economics."

Impossible in my opinion, at least in the USA. In the long run, fines and jury awards make safety the most cost effective alternative.

 

[civilperson]

Transmission lines and the associated towers are designed with the knowledge that a simultaneous breaking of the conductors on one side of the tower will fail the tower,(or winds greater than assumed in design or wind on ice). A moderation element is usually incorporated in every tenth or so tower, a "fuse", which stops the progressive failure,(domino like collapse). This strong tower is able to with-stand dead end forces, (all conductors on one side, wind, etc.). The spacing of the strong towers is an actuarial decision, taking into account the cost of replacing X many towers and lines vs. frequency of failure.

 

[epoisses]

"Safety is being compromised for the sake of economics."

Well at some point you have to, you can't build everything like a nuclear shelter. But it has to be a conscious and transparent decision.

 

[btrueblood]

What is the cost of replacing a several miles of line and several dozen towers, once every 50 years, compared to the one-time cost of adding a few braces and/or guy wires on each tower that is already having a crew working there to tie antenna structures to it?

Being a resident of the Seattle area, and having survived 8 days without power after our big windstorm last month, I'm considering copying your post and emailing it the the local papers. Wondering if similar decisions resulted in our area's main towers over the mountains going down. Geez, now I'm simmering. To my first paragraph add: what is the cost of the extra PR funds the utility will have to spend to recover from the public opinion debacle if a Seattle-like disaster was linked (even if only tenuously) to a decision like the one you're debating with them.

 

[dtn6770]

Oh let's not get the media involved. Next thing you know the State of Texas will catch wind of it and subpoena the site for as much information about transmissiontowers as its got. I'm not paranoid but I could see it play out that way or something close to it.

 

[transmissiontowers]

btrueblood; Please don't send my frustrations to the media. I can just ignore the request and analyze the tower for the loads I want and no one above me would know the difference. This is one of the plusses of having more knowlege than the people that manage your work, they have no clue if I did what they told me to do or not.

Civilperson; Yes, some utilities in heavy ice areas will use "stop" structures especially in H-Frame lines where the longitudinal strength is so low there is a possibility of a cascade failure. If the latice tower has enough long. strength and the insulators are long enough, the cascade will not go past 2 or 3 towers where the tension will drop off due to the slack in the system in the case of a broken wire.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[sdl]

My comment "Safety is being compromised for the sake of economics" was meant for that particular situation and not meant as a generality. We cannot remove all risk from any situation. What we can do is manage it and reduce our exposure to risk by taking certain steps, in this particular case, engineering. It does sound like the EE is making a decision that he might not be qualified to make and leaning towards what he does know - financial impact.

The term ALARP (As Low As Reasonably Practical) comes to play. If the towers are not reinforced, what is the likelihood they will fail? The next question is: Is that likelihood something we (the company) can accept? If it is, then they will not guy the towers.

Just because we get hit with a 1/100 year storm, do we now upgrade all of our design to meet that, even if what we are building probably will not be standing 100 years from now?

The reason I posted to this discussion was the view point that someone was making a decision that could injure or otherwise affect people without "really" considering all of the facts. Safety must be paramount in our designs and our work. We must perform our work in such a manner that we are reducing the risk to humans to a level that is socially acceptable. We do not have an obligation to reduce it further.

 

[stevenal]

"Just because we get hit with a 1/100 year storm, do we now upgrade all of our design to meet that, even if what we are building probably will not be standing 100 years from now?"

The NESC is pretty clear on this point. Old installations must be maintained at least to the level of the code in place at the time of installation. New must meet the latest code.

Please understand this particular safety decision is not one that transmissiontowers or his boss can make. In most states, the code has the force of law behind it. Try to visualize your turn on the witness stand explaining to Johny Cochran why laws and standards representing accepted engineering practice were ignored.

 

[michfan]

Umm, Johnny Chochran died a couple of years ago...

And I watched the OJ trial, he'd have figured out a way to get you off...

 

[MillR]

Btrueblood: to say "I'm considering copying your post and emailing it to the local papers" compromises the engineer's ability to anonymously gather peer opinion. An accusation has not been made, only an ethical question raised.

 

[civilperson]

Safety is a nebulous concept when interjected into engineering decisions. That is why we lean so heavily on codes and standards. The following of a code is what a prudent engineer will do when no other knowledge is available. The code is risk based in that some level of loading will compromize the integrity of the structure and this upper level of loading is rare and acceptable.
The electrical transmission sytem is built in the middle of generous ROWs that usually confine any failure to the utilities land,(protecting the public). Lack of power for some interval is an inconvenience not a hazard. That is why hospitals and casinos have generator back-up, they can not afford to be out of business due to electrical gaps.

 

[mrMikee]

I agree that these discussions should remain within the forum and be discussed by people who have an interest being here.

