tower fall zones in city limits?

[Lackey]

I'm trying to educate myself on if there is a standard for tower fall zones within city limits. Any type of tower at any height. Some at the city I'm trying to work with doesn't seem concerned at all (no additional setbacks other than being treated as a structure, like a building, at this time). Some 100ft towers and higher are built here 5 feet from commercial buildings across the street from houses. I am doing this as a concerned citizen, not an engineer.

Also, is there any kind of reporting for tower falls that I could research? It's the fall zones I'm researching.

Thanks for your feedback!

 

[TLHS]

What type of towers are you talking about? What were their design conditions?

If the towers are build to the same criteria (load return periods, load factors, etc) as the surrounding structures I don't know why you'd need spacing more significant than you would between adjacent buildings. The goal would be for them not to fall...

 

[TLHS]

"built to" not "build to"

 

[cvg]

it all comes down to risk. you would need to know what kind of safety factors were used to determine risk of failure. Also, if they have addressed all likely failure modes in the design. earthquake, wind, corrosion and fatigue come to mind. I'm not sure why the towers would ever have similar return periods as the surrounding structures or why that would be useful. Large radio and television towers generally have very large setbacks, not 5 feet. I lived next to one for a while and if I recall correctly, the setback was approx equal to the height of the tower (I'm guessing about 200 feet).

 

[Lackey]

What has gone through is mostly monopoles at this time-a few lattice. No less than 80ft. Cell and point to point radio seems to be what's on most of these towers. Everyone wants there own and since there is not sharing requirements, there are lots of them popping up for our town of 20K. Without any setbacks for towers, yes, they can be 5 ft if the zoning of the lot allows that for any structures (like commercial). At the most, 25 ft for being adjacent to residential. My kids can play in our own yard 25 ft away from a 200ft tower. There is no limit on the tower height and with no fall zone, no additional setback.

Planning has told me as long as an engineer has stamped the drawings with the permit, it's approved basically automatically as long as the building/structure setbacks are there. They trust no one would build something that would have little/weak safety factors. No input, no explanation of failure modes, no load factor considerations, no rules.

p.s. some of those I'm trying to persuade don't believe monopoles can catch on fire, or that one can fall over total height

 

[OHIOMatt]

Lackey, your statement regarding no rules etc. is not true at all. All structures are governed by codes or regulations that are typically adopted as law. A professional engineer must be resposible for the design and a reviewing agency must approve the design (permitting process). Often, as a part of the permitting process design calculation are requried.

The tower, has gone through the same or a similiar process to the commercial buildings in your jurisdiction.

 

[SteelPE]

I'm not an expert with these types of structures, but how many of them actually fall down? I don't think I have heard of any.... but then again, if a cell phone tower falls down does anyone care (would it be news worthy)?

As OHIOMatt states above, these structures would be designed just like any other structure. The engineer who is placing his/her seal on the drawings is stating that they have designed/reviewed the structure and that it complies with the jurisdictions building code requirements. If that is not true and something happens more than likely the engineer will loose their license to practice (an basically loose their way of earning an honest living). I doubt an engineer is going to cut corners and risk their license.

Sounds like you may be irritated that someone has to put a cell phone tower next to your house. Maybe you should push your jurisdiction to place restrictions on the locations you can place these towers possibly include some minimum set backs. Look on the bright side, at least you get good cell reception.

 

[JStephen]

I would like to point out that a lot of antennas are built in large lots because they have guy wires that cover a large area as well.

In some cases, additional room may be required for the erection of the structure.

 

[cvg]

according to Google, it appears that more people die from falling off the towers than from the towers falling on them.

http://www.metrowestdailynews.com/multimedia/x1278516165/Cell-phone-tower-collapses-in-Wellesley

 

[SteelPE]

JStephen,

Now a tower with guy wires is something somebody in cold weather should be a little scared of. My old boss once showed me a structure he did for a local television station. The structure was used to protect another structure from the falling ice from the tower. The station would sometimes loose equipment because the ice would come smashing through the roof and destroy the expensive equipment inside. His solution was to place a new roof above the existing using steel joists. The joists supported a heavy grating a few feet above the existing roof. The grading would break the ice into smaller sizes that wouldn't go through the roof. I guess it worked because he showed it to me many years later.

 

[Lackey]

Sorry about the long response, but wanted to address everyone.

OHIOMatt, no, there are no local requirements. Local Planning assumes the federal government has something that is appropriate for rules and that should suffice. Don't believe there is any state. Planning will approve the permit without doing any calculations. The only commercial building process here is to make sure inspections for electrical/plumbing is done, proper parking and the structure setbacks.

SteelPE, yes, the engineer would be in big trouble if designs are flawed and should not risk his/her reputation by stamping it. That is the argument Planning gave me. No verifying the engineer's credentials (like they are really licensed and not a fake-I doubt that would happen).
I have read in another thread here of an engineer asking for help because his boss (who is also an engineer) is ordering him to occasionally cut corners. hmmm.
As for can a monopole really fall?

http://www.firehouse.com/news/10530195/oswego-new-york-cellular-tower-crushes-chiefs-vehicle

https://www.youtube.com/watch?v=0cT5cXuyiYY

It can even happen to the fire department. I have verified with my local fire chief, protocol is to attend burning (of a monopole) to make sure the surrounding area has nobody in the danger/fall zone, but to do nothing about the tower itself except call the owner. Let it burn.
If you want the google earth address for a lattice fall (600 ft) not to far away from me, I can post it also.
I have been pushing for two years on ordinance (city is run by a lawyer who has better things to do). I hope to finally have something this spring. I don't use this cell company so reception doesn't matter. Nice thought though. Yes, I'm a little bitter at having my property value reduced and my safety compromised. Ever seen what happens when you drop a wrench from 100 ft up? or left one up there. I know a tower climber (with safety training) who this happened to. Should my kids wear helmets?
Real fear? Liability. Tower falls on my farm fence (yes, I'm in city limits). Farm animals escape and get hit by a car on one of the two adjacent highways that straddle the property. Guess who gets sued? This is my fault how?
Love the grate idea for falling ice! We have had this problem so will pass it on.
Not one of ours but makes the point:

https://www.youtube.com/watch?v=pfBp2QYOIbc

JStephen: guy wired towers usually do not extend out on the ground the equivalent of the full height of the tower.

cvg: I would agree...as long as you are not sitting in the fire departments truck (see above firehouse link Last week a platform jumper didn't let go of his parachute fast enough on a tower we have equipment on. 400ft. Tower even didn't have to fall to kill him. (btw, he broke in a secured area to do this)

http://www.kansas.com/2013/01/04/2624813/kan-daredevil-dies-in-leap-from.html

I can find an unofficial listing of deaths of BASE jumping, but nothing on tower falls.

 

[cvg]

there is a list on wikipedia for tower falls