You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
Given Storm Arwen and now Malik > Corrie creating chaos across the electricity network, primarily due to trees falling on lines, I wondered what preventative maint activities were likely to occur to reduce risk of failure nowadays?
In my relative youth, I remember much tree pruning and felling where routes deemed high-risk through trees, but that seems to have stopped over the last few years.
Within our area, 3 days now without power and it is exactly the same failure point as when Arwen took power out for 5 days. The line was fixed, but the immediate hanging trees were left.
Just curious...
You've answered your own question. You trim back trees and replace decaying poles before they get blown over.
As a slight over simplification I'd like to offer the following point for discussion.
Do with think this is more, or less likely to occur when the networks are run for the benefit of (mostly) foreign investors rather than for the benefit of the country?
The line was fixed, but the immediate hanging trees were left.
I guess if you're trying to bring back online 1000s of homes, you don't hang around to trim the trees, you just move on to the next outage.
Iain to the forum please.
We have our own in-house expert on such matters...
There are a couple of ways that the trees are managed around powerlines
Maintenance cutting - This keeps the trees out of the vicinity zone of the wires, vicinity zone is dependent on voltage. The idea being is that under normal conditions bits don't fall off of the trees and land on the conductors, or the branches don't come into contact from snow loading or from blowing about in the wind.
Resilience cutting - This removes all of the trees that are within falling distance of the conductors.
So, if the power networks cleared all the trees within falling distance of the conductors then the amount of faults occurring as a result of these storms would be reduced significantly.
However, the power networks do not own the trees, the owners of the land own the trees and permission is required from them to cut the trees. You'd be surprised at just how man landowners will not allow the clearances to be obtained for a maintenance cut, let alone complete removal of the trees.
I'm managing part of the tree cutting response from SSEN at the moment.
Appreciate the responses thus far. Thanks.
So, in terms of the ongoing prevention programme SSEN spends a significant amount of money each year maintaining the trees around the network on a rotating 4 year programme. A quarter of the network gets cut each year so in the 5th year the circuits from year 1 are being re cut.
Its roughly about 30k spans (from pole to pole) that get cut each year.
Beamers, thanks for your responses. It's certainly interesting to be aware of the complexities and challenges.
Is there any distinction between the HV and LV parts of the network - i.e. HV treated as a priority?
I sense part of the current challenge is that there have been a number of outage events relatively swiftly following each other which have resulted in notable disruption / loss.
It would be really interesting to understand our localised issue, being the same failure point and mode as per Arwen. Is there a method the Public could use to identify such potential areas to SSEN I wonder?
Ben’s called me out.
I had the privilege of being an NPg representative at the Hexham public meeting and the Bellingham one the fortnight before. I suspect I might be back again.
First - we invest more now than we ever have in maintaining and upgrading the network. The nationalised companies were pretty poor at that particularly during the 80s.
Yes overhead lines are inspected and yes poles without sufficient residual strength get replaced. However do note that the UK spec for an overhead line was significantly exceeded by Arwen’s wind speed - I don’t know about this weekend yet.
Note that about 25% of the poles that came down in Arwen were either almost brand new or near perfect condition. Normal pole life is upwards of 35-40 years.
Yes I can build an OHL that will withstand a higher wind - it will cost customers more and look ugly and there are still winds at which it will come down.
Or we could underground - perhaps 5-10 times the cost and good in winds but less so in floods.
The last storm similar to Arwen was 1953. That’s a lot of money for customers to shell out for a benefit that they might never see.
And yes we do tree trimming. Landowners don’t always like it and we try to walk the line between vandalism of woods and maintaining an acceptable corridor for the OHL. Not always easy.
I’m the Head of Innovation. I am always looking for answers so if you have any I really am interested.
Is there any distinction between the HV and LV parts of the network – i.e. HV treated as a priority?
Yes, HV prioritised over the LV. If it was the other way round then the LV could blow again when the HV gets switched back on.
Is there a method the Public could use to identify such potential areas to SSEN I wonder?
Yes, a couple of ways. The SSEN PowerTrack app allows customers to report damage to the network as well as seeing the locations of power outages. The other way is via the General Enquiries page on the SSEN website or by calling General Enquires on 0800 048 3516.
we invest more now than we ever have in maintaining and upgrading the network
I'm assuming that's in real terms, correct me if I'm wrong.
