The Chain Ladders

21 Aug 2021 21:02 - 21 Aug 2021 21:05 #77108 by tonymarshall
Replied by tonymarshall on topic The Chain Ladders
After being prematurely closed in April 2018 to be replaced, and that never happening, and the one anchor bolt of the newer lower ladder breaking in September 2019, the broken chain ladder anchor bolt has been repaired, and all four chain ladders are usable again. 

Neil Margetts and I had looked at the broken anchor bolt on the newer lower ladder earlier this year when we had gone up the chain ladders for the abseil down the Tugela Falls that Neil and his team did, when I led their support team. We were quite horrified at the delay at the chain ladders with a lot of day hikers and only one ladder open. We thought it was quite straightforward to do a repair of the broken anchor bolt, and discussed repairing it. Neil also discussed repairing it with some other well known climbers, but we never got as far as getting the necessary permissions from the various involved parties/authorities to do the repair. Recently an interested party contacted Gavin Raubenheimer about repairing the broken anchor bolt, and Gavin referred them to Neil, and so finally the wheels were set in motion to do the repair. The interested party arranged all the necessary permissions for Neil and I to do the repair. 

We were at Witsieshoek last Saturday morning, to do the repair, but we were unable to drive up to the Sentinel car park as the overnight snow was too thick on the road. We also assumed there would be more snow higher up which would make it more difficult and slower going to walk to the chain ladders, and when conditions on Sunday were pretty much the same, we left and decided to come back later in the week once the snow had melted to do the repair. 

The photos below show the broken off anchor bolt, and the newer lower chain ladder (this is the lower chain ladder on the right as one stands at the bottom looking up) hanging on just one anchor bolt with the no entry sign at the top of the ladder to warn hikers not to use this ladder.  

 
 

We could determine from examination of the broken off anchor bolt, that corrosion of the mild steel had led to weakening of the bolt and the breaking of the bolt due to this weakening. We don't know exactly when this chain ladder was installed, but believe that it was in the late 1970's, so the ladders had worked for about forty years, and the breaking of the bolt was thus not unusual for the age and conditions in which it operated, and the design life that it would have been designed for. It would of course have been better if the relevant authority had been doing proper inspections and had identified the corrosion problem and replaced the anchor bolts before one broke. This also made it apparent to Neil and I that the repair we planned to do should allow for a greater degree of redundancy, and should not just be a single anchor bolt again that could result in the failure of the anchor and closure of the ladder if it broke again in the future. So I did a design incorporating four stainless steel expansion bolts and hangers (the type that Neil uses for bolting climbing routes), and chains attached to the main chain, so if one of these failed in future, there would still be three holding. At the same time as repairing the broken anchor bolt, we would place the same new anchor system on the unbroken anchor bolt on the other side, but also leave this anchor bolt in place as back up, so both chains of the ladder would be on new anchors. The interested party who requested us to do the repair was happy with this proposal, and also that as a Registered Civil Engineer I could perform the design and installation. 

The photos below show the materials used in the repair, stainless steel chain, expansion bolts, hangers, D shackles and quick links. Stainless steel is significantly stronger than mild steel, and is also much more resistant to corrosion.  

 
 

So last Friday we were again at Witsieshoek, and could drive up to the Sentinel car park, and walk to the chain ladders to do the repair. Neil and I had Wisdom Chilanga, one of Neil's employees who has worked with Neil on ladders and bolting, and who has also worked with me, with us, to help to carry the tools and equipment and do the work, and make his first visit to the Drakensberg and hopefully see and feel snow for the first time. 

I secured the chain with the broken anchor with a chain block, and pulled it back up to the correct height, and Wisdom and I removed the old D shackle and broken piece of anchor bolt from the chain.  

 

We then secured two new chains to the chain of the ladder with a D shackle, and marked out the holes for the expansion anchor bolts on the rock. In the photo below Neil drills the first hole while Wisdom holds the new chains with the hangers attached.  

 

We used an epoxy to seal off the top of the anchor bolts at the rock face, and applied epoxy to all threaded fastenings to prevent loosening. In the photo below Wisdom applies epoxy to the threads of the four anchor bolts to prevent them from being loosened and removed.  

