As a technician in the broadcasting field, part of my job requires that I climb our TV transmitting masts to check that the structure is OK, check that the cables are in good order, and to check for air leaks. The large, hollow 150mm diameter cables are pressurised with dry air to keep them free of moisture. We sometimes have to climb these masts with a bottle of kids bubble blowing fluid, and a paintbrush, and we paint the mixture onto joints and areas of the cable that could be cracked or punctured. If there’s an air leak, you can see the bubbles forming.
The tallest mast in my area is a 220 metre mast, carrying TV, radio, cellphone, radio telephone, internet links, car tracking, trunking and digital transmissions. masterracksbd There is a ladder going up the centre of the mast, with rest platforms every 15 metres. The ladder is vertical, but it does have a cage around it, so you can’t really fall out, only down 15 metres to the platform below. At the very top of the mast is a spine, which is a long thin extension to the mast upon which all the TV transmit aerials are mounted. You can get inside this spine by pulling yourself up with your arms: it’s too narrow to lift your knees up inside. There are places where you can put your feet and stand. I once spent over 3 hours in this structure looking for an air leak. It’s not bad, and the view is spectacular at 220 metres. This is similar to a 72 storey building, except that it’s out in the country, with no other buildings in sight.
Climbing the mast is tiring, and a 200 metre mast takes about 30 to 40 minutes to get up to the top. We always climb with jackets, as even if it’s hot on the ground, there’s usually a pretty cool wind blowing up at the top. Often as we climb, clouds come past between us and the ground, which is quite strange, as you feel cut off from the earth. If there’s too much cloud, or if it’s wet, or if the wind is too strong, we are not allowed to climb for safety reasons. Some guys have climbed in winds where a 12 inch shifting spanner has been blown off the platform where they were working.
The masts are made out of solid steel legs 150mm in diameter, and the whole mast rests on a single ballbearing at the bottom. This is so that the mast can twist and flex with the wind without anything breaking off. The mast is held up by steel guy ropes which are anchored into 20 ton concrete blocks half buried in the ground. There are four anchor blocks, and a total of 4 sets of 4 anchor ropes at 4 different heights. Special teams called riggers, trained for working on high structures, come and grease these guy ropes to prevent them rusting. They do this by being winched up the rope on a little wooden seat, like a child’s swing seat, with a big drum of grease hanging on their side. When they get down they are black from head to toe with this thick grease.
Some of our masts have red winged starlings nesting in the aerial covers. These little birds get quite aggressive as we climb up towards them, and they dive bomb us and make a dickens of a noise, which is not very nice when you’re dangling around hundreds of metres above where you’d like to be! Quite a few of our masts are inside game reserves here in South Africa, and we are often able to watch the wild animals below without them knowing we are around. Eagles like to sit on the top of our masts, as it gives them a nice vantage point to spot rabbits in the grass far below.
I’ve been doing this job for almost 30 years now, and I don’t climb as much as I used to; the younger guys are now doing most of the climbing. I don’t actually like heights, but I still enjoy the view!
I will be posting some photos taken from the masts mentioned in this article. Check my website as detailed below.
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