Are you getting as much done for the money invested - what innovations (technology or otherwise) are helping you out? Or what modern costs (legals, safety?) are dragging you down?
Corrected for inflation the networks today cost around 50-70% of what the nationalised networks cost - someone will have the exact figures I’m sure.
Our reliability stats (brave I know) are much better, and our customer service stats improve year on year (although I fully expect that further improvements will be needed and found).
Our safety record is vastly better.
Investment in new assets (in cash or asset volumes terms) has steadily risen since privatisation.
We have our problems, and I am a vocal self-criticiser away from public forums (fora?), but DNOs really are staffed by some good people, top to bottom.
Expectations of us are changing though, and probably rightly. I asked in Hexham whether on the back of Arwen anyone was rushing out to get an EV or a heat pump. The answer didn’t surprise me.
People don’t want 99.9897% reliability of their electricity supply (they get around that today - possibly a bit better on average).
They want 100% - which they can’t have, but we can get closer to.
And everyone in a village getting the power at the same time doesn’t help.
We need to see what we can do.
PS - getting safety right, doing things safely, tends to reduce costs in an industry like electricity. The alternative is messy, costly and not very nice.
I'm in a bit of a catch 22 with this. We've got a power line across our land. Its got some massive pines over sailing it. The trees are completely in the wrong place and have previously been heavily trimmed around the line so are a weird shape. I want to remove them and replace with something more manageable but can't fell them because of the power lines. I asked the power company if they wanted to remove them but they would only trim more branches making them even more misshapen.
Are you getting as much done for the money invested – what innovations (technology or otherwise) are helping you out?
Satellite imagery analysis is starting to be used to monitor vegetation, with AI identifying areas of interest. Similar analysis can be used on video footage (whether collected by helicopter, plane, drone) to pick out areas of potential damage to powerlines, insulators, even woodpecker damage to wooden poles.
e.g. eSmart Systems.
I look after 3 UK energy companies (including SSE group) for a quite large technology company.
I’m the Head of Innovation. I am always looking for answers so if you have any I really am interested.
Old school - a herd of goats, each with collar and chain to a pole. Herder moves them on each day.
Repeat.
Like the goat idea. Not our land though so we’d need all the landowners to agree.
Also need to cover the spans as well as the poles - maybe a tether that hat allows the goat to cover a 80-100m long 5-10m wide area.
PS - old school is good if possible.
Easy. Have you seen those running lines for dogs? You already have the line running above. Just attach a shuttle and line to the OHL so the goat can wander up and down.
Seriously though, any good ideas I’m going to nick if I can (borrow / licence / buy if I have to).
Like the goat idea. Not our land though so we’d need all the landowners to agree.
Also need to cover the spans as well as the poles – maybe a tether that hat allows the goat to cover a 80-100m long 5-10m wide area.
Chain between two poles with each goat on a runner from this, then they can maximum roam 5m each side.
LLTNP have both cattle and goats IIRC working to reclaim land from all sorts, the cattle actually help plant new forests/bury seed properly. Goats are just natures dustbins and prevent any trees from getting foothold.
Agreed It won't work everywhere, but it could.
Goats are a cracking idea for spans where the trees have been removed to beyond falling distance.
The four legged munchers will keep any regrowth down.
They might have a challenge climbing the trees to nibble back the growth at conductor height where the landowners won't allow the trees to be removed.
I work for a landowner/operator that the power companies need to access to undertake their tree works. Based on my experience, they basically seem to feel they can rock up whenever they like, with whatever equipment they like and do whatever they want. Given the land is open to the public, contains opertional infrastrucutre and was not built to take current vehicle/plant loadings or vibrations, we object to that due to the risk their operations pose and the risk our infrastructure poses to their operations if not appropriately mitigated. Given that most of the Risk Assessment don't even state (initially) "working in areas where the public may access" as a hazard when I see them, there are often delays. Then comes bird nesting season which makes things more difficult, and as an organisation we are reluctnat to grant consent for tree works over the summer due to the risk of reputational damage (even if its not our works).
So basically the power companies need to plan their tree works better, and employ contractors that understand the hazards they pose/are exposed to, then they'd be able to deliver more work more efficiently....
Oh, and we charge them for the service of reviewing their Risk Assessments, so the worse they are the more it costs, and the longer it takes to get on-site.
They need to start planning their veg works in spring, get all the consents in place over the summer then do it from Septemer (after bird nesting sesason) but what normally happens is I get a request in late february claiming "emergency works" because bird nesting season is only weeks away....
