Ennis - I'm curious about the the Myrtle Avenue Subway in Brooklyn photo. Do you have any more details about this? Never seen that photo before
Sure, that's the intersection of Myrtle Avenue and Dennis Street in what was formerly known as the neighborhood of Campbell Hill. It was built to allow streetcars, pedestrians, cyclist, carriage operators, early automobiles, etc. to travel without being blocked by heavy rail traffic at the old passenger railroad terminal (now the Prime Osborn Convention Center). Here's a 2009 article about it:
https://www.metrojacksonville.com/article/2009-mar-the-myrtle-avenue-subway
1928 - Before
(https://photos.metrojacksonville.com/photos/3497367970_DnrpWcv-L.jpg)
After
(https://photos.smugmug.com/History/Myrtle-Avenue-Subway/i-zBZFKsF/2/a8d35a93/L/IMG_0173-L.jpg)
(https://photos.smugmug.com/History/Myrtle-Avenue-Subway/i-BdWfsXz/1/b75605d8/L/IMG_0175-L.jpg)
Urban Jacksonville in 1928(https://photos.moderncities.com/History/City-Plan-of-Jacksonville-1929/i-8dgh229/0/1e272986/L/1928-JACKSONVILLE-L.jpg)
QuoteRarely seen imagery taken between 1928 and 1929, of Jacksonville's neighborhoods by George W. Simons Jr.
Full article: https://www.thejaxsonmag.com/article/urban-jacksonville-in-1928/
Ah ok, that was what I thought it was. The photo taken in 1928 looks like there is actually a tunnel before the overpass but it looks like the drop in the road.
There was a difference in grade between the streetcar line and the road. That was likely due to providing necessary height clearances for the streetcars.