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September 19, 2019 2:13 PM   Subscribe

Fast-forward to today, and many utilities have now embraced the concept of trimming trees from a helicopter. They have found the technology works safely and efficiently, particularly in mountainous terrain, rural locations, wetlands and sensitive areas where environmental or regulatory issues are encountered” [Viral Tweet from today containing video]

“Trimming work is completed by flying above and along the power line right-of-way, cutting the lateral vegetation. Generally, more than one pass is needed to provide adequate clearance depending on the height and density of the vegetation.

“Aerial saw operations must maintain compliance with U.S. Federal Aviation Administration (FAA) regulations, which are governed under FAR Part 91 and Part 133. […] Part 133 (Rotorcraft External Load Operations) provides guidance on operating with an external load, requirements for certifications, training, emergency operations and operating limitations”

And, as seen in Bond movies.
posted by ambrosen (30 comments total) 16 users marked this as a favorite
 
How do they make sure that hikers, bikers, and others are not in the area before dropping limbs on them from a height?
posted by Midnight Skulker at 2:19 PM on September 19 [3 favorites]


Is it proper to hang a tree lopper from a chopper?
posted by mandolin conspiracy at 2:22 PM on September 19 [27 favorites]


Since late 2015, Rotor Blade’s Tree Topper Saw has been in use on at least seven investor-owned and cooperative utilities’ power lines, primarily on rural distribution lines. Although contract specifications vary from utility to utility, it is generally being used to safely and efficiently lower the height of dead, dying or storm-damaged trees so that any potential fall-ins will clear the line.

Here it is in action.

Off-label use: thinning zombie herds via wide-radius decapitation.
posted by mandolin conspiracy at 2:31 PM on September 19 [7 favorites]


Apparently they do have people on the ground checking everything's clear ahead of cutting: Ground crews work in tandem with the pilot, flagging traffic and removing limbs and smaller branches from roadways, trails, waterways, or other sensitive areas.
posted by ambrosen at 2:33 PM on September 19 [3 favorites]


Just... how do they avoid shearing through the power line? Like, if there's a gust of wind or the pilot scratches his nose with the wrong hand or sees a spider in the cockpit or something?

Knowing what I do of humans, I would think that human error might be a hazard here.
posted by Pallas Athena at 2:36 PM on September 19 [3 favorites]


It...should be kinda OK if they hit the power line? I think? I mean, it would break the line and cause a power outage, but the helicopter isn’t grounded, so it at least is OK, right?
posted by Huffy Puffy at 2:42 PM on September 19


Yes, it should be ok.
posted by aleph at 2:50 PM on September 19 [5 favorites]


I hope that I shall never see
A helicopter shave a tree.
A tree whose shaggy head is shoved
Against the power lines above;
A tree that looks like old Doc Brown,
With shocks of hair lit all around;
A tree that may in storms at night
Set 1.21 gigawatts alight;
Beneath whose falling limbs like rain;
I'd intimately discover pain.
If it were up to fools like me,
Choppers would not chop a tree.
posted by It's Raining Florence Henderson at 2:54 PM on September 19 [70 favorites]


I didn't realize The World is Not Enough was a documentary.
posted by allegedly at 3:04 PM on September 19 [3 favorites]


The tree trimming isn't even the coolest thing utilities are doing with the vegetation near their lines. I know a guy spent a year and a half with one recently working on this stuff.

Some of the leading utilities with the highest risk of lines being encroached from vegetation simply can't physically maintain all the vegetation in proximity to their assets, even if they were to full-time employ every tree contractor in North America - there's just too much vegetation growing too fast across millions of miles of conductor wires and the towers/insulators/switches that string them off the ground.

So what they instead have to do is identify where they do or do not have risk of vegetation encroachment, and then prioritize which lines will be serviced for veg management based on not just the yes/no of whether there are trees on this particular set of lines, but also on things like:
- the species of the tree*
- the density of vegetation fuel in the area**
- the impact of a fire spreading in this particular area were it to start here***
- the egress considerations of the area****
- climate considerations*****
- etc. - the list goes on, the point is there are a WHOLE LOT OF THINGS nobody thinks about that power companies have to consider since they'll be the one the public holds responsible if there is a fire.