Forget the goats - fence off the cleared area under the lines, add one way gates and the vast number of deer will keep any trees down. As they're wild animals you won't need to pay any vets bills either!
Or rent the area to grouse shouters, they'll make sure nothing gets above knee height.
Beamers / IGM,
I'm sure my local community would be absolutely delighted to be very supportive of some tree felling activity to avoid a repeat of the common failure point during both Arwen and now Malik > Corrie. If there are any land access challenges, then I am sure the local community voice would support your efforts if required. Feel free to PM me for location.
I sense some spending will happen in our household too - appropriate generator connection point to make us a bit more self-sufficient for the future.
Given these 'events' I really think getting folks in rural areas to move to EV's will be some time away - I get the sense that the current infrastructure is not supportive of this, regardless of what certain vote-chasing politicians - in Scotland - would have folks believe.
They need to start planning their veg works in spring, get all the consents in place over the summer then do it from Septemer (after bird nesting sesason) but what normally happens is I get a request in late february claiming “emergency works” because bird nesting season is only weeks away….
Tree cutting is a year round operation in SSEN. We are very mindful of bird nesting season and the legalities of disturbing active bird nests.
I'm just back from visiting a few sites where the teams are clearing up and getting the power back on. One was on a stretch through about 1.5km of woodland where several trees had fallen over, snapping the conductors and one of the poles.
The landowner flatly refuses to allow us to cut the trees at all as part of the ongoing maintenance programme, despite this being a regular tree fault site which causes his power, and quite a few other people's power, to go off.
Landowners like that are in the minority but there are enough to make continuity of power supply a challenge in some locations, storms or no storms.
Beamers, if you are in NE Scotland, can you have a look at the issue associated with JK1866? I sense this will require heavy machinery to resolve...
I also remember an outage some years back where an articulated generator was connected to our local sub-station when an underground cable went pop due to external casing being worn through by rocks.
Locally we've just finished burying all out LV cables, and after the weekends storm I'm glad that was done. However a cost I saw was that burying was 3 times the cost of pole to install, so someone, called the public, will need to stump up at some point.
Mind, given that fallen power cables were one of the main source of wildfires in California in the last few years, causing a few billion of damage and a few hundred deaths that seems a false economy... as does the attitude of seeing safety as a cost.
You can also generally take a more direct route with an OHL than a cable, small river crossover cheaper, pole mounted substations are cheaper that sort of thing. So 3 times the cost per km is more like 5-10 times the cost when looked at on the basis of networks that do the same thing.
I agree with the safety concerns and the wildfire concerns (I speak with my US and Canadian colleagues fairly regularly). Thankfully wildfires aren’t the concern in the Uk that they are in the US, and our safety culture is well ahead of the US - though they are probably catching up.
Note that it’s not necessarily falling OHLs - it can be cracked insulators causing pole fires then wildfires - again uncommon round here.
I reckon you could do a diminishing radius of shared costs equation for removals and major crown reductions within toppling distance of the lines but outside the immediate clearances. You could thIf you need a case study I've got some big sycamores (beyond my chainsawing) that I might be willing to let you practice on 😉
Goats are a cracking idea for spans where the trees have been removed to beyond falling distance.
The four legged munchers will keep any regrowth down.
They might have a challenge climbing the trees to nibble back the growth at conductor height where the landowners won’t allow the trees to be removed.
Giraffes. Nature's goats-on-stilts.
Giraffes and OHL? I’m out.
No power lines involved here but gives an idea of the level of tree damage caused by the storm.
@beamers, that's incredible. If that level of damage becomes common I can't see how the timber industry let alone overhead power can survive.
The guy from Forestry England at one of the public meetings was saying around a million trees lost. My mind cannot comprehend that sort of number in fallen trees.
10 years of recovery work for reestablishing the forests he reckoned. Some of the tracks in Keilder shut until summer just for clearance of the fallen / damaged trees.
Haddo House Estate in Aberdeenshire after Storm Arwen:
Up to 500,000 trees lost on wider estate.
Many of those trees were planted after a similarly devastating storm back in the 1950s.
We've smaller plantations around here that are 80% flattened. None are FLS owned, or even the bigger forestry managers, they are owned by farms and estates. They have basically cleared the road. How long it takes to clear them up and replant is anyones guess - and I can imagine it is not a priority for many.