The illustration looks lovely, however, the realisation would probably have been more like Docklands Light Railway, which is elevated but not following the existing streets as per the illustration. There is a certain amount of wasteland that goes in the immediate vicinity of the DLR, which is a 'light' railway with the electric propulsion that was what they were looking for with the pneumatic system.
Elevated railways like monorails aren't more widespread because of the added expense around elevated track and especially elevated stations. Somehow, you've got to get folks up and down from there. I'm glad because they are pretty unsightly.
An atmospheric railway would not be silent. Steel wheels on steel rails make a lot of noise, especially before the development of continuous welded rail, and also when without the dampening effect of being on the ground.
Here's an amusing podcast (with slides) about the atmospheric railway and why it didn't work. I recommend watching at 1.5x speed.<p><a href="https://www.youtube.com/watch?v=JaRVy31lTlQ" rel="nofollow">https://www.youtube.com/watch?v=JaRVy31lTlQ</a>
There's a good radio programme about Brunel's Atmospheric Railway (and Musk's Hyperloop): <a href="https://www.bbc.co.uk/programmes/m00027mg" rel="nofollow">https://www.bbc.co.uk/programmes/m00027mg</a>
That looks exactly like Seattle monorail.<p><a href="https://www.seattlemonorail.com/events-and-news/this-week-at-seattle-center/" rel="nofollow">https://www.seattlemonorail.com/events-and-news/this-week-at...</a>