*gray pines are much more likely to fall in than are other species
**in my home state, CalFire sets fire "tiers" where the foothills with thick underbrush and forests that are most likely to burn being the highest risk tier, descending down to the lowest risk tiers like the middle of the central valley where there are few to no trees to burn
***things like number and type of structures in the area, population density, etc.
****how do the road types (country 2-lane, intermediate highway, interstate freeway) in the area compare with the population density, thus creating an egress score that can tell you a particular town would be especially hard to evacuate people out of while simultaneously bringing fire fighting services into.
*****is this tower in proximity to the ocean and therefore at higher risk of corrosion? is this a high wind event area where weather can cause lines to go down / be impacted by veg, etc..

How do you solve for all of that, when basically you're not an energy provider so much as an asset management company that has a shit ton of assets (millions of wooden power poles and steel/composite structures with hundreds of millions of conductor miles between them) that run through the middle of all of this vegetation to bring power to people who have decided they want to build their communities in the nice shady places that are also the most likely to burn when fires run amok? Not to even get into the added complexity that in the US the policy for most of our history has been to fight and stop the fires rather than let them burn and keep ecosystems in their natural cycle, so when the fires do get loose, they burn hotter and faster than they would normally.

It's an almost impossible situation these energy companies are facing.

Fortunately they're coming up with some really novel solutions that are utilizing some of the most cutting edge technology and even in some cases building AI/Machine Learning models to help solve these problems in ways humans never really were able to at scale.

Enter LiDAR - Light Detection and Ranging, radar's more zoomed in, hyper focused cousin. You know, the technology Elon Musk says will never enable self-driving vehicles? May not be good at that level of detection, but it fits the bill for utility providers. All they have to do (natch) is pay a handful of helicopter / fixed-wing contractor outfits to strap LiDAR image detection devices to their arial vehicles, and then send them out to fly their lines, taking LiDAR shots of every inch of the line, anywhere from 60 to a couple hundred laser points per square meter. These points are beamed back to the helicopter, and then once the vehicle returns they are stitched together using complex software that accounts for things like the distance of the device from the point sensed, the speed of the vehicle housing the device, the GPS location and other metadata being captured along with the Lidar "point clouds," and a few other things. Once all stitched together they begin to form a 3D rendering of an image of whatever was between the sensor and the ground - power poles, insulators, conductor wires, birds sitting on those wires, people walking under those wires, tree branches extending out over those wires, the height of the trees next to the wires. All of those things and more haver to be classified, but you're still talking tens or hundreds of thousands of points, to have a human do it would take days just to get a span between two poles. But computers can learn how to do that really well and really fast, and all of a sudden you now have classified images of your assets and the vegetation around them.

Then you can start augmenting your existing knowledge of your asset data with annually-refreshed renderings of what the environment around this asset looked like when you last flew over it, and start to look for things like "danger trees" - trees that are in proximity to an asset and of sufficient height that were they to be knocked over could fall-in to an asset, and "risk trees" - trees unlikely to fall in for whatever reason but might have branches extending into the impact zone around a conductor wire, where those branches could fall in, thus creating an outage, that could potentially lead to an ignition. But even now that you have all this amazing wealth of data about both the assets and the environment around them, there are SO MANY lines and towers running through SO MANY remote locations that you still need to employ computer vision models to actually have computers look at all the imagery and renderings and do the math to tell you where your most at-risk lines are.

Then, once you know all of that, which has taken you dozens of teams of people and who knows how many contractors and how much dev time, you still need to operationalize it. How does it all translate down into operational plans that manage what work needs to be done where, and when, and by whom. You can't just send tree crews out willy-nilly, there are weather considerations, and terrain considerations (where the heli-saw comes in handy), and bird-nesting-season considerations (can't fly during raptor nesting in a lot of areas), and EPA restrictions, and right-of-way over private land considerations. The utility I worked with even kept a "BAD DOG" database to list landowner locations where they had a dog that was known to try to attack line maintenance engineers.

