Why use many streetlights when one will do?

I'm not allowed to climb this tower. I did ask, but not only does climbing this need proper training and safety equipment, it's also a protected historic site. The folks in charge are understandably a bit cautious. But while I can't go up there... the camera and you can. This is a moonlight tower here in Austin, Texas, and it's one of the last surviving municipal lighting towers anywhere, because if you're lighting up a city to keep people safe at night, why have thousands of small lamps down every street when you could have just a few, very bright and very high? - Each tower was intended to provide light equal to that of natural moonlight in an area 1500 feet from the base of the tower, and that is light by which somebody could read the face of their watch. These lighting systems were all throughout the Midwest and all throughout the west. - When these towers were installed in 1894, they used carbon arc lamps, the first practical electric lights. Those lamps were literally controlled electrical arcing, a constant spark shooting through the air between two carbon electrodes. These days, if you're seeing that kind of harsh white light at this scale, it's usually because there's a fault with something big and electrical and there's a short in the system. This was the same effect, just deliberate. The catch is that the electrodes on carbon arc lamps are steadily vaporized, wearing down as they're worn away by the spark, so they burn out quickly. And the city had to pay someone to climb every tower every day to replace the lamps. - The City of Austin Electric Utility, and as we know it today, Austin Energy, started with the moonlight towers. Every night, a utility employee would go up through this elevator pulley system through the middle of the tower and go light these carbon arc lamps. This pulley system, there's this little thing for the employee to stand in, and then you have workers on the ground who are hoisting him up. You're going up potentially 165 feet in the air. I don't know when hard hats came into play, but when you look at older pictures, our safety equipment is not as it is today. So then in the 1920s, they switched to incandescent bulbs, and in 1936 it was the mercury vapor lamps, and today we're using LED bulbs, and it's a little bit easier to get up there and exchange the parts. So we're using cranes and bucket trucks to get up to make those changes. - If ever there was a subject designed for vertical video, it's this one. Most cities took their towers down as electric street lighting became possible. For some unknown reason, Austin never got round to it, but they've not all been preserved. There's only about a dozen towers still standing. Not all of those are in the same locations they used to be. And in 1993, the city took them all apart, refurbished them, and put them back up again. As for what they look like when they're switched on, well, for that, we'll need to wait until after sunset. - Austin is the only city in the United States that still has functioning moon towers. Before the moonlight towers were put up around town, it was dark! The moon could only do so much. And so it really changed people's lives. I think it allowed them to keep businesses open after dark, which would increase commerce. People could enjoy themselves with friends and family, and also get home safely. Moonlight towers were the only game in town for light after dark, you know, in parallel with the moon itself, of course. - And these towers clearly work because, well, look at me, I've got a shadow, although admittedly I am standing right next to it. The name moonlight towers isn't just poetic. 31 of these towers were spread around what was then a much smaller and lower city before skyscrapers came along. That meant that except for some dark corners, most of the town would be lit up as if there was a full or maybe a half moon. Not that bright, but enough that you could see your way around. Hence moonlight tower. It's artificial moonlight. Although, turns out there's not much evidence for that name being used until the mid-20th century when historical preservation became fashionable and these towers became an icon of Austin. - They were not called moonlight towers from the beginning. The Austin newspapers just called these "the towers". There were no other towers. First reference that I found in a newspaper to these being called moonlight towers, it was 1938. In the early 1960s, the masthead of the Austin newspaper had the phrase, "As Austin As". The phrase changed each day, where the newspaper was comparing itself to other icons in the city of Austin. And in July, 1962, the masthead said, "As Austin as Moonlight Towers". They have become a symbol of Austin. - And every holiday season, one of those moonlight towers in Zilker Park gets used to put up hundreds and hundreds of bulbs of lights that look like a holiday tree. And you go and you spin around and you look up and you get dizzy, and you feel like Austin is just the best place to be. - There are modern versions of these towers for places like giant parking lots. Sometimes it is just better to stick a big light on a pole. In most cases, though, modern lighting is a much better choice, because every street got wired up to the grid anyway. Although that does mean in the 21st century, it's difficult to imagine what a city lit just by moonlight towers would feel like. These days there's too much other light around from every house, every building. On a night with low cloud, the skyglow from light pollution can be brighter than the old towers would be. At least, brighter than they would be at a distance. These aren't street lighting anymore. They're historic artifacts, kept running because, well, because the people of Austin like them.