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Last edit: 21 Aug 2021 21:05 by tonymarshall.
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21 Aug 2021 21:10 - 21 Aug 2021 21:18 #77109 by tonymarshall
Replied by tonymarshall on topic The Chain Ladders
Once the chain with the broken anchor bolt was finished, we repeated the process on the chain on the other side. In the photo below I cut off the new chain with a bolt cutter at the correct length. We decided to carry the bolt cutter with us to the ladders so that each chain could be individually cut to length to suit the best bolting positions on the rock, rather than use pre cut fixed length chains. This also allowed us to space the expansion anchor bolts far enough apart that they would not interfere with each other in terms of being too close together and concentrating the load into a small area of rock.  

 

The ladder suspended on the new anchors with the other chain ladder in background.  

 

The photos below show the completed installation with the stainless steel components.  


 

We spray painted the shiny silver stainless steel components with grey paint to make them blend in more with the chain ladder and rock.  


 

The lower left chain ladder (the older one) had noticeable looseness in the one anchor bolt, so we used some spare components to strengthen this anchor as well.  

 

The repairs were complete at about midday, and we headed off to the top of the Tugela Falls for lunch. Although it was misty and there wasn't much view, Wisdom had the opportunity to see and walk in and play with snow for the first time. 

There have been some comments about worn chain links on the chain ladders, but this is only on the two older ladders with the smaller chain, and on the lower section of these ladders where the mass of the ladder to support is lowest. The newer chain ladders with the larger chain have very little wear on the chain links, and with the anchor repair to the lower newer chain ladder this ladder will be serviceable for many years. It should also be pointed out that the chains used on the chain ladders are much larger than required to support the combined mass of the chain and other ladder components, and people on the ladders, so the amount of wear on the chain links is not necessarily dangerous. It would be wise though for the relevant authorities to have someone perform an inspection of all the chain ladders, and to repair or replace components as necessary before another break occurs, which may have more serious consequences than when the anchor on the newer lower ladder broke. There are people (like Neil and I and others) in the mountaineering community who are competent and would be happy to do these sort of things with just having our costs covered, and would act in the best interest of safety and practicality without purely having a commercial or financial interest in the matter. 

It was a privilege to be able to be part of the chain ladder repair, and to do this so that other hikers and mountain users can continue to enjoy using the chain ladders. 

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Last edit: 21 Aug 2021 21:18 by tonymarshall. Reason: Correct formatting

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22 Aug 2021 09:59 #77110 by DesPorter
Replied by DesPorter on topic The Chain Ladders
We were there shortly after the new ladders had been installed.  The person who did the installation was there as it had just been completed and he was monitoring its use.  That would have been the late 80's so it is not all that old.
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23 Aug 2021 06:33 #77111 by riaan300
Replied by riaan300 on topic The Chain Ladders
this is great news!!!
a Big THANK YOU to everyone involved 

Good Job!
:)

 
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23 Aug 2021 10:19 #77112 by Dillon
Replied by Dillon on topic The Chain Ladders

We were there shortly after the new ladders had been installed.  The person who did the installation was there as it had just been completed and he was monitoring its use.  That would have been the late 80's so it is not all that old.

Sounds about right. The first time I did the chain ladders in about '88 or early '89, there was only one ladder on each pitch (the ones WITHOUT the big loops). When I went back a couple years later the new ones WITH big loops had been installed.

"Mountains are not fair or unfair, they are just dangerous."
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25 Aug 2021 18:08 #77115 by intrepid
Replied by intrepid on topic The Chain Ladders
A big thank you to everyone who has contributed towards the maintenance of the ladders!

Take nothing but litter, leave nothing but a cleaner Drakensberg.
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26 Aug 2021 15:44 #77117 by mike_crom
Replied by mike_crom on topic The Chain Ladders
This is amazing, thank you so much guys!
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30 Aug 2021 17:11 #77119 by ivan
Replied by ivan on topic The Chain Ladders
a great job. Thanks so much 

 

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