I digress. Tl;dr - maintaining vegetation with the heli saw is only one of the many ways this stuff gets done, but there's a hell of a lot that goes into it before you even get the heli-saw off the ground.
posted by allkindsoftime at 3:45 PM on September 19 [88 favorites]


One interesting side note I learned in researching egress: the vast majority of science and research around egress historically has been on the egress of non-residential high-density buildings (i.e. how many stairwells do we need to build into this skyscraper to have a reasonably low risk in the event we need to get everyone out at once). The super interesting thing was the massive advancements we've had in this particular space thanks to mobile devices.

People working in skyscrapers typically have one of two major brands of smartphones. The providers of those devices have hardware and software that can tell them how many users of those devices are in a given place on the map at a given time. So if you're the one named after a fruit, for example, you know that in a given area you control roughly ~x% of the market share for smartphones in that locale, and you can see that right now, there are x,xxx of your devices online in this given city block, so you can with a fairly high degree of accuracy estimate how many humans are within the building that occupies that city block at a given point in time.

Super creepy, but super useful for planning for emergency events. Also for marketing to people stuck in their cars on a particular stretch of freeway at a given point in time, etc..
posted by allkindsoftime at 3:50 PM on September 19 [13 favorites]


I work at a utility. They do switching and de-energize the lines that they work on or trim around. As much of the electrical system as possible is built where there are multiple paths from substations separated by open switches out in the system.

Vegetation is trimmed along our system, supposed to be as often as every four years or so, minimizing outages drives this. Safety for the tree trimmers and the public is the top concern.

The right of way of pipelines is kept clear of trees too. The roots of trees can mess with pipes and change the chemistry of the soil causing corrosion issues. All pipelines also have to be leak surveyed (someone walks along the full length of them with a leak detection instrument) every 3-5 years.

Interstate pipelines have small planes fly along their routes every day, looking to make sure nothing odd is happening on the ground along the pipe or someone isn't digging. If you've seen those odd giant numbers next to the interstate that face upward at 45 degrees, those are markers for planes flying along a pipeline.

The utility industry is working on a lot of stuff with drones. They can scan an location and build a 3D model with sub-inch accurate measurements of everything from piles of coal to pipes. Right now they can't fly out of the operator's sight and the operator has to be stationary.
posted by Blue Tsunami at 4:11 PM on September 19 [20 favorites]


Edgiest edger evar
posted by chavenet at 4:28 PM on September 19 [4 favorites]


The drones are interesting too. One contract engineer inspecting lattice steel transmission structures can safely climb and inspect 2, maybe 3 max a day, if he's on flat ground that's easy to navigate close to in his vehicle. One drone team of a pilot and a photographer / navigator, they can fly prescribed routes around these structures snapping photos at different points to get a complete view of the tower. And they can safely do ~10-14 towers in the same day a regular climber can do his 2. So you have exponential scale already with the drone, but now you have the problem of ~40 pictures of that tower that all need to be looked at in composite, to actually complete a visual, albeit remote, inspection of that tower.

First problem: how do you get the drone contractors to move their photos and metadata from the SD card in the camera on to devices that are secured to your network (and how do you do it in an electronically safe way, that doesn't allow malware into your network, because after all, you're a utility provider, the last line of defense between the power grid and the terrorists that are cyber attacking it every day). Of course, the scale of the amounts of data you are dealing with quickly spirals into peta, so you pretty much have to figure out a scalable cloud solution from the get-go. A landing zone for your photos and metadata in the cloud.

So now you have them all, with their metadata, but having an inspector click around in folders of photos and metadata in the cloud is just going to create a mess, so you have to build him a photo inspection web-tool that associates all the photos with what you think is the asset ID and all of the related asset information in your source systems of record so that he can associate an inspection report with a specific asset. He has to be able to zoom in and out on all those pictures and create bounding boxes around specific components of the assets (i.e. a porcelain bell on an insulator string between a tower and a conductor wire, he has to be able to mark one of the bells as flashed, creating a repair ticket for that insulator, on that structure, in that location, which is then tagged against the larger inspection report for all the components on that structure). Then those inspection tags have to be risk-ranked by their level of severity (i.e. does this need to be fixed NOW, can it be fixed in the next 90 days? next year? next two?).

