"Ralph Mowery" wrote in
m:

I have 6 sections of Rohn 25 set in a yard of cement. It is guyed at
about 30 feet and about 5 feet under the top of the tower with 3 wires
at each place. I need to remove the wires on one side so I can cut a
tree to keep it from falling on the guy wires.

On top of the tower is about 15 feet of pipe sticking out. About a
foot over the tower is a 3 element triband, and at about 5 feet
spacing is a 5 element 6 meter antenna, two meter,and 432 antenna all
on 15 feet long booms.

Will it be safe to remove the two guy wires on one side of the tower
for about an hour to cut the trees, or should I let the tension off
all the guy wires ?
This would be done when the wind is not blowing.



As you have probably guessed, guy maintenance on towers is a high risk
activity. Lots of seriously large towers have failed because a single guy
was slackened. The taller the tower, the greater the risk.

In any circumstance, slackening (or removing) one guy of a set will
introduce a lateral force that bends the tower. With sufficient weight,
that may lead to buckling and structural failure.

If you remove all guys in a set by progressively slackening each them,
that may not introduce the lateral force describe above, but the greater
length between existing supports may allow buckling and structural
failure.

Can you remove all guys? Is the tower installation designed to be free
standing at reasonable wind velocity?

The safe answer is to consult a structural engineer.

Can you remove the tree without slackening guys and without risking
dropping parts of the tree on the guys? Perhaps cutting the tree into
smaller lengths that are lowered to the ground on ropes to guide and slow
the descent? I have watched tree climbers take huge trees down, lowering
all the pieces in a very limited space against the trunk.

Have you asked your arborist about the removal and the risk to the tower?

Owen

On Thu, 20 Aug 2009 07:55:55 GMT, Owen Duffy wrote:

Perhaps cutting the tree into
smaller lengths that are lowered to the ground on ropes to guide and slow
the descent? I have watched tree climbers take huge trees down, lowering
all the pieces in a very limited space against the trunk.

Here in the Pacific Northwest, tree country, I have never seen any
other way except for when trees are layed over indiscriminately as
part of a clearing operation.

73's
Richard Clark, KB7QHC

In article ,
Richard Clark wrote:

On Thu, 20 Aug 2009 07:55:55 GMT, Owen Duffy wrote:

Perhaps cutting the tree into
smaller lengths that are lowered to the ground on ropes to guide and slow
the descent? I have watched tree climbers take huge trees down, lowering
all the pieces in a very limited space against the trunk.

Here in the Pacific Northwest, tree country, I have never seen any
other way except for when trees are layed over indiscriminately as
part of a clearing operation.

73's
Richard Clark, KB7QHC

Depends on the quality of the crew.... But I always use a good tree
service and don't do it myself, If the tree could hit anything other
then the ground (I've done enough that I've seen them land every
direction, including the direction I wanted)

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