In addition to the visibility factor for small aircraft pilots, I was always told
(since most of these are found on high-voltage, long-haul transmission lines)
that they were there to help prevent shorting.
Such long cable runs are generally not insulated - the weight penalty would
be enormous. Since said lines are typically arranged in a horizontal plane,
a good gusty wind could easily slap 'em together. The balls keep that from
happening.
Relevant column:
This has always been my understanding too.
Yeah, except a) they’re not found on all long-haul high-voltage lines, and b) they’re found on regular roadside lines as well.
Powers &8^]
And, IME, if they need to worry about them hitting each other they attach insulated spacers to them, not weights that might cause them to sway even more.
Why does Cecil write off the idea that they are bird diverters? I know for a fact from experience in the transmission industry that if you are putting up conductor in an area with a high risk of collision (i.e. near a large complex of playas inside the Whooping Crane migration corridor) you had best have bird diverters on each horizontal plane, or risk running afoul of USFWS and organizations like the Audubon Society.
If you have worked in the transmission industry, can you cite the Federal regulation or USFWS ruling which requires bird diverters?
The Migratory Bird Treaty Act of 1918. The flight diverters are a compliance measure.
What happens is you cannot get a take permit for most migratory birds, so during the routing phase of a project you have a formal agency consultation with USFWS. During that time they will make compliance recommendations such as perch diverters, and flight diverters. Provided the project proponent follows the recommendations, in the event that an incidental take occurs, FWS will use their Prosecutorial Discretion to not prosecute the proponent under MBTA. If you would like I can link you to any number of NEPA documents that spell this process out.
How commonly is this done? I ask because I’ve worked at or visited 2/3-3/4 of all the fossil plants in the US and have never seen or perhaps noticed bird diverters.
If you can link to a specific document, then Cecil will look it over and see if the column needs updating or expanding.
What is a “bird diverter” and a “perch diverter”, and what do they look like?
As a child, I lived near an airport in a rural area, and there were plenty of those red balls on the power lines in the area. Especially on the power lines that were on top of a hill, or along fields and roads near the runway. I was told it was for the airplanes.
I have seen plenty of power lines being used as roosting sites for birds, with nary a fried corpse in sight. I can’t imagine how birds would be at significant risk. They are a lot smaller than airplanes, and thus have a lot finer flight control, and get much closer before there is navigation risk, given that they actually land on the darned things.
Now with regards to windmills, I have heard of the risk to birds. That’s because they move much faster and are much harder to navigate around.
Here are the USFWS Guidlines for Avian Protection regarding power lines
“…research indicates that marking the shield wire (transmission lines) or conductors (distribution lines) to increase visibility significantly reduces the incidence of avian collisions.
Marker balls, swinging markers, bird flight diverters, or other similar devices are commercially available products designed to increase the visibility of overhead wires to birds”
As far as how often these measures are taken here are a few links to NEPA EA’s that specifically mention the use of bird diverters:
http://www.blm.gov/pgdata/etc/medialib/blm/nm/programs/more/lands_and_realty/sunzia/sunzia_deis/sunzia_deis_volume.Par.22211
.File.pdf/SunZia_DEIS_Volume_I_01.Executive.Summary.pdf
I have seen the balls only in places where low-flying aircraft are expected. From the ground, looking up, wires are easy to see against the bright sky, but from above, they’re pretty much invisible, so they’re marked.
Are there any examples of the balls located where they would not be for planes?
stw004, thank you for the additional information. From reading the first link, the greatest risk seems to be from roosting and nesting, primarily for larger birds (i.e. raptors), but there is risk to a lot of birds.
It does make reference to flight diverters, but it is unclear exactly how they are supposed to work. The figures included do not show them attached.
One type appears to be a dangly card on a chain, another type is some sort of coiled wire extension.
emphasis mine.
I’m not arguing that lines are not marked for aircraft as well, that is most certainly a fact. I just think Cecil could have not been so dismissive of the idea of bird diverters, since they are a real thing.
They work just like diverters for aircraft work. They give the birds something easier to see when approaching a line. Raptors are not usually the species flight diverters are intended for. Raptors die of electrocution more frequently than collision. Collision deaths are common among large water fowl when taking off and landing.
They come in all shapes and varieties. I took a pitch from a salesman the other day whos diverter consisted of a PVC pipe with battery powered LED strobe lights.:smack:
Did he have a good answer on who would be responsible for changing the battery on so-many-dozen battery-powered devices suspended at fairly high heights from live power lines?
And exactly how many night-flying species of birds was this device intended for? Or were the LEDs the “OMG I’M BLIND” level of brightness that would register meaningfully in full daylight?
Thank you very much for the information. I will review it this weekend and send a note to Cecil.