Then you start to get into the logic puzzle of not just sending one engineer out to fix one asset in one location in the field, but how do you create smart projects where you can bundle work together in ways that reduces the most risk for the operational dollars you spend to send the guy out to the field? Because you don't get the luxury of targeting cost reduction, you're a level above that at targeting risk reduction.

Interesting side note on the drones: the lidar can feasibly provide a pre-programmed digital flight route around a structure / wires, so that eventually you have the computers flying the drones and taking the pictures rather than the human, further eliminating human error in the system.

Same computer vision / ML models can be applied to those photos, instead of having to have rooms full of humans look at them, computers can do the first scan and you can teach them to learn to see different types of assets, drawing bounding boxes around components and identifying defects that are failure risks.

Endless rabbit trails.
posted by allkindsoftime at 5:03 PM on September 19 [19 favorites]


This sets off alarm bells for me. It is glaring that no mention is made of the danger that flying a helicopter at low altitude and low airspeed presents. A transmission failure, fuel contamination, blade delamination, tail rotor failure—the slightest bobble at all and it is over. These ships have no where to go but down in a heap as there is insufficient altitude or forward motion to autorotate to a safe (or sorta' safe) landing and, even if there were, they are often over terrain and forests that are inhospitable to a forced landing.

Further, the Hughes/MD ships favored for this kind of work (and precision long-line logging as well) are getting old and cranky. The last 500D, like that shown in the article, was built in 1983.
posted by bz at 5:18 PM on September 19 [4 favorites]


...have now embraced the concept of trimming trees from a helicopter.

Was hoping for a 21st century, gyro-stablized version of the Papin-Rouilly Gyropter (with a sharpened leading edge or chainsaw tip), but alas.

Heli chopping trees down in Vietnam discussion at Professional Pilots Rumour Network Forums. Rotor blades were expendable, but the wounded were not.
posted by cenoxo at 6:04 PM on September 19 [1 favorite]


"aerial saw operations" is a fantastic phrase.
posted by doctornemo at 6:33 PM on September 19 [1 favorite]


Enter LiDAR - Light Detection and Ranging, radar's more zoomed in, hyper focused cousin

oh man i was really hoping the answer was goats.
posted by kaibutsu at 6:59 PM on September 19 [1 favorite]


bz, the FPP article addresses some of the flight safety issues:
Extensive Regulations

Aerial saw operations must maintain compliance with U.S. Federal Aviation Administration (FAA) regulations, which are governed under FAR Part 91 and Part 133. To comply with these regulations, ASI has developed specific safety and operation procedures that must be approved by the FAA. Part 91 (General Operating and Flight Rules) [link] provides guidance on all aspects of flight operations such as airworthiness, airspace rules, required equipment and maintenance. Part 133 (Rotorcraft External Load Operations) [link] provides guidance on operating with an external load, requirements for certifications, training, emergency operations and operating limitations. To ensure compliance, the FAA performs both on-site and field inspections.

Pilots must receive special FAA certification to perform external load operations. In addition, ASI has developed many modifications to its helicopters to ensure safe operation. These modifications can be employed only after undergoing the FAA certification process, which includes engineering, a stress test, a flight test and administrative approval.

Aircraft must be maintained in accordance with specific FAA and manufacturer’s guidance; ASI’s maintenance program meets and exceeds these guidance sources. All mechanics hold airframe and power plant (A&P) and inspection authorization (IA) mechanics certification. Mechanics perform inspections every 100 hours of flight time and a more in-depth inspection is completed every 300 hours.
...