-Mike

 

[transmissiontowers]

I took btrueblood's comment as a joke due to his frustration and my response was in a joking manner. Life is too short to be serious all the time.

To answer a couple of the points raised, the towers fail on paper (pixels on the screen) if the wind is at the correct oblique angle. Whether they would fail during an actual wind event is the big question. The design of lattice towers is covered in ASCE Std 10. The big unknown is the way wind on the structure is calculated. The towers are so large that there is no wind tunnel large enough to hold them. We apply our best guess and calculate wind on the members and assume a drag coefficient on the members.

Full scale tests are done to verify designs, but the application of the calculated wind loads is done with cables and winches, so you do not really apply a distributed wind on the structure. You are applying a point load meant to represent a uniform load which you calculated based on many assumptions.

Will the tower fall during a real wind event? We make every effort to make sure it does not. We use a pseudo LRFD approach in design. Overloads are applied to the loads and for the high wind they are 1.1 or 1.2 and the members are allowed to go to their yield or limiting condition such as buckling. The NESC specifies a minimum OLF of 1.0 so there is not a huge safety factor on high wind. When full scale tests are done, the ideal failure point is between 100% and 110% of the load. Any greater than 110% is cause for a redesign to remove extra weight.

The idea of wide ROW in a rural setting is true for some areas, but the territories in urban areas cross freeways and are near people, so a failure does not just inconvenience a few cows, it can come down on a freeway. There are not many cars on the road in a 140mph wind storm, but ice events do have the possibility to drop on cars.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[dik]

To all...

I note in the threads that there is some confidentiality required.

I often use google for research and occasionally end up with an Eng-Tips hit. This is the result of a Google search... If you don't want the material to be visible to anyone at any time, you might want to redflag this thread... Your postings here are not unique to this forum...

Tip: Try removing quotes from your search to get more results.
Professional Ethics in engineering Forum - Eng-Tips
My boss says look the other way? Helpful Member! Helpful Member! Helpful Member! Helpful Member! Helpful Member! cjd97 (Structural). 13 replies ...

http://www.eng-tips.com/threadminder.cfm?pid=765

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Dik

 

[jt12]

I definitely wouldn't be (4) reporting your superior to the state board. Since utilities are exempt from building code requirements, and no documents are being sealed, it is somewhat questionable whether a state board would have any power over this situation. Also, since utilities are exempt from building code requirements, correct me if I am wrong, but utilities have no legal obligation to follow the NESC code or any other. If something bad happened, and a tower fell down and killed someone, the utility still needs to have a backup for what they've done. Typically, following an up-to-date code would be the best way to provide back up, but another method could be argued in court.

I have no problem with your boss taking responsibility for making an economic decision based on the above. I do believe you are ethically required to make sure he has all the information needed to make an educated decision. I would run all the numbers ((2) oblique and non-oblique) and present them to him and make sure he is aware of the risk he is taking if something were to fail. If he still decides to do it the old way, I would follow up with either doing what you suggested in (3) or just turning your numbers into an e-mail and sending it to him thus providing a paper trail for yourself.

It should be noted that typically the wireless communication providers like going on top of transmission towers because they can get them permitted much easier, and much faster due to the utilities exemption. If your utility had good salespeople, they would realize this and getting the wireless people to pay for the price of tower upgrades. The wireless people (your customer) also does not want the bad publicity of their antenna falling and killing someone and knocking out service to a region. Or maybe your utility does have good salespeople, and by not upgrading the tower, your company is even pocketing more money.

It would make sense that if a tower is in the middle of nowhere that it could be designed to lesser loads than one within falling distance of a busy road. I've heard rumors that certain codes will eventually be implementing some sort of a factor to acount for this. You could maybe convince your boss to look at wind from any direction in the cases where a failure has a significant probability of a subsequent death.

 

[DRC1]

I don't design transmisso towers, but have designed structures of various types and done significant utility work.
1.) Tirty years ago when designs were done by hand (Wow! is that one of those new pocket calculators? Can I try it?) oblique wind angles were handeled by the design details to ensure they were not the weakest point in the structure. Since design software has made analsyis more exact, design stadards have moved away from this emoperical design. So what was acceptable practice 30 years ago is no longer true.
2.) Codes are established to define risk reward ratios. Based on years of research by a small army of starving grad students, acceptable limits have been established that work. It is impossible to arbitrarily say "30 psf wind load may be code, but 25 psf is good enough for me"
3.) Havng seen this more times than I care to count, if there ever is a failure everyone will forget that some one made a descion not to follow the code. It will be a structural failure and will be laid at your feet. Protect yourself. If you do not like the design do not stamp the drawings. that is your obligation as a PE.
Good Luck with a sticky situation.