Safety Core Value

One of the first questions people ask when first learning about the aerial saw concerns safety. Safety is highly important because helicopters must pick up more than 800 lb every time the chopper takes off. Thanks to intense training during the first year for new pilots and recurrent annual training for all pilots, safety has become a core value of ASI employees. The company has flown more than 140,000 hours since its inception in 1985. Field personnel have had no lost-time incidents in the last three years, and ASI’s experience modification rate is 0.74, well below the aviation industry average.
...
“What happens if the saw gets stuck in a tree limb?” is another frequently asked question. While this rarely happens, ASI has developed a set of procedures in the event of a hang up. First, the pilot attempts to maneuver the ship so it helps to pull the saw from the tree. If unsuccessful after several attempts, the pilot ensures the area surrounding the saw is clear of people, and then the saw is either released manually or electronically by the pilot.
posted by cenoxo at 7:23 PM on September 19 [4 favorites]


and then the saw is either released manually or electronically by the pilot.

So what's the contrapositive of yelling "Timberrrrrrr!" ?
posted by RolandOfEld at 8:27 PM on September 19 [5 favorites]


I’ve seen utility workers repairing lines from a helicopter, and the helicopter was rock solid. It absolutely did not comport with my instincts for what helicopters do in the air, to the point where it looked entirely uncanny. I was in awe of the pilot’s skill.
posted by BrashTech at 10:55 PM on September 19 [5 favorites]


I’ve seen utility workers repairing lines from a helicopter, and the helicopter was rock solid. It absolutely did not comport with my instincts for what helicopters do in the air, to the point where it looked entirely uncanny. I was in awe of the pilot’s skill.

I was about to post the very same thing, BrashTech. It really is awe-inspiring to see something like that. Even more amazing was the crewman sitting outside the cabin of the helicopter, doing whatever it was he was doing at the top of the tower, hundreds of feet in the air. The whole scene just defied my impression of reality. Like you don't exactly believe what you're watching at first. Impressive, to say the least.
posted by Thorzdad at 5:04 AM on September 20 [3 favorites]


...discussion at Professional Pilots Rumour Network Forums.

Well, there's a new (to me) forum I'll be lurking in. Thanks for the link, cenoxo!
posted by Thorzdad at 5:12 AM on September 20 [2 favorites]


I thought that this was about using the rotor blades of a helicopter to trim trees, and was glad to see that the forum that cenoxo links above eventually gives the book name as Chickenhawk by Robert Mason, a solid candidate for the best nonfiction book about the Vietnam War. There's a scene in which Mason, faced with nowhere to put his Huey down except in a clearing with overhanging branches from the trees surrounding it making the hole in the tree canopy smaller than the blade diameter, gambling that the blades will chop a hole in the canopy without breaking, and winning that gamble.
posted by Halloween Jack at 7:41 AM on September 20 [1 favorite]


oh man i was really hoping the answer was goats.

I would also watch a video of 20 goats hanging from a helicopter trimming trees.
posted by srboisvert at 7:47 AM on September 20 [9 favorites]


Cool, gyroscopes and pendulums.
posted by zengargoyle at 8:02 AM on September 20


I would also watch a video of 20 goats hanging from a helicopter trimming trees.

Looks like only three at a time here, and they're just being relocated, but this setup could be repurposed, no?
posted by mandolin conspiracy at 9:07 AM on September 20


On smaller city power lines, I think the trimmers cut just enough to ensure they have to come back often and repeat the trimming.

I've seen stands of pine trees along power lines, where one side of the tree is trimmed flush. If those trees had been cut down completely, the trees farther back could grow normally, and wouldn't reach to the power lines for decades, if ever. Cheaper and better aesthetically, too.

The big rural towers need brush cutting underneath anyway. Why not leave whole trees set farther back from the lines? Just trim the seedlings on the ground.
posted by jjj606 at 7:10 PM on September 20


I see your three Rocky Mountain Goats, and raise it to five: Relocating Bighorn Sheep in Montana with a Hughes MD 500D (369D).
posted by cenoxo at 10:05 PM on September 21


Per allkindsoftime’s comments above, Xcel Energy's Vegetation Management: Challenges & Solutions video highlights the use of helicopter LiDAR systems in Colorado forests. It’s a constant, enormous battle to keep power line rights-of-way clear of overgrowth and dead danger trees, decimated by legions of rice-sized Mountain pine beetles.
posted by cenoxo at 6:57 AM on September 22


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